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April 26

Stingray question

Do stingrays make a sound. I have looked extensively and have not found anything about stingrays making noises of any kind. thank you for considering this question. :)174.97.235.163 (talk) 00:45, 26 April 2010 (UTC)pat

Somehow I doubt it, as most fish don't (at least nothing we can hear). StuRat (talk) 00:51, 26 April 2010 (UTC)

Did you have something in mind, particular to a stingray? I used to have an electric catfish as a pet and it made lots of noise at night while electrocuting the minnows. Perhaps a stingray makes a sound (in the most general sense of 'making a sound') when it thrashes it's stinger into predator/prey...I mean, more so than a goldfish, let's say. DRosenbach ^{(Talk | Contribs)} 01:27, 26 April 2010 (UTC)

In this youtube video you can hear a clicking noise and you see a stingray: Octopus Attack - Fuertaventura 2009. Cacycle (talk) 06:53, 26 April 2010 (UTC)

Of course every type of fish makes sound as a result of water sliding over its body. When it comes to other types of sound, I wasn't able to find any reports in a quick Google Scholar search. There are apparently certain types of fish that "vocalize" by vibrating their swim bladders, but elasmobranches (sharks and rays) don't seem to be among them as far as I can tell. Looie496 (talk) 17:10, 26 April 2010 (UTC)

is there an exit valve? what about on the scuba fireman where? and on oxygen tanks in a ambulance or hospital?

Firemens SCBA apparatus.

where does the exhaled air go —Preceding unsigned comment added by Tom12350 (talk • contribs) 01:36, 26 April 2010

This question was answered above. Look for the section about 2-3 days ago labeled "scuba". --Jayron32 02:40, 26 April 2010 (UTC)

no they answered about scuba not scuba fireman where and on oxygen tanks in a ambulance —Preceding unsigned comment added by Tom12350 (talk • contribs) 05:21, 26 April 2010 (UTC)

In a hospital or ambulance oxygen is normally given in two ways. In an emergency where a patient has collapsed and respiration is administered with a mask and pump bag the pump bag apparatus has an exit valve. When oxygen is given over a longer period with a light mask or little tubes at the entrance to the nose then the excess oxygen just dissipates into the atmosphere as there is no closed circuit to contain it. I suspect that the equipment used by firemen is similar in design principle to an underwater scuba, a closed circuit with a one-way exhaust valve. Richard Avery (talk) 07:21, 26 April 2010 (UTC)

On the side of the mask. See if this article helps: Firemens SCBA apparatus and and Oxygen maskAnd see diagram on the right --Aspro (talk) 07:23, 26 April 2010 (UTC)

And again, to be pedantic - the firemans' apparatus is an "SCBA" because the 'U' in "SCUBA" stands for "Underwater". SteveBaker (talk) 12:17, 26 April 2010 (UTC)

you say "light mask or little tubes at the entrance to the nose then the excess oxygen just dissipates into the atmosphere as there is no closed circuit to contain it."

but hows that because isint the mask tight? like is this pic  ?

http://thumbs.dreamstime.com/thumb_54/1145221626xhnGC8.jpg

or this

http://fransonchiropractic.files.wordpress.com/2009/04/oxygen20mask.jpg

or this

http://www.watersafety.com/rescue-and-response-equipment/images/4225023.jpg —Preceding unsigned comment added by Tom12350 (talk • contribs) 22:07, 26 April 2010 (UTC)

milk

can buffered solutions like milk be used to naturalize acids or will it not work cause its buffered. —Preceding unsigned comment added by Tom12350 (talk • contribs) 01:55, 26 April 2010 (UTC)

So long as you don't exceed the buffer capacity of the milk, yes, it can be used to neutralize acid. The property of a buffer is that it works to neutralize BOTH acid and base (more properly, a buffer is something that maintains a constant pH with the addition of either acids or bases). See buffer for more info. --Jayron32 02:39, 26 April 2010 (UTC)

what is the "the buffer capacity of the milk" —Preceding unsigned comment added by Tom12350 (talk • contribs) 05:20, 26 April 2010 (UTC)

Please start signing your posts by using four tildes like this: ~~~~. Please read the Buffer solution article for more info. A buffer is basically an acid and its conjugate base. That is, it consists of a pair of compounds that differ by a hydrogen ion, for example a solution that contained both acetic acid, HC₂H₃O₂, and the acetate anion, C₂H₃O₂^1- would be a buffer. It works because, by adding either acid or base, the conjugate acid/base pair works by reacting with either an added acid OR an added base, and so neutralizes either. Also, because the system is a dynamic equilibrium, the system obeys Le Chatelier's principle such that it resists all changes to return to its initial state. The buffer capacity merely means that the buffer only exists so long as both parts of the conjugate acid/base pair exist in the solution. If you add so much acid that you use up the base part of the buffer, then you no longer have a buffer, and you have exceeded the buffer capacity. --Jayron32 05:27, 26 April 2010 (UTC)

Additionally, you should probably also read up on Brønsted–Lowry acid-base theory which is the basis for understanding how buffers work. --Jayron32 05:30, 26 April 2010 (UTC)

i already read those. what is the "the buffer capacity of the milk" —Preceding unsigned comment added by Tom12350 (talk • contribs) 06:35, 26 April 2010 (UTC)

I just explained that. A buffer consists of an acid and its conjugate base mixed together in water. If you add too much additional acid, you will consume all of the base, and thus destroy the buffer. --Jayron32 12:02, 26 April 2010 (UTC)

I'm not sure but perhaps the OP wants to know what the buffer capacity of milk actually is, not what it means. Having said that I wonder whether the OP actually properly understands buffer capacity or thinks it's a simple value that tells you precisely how 'powerful' a buffer is. In any case, the buffer capacity would vary depending on the type of milk I presume. Edit: These should provide a basic overview on what the buffer capacity of milk actually is [1] [2] [3]. Also [4] if you can find it. Nil Einne (talk) 12:32, 26 April 2010 (UTC)

With a complex solution like milk, it would be quite impossible to calculate directly. You could certainly do an experiment to find the value for yourself. You would need to titrate the milk dropwise with a strong acid, and track the effect of the added acid on the milk's pH. Then you would need to do the same experiment, but with fresh milk and a strong base. The resulting graphs should tell you roughly how much acid or base you can add before exceeding the buffering capacity of the milk. (after edit conflict) It looks like Nil Einne found the results of some of those experiments above. --Jayron32 12:46, 26 April 2010 (UTC)

Yes [5] is probably the most useful but needs a subscription. I have a tendency to reply and then search so often add my results after. I guess I should stop WP:AGF that the OP actually did a simple search before asking the question :-P Nil Einne (talk) 13:18, 26 April 2010 (UTC)

i dont need a exact value just a estimate. anyone know? —Preceding unsigned comment added by Tom12350 (talk • contribs) 21:56, 26 April 2010 (UTC)

From the article that requires a subscription: At pH7, the buffering capacity (dB/dpH) looks like it's around 0.02. It changes a lot depending on pH - eg. at pH 6 it's closer to 0.03. Aaadddaaammm (talk) 13:43, 27 April 2010 (UTC)

hats that mean? how strong a acid can it be used on —Preceding unsigned comment added by Tom12350 (talk • contribs) 21:15, 27 April 2010 (UTC)

"Used on" to do what? Maybe if you rephrase the original question, with more specifics about what you're actually trying to do we could help more. Aaadddaaammm (talk) 10:36, 28 April 2010 (UTC)

Source of pneumonia in bedridden elderly?

From what sources do the elderly often contract pneumonia? I'm thinking of bedridden individuals in nursing homes who are not likely to be able to spread it to other individuals in similar conditions, and who (because they're in the nursing home, not in hospital) by definition can't get hospital-acquired pneumonia. I don't see anything in our article that discusses the question, since it seems unlikely to me that the large number of elderly people who die from it are all infected with fungi, parasites, pneumonia-causing bacteria, or pneumonia-causing viruses when those around them don't have any of these problems. Nyttend (talk) 02:29, 26 April 2010 (UTC)

I think part of the problem is a lack of ability to clear the lungs while bedridden. Thus, any standard cold or flu can cause fluid accumulation in the lungs, which can suffocate the bedridden person. I am pretty sure that is the impression I get from the issue. I could be wrong though. --Jayron32 03:50, 26 April 2010 (UTC)

Also see the short article Aspiration pneumonia, which describes any non-infectious pneumonia caused by the inhalation of material, including one's own saliva and mucus. My guess is that this could explain many of these elderly, bedridden pneumonia cases. There's also Idiopathic interstitial pneumonia, "Idiopathic" being doctor speak for "We haven't the faintest clue what is causing this". --Jayron32 05:37, 26 April 2010 (UTC)

Hubble's "visible spectrum" image of the Carina nebula

I'm wondering what the moon, or the earth would look like if an image were compiled in the same way that the Carina nebula was. (wavelengths detailed here). Is it relatively simple to attempt this? 219.102.220.42 (talk) 02:30, 26 April 2010 (UTC)

If you could obtain the raw images taken at those wavelengths which record those spectral colours then yes. One could easily do the next stage of combining and balancing them in to one image. This image manipulation could be done with GIMP (which I have noticed the Jet Propulsion Laboratories in Pasadena have used) or Photoshop, etc. This web page explains in plain language, the technical bits about what needs to be recorded .Cameras and H-a Emission Nebulas. And what would Earth and the Moon look like? Well I sure: if people were able to mentally work that out, there would be no point using these imaging technique in the first place. However, the United States Geological Survey Spectroscopy Lab has some images of Earth. And the Jet Pro Lab has some images of the moon. [6] As always, Wikipedia has some articles:Imaging spectroscopy, Moon Mineralogy Mapper.--Aspro (talk) 08:00, 26 April 2010 (UTC)

Which elements do you want to use to make your images of the moon/earth? The picture basically shows areas where one element or another are more concentrated. If you use elements in the earths atmosphere, you'll have a white circle and nothing more, since those are basically perfectly mixed. If you choose elements on the ground, you'll see colors showing you where the elements you chose are more/less concentrated. Ariel. (talk) 08:05, 26 April 2010 (UTC)

Those nebula are emission nebulas wich emit light at particular wavelengths in a line spectrum. The earth and moon reflect are much more continuous spectrum, and so are not so easy to establish elemental composition by transition lines. In visible light what you see will be a good clue, eg yellow iron oxide, green chlorophyll. Graeme Bartlett (talk) 09:10, 26 April 2010 (UTC)

Dibenzodiazepines follow-up

I notice all the compounds listed in Category:Dibenzodiazepines are antiaromatic. So it must not be a coincidence. I guess the antiaromaticity destabilisation must not be very large? I'm curious about the relationship between conformation and agonism / antagonism of the target receptors. AFAIK lysergic acid compounds are planar ... right? Or are they? I notice some resonance structures are antiaromatic in LSD too. John Riemann Soong (talk) 03:24, 26 April 2010 (UTC)

What counts most for receptor binding are shape and charge. Antiaromaticity per se does not have a direct effect on binding (whereas aromatic rings allow for specific interactions such as pi stacking). Cacycle (talk) 06:49, 26 April 2010 (UTC)

Regarding LSD, the indole part is definitely aromatic. If you're considering "all the resonance possibilities" (treating them as distinct structures that contribute to the overall "real" average structure), you can mostly disregard antiaromatic ones if there are others that are aromatic. If you have an alkene or lone-pair or something that "maybe could resonate into a ring, but that would make antiaromaticity", that piece of the structure probably does not do that, and thus acts like an independent functional group. DMacks (talk) 08:47, 26 April 2010 (UTC)

Thanks... I was wondering because it doesn't appear to be a factor in LSD, whereas I can envision resonance structures in clozapine that would make it aromatic, not antiaromatic, e.g. by simply drawing benzene a different way. You know what I mean? John Riemann Soong (talk) 20:11, 26 April 2010 (UTC)

If you're interested in stereoelectronics in medicinal chemistry, you might like to get a good book on the topic, like this one, or search the literature. I did a quick Google search for "stereoelectronic QSAR" and found several interesting-looking articles, including Dynamic QSAR: A New Search for Active Conformations and Significant Stereoelectronic Indices.

Further Wikipedia articles of interest:

• Electronic effect
• Pharmacophore
• Quantitative structure-activity relationships

Books you could borrow from a library:

• A. J. Kirby (1996) Stereoelectronic Effects (Oxford Chemistry Primers)

Ben (talk) 19:16, 26 April 2010 (UTC)

Life expectancy of nuclear power plants.

What is the average life expectancy of a nuclear generating station? How do plants built in the US differ from ones overseas in terms of longevity? ataricom (talk) 05:00, 26 April 2010 (UTC)

According to Nuclear power#Economics, a reactor can last as long as 40-60 years. Dismas|^(talk) 07:27, 26 April 2010 (UTC)

Not if they are destroyed by sea level rise. ~AH1^(TCU) 23:14, 28 April 2010 (UTC)

So don't build them so close to water. BTW, isn't one of the reasons for building nuclear reactors the fact that they can generate electricity without polluting the atmosphere (barring an extremely unlikely Chernobyl-style catastrophic nuclear meltdown, of course)? 76.103.104.108 (talk) 02:08, 29 April 2010 (UTC)

Ant for ID

ID and extermination advice?

Hello! I must catch 10 of this type of ant everyday in my house. Is this a fire ant or a carpenter ant? What is the best way of getting rid of them, sort of calling an exterminator as a last resort? Could they be living outside my house in nests or in my house's foundation? I've found winged ants in my house, as well, which, as I understand, are the ones who help reproduce. Is that a bad sign? Any advice appreciated. Thanks.--el Aprel (^facta-_facienda) 08:17, 26 April 2010 (UTC)

If this was Australia I would say you had a sugar ant. Fill up all the holes they may come in through. You can spray poison around, but may poison you and may not last either. Graeme Bartlett (talk) 09:04, 26 April 2010 (UTC)

I'm not sure, but it does look like Camponotus sayi, red carpenter ant, to me. Red link for the red ant - isn't it ironic? Not really a harmful critter, there are much worse than it; but it can build nests (colonies) in wooden structures which is not something homeowners generally like. This article gives suggestions on how to deal with them, if that ant is really what I think it is. As I said, I am not sure. --Dr Dima (talk) 10:07, 26 April 2010 (UTC)

There are some more photos of Sayi on Wiki Commons [7]--Aspro (talk) 12:50, 26 April 2010 (UTC)

Thanks! Forgot to mention I live in Florida. Are Camponotus sayi ants common here?--el Aprel (^facta-_facienda) 19:30, 26 April 2010 (UTC)

No. Unless of course, their there on vacation. 'Florida' has however, narrowed it down a bit. Here's our next suggestion. Go to | Florida Ants. On the right hand column, under the heading 'Tools” is a link entitled - Florida ants in Google Earth. This link then gives you a map of which ants occur in which localities. I don't know how accurate it is but it looks impressive. In the mean time, see if they like water with some sugar added, because then use could try using borax.--Aspro (talk) 20:43, 26 April 2010 (UTC)

Did you mean to type "THEY'RE there on vacation"? Cuddlyable3 (talk) 23:45, 26 April 2010 (UTC)

• Mix a little jam with borax and smear it inside saucers, jar lids or the like, and leave them near where you find the ants. Replace daily. The ants come and eat the jam, and the borax poisons them. You get borax from places which sell old-fashioned cleaning materials (it's jolly useful stuff). DuncanHill (talk) 22:02, 26 April 2010 (UTC)

You could also get borax (sodium tetraborate decahydrate) at the grocery store. It is normally sold there for laundry freshening and a host of other uses. Are you sure you aren't talking about boric acid though? --Cheminterest (talk) 22:16, 26 April 2010 (UTC)

Not many grocers here sell borax anymore. I get mine at Boots the Chemists, and some old-fashioned hardware shops have it. Yes, I'm sure I mean borax. DuncanHill (talk) 22:32, 26 April 2010 (UTC)

I had a look at the "Florida ants" website, and think this is a Camponotus decipiens ant. I will try the borax solution. I remember treating another ant species, fire ants, with a powder poison that tricked worker ants to take back to their queen as food and exterminate the colony by killing the queen. Is there any poison like this for these carpenter ants? My guess is the borax solution only kills the ants that forage for it.--el Aprel (^facta-_facienda) 22:53, 26 April 2010 (UTC)

I think the powders of which you speak will contain borax or boracic acid. I've used the sweet borax mixture before, and after a few days what had been a steady stream of ants had reduced dramatically. DuncanHill (talk) 23:15, 26 April 2010 (UTC)

You will know if you have made the solution too strong because you will see dead ants. You want them to live long enough to get back and feed the others. The advantage of using borax has been already mention – its useful for so many other things and easier to buy.--Aspro (talk) 23:30, 26 April 2010 (UTC)

It you really want to see dead ants, you can leave out watermelon slices soaked in turpentine. They are highly attracted to the sugar, but the turpentine dissolves their exoskeleton. In the morning, you end up with a lot of black smudges, which clearly identifies the path they were using to get back and forth between the watermelon and their nest. -- kainaw™ 00:41, 28 April 2010 (UTC)

Be careful with the turpentine and watermelon. Make sure no young child tries to eat it. --Chemicalinterest (talk) 11:50, 30 April 2010 (UTC)

I live in the United States, and I can buy borax at Pathmark or Shoprite easily in the laundry section. --Chemicalinterest (talk) 11:50, 30 April 2010 (UTC)

You can buy some ant traps (some say "kills the queen") at certain stores. --Chemicalinterest (talk) 11:50, 30 April 2010 (UTC)

Mold

Is mold killed by pouring boiling water on it? 87.108.22.140 (talk) 09:02, 26 April 2010 (UTC)

Yes if you can heat it to close to 100 degrees. Eucaryotes are not good at surviving high temperatures. You may be left with a stain however. Graeme Bartlett (talk) 09:06, 26 April 2010 (UTC)

Thank you! I knew I could rely on Wikipedia! 87.108.22.140 (talk) 09:10, 26 April 2010 (UTC)

Also remember that mold is not just the blue stuff on the surface, but has hyphae in the material ti is decaying, you have to heat that too. And also mold may make poison in food, so don't just rely on boiling to make it fit for eating (if it is food). Graeme Bartlett (talk) 10:31, 26 April 2010 (UTC)

100 degrees C, right? Also, for what it's worth Aflatoxin is the stuff you still have to worry about even after the mold is dead. --144.191.148.3 (talk) 18:35, 26 April 2010 (UTC)

Yeah 100° F will just make it wet. Graeme Bartlett (talk) 21:44, 26 April 2010 (UTC)

Using a solution of sodium hypochlorite will kill mold too, and turn whatever it is poured on white. --Cheminterest (talk) 22:13, 26 April 2010 (UTC)

CCs?

Are CCs listed on Wikipedia?

eg, 10cc ( or 10ccs )

- 193.61.111.53 (talk) 11:15, 26 April 2010 (UTC)

Try HERE. Dolphin (t) 11:31, 26 April 2010 (UTC)

Unless you mean the music group, 10cc. AlmostReadytoFly (talk) 11:52, 26 April 2010 (UTC)

Also, see our orders of magnitude series entry for examples of things of a given volume: 1 E-5 m³. Paul (Stansifer) 12:17, 26 April 2010 (UTC)

Should I point out that this is probably a student of Loughborough College you're trying to get sense out of!--Aspro (talk) 12:21, 26 April 2010 (UTC)

And what's wrong with Loughborough? I'm from Loughborough, although I never went to college there. FiggyBee (talk) 00:50, 28 April 2010 (UTC)

I'm not referring to the good citizens of your fair town -nor you. Rather, I was err... well... view their talk page and you might get my drift. Now don't you think they could have formulated the question better if they were serious? --Aspro (talk) 19:34, 28 April 2010 (UTC)

Just to be explicit about it, when doctors on television say things like "10 ccs of adrenaline, stat!", the "cc" are an abbreviation for cubic centimeter, which happens to be the same volume as a milliliter. Other senses of the abbreviation can be found, not surprisingly, on the page cc. -- 174.24.208.192 (talk) 15:32, 26 April 2010 (UTC)

"Worst case of ice-cream induced brain freeze I've ever seen, administer 10 cc's of hot fudge, stat !" - Simpsons Ice Cream Social. StuRat (talk) 16:26, 26 April 2010 (UTC)

Another abbreviation for cc is cm³.--Cheminterest (talk) 22:14, 26 April 2010 (UTC)

Kepler mission field of view

Is it true that field monitored by NASA Kepler telescope roughly 24 times bigger then Moon angular diameter (as visible from Earth surface)? 70.52.182.184 (talk) 14:01, 26 April 2010 (UTC)

According to our article section Kepler_Mission#Mission_details its field of view is about 12 degrees. As the moons diameter is about half of one degree that seem to be about right.--Aspro (talk) 14:08, 26 April 2010 (UTC)

(EC) Kepler's field of view is approximately 10 degrees square. The moon subtends an angle of approximately 0.54°. So about 20x or so, yes. --Tagishsimon (talk) 14:10, 26 April 2010 (UTC)

Chromoscope pictures of the galaxy

on the site.. http://www.chromoscope.net/ when we observe the X-ray picture of our galaxy, we can see sumthing like the picture has been struck by a tiger paw or sumthing like that, like torn up in between, where none of the other images show such a thing. what makes it so? Prady —Preceding unsigned comment added by 116.73.242.109 (talk) 15:04, 26 April 2010 (UTC)

It looks like missing data. Dauto (talk) 15:39, 26 April 2010 (UTC)

Yes, it's missing data. This is more of a problem with X-ray telescopes because of their much narrower field of view. Other space telescopes do record the same thing, but over time they record the missing bits with a second or third pass. Why this happens can be understood if one just considers the sinusoidal curved black streak. This was the part of the celestial sphere hidden from the telescope by the sun. If you look at this website you will see an animate representation of the the celestial sphere. [8] Refer to the section: The tilt of the Earth's spin axis with respect to the ecliptic plane results in the Sun tracking out an seemingly sinusoidal path on the celestial sphere when viewed in the projection with the celestial equator horizontal. So, in short, the streaks and other black pixels are due to the fact that it is an incomplete scan of the of the celestial sphere.--Aspro (talk) 17:25, 26 April 2010 (UTC)

Who turns the machine off from a terminally ill patient?

If a decision was taken to turn the machines off, so that a terminally ill patient will die, who does physically push the button (or pulls the cable or whatever)?--Mr.K. (talk) 15:59, 26 April 2010 (UTC)

I'm guessing a nurse would do that. Dauto (talk) 16:00, 26 April 2010 (UTC)

That might make them legally liable, if it's later decided that proper authorization was lacking. For this reason, they may have the family member who requested that they "pull the plug" be the one who actually does it. StuRat (talk) 16:20, 26 April 2010 (UTC)

Do you have a reference for that? Matt Deres (talk) 16:56, 26 April 2010 (UTC)

(ec) Hmm. Do you have a source for that statement? It strikes me as very dubious. Looie496 (talk) 16:58, 26 April 2010 (UTC)

In general, a hospital's legal department would already have reviewed any request to "pull the plug" and certify that the requester has the proper authority and complies with any existing advance directives, etc. Once the lawyers sign off, I'd assume that the nurse is pretty well covered. Dragons flight (talk) 17:07, 26 April 2010 (UTC)

I do also believe that you if it is legally allowed (and it is), there must be a way of doing it without being sued for it. However, I am still not sure that a nurse will do it. Isn't it a huge psychological burden on a nurse, if she has to constantly kill people?Mr.K. (talk) 17:15, 26 April 2010 (UTC)

There are many psychological burdens in nursing. Compared to telling parents that their child has just died, removing a feeding tube from an unconscious person who is shortly going to die anyway is not that high on the list. Looie496 (talk) 17:38, 26 April 2010 (UTC)

I wouldn't say telling parents their toddler went to heaven is a heavier burden than actually killing someone. In the former case you can just use a euphemism and comfort yourself with the thought that it was unavoidable. In the latter case, Jesus, how can you don't think about what you are doing? Mr.K. (talk) 17:51, 26 April 2010 (UTC)

a) It is not up to the nurse/physician to tell parents their child "went to heaven". b) Turning off life support is distinctly different than "killing" someone. c) Don't assume for an instant that the doctors and nurses involved in the care of a terminally ill person do not think deeply about what is happening on a daily basis. Let's keep this discussion about facts and not emotionally charged rhetoric. --- Medical geneticist (talk) 22:59, 26 April 2010 (UTC)

I'm pretty sure you're all looking too much into this. The decision to pull the plug isn't made by the nurse, so they isn't responsible for the death even they did pull the plug physically. In the UK I think you need to have two consultant doctors who permit for life support to be switched off with the next of kin's consent, whereupon the nurse would switch it off. There is no real reason to feel guilt as I'm fairly confident the nurses will be of the same opinion as the doctors--that the person is dead anyway, merely being kept alive on machine. Regards, --—Cyclonenim | Chat  18:02, 26 April 2010 (UTC)

Besides which, there's always the possibility that the patient will stay alive even after the life support is removed... --TammyMoet (talk) 18:35, 26 April 2010 (UTC)

Not really. They go through thorough tests to make sure the person is really dead (which actually include disconnecting the machines for a while to see if the patient tries to breath on their own). While it is always possible that they have a mistake, the probability is negligible. --Tango (talk) 21:24, 26 April 2010 (UTC)

This is a reference desk. Please provide references when you give answers, instead of guessing. Here (page 4) is an article in which someone present at such an event wrote that a doctor and nurse were present, and the nurse switched off the breathing machine. Comet Tuttle (talk) 20:04, 26 April 2010 (UTC)

I second that. The first two answers were "I'm guessing" and sheer speculation. The original poster should look at the list of items under life support. Cessation of medical therapies (inotropes, total parenteral nutrition, dialysis etc.) are ordered by the physician. Feeding tubes and central IVs can be removed by nurses or doctors. Withdrawal of mechanical ventilation is performed by a respiratory therapist. Any of these steps would be discussed in detail with the next of kin or medical power of attorney. Hospital legal or ethical consultation would only be needed if there were a conflict between the medical team and the patient's family. --- Medical geneticist (talk) 23:11, 26 April 2010 (UTC)

According to this source (very small area is visible), the physician may also be the one to flip the switch. The book cited, Sourcebook on death and dying by James A. Fruehling seems like it would also be a good source regarding the possibility of a physician being criminally prosecuted in such an instance, though you'd need to purchase the book to find out for sure. Matt Deres (talk) 22:39, 26 April 2010 (UTC)

According to my wife (who used to be an operating department Nurse many years ago), any of the medical team might actually "flip the switch". The decision is the doctors' - but whoever happens to be standing next to the machine at the time might physically throw the switch - which could be the doctor, a consultant, a nurse, an OR tech or the anesthesiologist. It would be unlikely to be a relative or friend of the patient. She says it's like a prescription - the doctor takes the decision and is responsible - everyone else is just doing what they are told...following instructions...nothing more...it's just like administering any other treatment. Of course the actual making of the decision is an exceedingly complicated and legally 'careful' process involving lots of people. SteveBaker (talk) 02:47, 27 April 2010 (UTC)

No medical person would ever ever ever ask a relative to unplug a respirator. Horrible and cruel idea. Doctors or nurses do it when they are convinced that doing so is not killing the person since they are already dead. Often if any of the care team seem squeamish about it but do not actually oppose doing to, a more senior person will take the responsibility for flipping a switch. It isnt a daily event even in a busy ICU and it is treated seriously by those involved. And all institutions have careful brain death protocols with multiple tests and independent consultations. Been there done that. alteripse (talk) 04:00, 27 April 2010 (UTC)

I can corroborate Alteripse's account. (I am a physician as well.) From the perspective of medical ethics/philosophy, there is a clear distinction between doing something which actively harms the patient versus removing care that was keeping the patient alive. The decision to withdraw elements of care is a complex one, one which is not undertaken lightly. It's made as a result of discussion between the physician, the patient and/or family, and other staff members. Note that the original question referred to a patient who is still alive but dependent on life support. In many cases, the patient himself may be able to direct that care be withdrawn, or have specified an advanced directive. In lieu of that, family members are consulted to determine the patient's wishes. After careful consideration, the physician will write the order, and typically the nurse will carry it out. The family member would not be the one to do so. While the death of a patient is always a difficult and sobering event, the actual act is not considered "killing the patient" (as opposed to, say, euthanasia [administering medication to hasten death]). The hospital's legal department is normally not involved in a case-by-case basis. It is true that there is in general, a psychological burden in working with people who are very ill and who die, and it is something that physicians, nurses, and other team members face on a daily basis. — Knowledge Seeker দ 22:08, 29 April 2010 (UTC)

Reactivity of Na or Ca

Is sodium or calcium more reactive? --Cheminterest (talk) 22:12, 26 April 2010 (UTC)

The elementary answer is at Reactivity series and boils down to "sodium". No doubt others will explain why my GCSE Double Science (which was the last time I heard of that) is inadequate and the question is really rather complicated. 128.232.241.211 (talk) 23:04, 26 April 2010 (UTC)

Yes, sodium is more reactive because it has only one electron in its outer shell, whereas calcium has two. Since sodium only has one, it is much easier to get rid of, making it more reactive. --The High Fin Sperm Whale 00:04, 27 April 2010 (UTC)

That's not actually a good explanation. Having more electrons in your shell increases electron shielding, causes things like spin pairing, etc. which actually makes electrons easier to get rid of -- assuming ENC is constant. The reason why sodium is more reactive than calcium is that calcium has an effective nuclear charge of about 2 while sodium only has an ENC value of around 1. John Riemann Soong (talk) 05:06, 27 April 2010 (UTC)

Both calcium and sodium metal are strong reducing agents: reactive enough to react with water. But compare the reactions: sodium vs. calcium. Buddy431 (talk) 00:41, 27 April 2010 (UTC)

Look at the Table of Standard Electrode Potentials; calcium is higher than sodium. --Chemicalinterest (talk) 20:10, 29 April 2010 (UTC)

Protein

1) What happens when someone does strength training and doesn't eat much protein afterward? How do the muscles repair themselves? Thanks. --Mudupie (talk) 23:33, 26 April 2010 (UTC)

Difficult to answer absolutely. What do you mean by 'much protein'? Lack of any nutrient will very likely lengthen post exercise recovery time. But more is not necessarily better.
Note that in the early stages at least, strength can increase without increase in muscle mass, as the muscles are learning the new 'skill' of lifting weights.

In the 'west' we tend to eat far more protein than we need. If you have a good all round diet, you may not need any extra protein. Which I cannot judge. This website here has figures that seem consistent with current nutrition standards (Please don't pay too much attention to the ads for 'protein powders' etc!).

This one at (Massachusetts General Hospital) is aimed at adolescents, Weight lifting and training, from which I quote: (my bolding)

"Since adolescents in the United States already eat a diet high in protein, there is no need for most adolescents to take protein supplements during weight training. And scientific studies have not supported any enhancement of muscle growth or strength from protein intake greater than the recommended amounts." para. 7, © 2010 Massachusetts General Hospital

• Recommended 'normal protein' RDA (Recommended Dietary Allowance) is 0.8 grams per kilogram of lean bodyweight (1 kilogram=2.2 pounds).
• If you exercise you need more.(Pregnant women need even more than weight lifters!)
• For muscle building an intake of 1.6-2.2 grams per kilogram of bodyweight is recommended.
  • I think many of us exceed that intake, whether we exercise or not.(see quote above)
• Too much protein can be bad for you (or give no advantage).[9][10]
• As is too little. see Protein-energy malnutrition

See also Body building#Protein, Protein (nutrient), Outline of nutrition, Nutrition, Human Nutrition, Diet (nutrition),and any related articles. This ref Desk question from about 3 day ago may interest breakdown of muscles.

Feel free to ask more questions if I have not fully answered your query --220.101.28.25 (talk) 12:22, 27 April 2010 (UTC)

Addendum: Don't take what is here as 'gospel' truth. I suggest you read the references here, or in the articles I have referred you to yourself. Also, for personalised nutritional advice, consult a nutritionist or dietician. --220.101.28.25 (talk) 13:33, 27 April 2010 (UTC)

American scientists recently advised all but some professional athletes to stop taking protein supplements. They are not necessary. Imagine Reason (talk) 14:27, 27 April 2010 (UTC)

That is one of the the points I was trying to get across, though I was assuming 'normal' amateur training. If you have a link to the data you mention I'd like to read it. :-) --220.101.28.25 (talk) 14:35, 27 April 2010 (UTC)

Thanks! I have a lot of reading to do :) --Mudupie (talk) 17:44, 27 April 2010 (UTC)

Thank you for your thanks, Mudupie. You will find the subject can be rather contentius, as the bodybuilding.com website says at one point. It tends to be weight-lifter/bodybuilders on one vs scientific studies/researchers on the other. (Or perhaps purveyors of supplements vs nutritionists.) Views can be very divided. Educating yourself in this area is very wise, and can be very interesting! But again professional advice should be heeded, not someone with a possible conflict of interest trying to sell you a 'supplement'.! --220.101.28.25 (talk) 21:06, 27 April 2010 (UTC)

Soda Bottle Rocket

In science we are doing a project that involves us making rockets out of ordinary 2 liter soda bottle. We are allowed to modify the bottle in any way that we want. I could not find any information on how to find an ideal nozzle size for a given rocket. The wikipedia article on water rockets says that many people create a nozzle 9mm in diameter. I did not know if there was a means of calculating from chamber diameter, or more likely pressure (around one hundred psi in my case) what an ideal nozzle size would be. Additionally that 9mm nozzle is for a water rocket, and the means of propulsion for our rockets is compressed air. I was also wondering if anybody knew a way to connect two soda bottles, for added chamber volume, that could withstand 100 psi. If so, how should chamber diameter be proportioned to chamber length? —Preceding unsigned comment added by 71.112.13.57 (talk) 23:46, 26 April 2010 (UTC)

I think you need some water in there - it is the water being pushed out by the compressed air that propels the rocket. --Tango (talk) 23:53, 26 April 2010 (UTC)

We've got an article - water rocket, and if you google soda bottle rocket you should find lots of "how to" guides to help you. DuncanHill (talk) 23:56, 26 April 2010 (UTC)

100 psi is pushing it - these bottles are rated at 100psi and tested to 150psi when new...but this site says they may start to deform at 80psi when you have used bottle. So be really careful - stand well back - and FOR SURE don't be tempted to push it over 100psi! I strongly agree with DuncanHill - you need water as propellant if you want to make this thing really fly well. I don't see how using two bottles can help. You double the energy stored in the rocket - but you also double the weight (more than double it, probably because you've got to attach them together somehow. Real world rockets benefit from having multiple thrusters because they have payload other than the motors themselves...and even then, they used a staged approach where they drop the first stage motor before firing the second stage - so the second stage doesn't have to lift the weight of the first stage. Because you can't increase the volume - and you can't (evidently) change the propellant - so the trick is going to be to keep the weight down and to get the nozzle diameter right.

The scientific answer here lies in the "Tsiolkovsky rocket equation". It says that the 'delta-v' of the rocket depends on the log of (the mass of the fully fuelled rocket divided by the empty mass of the rocket) - multiplied by the exhaust velocity. Notice that the heavier the fully-fuelled rocket - and the lighter the empty rocket, the faster it will go. That's why you need some water in there...air at 100psi weighs very little indeed compared to a 2 liter soda bottle...so ln(m1/m2) is only a little bit bigger than zero. So you need a hell of a lot of exhaust velocity...so we're back to that nozzle again. Picking a decent nozzle is probably going to require some experimentation...there are equations, but they are touchy. The shape of the outlet matters in ways that are hard to figure out without supercomputers and such...so experimentation is the answer. SteveBaker (talk) 01:14, 27 April 2010 (UTC)

I second Steve Baker's "experimentation" suggestion. The trick is that you want to fill with enough water, and design the nozzle and air pressure charge, so that the air pressure equalizes at the exact instant that you run out of water. That way, you aren't carrying heavy, useless water around with you as inert mass. At the same time, if you put too little water in, and you have air pressure left over when all the water has already sprayed out, your rocket isn't making the most efficient conversion of potential energy (air pressure) into momentum. Swapping out nozzles is hard - so start with one rocket with a reasonable size nozzle; and vary your experimental parameters: quantity of water, and pressure of air added. Keep in mind that stored energy in this case is equal to pressure times volume - and the water isn't compressing. So, your total stored energy will decrease if you add more water (because you have less volume of air, so the P V product is smaller; but if you add water, your total momentum may increase because you have added mass. So, the question all boils down to: what is the optimum ratio of water to air to maximize the mass of water and its exit velocity, integrated over time? Try changing your parameters and experimenting and recording/graphing the data. When you have a lot of experiments, change the nozzle and see what changes. It's not likely that a mathematical treatment will actually be very useful here, because the messy parameterization details are so uncertain that even a computational solution would be prone to error. Nimur (talk) 14:24, 27 April 2010 (UTC)

April 27

Methanol poisoning

This might sound really dumb, but I thought ethanol was the only alcohol used in, well, alcoholic beverages. Since when is methanol used, or is not actually used at all and this incident rose from an accidental addition of methanol, instead of ethanol? Regards, --—Cyclonenim | Chat  00:30, 27 April 2010 (UTC)

The case you refer to appears to have involved the sale of adulterated Waragi. Methanol is not used, for exactly the reason that it tends to lead to illness and death. --Tagishsimon (talk) 00:37, 27 April 2010 (UTC)

Some people may substitute methanol for ethanol to increase alcohol content. Methanol causes blindness in lower doses (about 10 mL are needed), and death in higher doses. Ethanol is not as toxic. Most alcohols naturally contain a little methanol. --Cheminterest (talk) 20:58, 27 April 2010 (UTC)

Snowflake symmetry

Why do snowflakes form exactly the same on all sides? With billions of molecules between the edges, how does water freezing on one side affect the other side? Thanks in advance, --The High Fin Sperm Whale 01:55, 27 April 2010 (UTC)

Note that all crystals tend to be symmetrical, not just snowflakes. However, many do end up "deformed", too. StuRat (talk) 01:58, 27 April 2010 (UTC)

The edges in a snowflake do not affect one another. Rather the same thing is happening on both sides, so you get the same result on both sides. The shape is determined by things like humidity, wind, temperature, altitude, etc. And all of that is more or less equal on both sides. Ariel. (talk) 02:00, 27 April 2010 (UTC)

Then why don't you get a sphere instead of a crystal? --The High Fin Sperm Whale 02:05, 27 April 2010 (UTC)

You do, sometimes, but water is intrinsically a crystal, so if solidifies slowly enough it will naturally form a six-sided crystal. The exact shape of the crystal depends on temperature, humidity, etc. As the flake falls downwards through the weather, growing, sometimes conditions favor different shaped crystals, so you might wind up with a flake that is simple near the center, but complicated near its outer edge. but the entire flake is always in the same weather conditions, so usually, (but not always) all six sides will have formed the same way. APL (talk) 16:10, 27 April 2010 (UTC)

They are not perfectly symmetrical. There are usually lots of asymmetries (which our pattern-matching human brains tend to ignore because we perceive the similarities as greater). The physics of snowflake formation (and symmetry) is complicated and not fully understood. It is clearly some kind of fractal process, though, which produce lots of (approximately) self-similar objects in nature. --Mr.98 (talk) 02:42, 27 April 2010 (UTC)

You can see pictures of snowflakes at Snowflakes and Snow Crystals. -- Wavelength (talk) 02:49, 27 April 2010 (UTC)

According to our snowflake article, "The sixfold symmetry arises from the hexagonal crystal structure of ordinary ice, the branch formation is produced by unstable growth, with deposition occurring preferentially near the tips of branches." You start with a tiny hexagon, and new water molecules, in order to fit in, have to continue fitting in to the crystal, maintaining the hexagon shape. But this doesn't explain why one end of a snowflake is similar to the opposite end of that snowflake, but different from other snowflakes.

Scientific American has an more complete explanation: the snowflake grows slowly, and at the same speed in all directions. The ambient temperature controls how the crystal forms and changes frequently, but (because the snowflake is very small) is always almost precisely the same over all parts of the snowflake.

Snowflake#geometry covers what effects the various temperatures have. Presumably, snowflakes grown in a lab at a constant temperature would all look boring. The shape of a natural snowflake reflects the history of its formation. If two snowflakes stay near each other throughout their formation, they should have a family resemblance. Very cool! Thanks for making me look this up. Paul (Stansifer) 04:59, 27 April 2010 (UTC)

Here is another SciAm explanation (which also points out that it is not entirely symmetrical)... my understanding (from a talk I saw not too long ago) is that physicists hotly debate this particular question, that it is not totally understood yet in a way that everyone can agree upon. --Mr.98 (talk) 13:33, 27 April 2010 (UTC)

FWIW here's a bigger hexagonal mystery. Cuddlyable3 (talk) 13:04, 27 April 2010 (UTC)

Mechanics of motion sensors

According to Hollywood Sign, the famous sign is surrounded by motion sensors that call the police when triggered. Assuming that this is true (the source doesn't say that), how would such a sensor be able to avoid false alarms from large animals (the source warns readers that if they ignore security and try to reach the sign, they're at risk of being mauled by mountain lions) and yet always catch humans? Nyttend (talk) 03:22, 27 April 2010 (UTC)

Motion sensors only detect motion. They can't distinguish between motion by a person and a large animal. Dolphin (t) 04:36, 27 April 2010 (UTC)

I suppose you could design an infra-red motion sensing system to look for a "mostly vertical heat sources", which are presumably human, since we walk on two legs. However, people could crawl on all fours to fool it. StuRat (talk) 05:45, 27 April 2010 (UTC)

If I were building it, I would attach the motion sensor to a video camera. Then I could look ahead of time before calling the police. Also, you can make barriers that work pretty well against animals, but that humans can defeat. Ariel. (talk) 06:01, 27 April 2010 (UTC)

The article Hollywood sign mentions a 1994 installation of a $100,000 security system featuring video surveillance and motion detection. Cuddlyable3 (talk) 12:41, 27 April 2010 (UTC)

Those that have read Dune (novel) will remember the Thumper which had the same cadence, as the Fremen of Arrakis and so was used to distract the worms. Well, back here on Earth, Remote Intrusion Detection Seismic Sensors can be designed to detect the human cadence (between 1 Hz and 3 Hz), and not the higher cadence of four-legged animals. Find a reasonable flat bit of path where the intruder can walk at a regular step ( flat sections are sometimes created to draw intruders to where you want them) and bury a device along there. You can purchase them with radio senders to report back. WP appears to have missed this application out on Seismometer and yet they are becoming quite widely used. Needless to say, the way to pass by undetected is to employ the same technique that the Fremen taught Paul. Here is an external link with more info: [11]--Aspro (talk) 09:04, 27 April 2010 (UTC)

I fixed your link to the Dune novel and not just a hill of sand. Cuddlyable3 (talk) 12:45, 27 April 2010 (UTC)

Thanks. Aspro (talk) 13:25, 27 April 2010 (UTC)

microbes outside earth

Does the search for life on Mars and other space regions include microbes, especially bacteria which live in any extreme conditions? Or is the search meant for humans? - anandh, chennai —Preceding unsigned comment added by 125.21.50.214 (talk) 04:15, 27 April 2010 (UTC)

They are definitely looking for microbes. There's little hope of finding humans on Mars, so they don't even look for that. StuRat (talk) 05:20, 27 April 2010 (UTC)

They may have found such microbes. The research is still very scanty due to the extremely small samples, and the very sparce evidence in those samples, but there possibility has not been eliminated in as many as three meteorites found on Earth which originated from Mars. See Mars_meteorite#Possible_evidence_of_life. --Jayron32 05:39, 27 April 2010 (UTC)

SETI activities seek life forms with human-like or better intelligence but generally assume they will not be found living on the planets or moons of this solar system. Lack of evidence has not hindered people imagining fictional Martians some of whom are not very nice.Cuddlyable3 (talk) 12:29, 27 April 2010 (UTC)

Eeek! Martians!

There have been perhaps four serious efforts to test directly for life on Mars - The Viking landers, the analysis of Mars rocks that came to the Earth as meteorites - and the recent Phoenix lander and careful analysis of the Martian atmosphere by the Mars Express Orbiter. Both landers scooped soil and analysed it in test cells specifically designed to look for key signs of life. The results are a little odd.

• The Viking lander did it's tests - and the results of one test were positive! (Check out Viking biological experiments.) According to the criteria the craft was designed to test - it "found life on Mars". However, subsequent thinking on the subject has cast doubt on the findings - there are other ways in which the results could have come about - so nowadays, we have to say that the Viking landers didn't "find life"...necessarily. In other words, the experiments were not designed carefully enough.

• Then we had the Mars meteorites: Allan Hills 84001 in particular was first reported to show fossil lifeforms, to have trapped gasses that could only have come from living things, etc. It was announced that life had been found - they even got Bill Clinton on TV to announce it! But, again, more detailed analysis showed that both "fossils" and the gas evidence could come about in other ways...so again, ambiguous results.

• The Phoenix lander results are no better - at one point in the mission, it was reported that the White House had been alerted by NASA to make an important announcement on major discoveries concerning the "potential for life"...which sounded pretty exciting - right up to the point of the announcement when they basically said that they hadn't found anything very exciting.

• Then we have the anomalous nature of methane in the Atmosphere of Mars. This is a gas that would break down in the atmosphere and disappear. Yet it's still there (See: Atmosphere_of_mars#Methane) - and what's more, it comes and goes. There are no good theories as to why this might be - unless there were lifeforms there generating the stuff.

The problem is evidently that while we do really have some things that make it seem a lot like there is (or perhaps was) life on Mars - there is always another plausible explanation. Since we need to try to remain skeptical, we have to say that life has NOT been definitely discovered on Mars...but neither has it been disproved...yet.

However, it's very clear that 'macroscopic' lifeforms (things that might be visible to the naked eye -- or the many Rover & Lander cameras) are not present. If there is still life there - it's tiny stuff like bacteria.

SteveBaker (talk) 04:47, 28 April 2010 (UTC)

An apostrophe carelessly wielded can yield such nonsense as "The Viking lander did it is tests". Cuddlyable3 (talk) 20:18, 28 April 2010 (UTC)

You can let this bother you, or you can adapt, as I have done: Since Mr Baker tends to write relatively long and detailed responses, simply treat an early improper use of it's as a leading hint for the identity of the author, without having to scroll to the bottom of the post ... nearly as reliable as the signature itself. DaHorsesMouth (talk) 00:29, 29 April 2010 (UTC)

You may be interested in this recent discovery of possible organic matter present on Mars. —Preceding unsigned comment added by AstroHurricane001 (talk • contribs) 23:11, 28 April 2010 (UTC)

Sea blue - Sky blue

Why, at times, is sea-blue darker than the sky-blue when it is just a reflection of sky blue by the sea water? - anandh, chennai. —Preceding unsigned comment added by 125.21.50.214 (talk) 04:28, 27 April 2010 (UTC)

Water is not blue because of reflecting the sky, that's wrong. Water actually is blue, by itself, but so slightly that you need a lot of it to see the color. The deeper the water, the deeper blue it will look. Adding salt, as in ocean water, makes it more of a greenish-blue. StuRat (talk) 05:18, 27 April 2010 (UTC)

Thanks. colour of water is an interesting topic. 125.21.50.214 (talk) 05:51, 27 April 2010 (UTC)

THe colour of the sea here in England is usually grey most of the time, blue on sunny summer days, and rarely green. 78.151.102.119 (talk) 09:14, 27 April 2010 (UTC)

I've seen it purple, but that was in Cornwall not England. DuncanHill (talk) 22:45, 28 April 2010 (UTC)

Since we know the colour of the sea isn't a reflection of the sky, but intrinsic to the water, I can only conclude that the bright blue or dull grey sky must affect the intrinsic colour of the sea by some unknown means. 81.131.28.200 (talk) 11:24, 27 April 2010 (UTC)

Well, everything is darker outside on gloomy cloudy days compared to bright sunny days. Is that what you're talking about? Zain Ebrahim (talk) 11:55, 27 April 2010 (UTC)

In a mirror or on the surface of a still lake viewed at a low angle the reflected sky is as bright as the sky. However some of the light falling on a sea surface is refracted into the water so only a part is reflected towards the viewer who perceives a dark and diffused (because of waves) image of the sky. Colour of water is relevant only to seeing a light source deep in the water. Cuddlyable3 (talk) 12:20, 27 April 2010 (UTC)

The ocean color is partially derived from the skies. On a cloudy day, the ocean appears more gray, and on a sunny day, it appears more blue. It also can be green from underwater plankton which colors it. Water also has a very slight color. The molecules of water absorb certain wavelengths of radiation except blue. Needless to say, there are several reasons. --Cheminterest (talk) 21:03, 27 April 2010 (UTC)

"...the color of the sea isn't a reflection of the sky"

"...it is just a reflection of sky blue by the sea water"

This is a

complicated question.

SteveBaker (talk) 04:00, 28 April 2010 (UTC)

Human-Animal perceptions

If human perception varies from that of animal perception, say for example, in case of 'eye sight,' what exactly is the property (like shape, colour etc.,) of the entity (any object). Should we say that the object is rectangular,spherical etc., according to the human view? - anandh, chennai —Preceding unsigned comment added by 125.21.50.214 (talk) 04:33, 27 April 2010 (UTC)

I don't think we particularly care about animal perception, in general. Only animal researchers, trainers, etc., would care, as it affects their jobs. So, if a dog sees a globe, he probably thinks "uninteresting object" and doesn't attempt to classify it further, but so what ? StuRat (talk) 05:27, 27 April 2010 (UTC)

This is an extremely complicated, almost impossible question. The notion of property is a learned, acquired one. You learn what "round" or "straight" or "wavy" means when you see or touch it; you do not know if every human sees it the same way, but every (or almost every) human learn to associate those properties with the same categories. Now, when people study the anatomy and physiology of the eyes, lateral geniculate nucleus, and visual cortex of humans and Old World primates (Catarrhini), it turns out that the structure and function is fairly similar (size and exact shape notwithstanding) across individuals and even across species. This allows one to argue that humans, chimps, and macaques really see those things the same way. Now, cats or rats have eyes and brains that are less similar to ours; birds, reptiles, and fish are further yet; and insects with their compound eyes and ommatidia-lamina-medulla-lobula early visual processing pathway are nothing like the humans at all. Yet bees can be taught to distinguish shapes, and even properties of shapes, such even as the abstract notions of "sameness" and "difference". Do they see the same way as we do? No. --Dr Dima (talk) 07:52, 27 April 2010 (UTC)

An even more puzzling to our hopelessly anthropocentric perception is the question of what qualia (if any) does a rodent have when it "sees" objects with its whiskers (vibrissae); or a pit-viper has when it "sees" objects with its heat sensing organs, or a bat when it "sees" objects with its ears. --Dr Dima (talk) 08:04, 27 April 2010 (UTC)

Well, if you look at the center of a flower you may see a half dome where a bee might "see" a star shape http://en.wikipedia.org/wiki/Bee_learning_and_communication#The_Neurobiology_of_Color_Vision However, that would assume that the bee interpreted the visual information it gets the same way a human with a "bee eye camera" would. IMHO that is highly unlikely. I've linked this story before, but it shows that even an untrained human brain has trouble interpreting shapes. http://nfb.org/legacy/bm/bm02/bm0211/bm021105.htm 99.11.160.111 (talk) 08:57, 27 April 2010 (UTC)

Yes we should OBVIOUSLY say that an object is rectangular, spherical etc., according to our human view. Cuddlyable3 (talk) 12:09, 27 April 2010 (UTC)

"Rectangular" and "spherical" are objective criteria. Even if an optical illusion prevents you from intuiting the shape's true nature, or even if you're blind, you can use tools to measure the shape and determine whether or not it matches the definition of those criteria. APL (talk) 16:03, 27 April 2010 (UTC)

What you describe is not perception; it is measurement and inference. Properties of objects may be, well, objective, but perception is subjective. That is, if you agree with Kant's “Ding an sich” idea. Many philosophers don't, and conclude that fundamentally there is no escape from subjectivity; see e.g. this introduction. Wikipedia, too, has an article on Objectivity (philosophy). --Dr Dima (talk) 18:14, 27 April 2010 (UTC)

Is "Properties of objects may be, well, objective.." that so? We can't be sure even after measurements and inferences. Are measurements and inferences not human perceptions after all? Can science be subjective? If "the object is round," according to humans or anything else, what is the object scientifically? —Preceding unsigned comment added by 125.21.50.214 (talk) 09:51, 29 April 2010 (UTC)

Ambidextrous people

how better are ambidextrous people in terms of intelligence, compassion etc.,than a left-hander or a right-hander, while the ambidexterity is obtained either by natural or acquired ways? - anandh, chennai —Preceding unsigned comment added by 125.21.50.214 (talk) 04:50, 27 April 2010 (UTC)

I would suspect you'd find them midway between "right-brain" and "left-brain" individuals, so be able to integrate logic and emotions. StuRat (talk) 05:29, 27 April 2010 (UTC)

While Lateralization of brain function is a real thing (certain tasks predominate in certain areas of the brain) the whole "artsy people are right-brained and scientific people are left-brained" is mostly pseudoscientific bull crap. There's no hard evidence that things like personality or aptitude is connected in this way to "brainedness". --Jayron32 05:36, 27 April 2010 (UTC)

Nope, I'm just as daft as everyone else :-)) 99.11.160.111 (talk) 08:58, 27 April 2010 (UTC)

The Wikipedia article Ambidexterity is mostly about performance in sports. Cuddlyable3 (talk) 12:05, 27 April 2010 (UTC)

Cecil Adams very briefly mentions a study that showed that ambidextrous cats weren't as clever as cats with a definite preference.[12] but without reading the paper he mentions it's tough to say how much Cecil was paraphrasing. APL (talk) 16:01, 27 April 2010 (UTC)

While there is no correlation between being left- or right-handed and much intelligence-related, there is a correlation between being ambidextrous and various problems. [13] I've certainly heard it proposed that left-handed children underperformed historically partly due to being forced to use their right hand, leading to learnt ambidexterity which makes language and reading harder to acquire. 86.178.225.111 (talk) 20:39, 1 May 2010 (UTC)

What is this box?

Resolved

There is a large blue metal box in the office in which I work. The footprint is about 8'x3' and it stands about 6' tall. There is a white box on the outside (maybe 2"x6"x10") with two pressure gauges attached. This white box also has a temperature gauge that goes from 50 to 100 degrees F. There is also an electrical junction box on the outside with a big handle type on/off switch. Next to that is a card which is dated from 1999 which lists when various PMs were done. Notes for those PMs include mentions of replacing or checking tension of belts and greasing motors. In black permanent marker, someone has written on the side of the blue box, "CYMER". I have no idea if the writing is in any way related to the box. The only identifying marking is a logo which I've taken a picture of. I ran the image through TinEye and it didn't come up with anything.

The office in which I work used to be a lab of some sort but it was converted to an office years before I got my current job. None of my co-workers know what this box is and we're all kind of curious what it is and/or what it did. I work in the semiconductor industry if that helps. Anyone know what I've described? I'm putting this question on this desk since the room used to be a lab and this box might have been used for something in that lab. Dismas|^(talk) 08:32, 27 April 2010 (UTC)

I don't know what the box is, but you should also take a picture of the whole box from a number of angles. Did you try opening it? Does it make noise ever? Ariel. (talk) 09:37, 27 April 2010 (UTC)

Cymer, Inc.'s website [14] describes the company as a supplier of excimer light sources for photolitography. Pictures of their equipment suggest it fits the general dimensional description you gave, although none of the pictures on their website shows a blue housing. This U.S. patent [15] may provide some clues to the presence of a temperature gauge and a motor. --173.49.9.93 (talk) 09:42, 27 April 2010 (UTC)

It's been powered off ever since I've been in here (about 7 months). So, no, it's never made any noise that I know of. Considering the "L" logo, I don't think it's a Cymer product. There is nothing to open. The outside is just blue sheet metal. I don't see any access panels. One of the blue panels has had a couple screws removed but considering the 8' length and the fact that I don't have any business poking around in the box, I don't feel comfortable trying to pop the panel off if it will indeed come off. My work has nothing to do with it, so it would be rather embarrassing if I couldn't get it back together again. Dismas|^(talk) 10:03, 27 April 2010 (UTC)

Inside you might find a pre-193nm laser with cooling apparatus as it might be cheaper to leave useless technology in place when there is a radical change in node size as it evolves. Currently the plan is to shift to EUV for manufacture below the 17nm node when the power of EVU is able to match that of current 193nm lasers. Your box probably contains a light source for manufacture of older and larger node sizes of very long ago. I would consider it a showpiece in that case like the MARK I computer at Aiken Lab and care for it like a baby and show it off to friends. Plain vanilla with chocolate chips (talk) 11:23, 27 April 2010 (UTC)

Think we need more info. What is the range of the pressure gauges. It sound like it could be a compressor but compressors often run hotter than 100 deg F. Stand on some steps and see if there are any vents or disconnected pipe work on top. Are the pipes iron, stainless steel or copper? If pipe were at one time attached, there may still be the signs of pipe brackets on the ceiling and walls. Are there any vents, what shape? Any more signs on roof of box. Any inspection or access panels up there?. How are they fixed and are lead seals attached (or bits of twisted wire where they once where). Can you follow the cable from the switch box back to the main switchboard for that floor. It maybe that the electrician labelled what piece of equipment was on that circuit. The company you work for will have a department responsible for looking after the building(s) itself. They will have records of all plant and equipment that is permanently installed. I have found a good approach for eliciting a response from such departments in a reasonable time is too say to them: “Is this large equipment cabinet still used or important? Because we are just about to drill a large hole through it!” A manager or executive officer ( or maintenance guy) should know the name and how to contact this department. Maybe their listed in the internal telephone directory under “Site Management or Estates Management or Work Engineering Department, etc. Do however, steer clear, of involving the PHB. Lastly, I would consider that unknown cabinet could well be a safety issue, for one is just trusting someone else did their job properly and ensured that there are no hazardous materials left in side.--Aspro (talk) 11:10, 27 April 2010 (UTC)

The "L" graphic may or may not be the manufacturer's logo. It seems to communicate something about liquid and temperature. Just a guess. --173.49.9.93 (talk) 12:20, 27 April 2010 (UTC)

Wow, what a bit of history! I work for what became of the company that made that. The "L" graphic is actually a really really old Liebert Corp. logo. If you do a google images search you can see what the latest incarnation was (before they stopped using the logo altogether about 2 years ago.) What you are looking at is probably some sort of industrial chiller, installed to provide cooling for the Cymer device that someone else described. --Jmeden2000 (talk) 14:46, 27 April 2010 (UTC)

Could be -well done! The logo symbol does remind me a bit of a Dewar flask with a thermometer stuck in it (the pressure gauges for first and second stage compression maybe). Anything like that (including a compressor) is going to need loads of cooling though. I'm not going to speculate more without more info – it like clutching at straws. After all, it might just be something very obvious; like the new Doctor has almost fixed the Chameleon circuit and the logo is just part of its disguise – but its still suck at blue! --Aspro (talk) 14:57, 27 April 2010 (UTC)

It was colloquially referred to as the "Liebert Drip" since the company was largely in business to make temperature and humidity control products. The 'thermometer inside the water drop' logo (of various forms) was used until the company was bought by Emerson Network Power and internalized. The device in question, if as the OP states it is indoors and has no visible signs of ventilation, is almost certainly a chiller designed to take a water or refrigerant loop from a condenser type device outside the building, and make cool or chilled water for the supported device. These are very common to find in hospitals, cooling MRI machines, but have a multitude of other applications as well. I bet that the front of the device has three covers with horizontal seams. The covers are probably secured with a 3/8" allen key head and if you twist the two on the top cover it will hinge upward. I am *not* advocating taking it apart, this advice is for qualified personnel only! Ah well, enough babbling, back to work. --Jmeden2000 (talk) 17:17, 27 April 2010 (UTC)

Thanks all! I'll take "chiller" as the simple answer. I got on a chair and looked at the top. It's simply a welded wire cage behind which are several air filters. The panels on the front do indeed have horizontal seams. When I checked the top, I found an allen head T-handled wrench which doesn't have the size written on it but looks to be 3/8". Thanks again!! Dismas|^(talk) 08:19, 28 April 2010 (UTC)

Light-straight line; but how many?

It seems to be a ridiculous doubt. Light travels in a straight line. How do we measure/count the total number of 'straight lines' in a particular 'lighted' region? - anandh, chennai —Preceding unsigned comment added by 125.21.50.214 (talk) 10:20, 27 April 2010 (UTC)

Just because something travels in a straight line, does not mean that it is a line. Lux and candela are used to measure light intensity, if that's what you're after, though I don't know much about them. Vimescarrot (talk) 10:55, 27 April 2010 (UTC)

{ec)If I understand our question, the answer is, we do not tend to count such things. An illuminated area is being bombarded by photons. The path of each photon can be considered to be a straight line. If you consider the very smallest point of an area being illuminated, there will be countless straight lines connecting that point to the source of illumination - such as the sun. Trace all of those lines, and you get a solid cone made up of countless lines, with the illuminated point at one end, and, for instance, the sun at the the other end. --Tagishsimon (talk) 10:58, 27 April 2010 (UTC)

The path of each photon is a wave. For example, in the double-slit experiment, the photons each travel through both slits. — DanielLC 14:52, 27 April 2010 (UTC)

The path of each photon is not a wave, it is a straight line. The wave is a time-dependent variation in electric and magnetic field intensities, not a movement in space. --Heron (talk) 17:37, 27 April 2010 (UTC)

I don't think there's any way to argue that photons move in a straight line. Often in special and general relativity people talk about "photons" that are really classical particles moving in straight lines at the speed c. In quantum field theory, though, "a photon" is just a certain amount of energy in the electromagnetic field. Only the total particle number is meaningful. Talking about individual photons is the same as talking about individual liters of water in a river. Do they move in a straight line? It's a meaningless question. -- BenRG (talk) 20:19, 27 April 2010 (UTC)

Is the question "is space infinitely divisible"? 81.131.28.200 (talk) 11:40, 27 April 2010 (UTC)

A true line is an abstract thing with zero cross-sectional area. You could not make holes small enough in two walls some distance apart for a light beam passing through both holes to be reduced to a "line". Questions about how many infinitesimal quantities can add up to a finite quantity, such as how infinitesimal spots lit by lines of light can illuminate an area, are answered mathematically in integral calculus. Before calculus these subjects seemed paradoxical. Cuddlyable3 (talk) 11:47, 27 April 2010 (UTC)

1) Light only travels straight in the absence of gravity. The stronger the gravitational field, the more the path of the light will be bent. (There is an alternate way of looking at it that has the light straight and space-time curved, if you prefer that model.)

2) Light has a dual wave/particle nature. The particle models does have photons of finite size, so there would be a specific, very large, but not infinite, number of photons flying in any given room. StuRat (talk) 13:38, 27 April 2010 (UTC)

Area can theoretically be divided to smallest part up to 2.61223 × 10⁻⁷⁰ m2 (see Plank units). Don't know whether photon in straight line will need more or less than this. - manya (talk) 04:29, 28 April 2010 (UTC)

Objectively, what is the need for an area to be divided (may be infinitely) when the resulting subdivisions are of same properties? It(area) IS divided, fine, it(dividing by straight-line-travelling) is the property of light, fine, but Why?..... Oops, the question now becomes, light travels in a straight line, Why? --- Help me out. - anandh, chennai. —Preceding unsigned comment added by 125.21.50.214 (talk) 10:08, 29 April 2010 (UTC)

penury

Is the a mental disease characterized by penury? Plain vanilla with chocolate chips (talk) 10:53, 27 April 2010 (UTC)

No. Mental disease may lead to penury, but is not characterised by it. --Tagishsimon (talk) 11:00, 27 April 2010 (UTC)

penury noun: a state of extreme poverty or destitution. Cuddlyable3 (talk) 11:34, 27 April 2010 (UTC)

It's a pretty inevitable result of schizophrenia in the US. alteripse (talk) 12:06, 27 April 2010 (UTC)

Only if their family won't/can't take care of them. Dauto (talk) 14:30, 27 April 2010 (UTC)

Or if they don't have medical insurance. 76.103.104.108 (talk) 01:52, 28 April 2010 (UTC)

Only if their only option seems to get treatment, and not to be taught to try to fit in socially even with their illness. ~AH1^(TCU) 23:08, 28 April 2010 (UTC)

Spiders

What is the biggest spider found wild in the UK? Is it rare? If so, what would be the largest commonly encountered spider? I'm talking in terms of legspan here, although it would be nice to know the largest in terms of mass also. Thanks —Preceding unsigned comment added by Alaphent (talk • contribs) 14:58, 27 April 2010

Seems you can take your pick between the Raft spider and the Great raft spider as only an expert can tell them apart. --Aspro (talk) 15:45, 27 April 2010 (UTC)

Asystole and CSI: Miami

Calleigh from CSI: Miami was recently rendered unconscious by respiratory distress incident following smoke inhalation. The episode goes on to portray her in ventricular fibrillation with no (perceivable) pulse, followed by asystole. Eric complains they aren't shocking her, which makes sense, because asystole is a non-shockable rhythm, and then the ER physician slams her in the heart area with a syringe, possibly atropine. She then proceeds to jump up with her eyes open. Completely unrealistic, right? People don't just wake up from asystole. And she still has the endotracheal tube in, yet she's not gagging. DRosenbach ^{(Talk | Contribs)} 17:10, 27 April 2010 (UTC)

I generally don't use CSI:Miami as a reliable source for medical information. I assume that every utterance of every word, whether medical, forensic, or anything else, to be complete and utter bullshit made up entirely for advancing the plot of the show, without any hope that any such statements have any connection to actual real medical or scientific truths, except by dumb luck or pure raw coincidence. The same should be said of every single fictional TV show, from House to Lost to Thomas the Tank Engine. They all have an equal level of reliability with regards to medical or scientific information. --Jayron32 18:17, 27 April 2010 (UTC)

No Jayron, Thomas the Tank Engine has origins in the E2 Class designed by Lawson Billinton in 1913 and is a reliable source on matters of Rail transport. Cuddlyable3 (talk) 19:27, 27 April 2010 (UTC)

No, no...It's not like I can't seem to sneak medical advice out of the astute ref desk patrons and seek out CSI to fill that gap :) Rather, I just find it absolutely amazing that so many errors are made when, clearly, many other sorts of routes of medical happenstance could be utilized by the editor team to advance their dramatic agenda. I mean, I laughed when the CSI: NY coroner announced that a bullet had gone through the right occipital bone, when it's clear that the occipital bone is unpaired, and that mistake could have been eliminated without much disturbance to the plot. So when they make Calleigh's dramatic arousal from unconsciousness reliant on silly medicine when they could have made it reliant on actual medicine...I sense a tinge of arrogance on the part of the editorial team to care so little about reality in a show that focuses on reality. It's not the same as Archie Bunker having said, "Let's stop doing CPR because he's dead!" -- but that's what someone told Flack in CSI:NY last year. Can't they just get with the program? DRosenbach ^{(Talk | Contribs)} 18:32, 27 April 2010 (UTC)

It sounds like the doctor watched Pulp Fiction in a med-school course, 'cause it worked for Uma Thurman too. Concidentally, The Economist magazine has an article this week on the "CSI effect", defined as "the phenomenon in which jurors hold unrealistic expectations of forensic evidence and investigation techniques". That's a little more worrisome side effect. Franamax (talk) 19:02, 27 April 2010 (UTC)

Do you mean the CSI effect? WHAAOE. --Jayron32 19:08, 27 April 2010 (UTC)

Actually more than one. Cuddlyable3 (talk) 19:31, 27 April 2010 (UTC)

I dunno about that last one, it was written by someone with an obvious conflict of interest... Also a quick check with an MD confirms that intracardiac injection is never used nowadays; in the past it was likely epinephrine; and the Pulp Fiction scene at least bears no relation at all to medical reality. (Is it medical advice to say that you shouldn't stab your friends in the chest with a honkin' big needle?) Franamax (talk) 20:54, 27 April 2010 (UTC)

The "penny in the fuse" part of the episode was particularly idiotic, along with the notion that the batty neighbor lady could calculate that the penny was needed to prevent the fuse blowing when the plumber was electrocuted through clean water she sprayed on the floor. How did she calculate that more than 15 amperes would be carried through the water, across the floor, through the plumber to the pipe he was touching? I would estimate far less. And sticking an elongated penny into the FRONT of a fuse was not ever a common (but recognized unsafe) practice in the days of fuse boxes. (I will not elaborate on the "to be avoided" practice regarding pennies and fuses, nor should anyone else). What are the writers smoking when they come up with these plot elements? Edison (talk) 04:51, 28 April 2010 (UTC)

In most such cases they're probably performing under the constraint of "We don't need it good, we need it tomorrow!" 87.81.230.195 (talk) 14:57, 28 April 2010 (UTC)

Good thing that novelists like myself usually get about a year to work on the book. :-) 76.103.104.108 (talk) 05:58, 29 April 2010 (UTC)

Dropping a potato out of a plane

Yes, it's another of those "Never!" bets again. My friend is an amateur pilot, and through a rather convoluted path we got to the (enthralling) topic of dropping potatoes out of planes. She worried it might kill someone; I said this was unlikely (recalling the coins-off-the-Eiffel-Tower scenario). We promptly set off trying to determine (roughly) what would happen.

Our potato is (for argument's sake) a sphere of diameter 5cm and density of 1.6g/cm³ (it weighs ~105g) and we're dropping it from sufficient height that it will achieve terminal velocity but not so much that it might change during the process (freeze, splinter, gain mass from clouds or whatever). From this, we got a terminal velocity of around 8 m/s. So far, so good.

We now knew everything we needed to about the potato, but transferring this into a living/death thing proved tricky. I'd love to have your thoughts on how to model it - the simpler the better, I suspect the answer is unlikely to only just cause death or just not, so exactitudes don't really matter - we just need an answer! :) Thanks, - Jarry1250 ^{[Humorous? Discuss.]} 18:38, 27 April 2010 (UTC)

What does a potato weigh? About 1/4th to 1/2 of a pound? That's roughly 0.12-0.25 kilograms or so. Will an object, somewhat squishy, moving at 8 m/s and weigh 0.24 kees kill someone? Probably not. It has E = 1/2 mv² = 1/2 * 0.25 * 64 = 8 kilojoules of energy. I can't imagine an object imparting 8 kilojoules of energy actually killing someone, unless it hits just right. It would probably leave a nasty bruise, and that's about it. --Jayron32 18:59, 27 April 2010 (UTC)

Quite. Our imaginary "potato" weighed 0.11kg so slightly less than yours anyway. However, it says at HowStuffWorks (not the most reliable source, I know) that 100 foot-pounds in enough. Wolfram tells me 100 foot-pounds is about 136J (?). Which doesn't seem like much. Which worries me. Where am I going wrong? - Jarry1250 ^{[Humorous? Discuss.]} 19:10, 27 April 2010 (UTC)

Sorry. I mistyped. It should be 8 joules of energy. A joule is a mks unit, and I mistook it for a cgs unit. In that case, a dropped potato of only 0.11 kg should impart about 3.5 joules of energy. This is rougly 2.7% of the energy needed to kill you. In other words, it would need to be a large sack of potatoes to have enough energy to kill you reliably. --Jayron32 19:20, 27 April 2010 (UTC)

Of course. It all makes sense now :) Thanks. - Jarry1250 ^{[Humorous? Discuss.]} 19:30, 27 April 2010 (UTC)

(ec) Got some other figures for you, from Cycle, a national UK cycling charity. It seems that bike helmets need to meet a standard of protecting a head from about 65 joules upon impact with a rounded anvil. I know it's outside the potato/plane box, but I would suppose that realistically, a potato dropped from a great height would be travelling almost straight downwards due to air resistance and so the head would be the most likely impact zone. Cutting it short: it looks like a single spud is an order of magnitude too low to fracture someone's skull. The article states, for comparison, that an estimation of the energy of a fall onto flat tarmac from stationary is about 75 joules. Brammers (talk) 19:37, 27 April 2010 (UTC)

As a pilot myself, I would like to point out that the Federal Aviation Regulations explicitly forbid dropping any object from an aircraft in a manner that creates a hazard to persons or property. The FAA is pretty strict on this one, so it's far better not to drop it at all, as you cannot be 100% sure that there is nobody/nothing in the potential path of the potato. Falconus^{p t c} 19:18, 27 April 2010 (UTC)

Haha, don't worry, we weren't going to try it (although, as my friend rather humorously pointed out, I really ought not to be the one worrying). And we'd be under the CAA anyway, but meh, they probably have the same rules (I'm not a pilot myself). And of course the above omits the small chance it did perchance do serious damage, so not point relying on it. But I'm happy now. - Jarry1250 ^{[Humorous? Discuss.]} 19:30, 27 April 2010 (UTC)

Well they are not suppose to dump stuff out of the aircraft, but sh*t does happen. We hear things like this every now and then. See Blue_ice_(aircraft). --Kvasir (talk) 19:54, 27 April 2010 (UTC)

Impact on the head, pshaw, what sort of imagination is that? How about if it knocks the gun out of a soldier's hand as he's about to ambush an enemy, who hears the noise, turns around, and shoots him? Or it splatters over someone's windshield, blocking the view while they're on a twisty road, and they drift into the oncoming traffic? Or it lands next to a vicious dog or a poisonous snake, which looks around and fatally bites the nearest human? Or it drops into a tornado and is accelerated to 10 times its previous speed and then hits someone on the head? Or it knocks the camera out of someone's hand and breaks it, preventing them from taking the photo which would have been confirmed their testimony which might otherwise have been considered dubious, thus allowing a murderer to plead guilty to a lesser charge and be sentenced to only 15 years in prison, after which he commits another murder? (Insert butterflies here.) What about that, hmmmm??? --Anonymous, 20:55 UTC, April 27, 2010.

I was going to mention those, but decided on "the small chance it did perchance do serious damage" in the end, very much in the spirit of WP:BEANS. Heh. - Jarry1250 ^{[Humorous? Discuss.]} 21:00, 27 April 2010 (UTC)

Mr./Ms. Anonymous, whoever you are, you should be a writer of detective fiction. BTW, why don't you sign your posts so that literary agents would know who you are?  ;-) 76.103.104.108 (talk) 01:57, 28 April 2010 (UTC)

8 ms^-1 for the terminal velocity? That's not all that fast. Gravity is 9.8 ms^-2 - so your potato will get pretty close to that speed in about 2 seconds. You don't have to be all that high up to get that kind of speed - a third floor window would probably be enough. Now all you need is a "human analog" (to use a handy Mythbuster's phrase). I suggest a large watermelon. So find a nice high window - overlooking an enclosed area - stick a handful of representative melons out there and haul a few bags of potatoes up three or four floors. It may take quite a few drops to get a potato on target - but it'll get you an answer in an hour of trying. You can add some other interesting destructible objects too. Tell us what happens! SteveBaker (talk) 03:15, 28 April 2010 (UTC)

Don't forget to invite friends and have a cookout with the potatoes and watermelon. Ariel. (talk) 05:09, 28 April 2010 (UTC)

Railguns on ships

I took the info from this Cracked article, railgun, speed of sound, and a random ship: Spanish aircraft carrier Principe de Asturias.

While discussing the enormous destructive potential of railguns as mentioned in the Cracked article with a buddy, he asked if the sheer force of firing a slug at mach 7 wouldn't roll the ship. Railgun says that the slugs are 3.2kg, and seven times the speed of sound is 5,376 mph. A ship like the Principe de Austurias weighs roughly 16,000 tons, which would be 16,000,000kg, right? Accelerating a mass 5,000,000 times greater than this 3.2 kg slug would accelerate it 5,000,000 times less...meaning...it would accelerate 0.0010752 mph in the opposite direction that the railgun fires.

...Is all of this right? I'm asking on Science not Maths because I imagine most good scientists would be able to think their way through these calculations fairly easily, and I'm also after other factors that I might not have thought of. Vimescarrot (talk) 19:58, 27 April 2010 (UTC)

Note: The gun is not being fired at the ship, it's bolted to the deck and firing from the ship. Ran this scenario past a friend and he didn't realise, so I thought I'd best mention it. Vimescarrot (talk) 20:09, 27 April 2010 (UTC)

Hey, when I model the experiment in my mind, I come up with the complication that you can't simply take the whole weight of the vessel and use it as a denominator to find the ship's acceleration. The question is not 'will the ship move sideways in the water', but 'will the ship roll' (i.e. will the top of the ship move relative to the bottom in the vertical axis'). In this case, you can only use a fraction of the vessel's weight as the denominator. I think the calculation must be complicated but I would suggest that the majority of the ship's weight is low down, to prevent it from capsizing. The weight around the centre of gravity will be accelerated less, but the surface of the ship will be accelerated more because it is lighter and is some distance from the fulcrum. Nonetheless, it's still probably only a fraction of an mph, because you also need displace all that water in order to move the... what's it called... stern? --Seans Potato Business 20:24, 27 April 2010 (UTC)

Err, forget roll for a moment. How are you going to stop the gun's recoil from splinting the vessels structural joints?--Aspro (talk) 20:48, 27 April 2010 (UTC)

Time to break for a photo of the Iowa

An Iowa class battleship fires a projectile of around 1000 kg at about 820 m/s, which (if my dodgy math is right) is a muzzle energy of 336 MJ per projectile, and thus the same amount of recoil energy that has to be dissipated by the vessel. The numbers Vimescarrot quotes amount to 9 MJ for the railgun. And the Iowa has 9 such guns which it seems it can safely discharge simultaneously; that's 3TJ of recoil. -- Finlay McWalter • Talk 21:07, 27 April 2010 (UTC)

Use springs to prevent it from splintering.--Cheminterest (talk) 21:10, 27 April 2010 (UTC)

The 'force' being applied to the projectile is via the use of different principles of physics. So first one need to establish the nature of 'recoil' as it applies to a mass being accelerated in this fashion – yes? --Aspro (talk) 21:20, 27 April 2010 (UTC)

No. A force is applied between two objects, pushing them violently apart. Simplistically, it's an elastic collision, with half the energy used to imply each object with momentum, by Newton's third law. It doesn't matter whether the force comes from an exploding gas or a powerful magnetic field. In practice the process isn't perfect, so the collision is really elastic (stuff gets hot) and with cleverness you can spread the recoil energy around, but it doesn't go away because you're using magnets not cordite. -- Finlay McWalter • Talk 21:38, 27 April 2010 (UTC)

Another concern is resonance. I'd assume they will shoot more than one of those projectiles during a battle, so then the Q is how long they wait between each. If we assume that the rail gun is above the CG for the ship, then the ship should roll somewhat, then roll back the other way, and back again, less with each roll and counter-roll due to frictional effects.

If the time period between firing slugs is the same as a full roll-and counter-roll, then you would get an increase in magnitude with each new shot, due to resonance. I doubt if it would add up to anywhere near enough to roll the ship, but it might be enough to adversely affect accuracy. Of course, all these issues also apply to conventional shells, so I'm sure they already have strategies in place for dealing with the problem. StuRat (talk) 22:30, 27 April 2010 (UTC)

This chapter says that there is a recoil brake (which seems to be a gas cylinder damping arrangement - see fig 5B21) which it likens to a dashpot, which both spreads the recoil impulse delivered to the ship out over time (to lessen the otherwise shattering shock) and to dampen the oscillation. I'd imagine it'll also reduce the noise inside the ship. If they didn't have this, and instead had the gun firmly bolted straight to the main structural members of the ship, I guess it would feel like being inside a giant gong. -- Finlay McWalter • Talk 22:45, 27 April 2010 (UTC)

The scary bit is where they're going to get all the power to run this thing. Railgun#Railguns as weapons talks about a 64MJ muzzle-energy weapon. This General Atomics press release compares the size of the capacitor array to drive a smaller gun, and from that it looks like the whole arrangement (capacitor discharge and railgun operation) is less than 50% efficient (the railgun article also talks about the guns getting very hot due to this inefficiency). So that 64MJ gun will need something like 128MJ in the capacitors to run it, and railgun talks about a fire rate of 10 per minute, which is once every six seconds. To store 128MJ in six seconds they'd need a power supply of 21 MW. The twin Rolls-Royce Marine Trent powerplants they're planning on putting into the (possibly one-day railgun capable) Zumwalt class destroyer put out 78MW, so they'd be using a quarter of the ship's entire power to run one gun (and that assumes they can actually run the generators with the gas turbines at full, and have enough bus capacity to shift that power around). Still, with other power-hungry things like free electron lasers and Electromagnetic Aircraft Launch System (122 MJ) it looks like the US navy is going very capacitor-heavy. -- Finlay McWalter • Talk 23:19, 27 April 2010 (UTC)

So put the railgun on a ship that has a nuclear reactor for power supply. Destroyers are probably too small, but a cruiser could probably have one. Googlemeister (talk) 13:28, 28 April 2010 (UTC)

Sure, you could do that. But a Zumwald already costs getting on for 6 billion dollars, without railguns, nuclear reactors, or death rays. A cruiser like Ticonderoga is about four times the displacement of Zumwald; at that rate the US Navy would be able afford to field only a handful of ships. Railgun has to compete against TLAM for the shore-bombardment role, and while shot-for-shot TLAM is pricey the incremental cost of adding TLAM to existing vessels is pretty moderate and it's flexible enough to fit to Ticonderogas, Iowa, Arleigh Burkes, and submarines. -- Finlay McWalter • Talk 15:21, 28 April 2010 (UTC)

The destructive force of a railgun is given by its energy, which is proportional to the square of velocity. The roll-the-ship effect, however, is given by momentum, which is only linearly proportional to velocity. A 3 kg slug moving at 7 times the speed of sound just doesn't have enough momentum to matter to a thousand-ton ship. You wouldn't feel more than a small shudder. It's curious how poor people's intuition is about things like this -- in movies you often see somebody hit by a bullet who is knocked backward or even stopped in midair. Ridiculous! It happens, I think, because most people's intuition doesn't properly differentiate between kinetic energy and momentum. Looie496 (talk) 05:21, 28 April 2010 (UTC)

I think that pretty much covers everything I was after. Cheers Vimescarrot (talk) 13:03, 28 April 2010 (UTC)

The US Navy has a habit of spending billions on ships who's roles could be filled much more cheaply. For example the new Littoral combat ships fulfill a role that could probably be done better by a tug boat with a Bofors 40 mm. Any big ship could easily handly the recoil from a railgun. They already have fully automatic 5-inch guns that produce about the same recoil yet constatnly--92.251.243.109 (talk) 21:58, 28 April 2010 (UTC)

% of water when raining

How fast would it have to be raining in order for a person to drown from just walking around unprotected? I thought about figuring out what % of the air is replaced by water when it is raining at 1"/hour and then scaling it to a point that a human can not survive, but have not been about to figure out the first. Googlemeister (talk) 21:18, 27 April 2010 (UTC)

It's going to be hard to calculate properly (accurately) because the terminal velocity of rain depends on how much rain there is. According to this, 9m/s seems to be a good number to work with. The equation you want is: 1inch/hour / 9m/s = .000000784 = %.0000784, which is the fraction of the air that contains water. You'd need 1,275,590.55 inches per hour to have the air be solid water (if you convert the units, 9 m/s = 1,275,590.55 inches/hour), but a person may drown in less than that. Ariel. (talk) 22:15, 27 April 2010 (UTC)

it depends on how they face when they breath, too. The rain water in the air isn't randomly distributed, it's in discrete droplets falling downwards. Someone bent over in the rain doesn't inhale much water, but someone staring at the sky might inhale a good deal more. APL (talk) 22:29, 27 April 2010 (UTC)

Is this assuming that it's raining everywhere on Earth at the same time? As the clouds taper to an end, and there is no rain, wouldn't the rainfall adjacent to this circumference run off into the area where it wasn't raining...I mean, does your 1.3M inches an hour take this into account? DRosenbach ^{(Talk | Contribs)} 03:29, 28 April 2010 (UTC)

The 1.3M inch/hour figure is an estimate of how much water would be falling per area if what was falling was solid water coming down at 9m/s. (Of course in that case terminal velocity in air would not really come into play. The velocity would instead be limited by how fast the water on the ground was moving out of the way). Run off isn't an issue until after the water has hit the ground. Otherwise we're just talking about the conditions for flooding, no? Rckrone (talk) 06:05, 28 April 2010 (UTC)

It has to be close to 100% water in the air; if you bend down you will not get the water if it is less. --98.221.179.18 (talk) 19:24, 28 April 2010 (UTC)

If rain is falling down, air must be coming up. Cuddlyable3 (talk) 19:53, 28 April 2010 (UTC)

The relevant experiment is to walk under a waterfall and see how dense it can be before you can't deal with it. If you have any experience with waterfalls you'll probably see that the force of the water will knock you flat long before it gets dense enough to drown you. Looie496 (talk) 20:57, 28 April 2010 (UTC)

extreme human evolution

Assumming that the human race will live to see Pangaea Ultima in 250 million years, what speculations do you have as to how humans will evolve given that amount of time?—Preceding unsigned comment added by CHEMX (talk • contribs) 22:55, 27 April 2010

Since humans have so far been around for maybe 3 million years, and perhaps do not have the stability of cockroaches and trilobites, I would assume that there will be no humans recognizable to us even if the planet has survived that long. alteripse (talk) 23:17, 27 April 2010 (UTC)

Evolution seeks to increase the number of offspring for a given environment, and since humans are doing a fine job of creating offspring, unless the environment changes humans are unlikely to change at all. Except maybe evolution to make birth control impossible. Predicting how the environment will change in 250 million years might be hard. Also, given our intelligence, we are unlikely to allow evolution to do anything at all, but rather we will take control of our DNA on our own. Ariel. (talk) 23:21, 27 April 2010 (UTC)

Respectfully thats just silly. The time scale is nearly 2 orders of magnitude greater than a human history that has already seen changes to the point of speciation. The human birth rate and the rate of the change of the environment means that the only thing we can be sure of is that your prediction, of no real change, is the LEAST likely of all alternatives. alteripse (talk) 23:34, 27 April 2010 (UTC)

Well, the human birth rate suggests we'll see an increase in genetic diversity but for evolution you need a difference in reproductive success (often due to people with certain genes dying before reproducing). Given modern technology and welfare states, your genes don't have much impact on your reproductive success. The amount of evolution we've seen over the last few million years is irrelevant since it is almost all pre-industrialisation and the existence of modern industry cannot be ignored. Evolution due to being a better fit to our environment won't happen much since we tend to alter our environment to suit us rather than the other way around. Evolution due to sexual selection is still possible, I suppose (which some authors have suggested will result in the human race splitting in two [16]). --Tango (talk) 23:46, 27 April 2010 (UTC)

The reference desk isn't for speculation and there is no way to do anything more than guess. Evolution has a large random element. I can make some general comments, though. If humans do change significantly, there won't necessarily be a single human race because we could have undergone speciation, but that seems unlikely due to the ease of travel these days meaning populations won't get isolated (although isolation doesn't have to be geographic). The most rapid evolution tends to happen during times with lots of people dying (especially ones leading to population bottlenecks) and modern technology combined with the near-global spread of humanity means that doesn't happen much any more, so we shouldn't expect much change in the human race. A Google search finds lots of other people's opinions if you don't like mine. --Tango (talk) 23:33, 27 April 2010 (UTC)

There are a lot of speculative, futurology predictions about human genetics. Lee Silver's Remaking Eden has a particularly interesting one regarding the possible long-term effects of "reprogenetics" technology on the human genome. But yeah, 250 million years is a long time. A lot of stuff can happen in that amount of time that would affect things. Even if you imagined that nothing major would happen (which is impossible, really), it's not clear how you'd even extrapolate current trends in a meaningful way. --Mr.98 (talk) 23:48, 27 April 2010 (UTC)

The difficulty here is that humans are able to actively resist the effects of evolution. When someone has a mutation that causes them to be unable to procreate - in steps science and provides a variety of interventions that allow that gene to be passed on. This reduces the tendency for bad genes to be eliminated from the population. We'll get better at this - we'll be able to treat genetic diseases. This could cut out beneficial genes as well as bad ones. Furthermore, we're changing the environment vastly more quickly than evolution can track those changes. Given a few tens of thousands of years of online dating and cellphone texting - we might evolve to take advantage of that...but nobody believes that this technology will still be here, unchanged in 10 years - let alone 100 or 1,000 or the 10,000 it might take for a noticable genetic change. We're also living longer and having children later...that increases the generation length...longer generation length, less genetic change, less evolution. Then there is the possibility of 'designer genetics' - maybe we'll be able to choose the genes of our children? If that happened, evolution could be at the whim of fashion. We might start doing things like copying our brains into computers and becoming immortal, digital beings. No more evolution with an infinite generation time.

With all of those possibilities (and more besides, I'm sure) - the laws of evolution may simply cease to apply to humans. So where we end up in even 1,000 years is totally, fundamentally unpredictable. Most scientists are loath to make technological predictions beyond 25 years - and our lives are increasingly technological beings.

I believe that we are on the brink of a post-genetic era - evolution for us is becoming entirely memetic. Memes (ideas) evolve, mingle, reproduce, survive or die out. They can do it on short genetic timescales and reproduction is cheap in an intercommunication-rich digital world. I could easily imagine a future where ideas are all that's left - humans (and human bodies in particular) become an unnecessary (and difficult) part of the future. We could be out-evolved by our own memetic offspring.

SteveBaker (talk) 02:53, 28 April 2010 (UTC)

Just as an example as to how bad we are at predicting even basic technological advances, consider that the first three books of the Foundation series lacked anything resembling an actual computer. And this is from an author, Isaac Asimov, who was an actual honest-to-god chemistry professor and professional scientist. The first book was written in the early 1940's, before computers even existed, and the series came to be in the early 1950s; at that time computers were basically large devices used to calculate ballistics trajectories and stuff like that. The idea that computers would be as pervasive as they are today didn't even enter into people's mind, even in science fiction. If someone as well versed in the science and technology as Asimov couldn't have predicted something as core to modern life as computers, writing only 60 years ago, how can we meaningfulling make predictions any reasonable time into the future. 60 years from now, will will likely find our lives pervaded by some technology which hasn't even been invented yet and which no one is really even thinking about. --Jayron32 03:40, 28 April 2010 (UTC)

Well, by the early 1950s Asimov was writing about some extremely advanced computers in the form of robots with positronic brains. The thing that pretty much everybody missed until around 1990 was what would happen with the internet. Looie496 (talk) 05:11, 28 April 2010 (UTC)

The difficulty here is that humans are able to actively resist the effects of evolution. - Steve, I'm disappointed that you make such a claim. That's plain wrong. What we do is changing the parameters of the selection - we do nothing about the evolution itself. In fact, we currently select some genetic defects out of the gene pool (without really understanding all implications) by parent screening and pre-natal screening. --Stephan Schulz (talk) 12:41, 28 April 2010 (UTC)

Evolution has effects - we can (and do) resist them. I don't see anything difficult or controversial about that claim. A genetic change that is strongly disadvantageous in our present world would "naturally" have drastically reduced the probability of that individual reproducing successfully. 'Bad' genes may well be retained in the gene pool through artificial reproductive help, or through treatment of the genetic diseases. This is us actively resisting evolution - ensuring survival, not just of the fittest, but also of the profoundly unfit. As a consequence, we may wind up with increasing numbers of people who are accumulating disadvantageous genes who can only continue to survive and breed with advanced medical help. Under those circumstances, we're not evolving to better fit our environment - but developing technology to prevent us from better fitting into our environment by changing the environment to meet whatever genetic weirdness is thrown up by random mutation and recombination. Every time we 'cure' a genetic disease - or help a couple to have children who otherwise could not because of some genetic problem - we're fighting the tide of evolution. Don't get me wrong - I'm not saying we shouldn't do that - but we should be more clearly aware of the magnitude of the effect we're having on our own species by doing that. SteveBaker (talk) 23:46, 28 April 2010 (UTC)

No, that's not true - or at least it's a weird definition. Evolution = change of the gene pool over time. We do not actively resist that change, we only influence how it is expressed. In-vitro, for example, reduces the value of the trait to be able to conceive naturally. But it increases the value of the trait to be able to fit into society in a way to make society pony up the resources for in-vitro (i.e. in the US the ability to make enough money to pay for it). The definition of "fitness" in evolution is the ability to dump genetic material into the next generation. It does not imply being faster, smarter, or prettier, although all of these may help in some environments. In fact, being a penniless student living off donations for a sperm bank probably makes you "fitter" than most other life styles in our environment. --Stephan Schulz (talk) 06:15, 29 April 2010 (UTC)

What if humanity is able to finally escape the planet entirely? If it even survives the next 3 million years, it's likely that humanity will leave it's ancestral home. If there are colonies on multiple planets/moons/asteroids, even in our own solar system, there will likely be isolated populations and speciation will occur simply due to the general cost of interplanetary travel. It doesn't help that mutation will be even more likely once you leave the protective cocoon of Earth's magnetosphere. -- JSBillings 13:00, 28 April 2010 (UTC)

Well I don't see us colonizing very far from Earth for a very very long time unless relativity is proven wrong. 25 light years is the point of no return. Would you volunteer to go with a few hundred others to live on a unknown and unexplored, and likely extremely dangerous planet, with no chance of ever seeing the ones you love ever again?---92.251.243.109 (talk) 21:45, 28 April 2010 (UTC)

Would you volunteer to sail a small ship into the complete unknown? Would you sail to an uncharted and dangerous continent to live there forever and never come back? Would you set out into the wilderness determined not to stop until you reached the other shore, not knowing how far you'd have to travel and what kinds of dangers you might have to face? Would you volunteer to take an untested contraption of wood and wire into the air, knowing that it might crash and kill you? Would you volunteer to fly alone in a single-engined plane across the North Atlantic, knowing that if anything goes wrong, you're as good as dead? Would you try to find a tiny island in the middle of the vast Pacific even though the odds are a gazillion to one against you? Would you volunteer to ride a rocket filled with explosive fuel into the vacuum of outer space, not knowing if you'll ever come back again? This is a rhetorical question, 92 IP. If you're the explorer type, you'd volunteer for all those things and more without any questions; if you're not, then you'd stay home. It takes all kinds, y'know. 76.103.104.108 (talk) 05:13, 29 April 2010 (UTC)

"The difficulty here is that humans are able to actively resist the effects of evolution"—well, kind of, but not entirely. And in any case, over 250 million years, making that assumption seems wrong. Humans have really only been able to do this well for a few hundred years, maybe a few thousand if you are very generous in your definitions. The idea that we will be extending this capability into the millions seems unjustified to me. (The idea that the species—in any form—will last into the millions seems unjustified to me, as well!) --Mr.98 (talk) 13:51, 28 April 2010 (UTC)

The assumption that the human race will survive millions of years was an explicit part of the question, so it doesn't need to be justified (that is what "assumption" means). --Tango (talk) 14:04, 28 April 2010 (UTC)

I know, that's why I put it in parentheses, because it is a little peripheral. --Mr.98 (talk) 14:32, 28 April 2010 (UTC)

If an advantageous mutation comes along, it has a chance of staying. That's the idea behind natural selection. Imagine Reason (talk) 13:13, 28 April 2010 (UTC)

That's a tautological definition of natural selection; whether a mutation is "advantageous" or not depends on the selective pressures of the environment. --Mr.98 (talk) 13:51, 28 April 2010 (UTC)

Considering the fact that humans are not perfect in any normal sense of the word, this should not be a problem. Imagine Reason (talk) 14:00, 29 April 2010 (UTC)

Members of the Scientology "Sea Org" who signed a billion-year employment contract with the organization will have only 750 million years left to catch up on their confessionals. Cuddlyable3 (talk) 19:51, 28 April 2010 (UTC)

April 28

Molecular Electronics

I'm a physics undergrad who's starting to appraise his options for a research career, and one field in particular that seemed interesting was molecular electronics. There seems to be elements of both physics and chemistry involved (which I don't mind), but I was wondering if a physics degree would properly prepare me for research in this area. I'm betting that an undergrad program won't matter all that much in the long run anyways, but what should I be looking into for graduate school? Also, while I don't mind chemistry I much prefer physics, so I need to know if such research can be more physics-based than chemistry-based. In other words, will I end up being a chemist or a physicist? Thanks. 173.179.59.66 (talk) 00:41, 28 April 2010 (UTC)

You are right in terms of your undergrad degree being somewhat irrelevent here. Any degree in the hard sciences (Chem, Physics, Bio) or engineering would probably set you up just fine for a graduate program in molecular electronics. What you need to do for grad school is find a professor somewhere in the country who is working in the field you want to work in, and contact them directly, letting them know you are interested in the field. In the sciences, grad school is all about what lab you are working in, and networking with the professor you will be working under is much more important than the school itself. As an undergraduate, things like extracurricular activities, campus life, geography, appearance of the campus, location, dorms, etc. etc. are all important aspects of choosing a school. For a terminal degree (Masters or PhD), its ALL about the program you are interested in. So if you find a well-respected researcher who is working in your field of interest, you should seek him out and ask him if he has any openings in his lab; what sort of work he does, how to go about getting in there. That will make getting into the school much easier. --Jayron32 02:50, 28 April 2010 (UTC)

Warm Sector

All I need to know is the definition of a Warm Sector for a lab titled "Frontal Weather." 74.76.183.139 (talk) 01:26, 28 April 2010 (UTC)

See Air mass and Weather front. A warm sector would simply by the warmer of two air masses that meet at a front. If the cold air is pushing the warm air out of the way, the front is called a cold front. If the warm air is pushing the cold air out of the way, the front is called a warm front. --Jayron32 02:45, 28 April 2010 (UTC)

Usually, the warm sector of a frontal system in the Northern Hemisphere is in its southeast quadrant. ~AH1^(TCU) 23:05, 28 April 2010 (UTC)

Chemistry: Si face and re face

I read the article Si face but I still don't understand how to distinguish a si-face from a re-face. Please explain what they are. —Preceding unsigned comment added by 70.68.120.162 (talk • contribs) 01:46, April 28, 2010

They "are" a formal way of describing the two faces of a flat location (atom in a molecule), defined by the position the things attached to that atom. Consider your right hand: looking at the palm, the fingers in order thumb-first-middle-ring-pinky go around in a counterclockwise direction; looking at the back of your hand, those same fingers in that same order go around in the other (clockwise) direction. The terms "si" and "re" are a way of identifying which face of your flat hand you are looking at, based on clockwise-vs-counterclockwise direction of the things attached. The "order" is the atomic masses of the atoms attached to the one being analyzed. The "direction" is still clockwise (called "re") or counterclockwise (called "si"). DMacks (talk) 06:30, 28 April 2010 (UTC)

Are cars and planes Faraday cages?

If yes, why are we able to use the cell-phone in them? (I assume that a Faraday cage would block a cell-phone wave). If not, why do they protect against a lightning? One possible answer that comes to my mind is that they are good enough to protect us against a lighting, but not good enough to block the cell-phone. Right?--Mr.K. (talk) 11:37, 28 April 2010 (UTC)

Whether a Faraday cage blocks a cell phone signal depends (mainly) in the thickness of the walls and their conductivity. Lightning however, is a discharge which takes to path of least resistance. Here is a photo of a lightning resistant soft-top: [17]--Aspro (talk) 11:55, 28 April 2010 (UTC)

It's also a matter of frequencies - cellphones are up in the GigaHertz range - lighting is basically DC. SteveBaker (talk) 12:08, 28 April 2010 (UTC)

Lightning is an impulse-like burst, and has energy content at most frequencies. There is usually more energy at very low frequency, below 10 kHz, but there is also very strong RF in the VHF and even some energy in the gigahertz range. Lightning is also large and powerful enough to have very nonlinear frequency behavior and is known to couple energy and particles into the ionosphere and magnetosphere. The fact that it doesn't harm people inside airplanes is due the skin effect, not because the plane is (or is not) a Faraday cage. You can be certain that the radio signals can be detected from inside the plane - so it's not effectively shielding all energy. Here is a beautiful video of a lightning research aircraft, the audio includes RF signals detected inside the plane used to analyze the video footage. This video focuses on transient luminous events, which are rare atmospheric/ionospheric electromagnetic phenomena related to lightning. Nimur (talk) 18:07, 28 April 2010 (UTC)

The cell phone signals come in through the windows, which are big holes in the metal screen. Graeme Bartlett (talk) 12:11, 28 April 2010 (UTC)

The newer aircraft made from non-conducting composite material will need thin metal meshes and foil to be included in construction for lightning protection. However, with a cell phone's 800 MHz to 900 MHz frequency (equals wave length of ≈ 33 cm) and with so many gaps in protection it is unlikely that they will block cell phone signals either.--Aspro (talk) 12:17, 28 April 2010 (UTC)

I think you'll find that some cell phone frequencies are 900 MHz, not 900 Hz. And not all are, especially in countries other than the USA, where some of us live. --Phil Holmes (talk) 15:05, 28 April 2010 (UTC)

Thanks --Aspro (talk) 15:42, 28 April 2010 (UTC)

Nathan Stubblefield's wireless portable telephones used 900 Hz among other audio frequencies, circa 1902. As for cell phones and Faraday cages, I put my cel inside a microwave oven (turned off) and it rang when I called it. Ditto for an oven and even for a stainless steel pot with the lid on, and a sheet metal mailbox. The only thing that prevented it receiving the call was an old castiron Dutch oven (relatively thick metal). The cel towers must transmit quite a strong signal. Strangely, it does not get a signal in my basement. Edison (talk) 03:52, 29 April 2010 (UTC)

Has anyone mentioned Lightning rod? Pretty good article actually, even has a section on aircraft. Vespine (talk) 23:12, 28 April 2010 (UTC)

EM colours

Looking at this informative diagram, I was wondering about certain crustaceans (shrimps) that can see the UV spectrum (or animals that can see IR) and what colours they can actually see. Then I had a random but intriguing thought - if we could see sound, what colour(s) would it be? How/why did the mechanisms of animals adapt to see higher/lower frequency EM and why can't any animal see sound? Sandman30s (talk) 13:35, 28 April 2010 (UTC)

Animals cannot see sound because sound is MUCH lower in frequency than light. It's like asking why no animal can hear light either. The question if we could see sound, what colour(s) would it be? is meaningless; we could never see sound, and even if we could it would be impossible to describe with the very limited color selection humans have. 99.137.221.37 (talk) 13:42, 28 April 2010 (UTC)

Well, we need to define "see". If we mean perceive sound using eyes, then that's just nonsense, it's not what eyes do. If we mean get information using sound equivalent to that we get from light, then echolocation does something very close to that in some species (eg. bats). There is no concept of colour, though, since it is an active process - the sound is emitted by the animal, so the animal controls the frequency. --Tango (talk) 14:23, 28 April 2010 (UTC)

We don't really have words for the "Colors" you'd see if your vision used different primaries than human vision, if that's what you're asking. APL (talk) 14:07, 28 April 2010 (UTC)

There's a reason that color is the go-to example for the philosophical concept of qualia -- the important characteristic of red, green, and blue is that they are different from each other, nothing more. Philosophers will then argue about whether there is some kind of "essential redness", or if red can be completely described as "the color between 630 and 740mm in wavelength, associated with blood, fire trucks, and stop lights, etc."

Qualia haven't (and pretty much can't) be proved to exist, so questions about "what would it be like to see color differently" are philosophical ones. If you want some fun reading in the area, see philosophical zombie, and try to decide if p-zombies are impossible, possible but non-existent, or everywhere! Paul (Stansifer) 14:15, 28 April 2010 (UTC)

Second question first: It has been proposed by some scientist that bats may perceive their received echoes as visual impressions and in colour, but that's not proven yet. I will leave out people with Sound -colour-synesthesia fascinating as it is. However, to answer your question, it would be better to ask about the advantages of the visual spectrum for our sight and the evolution advantage that favoured it. Basically its down to frequency and the biological limitations of the two sensing organs. The retina evolved from part of the neurone network of the brain. It has many light sensitive nerve endings onto which the image of the external world can be focused. Or put it a different way: it can detect spacial separation of points to form a mental image. Whereas the ear evolved from part of the jaw and other bits of the anatomy into the organ it is today but each ear can only register one scale of frequencies. The two ears can detect differences in loudness and phase. But very often one has to turn one's head to determine the direction of the noise source. Now, this has a limitation that can be understood a little by understanding Information theory. Sound ( in air, S.T.P.) has a narrow bandwidth. Other noise sources easily swamp the 'useful' ( and sometime life preserving) information in such a system. Eyes, don't have that problem. Bats have mitigated this shortfall to some small extent and enough to hunt by, by using higher frequencies, which in effect increases the usable bandwidth well above ours. We evolved ( or so I'm told ) on the ancient, open, savannah. In this environment, it is useful to have astute discrimination for the phase shift of lower frequencies, as made by animals that wanted to eat out ancestors. It is also useful for hunting, as the phase shift give good spacial information as to location of our other hunting companions. It has been suggested that we evolved our ability to run efficiently for extended periods because that way we could run our quarry to exhaustion. The ability to hear as we do, is well suited to this type of pursuit. So, the answer is that visual sight gives animals an evolutionary advantage, which sound alone would not.--Aspro (talk) 15:11, 28 April 2010 (UTC)

If you could see sounds, you would have a seismic image or a sonogram. Sound does not have a color. It has a power spectrum, and can be described as many frequency components, each with their own amplitude and phase. In some ways, this is similar to optics, insofar as light also can be described with a frequency spectrum; both phenomena are waves; but the similarities end there. The type of waves are dramatically different; the scales (of both energy and wavelength) are dramatically different; and therefore, the transducers that can convert the physical effect into usable information are very different (microphones and ears, versus cameras and eyes). If you feel like redefining the word "color" to be equivalent to "frequency", you may consider any frequency-spectrum to contain "color" - but that's a matter of word-choice. In practice, when we generate images using non-visible sources of information, we typically create false color images, where the color in the graph indicates some other property (most often, amplitude, and not frequency). But we can create false color images using any parameter along the color axis. For example, hyperspectral images "compress" many non-visible wavelength spectral channels into the set of printable, visible colors. Nimur (talk) 18:26, 28 April 2010 (UTC)

A peculiar colourisation of Chopin (video) Cuddlyable3 (talk) 19:19, 28 April 2010 (UTC)

Thanks for the varied answers and fascinating links! Sandman30s (talk) 14:57, 29 April 2010 (UTC)

Dream Recall

I've tried everything to improve my dream recall. I kept a dream diary, I interrupted the sleep cycle during rem sleep etc, I followed all the guides for dream recall and none of it works. So I was wondering, are there any scientifically proven methods that improve the recollection of memories from dreams? 82.43.89.71 (talk) 14:15, 28 April 2010 (UTC)

I can't see why any scientist would see a need to do a review of the techniques, much less try to develop a protocol. The main use of a dream diary appear to be for indulging in the pastime (or art) of pseudo-psychotherapy dream interpretation. In these modern times (i.e. post Jung, etc), the phenomena known as dreaming is now thought by scientists to serve as a means to consolidate memory. Any 'high emotional' periods from one's past would naturally feature from time to time as links get made from the current day's events but this doesn't mean that they have any meaningful significance (or so I am informed). This seem reasonable to me, as I've known (2 or 3 if you include their spouse ) people get very intrigued by dream interpretation and spent time (after getting their doctorate) to studying it professionally, they all eventual come to the conclusion that it is bunkum. I know this is not a very useful answer but it might save you searching in vain for some scientific work that probably does not exist --Aspro (talk) 18:14, 28 April 2010 (UTC)

I may be wrong here, but it seems that the OP is asking about simply improving his ability to remember his dreams rather than interpret them-- for which things like keeping a "dream diary" can be quite helpful. AlexHOUSE (talk) 18:20, 28 April 2010 (UTC)

His asking is their any scientific proven methods and I'm suggesting probably not and explaining why. Isn't some answer better than non?--Aspro (talk) 18:26, 28 April 2010 (UTC)

Absolutely. Although there's nothing I can find in our articles on oneirology that would suggest scientists are actively plugging away at how to remember your dreams. OP: you might find more tips for dream recall by searching for methods for lucid dreaming-- a field with a little more scientific research put into it. AlexHOUSE (talk) 18:33, 28 April 2010 (UTC)

I don't see how the OP could interrupt their own REM sleep. An effective technique is having an observer wake the subject and record their dream account immediately.Cuddlyable3 (talk) 19:08, 28 April 2010 (UTC)

Alarm clock and notepad? AlexHOUSE (talk) 19:19, 28 April 2010 (UTC)

Bzzzzzz! Oh what a horrible noise, I must reach out and press the button to stop it. Now what was it I should do, oh yes, I have to write down stuff. So here is my notebook. It reminds me of other notebooks. Yawn. Is this pencil sharp enough? Right, how shall I phrase what I was dreaming about? Uh, what the **** was I dreaming about anyway? It was probably something silly anyway. This is not working! Cuddlyable3 (talk) 10:14, 29 April 2010 (UTC)

Alan McGlashan, author of “The Savage and BeautIful Country” said the best way to encourage the Dreaming Mind to facilitate recall of dreams is to respect it and them. Keeping a dream diary would definitely help. Also eating lobsters. Kittybrewster ☎ 20:38, 28 April 2010 (UTC)

Lobsters? Is there some chemical in lobsters that helps remembering dreams? 82.43.89.71 (talk) 20:45, 28 April 2010 (UTC)

No. Eating lobsters increases the likelihood of having dreams. Kittybrewster ☎ 20:26, 29 April 2010 (UTC)

What exactly is in lobsters that has that effect? 82.43.89.71 (talk) 20:31, 29 April 2010 (UTC)

Does it matter? It could be a chemical, a hope, an expectation or faith. Kittybrewster ☎ 20:45, 29 April 2010 (UTC)

Of course it matters. I want to know why eating lobsters would increase the likelihood of having dreams. References would be nice (this is the reference desk after all) 82.43.89.71 (talk) 21:40, 29 April 2010 (UTC)

Sorry if I wasn't clear with my question. I am indeed trying to remember my dreams more clearly, as currently I have extreme difficulty remembering anything from my dreams. I do understand that scientists aren't actively working on ways to improve dream recall, but I just wondered if there had been any discoveries at all that might improve remembering dreams. Perhaps a chemical that is known to improve dream recollection or something? 82.43.89.71 (talk) 20:45, 28 April 2010 (UTC)

Maybe some dreams just don't want to be remembered. Try to record the dreams when you can remember them clearly, and when you can't then record all the details you do remember before they fade away. ~AH1^(TCU) 23:04, 28 April 2010 (UTC)

Richard Feynman at one time had an interest in recording his dreams, didn't he? 86.21.204.137 (talk) 19:26, 29 April 2010 (UTC)

He sure did. I've recorded my dreams too, and it seems to work pretty well for remembering them (at least better than when I don't). But the OP has already tried this, and it's not working out, so he's asking if there's anything else he can try. Buddy431 (talk) 20:10, 29 April 2010 (UTC)

My suggestion to the OP would be, if he/she has a vivid dream that's worth remembering, he/she should make a conscious effort to wake up, and then write it down ASAP. I don't know how well it'll work for him/her, but it works for me (I've ended up with quite a few good song lyrics this way, not to mention an idea for my first novel -- though when I have dreams with new songs in them, I tend to awaken on my own). FWiW 76.103.104.108 (talk) 06:07, 30 April 2010 (UTC)

Ambient construction

My son is working through a college report on string theory and asked me for help in understanding some key concepts one of which is "ambient construction". I consulted the wiki page as I had no idea what it meant.

I read: "In conformal geometry, the ambient construction refers to a construction of Charles Fefferman and Robin Graham[1] for which a conformal manifold of dimension n is realized (ambiently) as the boundary of a certain Poincaré manifold, or alternatively as the celestial sphere of a certain pseudo-Riemannian manifold."

and I am now more confused then ever. Can someone please explain this to me at a level most adults would understand? TheFutureAwaits (talk) 14:26, 28 April 2010 (UTC)

Not really, no. It is very technical. I've studied quite a lot of topology and even I would have to look up some of those terms (I've never come across the phrase "celestial sphere" in this context). String theory involves a lot of topology. If you don't have the necessary background, you won't be able to understand the more technical areas of the subject. If you want to try and understand it, you should start with manifold, but don't expect it to be quick or easy. Your son should probably ask someone that already knows about the subject (classmates, lecturers, tutors). --Tango (talk) 14:47, 28 April 2010 (UTC)

"Poincaré manifold" means hyperbolic space in this context. The boundary of hyperbolic space (at infinity) is a circle/sphere (it's the boundary of the Poincaré disk model). There's no natural notion of distance on the boundary, because everything is at infinity, but angles and distance ratios make sense: the geometry of the boundary is conformal. You need hyperbolic space, rather than Euclidean space, for this because the conformal boundary of Euclidean space is just a single point (the north pole of the Riemann sphere in the two-dimensional case). "Pseudo-Riemannian manifold" means "curved spacetime as found in general relativity", but in this case they're probably talking about some very specific curved spacetime, like Minkowski space or anti de Sitter space. "Celestial sphere" means the boundary at infinity of the future (or past) light cone at some point in that spacetime (it doesn't matter which point if the spacetime is symmetric enough). The celestial sphere of n+1 dimensional Minkowski spacetime is the same as the boundary of n dimensional hyperbolic space. This isn't exactly "at a level most adults would understand", but maybe it will help somewhat. -- BenRG (talk) 21:42, 28 April 2010 (UTC)

Actually I think that does clear things up a bit. Essentially it's a particular type of model that enables establishing boundries in what would otherwise be infinite space. I still don't get what that would imply but at least I get the basic meaning. TheFutureAwaits (talk) 23:00, 28 April 2010 (UTC)

Ions

Why Hg₂²⁺ is called Mercury(I)?--Mikespedia is on Wikipedia! 14:36, 28 April 2010 (UTC)

It is an example of Stock nomenclature. The Roman numeral in mercury(I) indicates the oxidation state of each mercury atom, whereas the 2+ superscript in Hg₂²⁺ denotes the total charge of the compound ion. TenOfAllTrades(talk) 14:42, 28 April 2010 (UTC)

The symbol Hg is Latinized Greek: hydrargyrum, from "hydr-" meaning watery or runny and "argyros" meaning silver. See the article Mercury (element). Cuddlyable3 (talk) 18:52, 28 April 2010 (UTC)

Since the mercury ion contains two atoms and has a total charge of 2+, each atom has a charge of 1+, making it mercury(i).--98.221.179.18 (talk) 19:21, 28 April 2010 (UTC)

Mercury(I) is also a weird case because it dimerizes. Unlike most metal ions, which are happy to live by themselves, the Mercury(I) ion forms a dimer, much like the neutral Halogens to (hence chlorine gas = Cl₂.) There are reasons for this, but if you are just at the state of learning how oxidation numbers work in your education, you can just take it as a "weird" case. If you are interested in more details on this, Mercury polycations discusses it. --Jayron32 20:46, 28 April 2010 (UTC)

help me please (eating heroin rabbits)

I must be knowing any effect or dangers that would be coming if someone (not being me!) were to be ingesting 5 heroin filled game rabbits. please be helping. This is urgent! —Preceding unsigned comment added by TalipTaste (talk • contribs) 16:02, 28 April 2010 (UTC)

If you think it's urgent, call the emergency services - the operator will at least be able to tell you if it's an emergency or not. Heroin#Effects. I imagine the actual quantity of heroin would need to be known. We can't give medical advice, by the way. Vimescarrot (talk) 17:01, 28 April 2010 (UTC)

Also, see gluttony if you have in fact eaten 5 rabbits in a short time. Googlemeister (talk) 19:03, 28 April 2010 (UTC)

And protein poisoning. AlexHOUSE (talk) 19:08, 28 April 2010 (UTC)

Also, rabbit starvation. ~AH1^(TCU) 23:01, 28 April 2010 (UTC)

(Same thing.)AlexHOUSE (talk) 23:05, 28 April 2010 (UTC)

Also, see troll —Preceding unsigned comment added by 86.4.186.107 (talk) 07:56, 29 April 2010 (UTC)

Foiled again. AlexHOUSE (talk) 17:32, 29 April 2010 (UTC)

Naming of a species

The new British moth is named after its discoverer.[18] I thought he was supposed to name it after something other than himself, according to conventions. Imagine Reason (talk) 17:33, 28 April 2010 (UTC)

I think you've misparsed the article. Nowhere does it say HE named it after himself - to quote the article - "In January this year, the moth was officially recognised in the journal Zookeys as a new species, named Ectoedemia heckfordi after its discoverer." - implying it was named in his honour by a third party. Exxolon (talk) 18:21, 28 April 2010 (UTC)

As I understood it, the person who discovers a species gets to name it. Why didn't it happen in this case? Imagine Reason (talk) 13:54, 29 April 2010 (UTC)

The article is poorly written. The discoverer is sometimes referred to as an amateur naturalist and sometimes as a biologist. In theory that's certainly possible, but sure sounds weird. Anyway, it only says he was the discoverer, not the person who described it scientifically, which is who would have provided the name. You see this sometimes in dinosaur circles - some kid finds the bones and "discovers" the dino, but it's a professional palaeontologist who actually does the write up and determines whether it's a new species or not. The kid (or whoever) often gets his/her name worked into the species name. For example, see here. Matt Deres (talk) 16:18, 29 April 2010 (UTC)

Mass to energy conversion

If One could efficiently (100%) convert mass to energy and v.v., how much mass could you get out of the energy stored in a AA battery? How much mass could a 1GW nuclear reactor produce in an hour? Googlemeister (talk) 19:37, 28 April 2010 (UTC)

E = mc**2, and this page says an AA battery has at most 11050 joules of energy, so:

11050 J = m * c**2
11050 J / c**2 = m
11050 kg*m**2/s**2 / (3*10**8 m/s)**2 = m
11050 kg / 3*10**8 = ~0.00000000000012277778 kg

Similar math applies for the reactor case. --Sean 20:18, 28 April 2010 (UTC)

That would be about the mass of a few hundred bacteria. That's a lot more than I'd have guessed.

11000 / (3x10⁸)² = 1.1x10⁴ / 9x10¹⁶ = 1.2x10^-13kg.

SteveBaker (talk) 00:55, 29 April 2010 (UTC)

According to [19], an AA battery contains 1kJ. If we plug that into E=mc², we get a mass of 1000/c²=1.1*10^-14kg. 1 gigawatt-hour is 3.6*10¹²J, or 40 milligrams. --Tango (talk) 20:17, 28 April 2010 (UTC)

If you compress a mass of 6*10^11 kg to within its Schwarzschild radius of 8.9*10^(-16) meters, you'll get a micro black hole that will emit about 1 GW of power in the form of Hawking radiation (at a temeperature of about 200 billon K). Then, as Tango has calculated, it will only lose 40 milligrams per hour, which is 1 kg per 2.85 years. So, we would have plenty of energy and no headaches about what to do with waste! :) Count Iblis (talk) 22:05, 28 April 2010 (UTC)

Now all we have to do is figure out where can we get one of those. Dauto (talk) 23:14, 28 April 2010 (UTC)

Well, that and how we're going to stop it falling through the floor and bouncing back and forth through the earth from now until doomsday. Sure, you can charge it up and hold it in a suitable electric field - but you need to be really careful...one tiny "oopsie" and you're in deep poop! SteveBaker (talk) 00:55, 29 April 2010 (UTC)

Yes, one has to be careful with these things! One could perhaps put such a micro black hole in orbit around the Earth. Count Iblis (talk) 02:18, 29 April 2010 (UTC)

See The Hole Man. Ariel. (talk) 02:40, 29 April 2010 (UTC)

Is it normal for men to have a noticeably reducing libido at the age of 50.

Some of my colleagues of a similar age still shout "phwar" when a teenage girl walks past our window. I find I'm thinking "she's younger than my daughter" and only feeling fatherly thoughts. One guy said "what would you like to do if you had a night out with her" when one walked past. Of course I said "cor just imagine", but I was really thinking that if I would probably just treat her like my daughter and take her to the Pizza hut and talk about how her careers going! Is this normal for someone in their early fifties? —Preceding unsigned comment added by 88.107.183.51 (talk) 20:07, 28 April 2010 (UTC)

Congrats, you're one of the few non-perverts in the world. :-) But seriously, male libido starts decreasing from around 18, hence the popularity of Viagra. StuRat (talk) 20:17, 28 April 2010 (UTC)

Yes. You have a daughter and therefore a different reference point. Very healthy and much more grown up. Kittybrewster ☎ 20:20, 28 April 2010 (UTC)

Your colleagues may be doing exactly the same thing you are are just saying it because they thing it's what they should say. --Tango (talk) 20:22, 28 April 2010 (UTC)

As another guy in his 50's (without the daughter) - I doubt it's a matter of libido so much as a matter of maturity and respect. I suspect that (assuming you're otherwise unattached) you'd have no trouble getting sexually interested in an attractive person with the right attributes whom you met under reasonable circumstances. I too don't see the attraction in young women encountered at random like that. Like the majority of people of that age, I find them mostly superficial and uninteresting after not much time spent with them. But reduced libido is another matter entirely. Don't confuse selectivity with disinterest. But all of that bravado from younger guys definitely gets tiresome - and I'm pretty damned sure it doesn't do much for the ladies either. Those of us who have been around the block a few times can more easily tell what's just bullshit and what's not. So don't sweat it...go out and buy yourself a brand new convertible...a red one...with turbo...it's time! :-) SteveBaker (talk) 23:14, 28 April 2010 (UTC)

An old adage says something like (for men's sexual prowess) "Age 20:Triweekly. Age 40: Try weekly. Age 60: Try weakly." If there's any compensation for the decreased libido, it is said to be that 60 year old women look far hotter to a 60 year old man than they do to a 20 or 40 year old man, while 20 and 40 year old women still look hot. Edison (talk) 03:35, 29 April 2010 (UTC)

"I'd rather have two girls at 21 each, than one girl at 42." -- W.C. Fields (singing) ←Baseball Bugs ^{What's up, Doc?} carrots→ 17:49, 30 April 2010 (UTC)

But would a 60-year-old man still look hot to a 40-year-old woman? 76.103.104.108 (talk) 06:10, 30 April 2010 (UTC)

If he has enough money. Those babes don't hang around Hugh Hefner because of his looks, you know. ←Baseball Bugs ^{What's up, Doc?} carrots→ 17:49, 30 April 2010 (UTC)

Is the OP aware that his expletive "cor" is derived from "cor blimy", itself derived from "God blind me (if I tell a lie)"? This list can help linguistically challenged Americans.Cuddlyable3 (talk) 10:00, 29 April 2010 (UTC)

Chromate formation

Can chromates be formed by reaction of chromium(III) oxide with a hypochlorite. When I react a chemical (formed by the neutralization using ammonia of Nichrome previously dissolved in acid) with sodium hypochlorite, a yellow solution is formed. How could you tell whether it was iron(III) chloride or sodium chromate? I duplicated this reaction with a chromium-containing stainless steel screw and it formed the yellow color too. --Chemicalinterest (talk) 20:41, 28 April 2010 (UTC)

Add thiosulfate to the solution. If Iron(III) is present you will form the blood-red Thiocyanatoiron(III) complex ion. If Iron(III) isn't present, the yellow is probably from Chromate or Dichromate. --Jayron32 20:55, 28 April 2010 (UTC)

ED: I screwed up. You should add thiocyanate to the solution. My bad. --Jayron32 01:59, 29 April 2010 (UTC)

Unfortunately I do not have thiosulfate or thiocyanate. --Chemicalinterest (talk) 21:13, 28 April 2010 (UTC)

These are the reactions: 2 Ni + 2 Cr + 10 HCl → 2 NiCl₂ + 2 CrCl₃ + 5 H₂ | NiCl₂ + CrCl₃ + 5 NH₄OH → Ni(OH)₂ + Cr(OH)₃ + 5 NH₄Cl | 2 Ni(OH)₂ + 2 Cr(OH)₃ + 4 NaClO + 4 NaOH → 2 Na₂CrO₄ + 4 NaCl + 7 H₂O + Ni₂O₃ --Chemicalinterest (talk) 21:24, 28 April 2010 (UTC)

Iron(III) is a major Lewis acid (in addition to being an oxidant). I don't know as much tests but I am sure there are plenty. Cr(VI) prefers to oxidise over any Lewis acid ability, I think. Also Fe3+ forms many insoluble complexes ... whereas I believe Cr(VI) compounds tend to be more water-soluble. John Riemann Soong (talk) 22:29, 28 April 2010 (UTC)

Btw, Iron(III) chromate forms an insoluble salt. If you didn't observe this, well you probably don't have both ions in there. I would test with some copper (II) chloride (will precipitate copper chromate), sodium sulfide (will precipitate FeS), etc. Your reaction might have just worked because iron(III) hydroxide is very insoluble in water. John Riemann Soong (talk) 22:45, 28 April 2010 (UTC)

Adding a source of phosphate will also precipitate any Fe(III). (Try not to add it in the form of phosphoric acid...monoprotonated or free phosphate is preferred...) John Riemann Soong (talk) 22:51, 28 April 2010 (UTC)

I did react it with ascorbic acid, a reducing agent, and the color faded, but the Fe(III) could have been reduced too. I wonder if alkali would work. --Chemicalinterest (talk) 12:53, 29 April 2010 (UTC)

Alkali/base wouldn't reduce Fe(III) normally (you would be forming N-oxide, peroxyacid, O2, etc. depending on base used). But OH- would precipitate Fe(III). How much excess NaOH did you add? John Riemann Soong (talk) 15:19, 29 April 2010 (UTC)

I was wondering whether it works. I plan to try it soon. --Chemicalinterest (talk) 19:53, 29 April 2010 (UTC)

I happen to only have ammonia, so I'll make sure I do it outside or I might not be here to tell the results. :) --Chemicalinterest (talk) 19:54, 29 April 2010 (UTC)

I added 10 times its volume of ammonia and no precipitate formed. So then it is hexavalent chromium. --Chemicalinterest (talk) 20:03, 29 April 2010 (UTC)

Well the thing is that ammonia tends to form complexes, not insoluble salts. John Riemann Soong (talk) 05:20, 30 April 2010 (UTC)

Oh whoops, silly me, you were using it as a replacement for NaOH, not using NH3 to complex the Fe(III) directly. John Riemann Soong (talk) 05:21, 30 April 2010 (UTC)

Do you know why you have to put the test tube outside? When bleach is reacted with ammonia, it forms toxic chloramine gas. --Chemicalinterest (talk) 11:53, 30 April 2010 (UTC)

Geology

Recently a large quantity of "river rocks" have been imported to our area to be used in landscaoing. These rocks came from somewhere in Arizona. The rocks appear to be of great variety. some are granite some basesalt etc. They vary in size from one inch to one foot. A few of them are almost perfectly round, but the top and bottom are slightly and equally convex. They are, of course, smoothed by errosion. I do not think, however, that errosion alone explaims there near perfect symmetry. I suspect that they were magma which was blowen into the air by a volcano. As they spun in the air they would have developed into a ball shape. When they struck the ground they would have been flattened like a pancake. But if such were true, one would expect one side to be flatter than the other side. Such is not the case. Can some one explain to me the origin of these beautiful rocks? Thanks, wsc—Preceding unsigned comment added by 66.27.177.28 (talk) 23:04, 28 April 2010

How about if they just got rounded off by rolling down a stream ? Perhaps one got stuck somewhere and had the top erode more, making it slightly flattened. Then, the next time the river flooded and it rolled, it settled on that flatter side (and then the opposite side eroded the same way). StuRat (talk) 23:11, 28 April 2010 (UTC)

If these have been imported in large quantities, then I think the easiest and most reliable way to find out, is to approach such a home owner with said landscape and inquire. Take a pen and paper for making notes. If your impressed with their garden rock feature, then that is likely to please the owner who may be happy to tell you the supplier, and from them you can find the rock's geological details, formation etc.--Aspro (talk) 23:30, 28 April 2010 (UTC)

Did you mean to type "If you're impressed..." ? Cuddlyable3 (talk) 09:50, 29 April 2010 (UTC)

Rock that is flung out into the air turns into light stuff like pumice, not into basalt; and granite doesn't form unless cooling is very slow. I'm not aware of any other mechanism that erosion that gives rounded rocks. Looie496 (talk) 00:19, 29 April 2010 (UTC)

It is quite possible that decorative rocks like those you describe could be artifically ground into shape. Imagine an industrial scale tumble finishing process. Astronaut (talk) 01:58, 29 April 2010 (UTC)

What's wrong with the theory that they are just perfectly normal and abundant river rocks? ok some of the rocks in that pic don't look PERFECTLY symmetrical, but some do. Vespine (talk) 05:18, 29 April 2010 (UTC)

You can get some remarkably symmetric shapes in volcanic bombs, the article has a wonderful example, but I don't think that's what is being described here. Pebbles in rivers (and on shorelines) become progressively rounded due to lots of knocking together with other pebbles (that sort of tumble finish comes free of charge and on a vast scale). They don't quite make perfect ellipsoids but they can be pretty close.[20] It's possible that someone has selected the most symmetrical from some natural examples but that seems like a lot of work to go to. Mikenorton (talk) 19:45, 29 April 2010 (UTC)

Ghost

Is ghost really exist?75.168.119.109 (talk) 23:38, 28 April 2010 (UTC)

Real ghosts on TV. Cuddlyable3 (talk) 09:47, 29 April 2010 (UTC)

Scientists are very sceptical about their existence. Wikipedia has an article about them. Ghost#Scientific_skepticism--Aspro (talk) 23:48, 28 April 2010 (UTC)

Thank You!75.168.119.109 (talk) 00:04, 29 April 2010 (UTC)

No - they don't exist. Aspro: we shouldn't sugar-coat this. I don't know of any scientists who are actually "skeptical" about ghosts. They know ghosts aren't remotely possible - period. Some might come out with some wishy-washy super-formal "we haven't yet proven that they don't exist" statements if forced into it - but nobody in the hard sciences really believes there is even a one in a billion-trillion chance that they could exist. There is absolutely zero solid evidence FOR ghosts - and against that are all of the laws of physics and biology that say they can't exist. The hypothesis that there are ghosts fails the falsifiability test. Occam's razor says the best approach is to assume that they don't exist because that assumption violates no known laws and the guess that they do exist violates many. Russell's teapot asks why you'd believe in ghosts but not the much higher chance that there is a teapot in orbit about Mars (or pink piano-playing aardvarks on the dark side of the moon - or any other crazy thing you might think up on a boring Wednesday afternoon). There are a literal infinity of things one might believe in without any evidence whatever - why pick the ghosts rather than the pink aardvarks? SteveBaker (talk) 00:05, 29 April 2010 (UTC)

How is it sugar coated. In science one is never absolutely dogmatic about anything. Also, accepting somebodies word on their say so alone, is stupid and foolish. Judgement, comes with practise and experience. To sort cut this process with blunt dogmatic statements is to encourage the slow acceptance of Argument from authority fallacies, which can lead to pseudo- scepticism, where what one feels should be over powers logical deduction, because the right way to think, has never been learnt properly. Scientists who are not naturally sceptical -even about their own beliefs- are not really scientists but merely highly qualified lab technicians.--Aspro (talk) 00:59, 29 April 2010 (UTC)

I agree with Steve in principle. There is a large class of "paranormal" that we can categorically discount as "absolutely untrue." Things like ghostly apparitions that take human-like form and preserve the consciousness of the individual in the form of some type of gaseous mist - well, these are just plain contrary to all kinds of laws of physics and chemistry and biology. If somebody wants to go out and concoct an extremely restricted concept of "ghost" by playing games with definitions, and putting a bunch of conditions they might be able to weasel out a bizarre definition that a scientist could say "well, unlikely, but not inconsistent with scientific fact." But any such definition of a ghost would not look like the representations of ghosts in mythology and fiction - a God of the gaps sort of approach that would leave the ghost-enthusiasts pretty dissatisfied. As we have become better able to explain the biological processes that constitute life, it has become harder and harder to justify an afterlife - especially in the form of ghostly apparitions - in any way that is even remotely scientific. Ghost ideas can persist because people are unscientific and inexact in their descriptions. "They're sort of transparent", for example. The details and descriptions are vague, but if somebody with an attention to detail and a methodical, analytic approach (ergo, a scientist) starts thinking about any particular set of observations, it becomes blisteringly clear that the cultural portrayals of ghosts are pure fiction. Follow up on the "semi-transparent ghost" - define some optical properties; measure some reflectance coefficients; measure an optical spectrum and deduce a chemical composition. Is it a solid, liquid, or gas? Where does it get its energy for locomotion, if not by conventional biological metabolism? If it is flying, is it suspended buoyantly, or is it exerting energy to hover? If it is a skeleton, how does it move its structure without musculature? Find a way to make any of these observations remotely consistent with some type of explanation. We can not, so we can categorically say that descriptions of ghosts are due to faulty observation - and are better studied by psychologists and anthropologists. A fascinating, and scientific question, is "what causes groups of people to share similar descriptions of fictional things?" The answer is a complicated melange of biological/psychological predispositions, cultural and social conditioning, confirmation bias, and so on. Nimur (talk) 08:03, 29 April 2010 (UTC)

What about a mental image that is in the form of a semi-transparent ghost? That wouldn't break the laws of science 'cause it's all in the observer's mind, right? 76.103.104.108 (talk) 06:15, 30 April 2010 (UTC)

As I said, "better studied by psychologists... ." The neurobiology of unstimulated perception is definitely fascinating, and has many unanswered questions that are open to actual scientific research. Nimur (talk) 14:41, 30 April 2010 (UTC)

You are right that scientists should always be sceptical, but I think it would be more precise to say "Scientists are confident that ghosts to do not exist, but they accept that they could be mistaken." (You don't really need to include the last part since it applies to any statement of science and is implicit in the work "scientists".) --Tango (talk) 13:34, 29 April 2010 (UTC)

I disagree, just because science has not proven something yet, does not mean it is untrue. Also, if one has experienced paranormal activity, one is more likely to beleive, even if it cant be explained by science yet. Auschwitz is a good example, there is a presence there that cannot be explained by science. But it is there, and for obvious reasons. —Preceding unsigned comment added by 62.172.59.90 (talk) 13:13, 29 April 2010 (UTC)

Science has never proven anything. Proof is a mathematical concept. You have to weigh up two possible explanations for people's paranormal experiences: 1) They are somehow mistaken about what they experienced. 2) All of science is wrong and all the accurate predictions we have made have just been luck. Both of those are entirely possible, but the former is overwhelmingly more likely. --Tango (talk) 13:34, 29 April 2010 (UTC)

Proof is indeed just a concept. There's always a very small, negligible chance that in the second something could come along to disprove your hypothesis. Probability is a better term. The probability that ghosts exist is miniscule, but many would choose to exaggerate that even further. Regards, --—Cyclonenim | Chat  16:50, 29 April 2010 (UTC)

What does "just a concept" mean? --Tango (talk) 16:59, 29 April 2010 (UTC)

Just an idea, in practicality. It may have a mathematical basis but in every day terms we use probabilities. Regards, --—Cyclonenim | Chat  01:21, 30 April 2010 (UTC)

And probabilities aren't an idea? --Tango (talk) 06:14, 30 April 2010 (UTC)

April 29

Albert Einstein

Who is the next genius, i meant the smartest person, after Albert Einstein's Death?75.168.119.109 (talk) 00:04, 29 April 2010 (UTC)

Tricky: My vote goes to Richard Feynman - but there are a lot of other possibilities. The problem is that the word "smart" is hard to pin down - the concept of "intelligence" and even "IQ tests" is very fuzzy - and the most intelligent people of all sometimes do very badly at those kinds of tests because they are so much smarter than the people who designed them. If you read biographies of Einstein, you tend to come away with the idea that aside from his abilities in the areas of theoretical physics - he was a complete idiot and a general pain in the ass. I don't think I would have liked him - or found him particularly interesting to talk to. Similar complaints may be raised against other possibilities such as Stephen HawkinsStephen Hawking. Personally, I respect Feynman precisely because he was brilliant (and funny and talented) in absolutely everything he approached - the sheer breadth of his talent was impressive. But I'm sure we'll have a lot of alternatives put forward. SteveBaker (talk) 00:19, 29 April 2010 (UTC)

I'm not convinced that Steve meant to link Stephen Hawkins (an Australian rower) in the above comment. Perhaps he meant Stephen Hawking (the physicist). Astronaut (talk) 01:51, 29 April 2010 (UTC)

No, no! I'm in awe of australian rowers! sorry SteveBaker (talk) 02:48, 29 April 2010 (UTC)

You mean nobody is the smartest person? I would agree with that because nobody know everything. I'm sure Albert Einstein didn't know much about other areas beside science and physic like art, genetic, biology...75.73.152.238 (talk) 00:32, 29 April 2010 (UTC)

The problem is that Einstein is not the "smartest person," he's just an icon, a popular hero. He was a smart guy and did smart things, to be sure (Many of his "big ideas" were clever; a few were downright brilliant and have stood the test of time; a few did not pan out at all and we now think he was wrong). But the popular representation of him is simultaneously exaggerated and misunderstood. (He was not doddering and out of touch with the world. He was intensely political and controversial and pushed the envelope on things like war, race, and democracy to the point that he accrued a large FBI file.) Einstein is a singular icon... there is almost nobody else like him in the 20th century, from the point of view of being the living embodiment of what it means to be a "scientist" in the popular mind. Stephen Hawkings is something of a comparison (his "iconic" status is derived in a large way from his disability in a fairly obvious way). Newton, Galileo, and Darwin served the role for earlier generations (and our own, of course). Anyway, SteveBaker's point is not that "nobody is the smartest person" but that "smartest person" is an ill-defined concept—it makes it sound like you can measure all-around smartness with one number. Nobody thinks that is case, at least not on the level of pitting individual geniuses against each other (which is not, for example, what IQ tests do). --Mr.98 (talk) 01:02, 29 April 2010 (UTC)

Right. If we had a really solid definition of "smart" we'd have a "smartest person". So maybe: "The person who is able to memorize and recite the most digits of PI" is the smartest - and currently that is a guy called Lu Chao who memorized 100,000 digits and was able to recite 65,000 digits before he mis-spoke and screwed up one digit. If you say it is the person with the highest recorded score on an IQ test then the answer is Marilyn vos Savant (who always strikes me as kinda stupid and annoying...but that's just my opinion). If it's "the person with the most Nobel prizes" then John Bardeen, Marie Curie, Linus Pauling and Frederick Sanger each have two - but Fred Sanger is the only one of them who is still alive. But which of those (or a gazillion other things I could come up with) should count? It's entirely a matter of opinion. My opinion is that being 'smart' at just one thing isn't so impressive as being good at a wide range of things - and that's why Richard Feynman gets the prize as far as I'm concerned. He only had one Nobel prize - but he also became an expert bongo player, he learned to write the Tuvan language by reading an English-Russian and a Russian-Tuvan dictionary, he was a working theoretical physicist - who became a biologist as a 'vacation', he was a self-taught safe cracker, he taught himself how to 'lucid dream', he figured out the cause of the Challenger disaster and demonstrated the problem live on TV with a $2 clamp and a glass of iced water, he learned how to pretend to be drunk and to pick up women in bars using scientific principles!...he had a life that was filled to bursting with intellectual pursuits. I think he was the "all-round" smartest guy ever...but that's just my opinion - yours will undoubtedly be different. SteveBaker (talk) 01:29, 29 April 2010 (UTC)

See, and I would actually vote for Linus Pauling. His contributions to Chemistry are as important and wide reaching as Einstein or Feynman's were to Physics. He's as close to a Chemistry Polymath as there can be; his work stretches to nearly all aspects of chemistry. Pauling's rules are central to X-ray crystalography. He formalized the concept of electronegativity and used it to explain the ionic - covalent bond continuum. He invented the concept of resonance and of delocalized electrons. He worked in biochemistry, being the among the first people to explain how hemoglobin binds oxygen. He explained the main secondary structure in proteins, the so-called "alpha helix" and "beta-pleated-sheet" models. He helped explain the molecular causes of sickle-cell anemia. He also worked on nuclear mechanics, devising his own "spheron model of the nucleus". Oh, and he also won the Nobel Peace Prize for his anti-nuclear weapons activism. I've always placed him as second after Einstein in terms of overall importance to the general scientific world. --Jayron32 01:55, 29 April 2010 (UTC)

Sure - Pauling was a god in Chemistry - but what did he do outside of that? This isn't a question about what someone achieved - it's a question about how smart they were. Knowing absolutely everything there is to know about Chemistry requires you to be pretty smart - but that's not the limit on smartness...how smart was he in his daily life? Einstein really wasn't very smart when you took away his physics. Did Pauling do smart things in his spare time? What about on vacation? What did he do for fun? Did he use all of those 'smarts' in lots of other ways? Those are all rather important to me.

My "hero" (for want of a better word) has to be good at everything he/she does - and has to do a huge variety of things - inside and outside of some narrow career path. I could come up with a long list of theoretical physics stuff that Feynman did - but he also worked to improve science and math textbooks in schools, he worked on the Manhatten project but worked to subtly subvert the military - to mock their censorship rules by doing things like writing letters to his wife in codes that they couldn't break so they had to sheepishly ask him to please tell them how to decode the letters! He achieved many breakthroughs in computing algorithms...before there were actual electromechanical computers and "computers" were people. He trained his small army of "computers" to do impressive military-style drill with their pencils on command in order to impress the generals when they came around to visit!

Pauling's biographies are mostly stuff about chemistry - a bit about his anti-nuke activisim and a bit about the sad loss of his wife and subsequent bringing up of his daughters. He's a completely two-dimensional character. Chemistry - activism - kids...the end.

SteveBaker (talk) 03:17, 29 April 2010 (UTC)

Feynman's awesomeness comes mostly from being a character. I will not attempt to diminish his awesomeness, but most of his intrigue comes from his quirky personality and his expressions thereof. I would not attempt to compare the intelligence of Feynman vs. Pauling, except that Feynman's expressions of his intelligence come off as far more entertaining which is why he gets better pub. Surely You're Joking, Mr. Feynman! is a far more entertaining read than any biography of Pauling, and much of our impressions of Feynman come from that and other books about him. I will grant you that Feynman is a far more interesting person than Pauling, but that doesn't necessarily mean he was either smarter or more important to his field or to the general advancement of knowledge. I will grant you a "tie" with Pauling on anything except "entertainment factor" which Feynman wins hands down. --Jayron32 05:14, 29 April 2010 (UTC)

Linus Pauling was of course also known for his controversial work in and advocacy of orthomolecular medicine and megavitamin therapy, particularly vitamin C, in his later years. Nil Einne (talk) 09:00, 29 April 2010 (UTC)

I nominate Raquel Welch for contributions to Paleontology and medicine. Cuddlyable3 (talk) 09:40, 29 April 2010 (UTC)

Well if you're talking about people with major achievements in more than one field, then a modern candidate would be Professor Brian Cox (physicist), who had a Number One hit in the UK in the 1990s with D:Ream (Things can only get better), went on to become an astrophysicist and work at CERN, and now is a bit of a celeb. (oh and he's a bit dishy too!) --TammyMoet (talk) 10:56, 29 April 2010 (UTC)

Brian May. --Phil Holmes (talk) 13:28, 29 April 2010 (UTC)

Intelligence is task-specific. Einstein was great at physics and math and taking a high-level view of humanity. If you want to ask about who may be exceedingly learned in some regard, you will have to specify which regard. And if you don't want to be bothered with that, if you just want some names thrown out there, I will offer singer-songwriter Mark Knopfler. An account of his humanism, and ability to express it in majestic fashion. Vranak (talk) 14:23, 29 April 2010 (UTC)

Why Mark Knopfler, and not for example Johnny Cash? 76.103.104.108 (talk) 06:18, 30 April 2010 (UTC)

I think we've had a good demonstration on why it's so hard to define intelligence. I can think of at least three kinds of outliers - the genius that's virtually the best in the world at a certain thing (think: Albert Einstein), the polymath that's exceptionally good at a wide array of things (think: Leonardo Da Vinci), and the teacher that can seemingly understand virtually everything and relate it to laypeople understandably (think: Isaac Asimov). Now take the first kind and multiply it by however many branches of study have ever existed. Is Stephen Hawking smarter than, say, Bach or Mozart? How could you even compare them meaningfully? Or take guys from a millennium ago like Abu Rayhan Biruni and Avicenna. How could you compare their staggering accomplishments in virtually everything to a polymath of today? Do they get credit for figuring out huge swaths of the sciences during a time when getting eaten by a bear was a realistic cause of death for people - or does someone from today get credit for reaching even further, after the "easy" stuff has been done? Matt Deres (talk) 16:42, 29 April 2010 (UTC)

Cell

I knew all cells come from cell then where the first cell come from?75.168.119.109 (talk) 00:04, 29 April 2010 (UTC)

You should read our article Abiogenesis. The short, honest answer is that we don't know for sure - but we suspect that chemicals that can copy themselves (like, maybe RNA) could come about spontaneously from random chemical reactions in the soil or the oceans - then for such molecules to become trapped inside a lipid bubble and thereby form primitive cells. But we don't know for sure. We're pretty certain it wasn't magic though. SteveBaker (talk) 00:10, 29 April 2010 (UTC)

Evolution can't explain it. --Chemicalinterest (talk) 14:55, 29 April 2010 (UTC)

Evolution doesn't attempt to explain it: evolutionary theories aim to explain how existing forms of life change over time, not how life came to exist in the first place. 87.81.230.195 (talk) 21:14, 29 April 2010 (UTC)

Aliens

I have heard and read many resources show that aliens are really exist or do not exist. Is alien really exist?75.168.119.109 (talk) 00:07, 29 April 2010 (UTC)

You're aiming for all of the difficult questions today! See our article on the Drake equation which estimates the probability that there is intelligent life on other planets - and comes to the conclusion: "Yes, there probably is". But we haven't found life anywhere - so the answer can only be "probably". On the other hand, aliens visiting Earth...No - that doesn't seem either likely or possible from the evidence we have available. SteveBaker (talk) 00:12, 29 April 2010 (UTC)

I think the aliens have came to Earth before at least one time. If not then how could you explain all the UFO we have seen from the ancient time until today.75.168.119.109 (talk) 00:23, 29 April 2010 (UTC)

I don't explain "all of the UFO's" - there is not one single reliable sighting of such a thing. The ideas put around by "UFOlogists" are just typical 'nut job' stuff - packed full of unlikely conspiracy theories and unreliable "eye witness" testimony. The idea that a small craft could cross hundreds of lightyears and somehow hide from us for 60 years while still revealing itself in conveniently unconvincing ways to individual humans in the numbers they claim...it's not remotely credible. The idea that governments are 'covering up' the evidence is crazy - the government are completely inept at covering things up. Go to a UFO conference sometime (I did...once!) and the people there who claim to have been visited or abducted are the least convincing people you'll ever meet - their stories fall apart once you start asking careful questions - they are liars, one and all - mostly, they seem to be people who have had nothing interesting happen in their lives who have come up with this story to make themselves seem different, interesting, important. It's just sad. SteveBaker (talk) 01:54, 29 April 2010 (UTC)

Actually, Steve, UFO's really do exist on Earth -- just not the alien kind. See List of experimental aircraft, Skunk Works, Nellis Air Force Base, and Edwards Air Force Base for more details. :-) 76.103.104.108 (talk) 02:33, 29 April 2010 (UTC)

I don't think all of the people who said they have seen the aliens are all liars. There must be at least one of them say the truth. And also in ancient time there are some UFO were written by historian, i don't think their purpose is lying to us.75.168.119.109 (talk) 22:46, 29 April 2010 (UTC)

I expect very few UFO sightings are lies. Most of them are simply mistakes. --Tango (talk) 06:15, 30 April 2010 (UTC)

I wonder why aliens never try to contact us. Does anyone know?75.73.152.238 (talk) 00:32, 29 April 2010 (UTC)

Most aliens keep a low profile, because even if they are here legitimately, the Arizona police will stop them and demand their papers. Nimur (talk) 08:26, 29 April 2010 (UTC)

I agree with Steve! Just because YOU can't explain something, doesn't mean Aliens did it. As to why they haven't tried to contact us, well maybe they have but we missed it? One of the difficulties is the vast amount of empty space and time involved. I believe it is extremely likely there would be intelligent life somewhere else in the universe, but it might be a million years ago, or a million light years away, or billion, or any combination of the two. In any case, there's no real way to know, let alone communicate anything meaningful. Vespine (talk) 01:44, 29 April 2010 (UTC)

The universe is very, very empty, but it is also very very big. There are billions of galaxies, each containing billions of stars. A large proportion of those stars probably have planets. Using the Drake Equation it is easy to calculate there are probably other planets with intelligent life - quite possibly millions of planets. Because eveything is so far away that even light takes years to travel between the stars, it is unlikely that aliens would be able to make the journey to visit Earth, or for us to make the journey to visit them. Using current technology, it would take many thousands of years to travel to the nearest stars (see Voyager 2#Escaping the solar system and Voyager 1#Current activities for estimates of when these NASA probes could reach interstellar distances). Astronaut (talk) 01:46, 29 April 2010 (UTC)

Perhaps they do - but if they are out there - they are hundreds of light-years away. If you put the most powerful radio transmitter mankind has ever made on a planet orbiting the nearest star to us - then our most sensitive radio telescope would be unable to detect it. So unless these aliens have vastly more powerful transmitters than we do (or unless they know that we're here and can use a laser or something) - then we stand no chance of hearing them. Because the only way they could "know we're here" is if they can detect the signs of civilization in our atmosphere or something - and those changes only proceed outwards at the speed of light - they would have to be pretty close to us in order to have time to notice that we're here. Furthermore - their idea of "clear communications" might be very different from ours. We're expecting something like a sequence of prime numbers, transmitted in binary on a frequency near the "hydrogen hole" - but it might come in the form of choreography instructions for interpretive dance steps designed for creatures with eleven hooves and nine tentacles transmitted using 'spread spectrum' techniques. They might well be blasting us with copies of "The Encyclopedia Galactica" and "Welcome to the space-faring species club!" messages - and we'd never know it. SteveBaker (talk) 01:54, 29 April 2010 (UTC)

Also, aliens may not use electromagnetic radiation to communicate. For some alternative possibilities, see here and here. Count Iblis (talk) 02:05, 29 April 2010 (UTC)

There are many more possibilities - how about aliens who live long lives - but who's brains work v-e-r-y s-l-o-w-l-y. Suppose they sent their messages by radio or light at a rate of one bit per month or something. Would we notice such incredibly low frequency messages? Or suppose they were incredibly patient and sent messages by changing the chemical composition of immense gas clouds around some star or other - expecting us to decode the spectral characteristics resulting from that? If you consider all of the ways we could imagine they might communicate - and then realise that there are just about guaranteed to be a bunch of other ways we couldn't imagine...it's easy to see how we haven't heard anything as a result of the SETI work. A darker possibility is that there are dangerous races of aliens out there and all of the others realize that the risk of broadcasting their position is simply too great. Maybe they just aren't particularly talkative - it could easily be that this desire to communicate is a uniquely human characteristic. Maybe their technology just took off in a different direction and they never bothered much with astronomy or even physics in general? Until or unless we find something 'out there' we simply cannot know why we aren't. SteveBaker (talk) 03:33, 29 April 2010 (UTC)

The Fermi paradox discusses these reasons. CS Miller (talk) 12:49, 29 April 2010 (UTC)

You know, if I were an alien species with super-duper technology, and I wanted to make other intelligent beings know I existed, then I would make a star blink. Create a giant movable star-shade and send out ultra low-frequency bits (showing primes or whatever). That would give you enormous power, a broadband signal, and a wide viewing angle. And of course, a flickering star would be easily noticed with even the level of technology available to stupid apes like us. Dragons flight (talk) 07:08, 29 April 2010 (UTC)

"Create a giant star-shade" Hmm?!! —Preceding unsigned comment added by 86.4.186.107 (talk) 07:48, 29 April 2010 (UTC)

Very good, and there's me thinking we were discovering hundreds of exoplanets, and all it was was some alien race putting on a light show with morse-code. How disheartening.... :) --KägeTorä - (影虎) (TALK) 12:11, 29 April 2010 (UTC)

That's not a bad idea. It is probably centuries beyond our technology, though (the usual caveats about any technological prediction beyond 25 years apply). The shade would have to be planet sized to result in a noticeable dimming to our best current telescopes. It would have to be star sized to noticeable to the naked eye. --Tango (talk) 14:10, 29 April 2010 (UTC)

I think if an alien intelligence wants to send a detailed message then some kind of mathematical signal sent using EM is by far the most likely. The aliens will go through the same thought process as us and try to work out what is likely to be in common between technological species and they are likely to come to the same conclusion we did - mathematics. If they are intelligent enough to be sending messages to other species then they are likely to be intelligent enough not to assume all intelligent species have the same number of legs they do. EM is the most likely medium because the only other option is gravity and that is much harder work (due to elementary particles having much greater charges than they do masses, in natural units). One thing we should keep in mind is that they may not be trying to send a detailed message but just something that unambiguously says "We are here". In that case they don't need mathematics, just anything unnatural. Changing the spectra of nebulae could do that. They may think it is easier to do something like that and look for responses so they can send their detailed messages to a specific target. --Tango (talk) 14:10, 29 April 2010 (UTC)

One possible explanation for the lack of alien contact may be that aliens don't think it is worth it. Travelling between stars takes a long time (aliens could have longer lifespans than us, but they aren't likely to be much longer since that would tend to slow down evolution, so they wouldn't have reached intelligence yet - of course, I'm extrapolating from a single data point, so the margin of error is rather large!), so they may well assume they will never actually meet any aliens and will just be communicating with a round-trip time of decades or centuries. Such slow communication won't allow for much information to be exchanged, so the practical benefit is likely to be minimal. --Tango (talk) 14:10, 29 April 2010 (UTC)

They could be completely different from humans in a way that no one ever dreamed of. There is no evidence either way. --Chemicalinterest (talk) 15:06, 29 April 2010 (UTC)

I agree, but we can still make educated guesses based on the basic principle that a notion of "technologically more advanced" should correpond to "being able to utilize resources to achieve more objectives". Then I think that since we are all machines, but that in biological form we don't have much control over our lives, more advanced civilizations will be machine civilizations. Space travel is far more practicical if you are an electronic machine because then you can just upload yourself to a machine on the place of destination via radio communications.

You can then also imagine that civilizations repeatedly transmit radio messages that contain details on how to build their hardware, followed by messages containing their software. Such messages can be picked up long after the civilization is gone, billions of years later, by another civilization who could decide to build the machines and then download the aliens into the machines. Count Iblis (talk) 15:55, 29 April 2010 (UTC)

If we have absolutely nothing in common with them, then we'll never be able to communicate with them (or perhaps even recognise them) anyway, so we might as well assume we do have something in common with them. The something is the technology necessary to send and receive messages between stars. There are different ways of doing that, but it doesn't seem likely (and I'm only talking about likelihoods, I'm not ruling out anything as impossible) that they could be built without mathematics. --Tango (talk) 16:18, 29 April 2010 (UTC)

The Drake equation makes sense, it is just that for most of the variables going into this equation we could be off by orders of magnitude and not realize it since our observations of extrasolar items smaller then stars is extremely limited and prone to observation bias. Googlemeister (talk) 20:03, 29 April 2010 (UTC)

I don't think all of the people who said they have seen the aliens are all liars. There must be at least one of them say the truth. And also in ancient time there are some UFO were written by historian, i don't think their purpose is lying to us.75.168.119.109 (talk) 22:46, 29 April 2010 (UTC)

God

There are many religions in the world. Is god really exist? Or big bang.75.73.152.238 (talk) 00:35, 29 April 2010 (UTC)

If god does exist then who create god? —Preceding unsigned comment added by 75.73.152.238 (talk) 00:42, 29 April 2010 (UTC)

Start with God and then move onto Big bang. People here might tell you that science does not deal with questions regarding God, but there are people who would disagree. For a scientific treatment of God you could try reading God: The Failed Hypothesis by Victor Stenger, I've just started reading it myself. No prizes for guessing Vic's stance on the subject ;) . Vespine (talk) 01:19, 29 April 2010 (UTC)

You have to take it on faith that (the christian interpretation of) god has always existed and was therefore never created. On the other hand, there is reasonably compelling scientific evidence that the big bang occurred around 13.7 billion years ago. Astronaut (talk) 01:18, 29 April 2010 (UTC)

God and the Big Bang are not mutually exclusive concepts; there is nothing that prevents a person from understanding the implications of the Big Bang and also believing in God. To understand how philosphers have long tried to reconcile these ideas in a more formal way, you may want to read Primum movens and Unmoved mover and Cosmological argument. The notion of a God who exists before creation (whatever the nature of that creation may be) has been pondered since the time of Aristotle. --Jayron32 01:43, 29 April 2010 (UTC)

And these concepts have been disproven long ago. At the end of the day the unmoved mover cannot be questioned, because there's no answer there. Imagine Reason (talk) 13:52, 29 April 2010 (UTC)

Where did the material from the Big Bang come from? It requires just as much faith to believe that it came from nothing as to believe that God created it. --Chemicalinterest (talk) 15:30, 29 April 2010 (UTC)

It takes no faith, but perhaps some courage, to say simply: "I don't know." Dragons flight (talk) 18:39, 29 April 2010 (UTC)

But it is simpler to say "The universe appeared from nowhere." than "God appeared from nowhere and created the universe". They both require the same amount of unexplained appearance, but one involves an extra entity. (See Occam's razor.) --Tango (talk) 19:05, 29 April 2010 (UTC)

One does not involve an extra entity; both require that something was there already. In science, things cannot appear. That's why origins is not science; its philosophy, regardless whether somebody doesn't like philosophers. I believe that God was always there, even though it is difficult to comprehend. --Chemicalinterest (talk) 19:15, 29 April 2010 (UTC)

We have pretty good evidence for the Big bang now (See: Cosmic microwave background radiation, for example) - so it's pretty much certain that it happened. God is the opposite. Zero proof - zip, nada. Worse still, the descriptions of god (or gods, plural) that people come up with seem carefully thought out so as to make the hypothesis that god(s) exist "unfalsifiable". This is a serious matter in science - if a hypothesis cannot (even in principle) be proven to be false - then we generally discount it. The proponents of gods claim that god can do absolutely anything and has no restrictions on his/her/its' behavior whatever - and (worse still) that he actively works to deceive us (in order to "test our loyalty"). So scientists say "Hey - look at all those fossil dinosaurs! We can test them with radioactive dating techniques they are a bazillion years old! We must be right about evolution and that whole Noah's ark and Garden of Eden story is definitely false!"...and the religious folks say "No, the Earth is 6000 years old. God put the fossils in there - and deliberately created the right amount of radioactivity in them to 'test your faith'...you have no faith! Hahahahaha!". If you're happy to take that shit on trust - then there is nothing science can do to 'falsify' that. There is no possible experiment we could do that the religious nuts can't just turn around and say "Gotcha! Proved you don't have faith!". It all seems kinda childish actually - but that's how it is.

Some atheists have created 'fake' religions - The Invisible Pink Unicorn (mhhbb) is a popular one. The point being that there is quite literally nothing to say that the god of the christians or the jews or the muslims is any more or less real than the IPU (pbuh). Anything that suggests that the IPU (whans) isn't real or shouldn't be worshipped (for example, by eating ham & pineapple pizza - She is not a particularly demanding God) can easily be dismissed by using the exact same arguments that the 'real' religions use. They'll say "but our religion has been around for two thousand years - God has been worshipped for millennia" - and the response is that the universe was created last Thursday and all those old churches and gorgeous pieces of music were created by Her to test the faith of the righteous. They don't have a leg to stand on.

The scientific answer is: "There is nothing whatever out there that even hints at the possibility that there are gods out there."...the hypothesis that there is some kind of divine presence is unfalsifiable and Occam's razor says we should ignore all of that stuff. Russell's teapot bears reading.

SteveBaker (talk) 02:42, 29 April 2010 (UTC)

There is evidence for a God; it just depends on one's prejudice, whether they ignore the facts or not. --Chemicalinterest (talk) 19:19, 29 April 2010 (UTC)

It's a category error to try to apply science to things that don't admit direct observation. (Now, it is possible to just reject all things that can't be scientifically observed; logical positivism does that. It's a very simple philosophy that rejects the existence of all of the fun things philosophers talk about: ethics, qualia, souls, God, etc. Our article explains why most philosophers don't do that.)

This all is to say that the science reference desk can't help you with this question. Since a metaphysics reference desk doesn't (and can't) exist, all we can do is point you to the Existence of God article. Paul (Stansifer) 03:10, 29 April 2010 (UTC)

Oh nonsense! Science is successfully applied to all sorts of things that we can only deduce indirectly - quantum theory, string theory, dark matter, dark energy, neutrinos...many, MANY things! Religious types wish science would just leave them alone and decide that religion is outside the scope of study - but that's not gonna happen. (Besides, philosophers are a waste of quarks! Their function in the universe is to hasten its end by accelerating entropy - taking in ordered information and producing hot air.) SteveBaker (talk) 03:53, 29 April 2010 (UTC)

False religion, which as I said in Cheminterest's talk page, is just another method of controlling people (as are dictatorships). True religion accepts science, knowing that it will never contradict God's word. False religion is disproved by science; true religion is supported. --Chemicalinterest (talk) 19:21, 29 April 2010 (UTC)

Steve the first bit is right but the second an absurd generalisation. Sure Stupid types wish science would just leave them alone and decide that they could hang on to any superstitious or religious beliefs (tried telling an old lady she is silly to believe her horoscope?) but I see no evidence that more stupid people are religious than are not. It may be true of course especially in the US where the default belief set might be religious it does not seem to be in most of Western Europe, where the no thought>>no religion (not the converse, of course). But I think there should be an absolute prohibition on people discussing the existence of God before they can demonstrating their grasp of the much more straightforward question of whether a scientific test can be devised for the existence of people, will science ever see beyond the atoms and cells? --BozMo talk 07:42, 29 April 2010 (UTC)

There is evidence that less intelligent people are more religious. See Religiosity and intelligence. Whether the evidence is conclusive or not, I will leave to you to decide (the main difficulty is quantifying intelligence in a meaningful way). --Tango (talk) 14:22, 29 April 2010 (UTC)

It does not mean that more intelligent people are less religious; it is just that people who think themselves more intelligent are less religious. --Chemicalinterest (talk) 19:17, 29 April 2010 (UTC)

Not seen that before but as you can imagine it is pretty weak, First, "religiosity" not religiousness(the former apparently means superstitiousness) and of course the fact it is all tgs data (which as I mentioned is the obvious case). There are good reasons to believe less intelligent people are less likely to question the prevaling beliefs where they are. But no visible evidence beyond that, and some counter data (e.g. religious expression by Mensa members if ever you wanted a contrived selection of clever people... --BozMo talk 18:21, 29 April 2010 (UTC)

There was a US study published this year (I think) claiming to find a statistically significant difference of ~7 IQ points between Americans who attend church weekly and those who attend never or only a few times a year. Of course, even if the difference is statistically significant, 7 points is too small to be of any practical impact with individual cases. Undoubtedly there are nonetheless many smart religious people and many dumb atheists. Dragons flight (talk) 18:33, 29 April 2010 (UTC)

The true God wants man to use his full brain power. Some people may think otherwise, but God isn't a crutch (to lean on instead of using your God-given abilities), he is an assistance (to enhance your abilities and help you when you try to think over some problem). --Chemicalinterest (talk) 19:25, 29 April 2010 (UTC)

Neutrinos are observable; it's just that the experiments that you need to run on them are very expensive and long. We can't experiment on goodness at all. (You can experiment on what people think about goodness, but that's not nearly as important a problem.) The only way to approach it is through philosophy. It may not be that rigorous, but it's the only thing we've got! Paul (Stansifer) 09:45, 29 April 2010 (UTC)

Careful there... It's a common mistake, but people very commonly misunderstand the concept of religion, and assume that we all blindly reject science for our religions. It is my belief, as a Christian (and I am NOT trying to tell people what to believe, this is only my belief as a supporting example) that God created the Universe the way it is, along with all of the science. I believe that it is billions of years old, and that humans are evolved. I am unabashedly Christian, a "proponent of God", and I can certainly say that Steve Baker's understanding of religion only applies to certain groups. Religion and science are not inherently exclusive. I already accept science without any hesitation, but some scientists seem incapable of allowing for the unknown, which makes me question their motives of even positing theories. Falconus^{p t c} 12:02, 29 April 2010 (UTC)

Humans don't need redemption or salvation in the theory of evolution. Imagine Reason (talk) 14:01, 29 April 2010 (UTC)

Falcon, if you accept the laws of physics then the God you speak of is a God of the gaps. We don't need to use the god-hypothesis to explain any phenomena that we've observed because the laws of physics explain everything. In this case, all outcomes are simply the result of previous outcomes (plus a bit of randomness perhaps) so all God did was to press the big red button that says "start big bang" and then he just walked away - in this belief system, prayer is futile. 196.38.62.178 (talk) 15:14, 29 April 2010 (UTC)

That;s not necessarily so. The "God of the Gaps" explanation purports that people assume that all unexplained phenomena are proscribed to God, and that when the unexplained becomes explainable, God is somehow "removed" from the equation. Falcon's philosophy seems to mirror mine very closely, and I can tell you its a very different understanding of God (at least for me, I won't speak for him). I have no doubt that God exists, and yet I also have no desire to explain the as-yet-unexplained phenomenon as "miraculous" or "from God". I fully expect that all observable events and the basic laws of how the universe works are perfectly describably by science. I don't expect to find God in any of the gaps. Instead, I find that God serves a purpose in human experience in that God helps define those things, such as purpose and morality and the like, which science is incapable of describing. Science can describe how I got here, but it does a terrible job of describing for what purpose am I here. For many people, "we are here for absolutely no purpose" is a fine conclusion, but that conclusion is as unsupported by anything scientific. It is equally as valid as "We are here for God's purposes, he gives us our purpose" insofar as neither statement has any evidence which supports or refutes it. Another way to look at it: No matter how detailed we get in describing God's creation, such detail in no way denies the Creator. I can study the details of my TV and know exactly how every component came to be and the chemical composition and organization of every single bit in it; I can understand the processes that brought it into being, but none of that denies that my TV was made by something. The TV was built by someone for a purpose, and did not become a TV by random chance. Describing the laws of the universe is much the same for religious scientists. No aspect of understanding God's creation is off-limits, but no level of detail in describing that creation denies the existance of the creator. I am not so arrogant that I think I should tell God how he should work. If he works through the laws of physics so be it. If his plan to create me was evolution than so be it. I accept God as he is, insofar as my observational skills can understand him. --Jayron32 18:26, 29 April 2010 (UTC)

Wow, Jayron. We both posted very similar perspectives, about 3 minutes apart (see below). Well done, sir. Kingsfold (talk) 18:35, 29 April 2010 (UTC)

IP 196 logged in Jayron, two quick comments. If you expect that all observable events are described (or describable) by science, how can God perform miracles (i.e. answer prayers)? Surely He would have to violate the laws of physics if he were to intervene on Earth - i.e. all events are a function of previous events and the laws of physics (assuming determinism, but this argument still applies if things are non-deterministic) so either A)God will have to break the laws of physics to change things, or B)God set out his grand plan at the begining and everything is unfolding exactly as he wanted including people worshipping and praying to Him. There is no point to praying under B and A can't be true if things are describable by science. Second comment: Occam's razor says "We are here for no purpose" is preferable to "We are here for God's purposes". Zain Ebrahim (talk) 21:41, 29 April 2010 (UTC)

First comment: That's not necessarily true -- many miracles described in the Bible would not actually require God to break the laws of physics, but only to apply a sufficiently large amount of energy, of the right kind, in the right place, at the right time. To illustrate what I mean: Suppose there is some person on some big battlefield somewhere, hunkering down in his foxhole under intense artillery bombardment, and praying for God to protect him. Suppose further that God has some special reason to protect that particular doughboy from harm, because this person plays some important role in His plan. Further suppose that God sees that the enemy has just fired, or about to fire, a big shell that will kill the aforementioned doughboy if allowed to follow its own ballistic trajectory. Finally suppose that He decides to protect this special doughboy by subtly altering (directly or indirectly) the atmospheric pressure/temperature distribution of the atmosphere in the immediate area of the battlefield in order to set up a high-altitude wind shear that would cause the shell to miss its target point and explode harmlessly in an empty area of the battlefield. What laws of physics can you name that would categorically prevent the scenario I just described?

Second comment: "We are here for no purpose" is a thoroughly despicable position from an ethical and sociological point of view, because it encourages apathy (thus discouraging people from working for the betterment of their nation) and moral laxity (which abets all kinds of self-destructive tendencies within society, like drug abuse, unchecked promiscuity, etc.) For this reason, "We are here for God's purposes" is preferable to "We are here for no purpose", absolutely regardless of Occam's razor or any such philosophical shenanigans. Occam's razor (and the scientific process in general) is intended to explain how the world around us works, and NOT what our own purpose in this world is. The first is the proper domain of science, the second is the proper domain of philosophy, ethics and (in some philosophical systems) religion. 76.103.104.108 (talk) 06:57, 30 April 2010 (UTC)

We make our own purpose. Imagine Daniel Dennett's survival machine, which is made to keep us alive under stasis for centuries. If the machine becomes self-conscious, it will make its own purpose, regardless of what we programmed into it. Thus even if the bible is correct, we humans, once self-conscious, do not serve the god's purpose anymore. 67.243.7.245 (talk) 14:00, 30 April 2010 (UTC)

76, First comment: the laws of physics don't allow for a God to change things as He pleases. Initial conditions plus physical laws determine future events - so if God wants to change future events, he'll have to change the physical laws (assuming determinism). Second comment: Maybe I should have been clear about what I meant by "preferable" - I meant "a more likely statement". Ethics, apathy, laxity and whatnot are irrelevant to the discussion of whether we have a purpose or not. All of those things say that it might be nice if we had a purpose but they don't provide any evidence that we do. 196.38.62.178 (talk) 14:23, 30 April 2010 (UTC)

Most every assertion about God that you could come across tends to unravel into ribbons of illogic flapping silently in the breeze, once put under close scrutiny. But logical rigour is not what religion is about. It is about social control. I will admit that it is not a bad ideology under some circumstances. So to answer your question -- yes God has substance and reality, insomuch as there are definite and concrete forms that the concept takes within the human psyche. Apart from that though, no, plainly God does not manifest itself in the world. God is the world, a theologian might tell you. Vranak (talk) 14:19, 29 April 2010 (UTC)

Please allow me to offer another perspective. Please also understand that I write not to preach or to assert, but to simply provide what I feel is a sufficient explanation for my belief system. I realize and completely understand that for many people, belief in a higher power is illogical and unproveable. However, my belief isn't founded in intellectual logic or proof-- it's founded in faith.

It has been stated above that there is absolutely no evidence that God exists, but depending on where you lie on the continuum of what to accept as proof, from as little as the beautiful and complex perfection of the Charonia tritonis to as much as God Himself descending from a sky accompanied by concourses of angels; anything and everything could be accepted as proof. I would also suggest that the most steadfast non-believers would probably not accept even a personal visit as proof… In other words, “absence of evidence is not evidence of absence.”

I feel like I can both accept science AND believe in God because for me, science answers the “what,” while my beliefs answer the “why.” For me, science can’t begin to answer the reasons for our existence, or where our spirits go when we die. Admittedly, those that don’t believe will assert that there is no greater reason for our existence, and we aren’t headed anywhere. That’s OK for them, but I suppose I need to understand for myself.

For me, God actually knew the science of what he was creating, used it, and doesn’t go around saying, “Hey—I’m God! I did that!” (Would we believe Him if He did? Probably not.) I believe that He initiated the Big Bang, wistfully aware that many of his children would not see his omniscience behind the science. I’ll probably draw fire from both sides on this one, but I don’t believe either the ex nihilo principle, or the literalist principle that the Earth was created around 6000 years ago. In my belief set, the dinosaur question can be answered by the principle that God organized already-existing materials into the earth that we live on. As such, this could mean either that dinosaurs existed on older planets and were within fragments used to create this earth, or that God can manipulate our understanding and measure of time, and the dinosaurs existed here on this earth but were extinct before Adam was created. It may just be remotely possible that God knew that our imperfect civilizations would one day rely (for better or worse) on fossil fuels, and made them available for just that purpose.

I also am not compelled to believe that God, as we know Him, has always existed. Realizing that this is somewhat “deep water,” spiritually speaking, I would suggest that God learned to do what he is now doing in a process of self-perfection. He, then, was created by His God, who was created by His God, who was created by His God, etc., etc., etc. For many, this will smack of blasphemy and polytheism; neither of which I intend. I worship my God, or in other words, the God that corresponds to my sphere of existence. This may kind of boggle the mind a little bit, but I simply keep the First Commandment… or at least I try to.

I also don’t believe, as was asserted, that God can do absolutely anything and has no restrictions. He operates under natural laws, many of which we may just be unaware of. He also has the so-called “restriction,” of not being able to suspend free will. He cannot force me to believe in Him or obey His commandments. I act as my own agent, but I am also bound to accept the eternal consequences of those actions.4

So to sum up—while I believe in God, I hope that I don’t come across as an illogical religious zealot, because I’m not. I just feel like I’ve found a system that accommodates both science and religion, and that offers the best explanations on the reasons for them. Thanks much! Kingsfold (talk) 18:29, 29 April 2010 (UTC)

That's pretty much what I said (which is what you said). Also consider the following analogy. Lets say you are an engineer designing some system to do something. A big machine that does something really important. Who's the better engineer: The one that designs a machine that needs constant maintaince, such that the engineer has to show up every few days to make it work; that requires constant input to get the right results, or the one that designs a machine that just needs to be turned on and runs smoothly and does what it is supposed to do with very little tending. Seems to me that the better engineer is the one that designs a well-made machine that needs very little interference. Which kind of engineer is God? To me, its OK for God to be a good engineer, who designs a system that runs smoothly in His absence. I don't need him to be a bad engineer whose system needs constant maintenance. He can still show up once in a while to make sure everything does run smoothly. But he doesn't have to... --Jayron32 19:01, 29 April 2010 (UTC)

God enjoys watching what he makes. He likes to communicate and be friends with people on earth. --Chemicalinterest (talk) 19:52, 29 April 2010 (UTC)

@Jayron32 and Kingsfold. You've both mentioned (explicitly or implicitly) that science answers the hows, while religion has provided answers to the whys for you. As a very firm non-believer, I'm curious which "why" questions religion has answered for you and what the answers were. Again speaking only for myself, as you have done, I wouldn't see any reason to accept why answers from a source that's gotten virtually every single how question wrong it's ever tried to answer, so I suppose my third question would be why would you make the decision to do that. Matt Deres (talk) 20:30, 29 April 2010 (UTC)

Sure Matt Deres. Here are some of the questions religion has answered for me, that science has been unable to:

• What is expected of me as a human, in terms of how I am to interact with other humans.
• What is expected of me in relation to my creator; that is having created me, how does he expect to relate with me
• The expectation that life has a purpose, even if I may never know that purpose. For me, living a meaningful life means that I am here for a reason, knowing that the creator has a reason, even if I am incapable of understanding it.
• Knowing that there is more to my existance than the short time I am "alive", and also knowing that my time being alive is special and not to be wasted, since it will effect what happens after death.
• Knowing that there is a path to atone for all of the mistakes I have made, and that there is an end to the cycle of guilt for those mistakes.

I actually find it quite suprising that many people don't, at some point, think about the purpose of their lives. I have been an athiest for a sizable part of my life, and I found that the greater sense of purpose, and the sense of well-being knowing that there is a plan, was what was missing from my life at the time. --Jayron32 21:07, 29 April 2010 (UTC)

True religion and science complement each other. One helps the other. False religion may prevent scientific discoveries. Life is purposeless without God. As the Bible puts it, "We may eat, drink, and be merry; for tomorrow we die." When people know God in their lives, it gives them a purpose. They are here to bring others on the right path. BTW, some people find their atheist beliefs comforting because they can understand science. People cannot always understand God, which makes them uncomfortable because of their pride. That is why true religion humbles you. You are not infallible. --Chemicalinterest (talk) 00:13, 30 April 2010 (UTC)

I'm not surprised you find such beliefs comforting. Many people take comfort and strength from religion. However, I am curious that you say you were an atheist for many years. If you don't mind my imposing on you further, I wonder if you could explain what changed to make a scientifically inclined atheist believe in God, and an afterlife, and a divine plan, etc.? Dragons flight

(talk) 21:42, 29 April 2010 (UTC)

What makes atheism science, and God religion? Both are religions, one glorifying man's reason, and the other glorifying a Supreme Being. --Chemicalinterest (talk) 00:15, 30 April 2010 (UTC)

Don't want to be a party pooper, not that I don't find this kind of stuff personally interesting, but this has long ago ceased being a ref desk topic and turned into a general opinion debate. If you want to continue maybe you can take it to aa user page or something? Vespine (talk) 22:22, 29 April 2010 (UTC)

The problem is: people make many more opinions about God and religion than they do about mercury I and II ions, which will necessarily make the discussion much bigger. As I said earlier, feel free to use my talk page too. --Chemicalinterest (talk) 00:22, 30 April 2010 (UTC)

No Vespine, you're not being a part pooper; you're correct (though I guess that doesn't preclude to also being a party pooper!). Anyway, my apologies for my part in the shift away from references. Jayron, I've learned quite a bit about various topics from you on these pages over the years. If you'd care to continue the conversation off-board, my email works. If not, then I thank you for your indulgence here. Matt Deres (talk) 22:36, 29 April 2010 (UTC)

This conversation seems is not going to end. you could argue forever whether god is exist or not because nobody could prove god is exist. Same as big bang. I think the big bang theory is make more sense because god could not just come from no where and has superpower to create Earth. Perhaps big bang is the one who create god then god create us. Conclusion: Nobody knows for sure what actually happen at the beginning of the universe whether god or big bang create the universe. By the way, just for you guys know English is my second language and I'm not fluent on it yet. Therefore my English grammar is bad.75.168.119.109 (talk) 22:31, 29 April 2010 (UTC)

The Big Bang could just as easily have come from nowhere and created the world as God came from nowhere and created the world. Time seems to make the ludicrous seem more scientific. If someone said that an explosion happened and H2 and O2 changed into amoebas in one second, fish in another, horses in another, and man in four seconds, people would laugh you away. But eons of time makes it seem much more appealing to others. Its a subtle strategy. --Chemicalinterest (talk) 00:22, 30 April 2010 (UTC)

Actually, whether god exist or not. It doesn't matter. we, humans, still humans whether god exist or not. God doesn't do anything impact to us anyway. But we, humans, alway curious about everything around us. We alway want the correct and make sense answer. I believe one day someone will find out the true but at least several more hundreds years.75.168.119.109 (talk) 23:07, 29 April 2010 (UTC)

How do you know that God does not do anything to impact you? You might have just never experienced life without God (e.g. in hell). --Chemicalinterest (talk) 00:22, 30 April 2010 (UTC)

Because i don't see anything that god impact human.75.168.119.109 (talk) 01:35, 30 April 2010 (UTC)

I also think as humans become more advance technology the less people believe in god. An example: Before 18th century most people believe in god because they could not explain anything in the life. The only thing they could think is someone has superpower do all of them. In 20th century, as we become much more advance the people believe in god continue to reduce more. At my parents time, in school, they teach about evolution and the creation of god but today, they get rid of the creation of god already.75.168.119.109 (talk) 23:36, 29 April 2010 (UTC)

Actually they used to attribute more things to spooks, magic, ghosts, and the devil than God, like St. Elmo's fire and lightning. --Chemicalinterest (talk) 11:37, 30 April 2010 (UTC)

They trust in their technology rather than in God. That does not mean that God is not real; it is just that people are becoming proud of their achievements and would rather be independent. Thinking that they are responsible for all of their actions to someone who created them is too restricting. --Chemicalinterest (talk) 00:22, 30 April 2010 (UTC)

LOL! Less people believe in god because the more we are advance the more we find out that a lot of things aren't doing by god as we thought.75.168.119.109 (talk) 01:23, 30 April 2010 (UTC)

A lot of great responses here. I have a lot I could say, but I don't really feel the need to, because others have covered my sentiments well. Falconus^{p t c} 04:44, 30 April 2010 (UTC)

Which way do they lie? Everyone has their own subtle differences. --Chemicalinterest (talk) 11:37, 30 April 2010 (UTC)

That both faith and science can exist together without issues. Indeed faith and science compliment each other. Falconus^{p t c} 12:36, 30 April 2010 (UTC)

Yes. They never contradict each other, if the faith is true. --Chemicalinterest (talk) 16:41, 30 April 2010 (UTC)

Science has found that humans die like other animals, and nothing but molecules live on. It has also found that humans evolved for no particular reason but that we tend to have survived better. We are not special, and this troubles religious people. You can continue to claim the god of the gaps, but that is not one of the bible. 67.243.7.245 (talk) 14:02, 30 April 2010 (UTC)

Consider these points, from a friend who is a biologist and is religious:

1. Regarding dinosaur bones being faked by God to test faith: "God does not deceive."

2. Regarding evolution: "Evolution is how God works."

My additional thought: Substitute "Nature" for "God" and that covers it. ←Baseball Bugs ^{What's up, Doc?} carrots→ 16:50, 30 April 2010 (UTC)

Black hole

What inside the black hole?75.73.152.238 (talk) 00:42, 29 April 2010 (UTC)

Gravitational singularity, you might also find our Black hole article interesting. Vespine (talk) 01:13, 29 April 2010 (UTC)

"The black hole?" Which black hole do you mean? Astronaut (talk) 01:11, 29 April 2010 (UTC)

It is (technically) impossible to ever know what's inside a black hole because nothing (not even information) can escape from the hole. All we know about it is its mass, it's electrical charge and whether it's spinning or not...but what's inside the 'black' event horizon is literally impossible to know. Because the black hole is made of ordinary matter that's gotten so massive that the very atoms that it's made of are crushed by the pressure - it seems likely that the material keeps collapsing until it's an infinitesimal 'dot'. This dot would soon have literally zero size - a "singularity". But because we can't examine the physics of what happens to matter when it's crushed to that crazy extent, we can't EVER know for sure. SteveBaker (talk) 02:04, 29 April 2010 (UTC)

It's not actually known if information can escape a black hole, see Thorne–Hawking–Preskill bet. Ariel. (talk) 05:01, 29 April 2010 (UTC)

We know is that there is a ball of great mass in the center of the black hole with a radius less then the event horizon. I do not think there is a way to definitively determine whether the ball is an infinitesimally sized sphere, or a house sized sphere, or for large black holes, even a planet sized sphere, but we do know that it is incredibly dense. Googlemeister (talk) 19:07, 29 April 2010 (UTC)

To be a bit snarky, it isn't clear whether it is possible to find out what's inside a black hole (many physicists don't believe there would really be a singularity), but whatever the answer is, you wouldn't be able to tell anybody outside about it. Looie496 (talk) 21:12, 29 April 2010 (UTC)

Wormhole

Have we found any of wormhole? does wormhole really allow time travel?75.73.152.238 (talk) 00:46, 29 April 2010 (UTC)

No. Wormholes are theorised to exist, but none have yet been discovered. Parts of the same theory predict that an object falling into a wormhole might travel in time, as well as in space. Astronaut (talk) 01:06, 29 April 2010 (UTC)

Wormholes are just theoretical - we've never found one - we might never find one. However, that was true about black holes until we started finding them - and now they've gone from "unlikely theory" to "definite fact", to "found in the center of every galaxy" and now to "fundamentally important to the formation of galaxies"...so there is still hope for wormholes! However, the time-travel thing is MUCH more tricky. It's not really enough for wormholes to exist - we'd need to be able to create them, move them around - enlarge them - and even then, the odds are very good that the whole thing would turn out to have a horrible snag. So I'd put the odds of Wormholes existing at maybe one in ten (gut feel) - and the chances of them being usable for time-travel as one in a trillion...I strongly believe that the laws of physics will conspire to make time travel (into the past) impossible. SteveBaker (talk) 02:16, 29 April 2010 (UTC)

About blackholes found in the center of galaxies - do they know it's a black hole specifically, or just a super massive object? But not necessarily a black hole with all it's strange properties. Ariel. (talk) 02:45, 29 April 2010 (UTC)

Well, the one at the centre of the Milky Way is the mass of 3.7 million Suns and occupies a small volume. See Supermassive black hole and Schwarzschild radius#Supermassive black hole for more info. Astronaut (talk) 03:01, 29 April 2010 (UTC)

Yep we know it's a black hole. Anything with that much mass and that little volume has enough density to crush itself down to a singularity - it's way too big to become a neutron star - so yep, it's the real McCoy alright. Schwarzschild radius, Event horizon, Devourer of Worlds, singularity, australian-rower-radiation, spaghettification, The Whole Shebang. SteveBaker (talk) 03:42, 29 April 2010 (UTC)

That's actually circular reasoning. The assumption is that a large mass will become a black hole (due to the math). Then you find a large mass, assume it's a black hole, and prove the theory is correct. Perhaps there is something currently unknown that prevents the mass from fully collapsing? That's basically what I was asking, is there evidence that the mass actually collapsed? Because until there is such evidence I would hold off on saying black holes were found. To flesh out what I was saying, let's assume (for no reason at all) that quark degeneracy pressure is infinite. Could our current observations distinguish such an object from a true black hole? Ariel. (talk) 04:52, 29 April 2010 (UTC)

That assumption violates causality, but I get your point. It's just not a very good one. Everything we observe is interpreted within theoretical understanding. Dauto (talk) 04:56, 29 April 2010 (UTC)

I know everything is interpreted within theoretical understanding, I just wanted to know if there was evidence for a black hole, or if we are still working with theoretical models. Why would it violate causality? Ariel. (talk) 05:04, 29 April 2010 (UTC)

Even before the discovery of real life black holes, no theoretician worth their salt would have placed black holes and worm holes in the same bag of goods. the former is an almost unavoidable consequence of the collapse of very massive objects while the later is more of a theoretical chimera that likely doesn't exist at all. Dauto (talk) 04:56, 29 April 2010 (UTC)

Titration curve: help!

Let's say we have a solution of HCl of known volume and concentration, being titrated by NaOH of known concentration. I want to know what the pH is after x mL of NaOH have been added. According to my book, we can assume that all the OH in NaOH react completely with all the H+ in HCl and neutralize. The obvious problem is, what happens near the equilibrium point? Following the textbook's logic, all the H+ in the solution would eventually react with OH- and disappear, which is obviously impossible because that would make the equilibrium point have a pH of infinity instead of 7. So, how would I calculate pH's near the equilibrium point? --99.237.234.104 (talk) 00:48, 29 April 2010 (UTC)

It hardly "disappears". It turns into H2O, which has a pH of 7. 69.210.129.248 (talk) 01:17, 29 April 2010 (UTC)

H2O doesn't have a pH of seven; pure H2O self-ionizes into H+ and OH-, and the H+ cause the water to have a pH of 7. --99.237.234.104 (talk) 01:27, 29 April 2010 (UTC)

It does have a pH of 7; the ionization does not affect the pH because the OH- causes the water to have a pH just as much as the H+. --Chemicalinterest (talk) 19:29, 29 April 2010 (UTC)

(edit conflict)To explain a bit better. Under all conditions, all water solution obey the equilbrium of the autoionization of water. In all conditions, the equilibrium constant for this reaction, Kw = [H3O¹⁺] * [OH^1-] = 1.00 x 10^-14. That is because at 25^oC, the reaction goes to the point where [H3O¹⁺] = [OH^1-] = 1.00 x 10^-7 M . Since pH = -log [H3O¹⁺], pH of neutral water = 7. Now, since the expression Kw = [H3O¹⁺] * [OH^1-] must always be true, if we change the value of either [H3O¹⁺] or [OH^1-], the value of the other one must change in the opposite direction. So, if you add [OH^1-], the [H3O¹⁺] drops by however much is needed to keep [H3O¹⁺] * [OH^1-] = 1.00 x 10^-14. The article pH also discusses this some. --Jayron32 01:33, 29 April 2010 (UTC)

I know the basics, so although I'm grateful that you tried to help, your post wasn't very useful. I was asking how you find the pH of a solution that's being titrated when the solution is near, but not at, the equilibrium point. --99.237.234.104 (talk) 02:24, 29 April 2010 (UTC)

pH meter? --Jayron32 02:34, 29 April 2010 (UTC)

He's trying to find it theoretically. You would assume that your acid and base react completely, and then use whatever you have left (either a small amount of acid or a small amount of base) as the starting concentrations in an ICE table for the autoionization of water: H₂O → H⁺ + OH^-.

That's exactly the method suggested by the textbook. As I noted in the question, this doesn't work if the amount of NaOH added is exactly the same as the quantity of HCl in the beaker. In that case, your method would suggest there would be no H+ left in the solution, which is not possible. Intuitively I suspect your method breaks down close to the equilibrium point, not just exactly at the equilibrium point, but I'm not sure about that. --99.237.234.104 (talk) 03:04, 29 April 2010 (UTC)

The ICE table works fine. Use the expression Kw = [H+] * [OH-]. If there is zero added H+ or OH-, this still works fine, since 1 x 10^-14 = Kw, and if there is no added H+ or OH-, you know that, because of the autoionization of water reaction, you can use the stoichiometric relationships in that reaction to prove that [H+] = [OH-]. If that is the case then [H+] = [OH-] = SQRT (Kw) = 1 x 10^-7. If you have a SMALL amount of added H+ (i.e. within an order of magnitude of the amount in neutral water), then you can assume that [H+](eq) = [H+](Init) + [H+](added) and simply recalculate [OH-] from the Kw expression; and visa versa. --Jayron32 03:12, 29 April 2010 (UTC)

You have to know the number of moles per liter of H+ and OH- ions. Subtract the OH- from the H+ because a certain amount of OH- was added, and calculate the pH using the negative logarithm of the moles per liter of H+ to find the pH. --Chemicalinterest (talk) 19:31, 29 April 2010 (UTC)

conductivity of crumpled aluminum foil

I seem to have forgotten my basic MSE ... does work hardening increase or decrease the conductivity of a material? I know you dope semiconductors with foreign atoms ... but this is effectively a form of hardening by encouraging defects, right? John Riemann Soong (talk) 04:50, 29 April 2010 (UTC)

I think it decreases slightly due to dislocations impeding the flow of electrons, but this effect is negligible compared to other factors like temperature. FWiW 76.103.104.108 (talk) 05:29, 29 April 2010 (UTC)

Wrong. See Doping (semiconductor). Doping increases the number of available carriers, and therefore reduces the resisitivity. Putting defects into a semiconductor typically increases resisitivity. --Phil Holmes (talk) 13:20, 29 April 2010 (UTC)

Oh hmm... now I remember... there is a tradeoff right? Doping increases hardening, so if you dope too much you end up decreasing conductivity overall, so there is an "optimum". John Riemann Soong (talk) 15:03, 29 April 2010 (UTC)

Broadly speaking, doping a semiconductor has no effect on its hardness. In the normal range of dopant concentrations (which are in between very low and low in everyday terms) doping has a linear relationship with resistivity - see http://cleanroom.byu.edu/ResistivityCal.phtml for example. At very high levels of dopant, it's possible that the semiconductor becomes degenerate and so adding extra dopant adds no further carriers. However, the extra impurities would reduce the carrier mobility so the resistivity would increase. I can't currently find a reference for this actually happening, though. --Phil Holmes (talk) 16:12, 29 April 2010 (UTC)

I'm pretty sure I remember seeing a graph for that in my MSE class. Conductivity increases then decreases with increasing dopant concentration. John Riemann Soong (talk) 05:08, 30 April 2010 (UTC)

As I said - if this does happen, it would only be at very high dopant levels - higher than are normally employed in semiconductor manufacture. --Phil Holmes (talk) 08:22, 30 April 2010 (UTC)

Hmm, yes, now that I remember, the x-axis (dopant concentration) was plotted logarithmically... but it seems someone did experiment with this (rather than this being based on any industrial data). Perhaps the dopant levels in industry are set this way precisely to avoid conductivity issues? John Riemann Soong (talk) 12:51, 30 April 2010 (UTC)

I can't remember well off the top of my head, but I believe the dopant was a p-type and conductivity started decreasing around 10^-6 to 10^-5 molar... if I remember correctly. John Riemann Soong (talk) 13:51, 30 April 2010 (UTC)

No. That's roughly 1e17cm-3, which is pretty low doping. I think you may be thinking of mobility, not conductivity. This decreases with increasing doping owing to carrier scattering at the dopant sites. Conductivity is a function of mobility and carrier concentration, but since carrier concentration increases way faster than mobility decreases, conductivity still decreases with increasing dopant levels at this dopant level. Boron is the only commercially used p-dopant with silicon. --Phil Holmes (talk) 14:40, 30 April 2010 (UTC)

Reactivity series for anions

I know the Reactivity series for metals, but is there any such list for anions (such as NO₃^-, SO₄^2-, Cl^-, etc.)? Thanks in advance, --The High Fin Sperm Whale 05:16, 29 April 2010 (UTC)

Exactly what kind of reactivity are you talking about? 76.103.104.108 (talk) 05:31, 29 April 2010 (UTC)

If you meant reactivity in redox reactions, then yes, there is such a list, but it's called a table of standard reduction potentials. Clear skies to you 76.103.104.108 (talk) 05:36, 29 April 2010 (UTC)

See Standard electrode potential (data page) for a complete list. The activity series is basically derived from the Standard reduction potential data; you get it by pulling the metals out of the list, and ignoring the numbers. Before chemistry students are introduced to electrochemistry and redox it is a way to predict the likelyhood of a single replacement reaction occuring, as identifying the products of basic chemical reactions is taught several months before electrochemistry is. Once you have learned basic redox stuff, the activity series is moot. --Jayron32 18:13, 29 April 2010 (UTC)

I also was looking for the activity series for anions, but I didn't come up with very reliable results. One thing I have found is that metal ions lower on the activity series tend to take the conjugate base of the weaker acid. In other words, the metal ions higher on the activity series take the anions that come from stronger acids. HCl is stronger than H₂O. OH^- is the conjugate base of H₂O, and Cl^- is the conjugate base of HCl. NaOH will react with CuCl₂ to take the stronger acid's conjugate base Cl^-, giving CuCl₂ the weaker acid's conjugate base OH^-. This may vary, though. --Chemicalinterest (talk) 19:36, 29 April 2010 (UTC)

Actually, you are completely mistaken about the NaOH and CuCl₂ reaction. The reaction is a simple precipitation reaction. Neither "NaOH" nor "CuCl₂" exist in solution. Both are strong electrolytes, meaning that they dissociate 100% in water. So if you have a solution of NaOH, you actually have a solution that has equal parts Na¹⁺ and OH^1- ions. Likewise, a solution of CuCl₂ has one part Cu²⁺ ions and two parts Cl^1- ions. When you mix the solutions, the Cu²⁺ ions from the second solution clump together with the OH^1- ions from the first solution (they are now in the same batch of water) and the clumps stick together and sink to the bottom. The reason the clumps form can be explained electrostatically or thermodynamically, but solubility rules provide a nice list of how to predict what sorts of ions are incompatibile in solution with each other. The Na¹⁺ and Cl^1- ions don't do a darned thing. They are floating in water before the reaction, and they are floating in the water after the reaction. The net reaction when you mix sodium hydroxide and copper(II) chloride is:

• Cu²⁺ + 2 OH^1- --> Cu(OH)₂

There are further reactions that can occur if the OH^1- is in enough excess. Complex ions like Cu(OH)₄^2- can form as well. The reaction between copper and hydroxide, to form both the precipitate and the complex ion, is best explained by Lewis acid-base theory. --Jayron32 20:53, 29 April 2010 (UTC)

What makes the Cu++ and the OH- ions bond? The forces between the anions and cations. I measure those forces by my rule: Ions of a more reactive metal tend to react with anions of stronger acids. The NaCl does theoretically form, because the other ions are evacuated.--Chemicalinterest (talk) 00:04, 30 April 2010 (UTC)

NaCl does not form. There are no discrete particles of NaCl in the solution. There are only sodium ions and chloride ions. Saying it exists does not make it so. It just doesn't exist as discrete particles. You cannot find a single "NaCl" moety in the water solution, so its a pointless distinction. There is no reaction, they are spectator ions pure and simple. The Cu++ and OH- form bonds because the ion-ion interaction is more favorable from a gibbs free energy standpoint than the ion-water interaction. --Jayron32 02:59, 30 April 2010 (UTC)

dietary fiber supplements such as methycellulose and inulin. What is each of these, and what is the difference between the two?

Having bought both, I called the makers, who explained they were fiber derived from plants/vegetables but they were unable to tell me what the difference between them is or why one might be easier to digest then the other. The labels indicate, however, that you need to take a lesser quantity of inulin than methylcellulose for same result. Can you explain the difference? —Preceding unsigned comment added by 71.51.75.185 (talk) 06:21, 29 April 2010 (UTC)

Do you mean Methyl cellulose? We have an article about Methyl cellulose as well as about inulin. I am not personally familiar with those dietary supplements, and I cannot offer any help or advice. Sorry. --Dr Dima (talk) 07:25, 29 April 2010 (UTC)

Neither can be digested, by you, that is. Inulin and methylcellulose are both dietary fibres, and as such, are not metabolized by the human body. Inulin, however, can be metabolized by intestinal flora and promotes their growth. It can also have positive affects on kidney function. Which one is better for you is something you could discuss with your doctor or nutritionist. Someguy1221 (talk) 07:37, 29 April 2010 (UTC)

Eagles and their Wings

Eagles unlike other birds do not flap its wings often (mostly). How do they fly so high and for a longer time? I presume that it flies higher flapping the wings and just descends down with no wing movement, searching for a prey. Let me be clarified. - anandh, chennai —Preceding unsigned comment added by 125.21.50.214 (talk) 06:45, 29 April 2010 (UTC)

We have an article on Bird flight. If you still have questions after reading it and following links, please ask. --Dr Dima (talk) 07:10, 29 April 2010 (UTC)

Thanks. gliding (flight) is also informative. Do all predators (birds) show flight movements like eagles? —Preceding unsigned comment added by 125.21.50.214 (talk) 09:12, 29 April 2010

It's not just the predators. Few things are more beautiful than watching a kettle of turkey vultures soaring a thermal. --jpgordon^{::==( o )} 16:08, 29 April 2010 (UTC)

Turkey vultures? They aren't normally considered beautiful. Should I edit your comment???... --Chemicalinterest (talk) 19:37, 29 April 2010 (UTC)

If you can watch what I've just described and not find beauty, I feel deeply sorry for you. --jpgordon^{::==( o )} 01:04, 30 April 2010 (UTC)

Turkey vultures are very graceful in flight, indeed. Quite common, too, so easy to observe. --Dr Dima (talk) 07:49, 30 April 2010 (UTC)

Living and Non-living

How are we (creatures) differentiated from inanimate objects when everything in this world is of chemicals (elements, atoms, molecules or compounds)? Is that like we have active components, being recycled in search of stability, supporting the entropy of the universe, reactions with delta E negative etc., etc.,? If so, why don't inanimate objects have this sort of happenings (nevertheless, the entropy of the universe is positive anyways)? I am not sure if am clear, hope you get the question(s). - anandh, chennai. —Preceding unsigned comment added by 125.21.50.214 (talk) 06:59, 29 April 2010 (UTC)

Life#Biology is a good place to start reading. --Dr Dima (talk) 07:19, 29 April 2010 (UTC)

Cogito ergo sum. How about you? Cuddlyable3 (talk) 09:18, 29 April 2010 (UTC)

Would that work for AI? 67.243.7.245 (talk) 13:55, 30 April 2010 (UTC)

I think therefore I am. The question is why can't inanimate objects think? (they don't think and therefore they are not?, but WHY "they don't" and what in us makes us to "think" is what i wish to know) - anandh, chennai —Preceding unsigned comment added by 125.21.50.214 (talk) 09:42, 29 April 2010 (UTC)

Keep in mind that it's cogito ergo sum, not cogito igitur sum. That is, my cognition proves my existence, because nothing that does not exist can think. There is no suggestion that my thought is the cause of my existence, or a necessary condition for my existence. (Actually I'm not sure at all that ergo and igitur are used distinctively in this way, but I am sure that this is what Descartes meant.) --Trovatore (talk) 18:13, 29 April 2010 (UTC)

How do you know they don't think? --TammyMoet (talk) 10:50, 29 April 2010 (UTC)

As a sidebar from a humanities person, this is sometimes taken as evidence of a higher being. I am not endorsing or refuting this view on this reference desk, and I don't particularly want to start a massive debate; since it is a fairly common explanation even to today among large groups of people, I felt it worth mentioning, despite the lack of scientific evidence. That is all, Falconus^{p t c} 11:49, 29 April 2010 (UTC)

I think you should avoid the cogito ergo sum approach. That barely works with humans (if it does) and certainly can't be extrapolated to all living creatures (and not even to all humans). The article Dr Dima linked to has a more generalizable description of how we define things and why it gets tricky in border cases.

As for understanding why animate objects exist: if you start with very complicated organisms (humans, for example), it looks endlessly miraculous. Start small and build up. Bacteria and viruses are a bit more easy to understand, and what makes them "alive" or "dead" or "neither" (in the case of viruses) is easier to see. Then realize that every cell of in a multi-cellular organism meets the criteria for "life", and that we are a very complicated amalgamation of many types of specialized cells all working together. (Then wonder where our sense of consciousness and individuality comes from out of all of this mass of cells.) --Mr.98 (talk) 12:55, 29 April 2010 (UTC)

The border between living and nonliving isn't a bright line. It gets quite fuzzy. You first have to consider whether you are talking about individual living things or about Life as a system (i.e. the entirety of the biosphere or all of living things taken together) Consider things like viruses and prions. Are they alive? Depends on how you define life. Is a virus alive when it is isolated on a petri dish? What about when it is actively infecting a cell? Could viruses exist outside of Life as a system? Could viruses have come to exist outside of Life as a system? Do viruses do anything we expect an organism to do? There's some stuff which is unquestionably alive (like me). There's other stuff which is unquestionably not (like say, a chunk of granite). Things just get a bit fuzzy at some of the border conditions. --Jayron32 18:56, 29 April 2010 (UTC)

Ancient pagan religions considered everything to be alive, i.e. to have a "spirit" associated with it, yes? And even now we anthropomorphize storms, bodies of water, the earth itself. ←Baseball Bugs ^{What's up, Doc?} carrots→ 16:39, 30 April 2010 (UTC)

Gas and Gravity

Why are not gases influenced by gravity? - anandh, chennai. —Preceding unsigned comment added by 125.21.50.214 (talk) 07:07, 29 April 2010 (UTC)

They are influenced by gravity, of course. If they were not, the atmosphere of the Earth would have escaped into space almost immediately. --Dr Dima (talk) 07:15, 29 April 2010 (UTC)

Perhaps you are asking, "If gas is influenced by gravity, why doesn't it all fall to the surface of the Earth?" Mm? It's a good question. And I can answer it with another question: "Why don't your feet sink into the ground?" Obviously, because the ground is solid, and it pushes back on your feet. Now, we all know that gas is not solid. But have you ever tried squeezing a balloon? Even though gas is not solid, it does push back when you try to compress it. And that's why air stays "up". Earth's gravity does pull it down, but air resists from being compressed infinitely. Someguy1221 (talk) 07:22, 29 April 2010 (UTC)

Atmospheric escape might be a good article to read in order to understand the role of gravity. A Balloon (aircraft) also, requires the action of gravity on gases in order to obtain its buoyancy.--Aspro (talk) 07:58, 29 April 2010 (UTC)

Thanks. But i think the explanation with gas compression is paradoxical when degree of randomness is considered. —Preceding unsigned comment added by 125.21.50.214 (talk) 08:09, 29 April 2010 (UTC)

OK, how about this. Let's go to extremes, the gas Sulphur Hexafluoride is heavy enough to float a boat (sort of), as can be seen here in this demo. [21]. Just think about how much you could support with Uranium Hexafluoride! --Aspro (talk) 08:35, 29 April 2010 (UTC)

Gas molecules do fall to the surface of the Earth, but then they bounce up again. The reason they never lose all their energy to friction and settle down is that the surface of the Earth is vibrating (because it's warm). It's not obvious to us but it's very obvious to the gas molecules with their very tiny masses. There's a nice mechanical model of this at the Exploratorium in San Francisco—here's a photo of it. The molecules also bounce off of each other, but that's not essential. You can pretend that each molecule moves independently, bouncing off the ground over and over, and get basically the right physical predictions (this is the ideal gas approximation). -- BenRG (talk) 09:14, 29 April 2010 (UTC)

Thanks. Warm air (or hot land surface in this case) expands gases and so it is above. Obviously because of warm air, gases raise and tend to be in a region where it is not influenced (means, concentrated there) but below that region, the concentration is less. Fine, to what extent the effectiveness of warm air is...to keep the gases from moving to a region with lower concentration? —Preceding unsigned comment added by 125.21.50.214 (talk) 09:31, 29 April 2010 (UTC)

Each parcel of gas is attracted to the Earth's gravity, but it is also repelled by the pressure of the gas below (which is minutely greater than the pressure of the gas above.) The end result is that the forces on each parcel of air are in equilibrium. (If we imagine too much gas moving closer to the Earth we must also imagine the pressure gradient increasing too, and that would drive the excess gas upwards again, to restore the equilibrium.) Dolphin (t) 13:15, 29 April 2010 (UTC)

See hydrostatic equilibrium. You can actually model this using a computer program. Model a bunch of bouncing balls under a constant force of gravity, but make all the collisions elastic (i.e. flip all the vector components the opposite sign when it hits a wall or another ball). You'll get a distribution of balls heaviest near the bottom and light near the top. Interestingly, that's what the atmosphere behaves like...

The reason why we don't behave like air molecules is that generally our collisions with the ground are not so elastic. But if every time we jumped we didn't lose any kinetic energy, we would behave like gas molecules. John Riemann Soong (talk) 15:10, 29 April 2010 (UTC)

Alarm clock

My wife and I each have an alarm clock on our nightstands. They are not identical, but both are of the common type that has a red LED display, plugs into the wall outlet, and has a 9 volt battery for backup during power failures. They're probably both 10–15 years old. Yesterday there was a power failure while we were at work. I don't know how long it lasted, but no more than ~8 hours and probably less. After the power failure, both alarm clocks were ahead of the correct time by 10–20 minutes. This is, of course, horrible accuracy compared to even the cheapest wristwatch. Why are these alarm clocks so inaccurate when running on battery? -- Coneslayer (talk) 11:05, 29 April 2010 (UTC)

When running on alternating current, the frequency of the supply provides an accurate source of information, and the clock is designed to make use of that information. When running on battery the clock has an alternative mechanism for keeping track of time, probably some sort of resonant circuit. It seems the mechanism for time-keeping on battery is simple and inexpensive, and remarkably inaccurate. The designer of the clock was presumably of the view that the battery would only be required for relatively short periods, and designed the resonant circuit accordingly. Dolphin (t) 13:09, 29 April 2010 (UTC)

I knew that analog wall clocks often used the AC frequency for timekeeping, but didn't realize that digital clocks did as well. Is it possible that the frequency of the DC circuit has a dependence on the battery voltage? After all, the voltage of an alkaline battery varies considerably over its useful life. -- Coneslayer (talk) 13:25, 29 April 2010 (UTC)

I had one which allowed you to switch between 50hz and 60hz before. Have you ever looked closely at your clock and/or the manual if you still have it do see if yours does? Nil Einne (talk) 06:57, 30 April 2010 (UTC)

Very intersting. I would've expected the clocks to be BEHIND the real time. --Kvasir (talk) 16:24, 29 April 2010 (UTC)

Since I didn't notice the discrepancy until I was early for work this morning, I'm glad they were ahead. -- Coneslayer (talk) 16:28, 29 April 2010 (UTC)

Maybe the quartz crystals were defective. --Chemicalinterest (talk) 19:39, 29 April 2010 (UTC)

It may be by design. If you know the backup you're designing is generally going to be inaccurate it makes sense to make it so it's normally faster rather then slower when one of the likely intentions is to keep an alarm, for obvious reasons. Nil Einne (talk) 06:55, 30 April 2010 (UTC)

Since even a $5 wristwatch runs much more accurately than that, it's probably just that the manufacturer used the cheapest timing circuit they could find, figuring that it would very rarely come into play. Looie496 (talk) 21:05, 29 April 2010 (UTC)

$5? I actually saw a wristwatch for $1 plus tax in a dollar store. Everything in it was a dollar. --Chemicalinterest (talk) 00:40, 30 April 2010 (UTC)

Just as a point of information, this is something that varies (or has varied) from one brand so another. There are three alarm-clock-radios in my house with digital time displays and battery backup: a Toshiba, an Optimus, and a Sony Dream Machine. The first two behave in the way the original poster describes. But the Sony's designer evidently felt differently about this issue. When the power goes off and comes back on, the display starts flashing so you're warned it might not be accurate. And, ironically, it's also much more accurate than the other two in this situation. Of course, that might not apply to this year's equivalent model. --Anonymous, <blink>01:02</> UTC, April 30, 20, 10. —Preceding undated comment added 01:02, 30 April 2010.

These refs [22] [23] suggests it a common issue, they usually use a cheap and crap RC oscillator for the purpose. Nil Einne (talk) 06:50, 30 April 2010 (UTC)

Quartz crystal oscillators usually have a Q factor on the order of 10 x 10⁶, or one part in ten million error (this one is 10 parts in 1 million, but still darned good). So, if the clock is losing or gaining minutes on the day, it's clearly not using a quartz oscillator; I'd assume such a clock keeps time with a poorly tuned RC oscillator whose accuracy is under-engineered for cost-reduction. It's probable that it uses a separate clock for its backup than it does for its powered, normal operation - probably because "backup" was tacked on as a feature. Again, the OP's assertion is totally correct - it could be designed to operate entirely on battery and use the power only to drive the LED lights and alarm speaker, and therefore the accuracy would not change when power goes out. It probably uses a "sloppy" design to save costs or use up stock components in a manufacturer's warehouse. Nimur (talk) 14:50, 30 April 2010 (UTC)

How to Identify nylon 6 from nylon 6,6?

I was wondering if anyone knew of a way to tell the difference between nylon 6 and nylon 6,6? This information would be useful to help me recycle the nylon with more efficiency. Thank-you for your time. —Preceding unsigned comment added by 70.229.42.54 (talk) 12:46, 29 April 2010 (UTC)

In the lab one can use a rather large spectroscope machine and look for their respective signatures. On that basis, I did a search and found there is now a hand-held Fourier transform infra-red spectroscopy unit that will do the same thing. No idea how much it is though. No doubt the same technique could be used to automatically sort wast on a conveyor belt. Here's the instrument[24] and here is a PDF in which the claims that it can do these two Nylons is specifically made [25] --Aspro (talk) 13:47, 29 April 2010 (UTC)

I actually already have an IR machine unfortunately this only lets you know that you are dealing with nylon and not what kind of nylon. are there any other tests that can be done?

animal government

I know we talk about "queen ants" but do any animals actually have any government? 82.113.106.110 (talk) 14:32, 29 April 2010 (UTC)

Depends on definitions. Wikipedia defines "Government" as:

"A government is the organization, machinery, or agency through which a political unit exercises its authority, controls and administers public policy, and directs and controls the actions of its members or subjects"

Animals are known to exert some kind of "authority" (again, this needs to be defined) over other animals. But as for controling/administering policy, nope. I think you need to tell us what definition you're using. 196.38.62.178 (talk) 14:40, 29 April 2010 (UTC)

(ec) It depends how you define "government." Certain animals do cooperate and have extremely intricate social hierarchies (meerkats, mole rats, wolf packs) that we sometimes call "clans" or "colonies" or things of that nature. They look not dissimilar from certain "primitive" forms of human government. Ants are eusocial, and are maybe best understood as superorganisms, which may or may not be similarly to your definition of "government." --Mr.98 (talk) 14:43, 29 April 2010 (UTC)

Rooks and owls have parliaments [26].--Shantavira|^{feed me} 15:01, 29 April 2010 (UTC)

Do you mean do any animals have leaderships made up of more than one individual? Some species have groups with an alpha pair - a breeding pair that are in charge, rather than just an alpha male (or alpha female) in charge. There are also species where the group will have a detailed order of precedence, but I don't think any individuals other than the one (or two) at the top play a significant leadership role. --Tango (talk) 15:09, 29 April 2010 (UTC)

If we take government to be equivalent to 'social hierarchy', then plainly yes. You could probably even discern 'taxation systems' and 'public infrastructure projects' if you looked closely. Vranak (talk) 15:51, 29 April 2010 (UTC)

BTW, queen ants are only egg-laying machines; they don't govern. --Chemicalinterest (talk) 19:40, 29 April 2010 (UTC)

See http://multilingualbible.com/proverbs/30-27.htm. -- Wavelength (talk) 23:12, 29 April 2010 (UTC)

Not sure what you're trying to do here. The biblical proverb is "The locusts have no king yet they go forth in bands" and it looks like it means that a group of people don't need a leader to be united (or something like that). This really doesn't help our questioner. 196.38.62.178 (talk) 14:30, 30 April 2010 (UTC)

Biological Classification

I was thinking about biological classification and I came across this picture. How does man fit into it? Could someone please list my labels in this list. For example, my species is human, my genus (I think) is primate, etc... THANKS! •• Fly by Night (talk) 15:03, 29 April 2010 (UTC)

See species:Homo_sapiens_sapiens. CS Miller (talk) 15:12, 29 April 2010 (UTC)

...and note that primate is an order, not a genus. Gandalf61 (talk) 15:16, 29 April 2010 (UTC)

A somewhat less daunting list, with all the relevant entries from kingdom on down, is in the taxobox at the top of Human. Deor (talk) 19:07, 29 April 2010 (UTC)

Fact checking from Fight Club

I found some parts from the novel Fight Club extremely suspicious (for not saying, outright false). I pasted them below. Is there any truth in them? Mr.K. (talk) 15:18, 29 April 2010 (UTC)

1. "they used their urine and the urine of their dogs to wash their clothes and hair because of the uric acid and ammonia."
2. "Spiders," (...) "could lay their eggs and larva could tunnel, under your skin."
3. "It doesn't matter," Tyler says. "If the applicant is young, we tell him he's too young. If he's fat, he's too fat. If he's old, he's too old. Thin, he's too thin. White, he's too white. Black, he's too black." This is how Buddhist temples have tested applicants going back for bahzillion years, Tyler says.
4. "The three ways to make napalm: "One, you can mix equal parts of gasoline and frozen orange juice concentrate," the space monkey in the basement reads. "Two, you can mix equal parts of gasoline and diet cola. Three, you can dissolve crumbled cat litter in gasoline until the mixture is thick."
5. "A cathode ray tube can hold 300 volts of passive electrical storage, so use a hefty screwdriver across the main power supply capacitor, first. If you're dead at this point, you didn't use an insulated screwdriver."
6. "A sort of fun explosive is potassium permanganate mixed with powdered sugar. The idea is to mix one ingredient that will burn very fast with a second ingredient that will supply enough oxygen for that burning. This burns so fast, it's an explosion. Barium peroxide and zinc dust. Ammonium nitrate and powdered aluminum. Barium nitrate in a sauce of sulfur and garnished with charcoal. That's your basic gunpowder."
7. "You take a 98-percent concentration of fuming nitric acid and add the acid to three times that amount of sulfuric acid. You have nitroglycerin. Mix the vitro with sawdust, and you have a nice plastic explosive. A lot of the space monkeys mix their vitro with cotton and add Epsom salts as a sulfate. This works, too. Some monkeys, they use paraffin mixed with vitro. Paraffin has never, ever worked for me."

1. You don't think Wikipedia would over look that particular use of urine do you.--Aspro (talk) 15:36, 29 April 2010 (UTC)
2. No larva, no burrowing under the skin. The Burk Museum of Natural History and Culture has a myth busting site: [27]--Aspro (talk) 20:11, 29 April 2010 (UTC)
3. *
4. It would be a bit irresponsible for the publisher to allow the author to be too precise about these things -don't you think?--Aspro (talk) 15:48, 29 April 2010 (UTC)
5. Yes, the output capacitor and tube can hold a charge. See Wikipedia:Reference_desk/Archives/Science/2010_April_12#Old_television_smoky_exploding_madness.21. --Aspro (talk) 15:55, 29 April 2010 (UTC)
6. Potassium permanganate reacts with glycerin; it probably does with sugar, belching clouds of water vapor, carbon dioxide gas, spattering black manganese dioxide smoke; messy, messy, messy... Zinc dust will react with barium peroxide to produce barium oxide and zinc oxide smoke. It might not make a good explosive since there are no gaseous products. Ammonium nitrate and aluminum would make aluminum oxide, nitrogen gas, and probably water vapor. Potassium nitrate is normally used instead of barium nitrate in gunpowder. Caution: Barium fumes and compounds are toxic.--Chemicalinterest (talk) 19:48, 29 April 2010 (UTC)
7. Where is the glycerin? Nitric acid reacts with glycerin according to the nitroglycerin article using sulfuric acid as a catalyst to produce nitroglycerin. Extremely dangerous, may detonate when created. --Chemicalinterest (talk) 19:48, 29 April 2010 (UTC)

Wikipedia contains details on nitroglycerin and napalm and gunpowder among other dangerous things. I'm not sure it makes any sense to assume that just because the work is fiction, the author couldn't—or wouldn't—have looked into these things and published them accurately. There is no law against it. --Mr.98 (talk) 16:07, 29 April 2010 (UTC)

According to an interview with Palahniuk, his explosive recipes in the book are correct, but the ones in the movie are not. --Mr.98 (talk) 16:04, 29 April 2010 (UTC)

I've uncollapsed and numbered the questions, so they're easier to respond to. Buddy431 (talk) 19:39, 29 April 2010 (UTC)

6. I think permanganate (a strong oxidizer) and powdered sugar would likely deflagrate quickly in an explosion like manner. He's essentially right in his assertion: pretty much any pyrotechnic is a fuel (sugar, charcoal, metals like zinc or aluminum will work) along with a strong oxidizer (permanganates, nitrates, peroxides all fit the bill). And he's right about gunpowder: a nitrate, charcoal, and a bit of sulfur. Usually potassium nitrate is used because it's more widely availiable than Barium nitrate, but it's only the nitrate that's important.

7. I think you're missing an ingredient in nitroglycerine: you need a source of glycerol! But yes, nitroglycerine is made by adding glycerol to a solution of concentrated nitric and sulfuric acids. This mix generates Nitronium ions, a strong electrophile that attacks the oxygens on glycerol. As in the previous question, the nitrates are acting as an oxidizing agent. I suspect that all of the mixes listed would at least burn, though maybe not explode like you want them to (sawdust, cotton, and paraffin can all act as a fuel). However, 98% nitric acid is quite expensive. It's much cheaper to buy nitrates and make some of the gun-powder like substances that are mentioned in your question number six.Buddy431 (talk) 19:58, 29 April 2010 (UTC)

And please don't try making any of this. Apart from the obvious explosion/fire risk, concentrated nitric acid and sulfuric acid are uber nasty. Buddy431 (talk) 19:57, 29 April 2010 (UTC)

Plus, playing around with these kinds of things could easily land you in jail with no parole (either for attempted murder/terrorism with weapons of mass destruction for an extra 20-years-to-life tacked on, or at the very least for criminal endangerment of others). Definitely not a good idea. 76.103.104.108 (talk) 07:11, 30 April 2010 (UTC)

2. While not a spider, the Botfly will lay eggs under the skin of the host. Icky. Buddy431 (talk) 20:01, 29 April 2010 (UTC)

Fuming nitric acid is probably restricted because of the ease by which explosives may be made from it. --Chemicalinterest (talk) 20:07, 29 April 2010 (UTC)

1) Urine was used in Ancient Rome to wash clothes (at least by those Romans who couldn't afford soap -- which was at the time damnably expensive).

4) Of these three recipes, only the one with the cat litter would produce a useful grade of napalm. A better recipe, though, would be to dissolve rubber or Styrofoam instead of cat litter.

5) Capacitors can indeed store enough charge to zap you very badly (in extreme cases, they could even deliver a lethal shock). Don't screw around with high-voltage components unless you really know what you're doing.

6) KMnO₄ + C₆H₁₂O₆ → MnO₂ + CO₂ + H₂O (gunpowder-like deflagration). BaO₂ + Zn → BaO + ZnO (will burn with green flame and white smoke, but will not explode). NH₄NO₃ + Al → NH₃ + Al(NO₃)₃ (will also deflagrate, but with less explosive force than plain ammonium nitrate, and will release toxic ammonia gas). Ba(NO₃)₂ + S + C → BaO (highly toxic) + N₂ + SO₂ + CO₂ (explosively deflagrates just like gunpowder). Actual gunpowder uses KNO₃ or NaNO₃ because they're more readily available and contain more oxygen (as nitrate) per unit weight. Don't try any of this at home if you don't want to risk your own life and those of your family.

7) A mixture of fuming nitric and sulfuric acid will react with glycerin to make nitroglycerin; mixing this with sawdust will produce a form of dynamite. Nitroglycerin is EXTREMELY unstable and liable to blow up in your face upon the slightest shock, like if you sneeze on it; and when it does blow up, it can explode with enough force to turn a good-sized apartment building to a pile of rubble (with you at the bottom of the pile). In summary: DON'T TRY ANY OF THIS AT HOME!!! 76.103.104.108 (talk) 07:47, 30 April 2010 (UTC)

Notes to 76.103.104.108: When KMnO4 oxidizes sugar, it produces potassium hydroxide, a strong base. When NH4NO3 reacts with aluminum, nitrogen is produced. You can never get your equation balanced because the aluminum is being oxidized and the nitrate isn't being reduced. The reaction is: 3 NH₄NO₃ + 2 Al → Al₂O₃ + 6 H₂O + 3 N₂ SO₂ isn't normally produced in gunpowder exhaust. It would be a form of BaS. --Chemicalinterest (talk) 16:24, 30 April 2010 (UTC)

Superconductivity and gravity

What are the latest news regarding superconductivity and gravity? Are there any hopes to levitate objects as done with magnetic field? If so, then how is the object's response to this force cancellation; is it just apparent on the surface or in every point?--Email4mobile (talk) 18:15, 29 April 2010 (UTC)

Lots of things are levitated via magnetic field. And you don't even need a superconductor to do it. See Maglev train. --Jayron32 18:43, 29 April 2010 (UTC)

Some maglevs are using superconductors now, though. There now exist "High Temperature" superconductors that operate at the balmy temperature of -196 C. This may seem very cold (and it is), but that's the temperature of liquid nitrogen, a relatively cheap and easily handled coolant. Buddy431 (talk) 19:30, 29 April 2010 (UTC)

I meant something like this.--Email4mobile (talk) 02:12, 30 April 2010 (UTC)

I don't have the physics background to evaluate any of those claims, but a lot of it looks pretty fishy. Wikipedia has articles on a number of the characters mentioned: Ning Li (physicist), Martin Tajmar, Eugene Podkletnov. They seem a bit shady. Our Antigravity article covers some of the claims by these characters, i.e. here, and indicates that as of yet, none of their claims have been verified by any independent experiments. Buddy431 (talk) 05:53, 30 April 2010 (UTC)

The PDF rang loud bells for me too as it mentions Eugene Podkletnov more than once. Don't bother trying to get your head around anything he says, nor to even finish reading anything that mentions his name. It's all nonsense, based on some odd measurements in physics . Cold fusion is a piece of cake in comparison and far more likely to succeed.--Aspro (talk) 15:12, 30 April 2010 (UTC)

Edge of the Universe

I understand current models of the universe establish there is no boundary in three dimensions as we may live within a 4-sphere. If that's the case though then if you consider the universe in 5 dimensions there will still be an edge. So what's over THAT edge? TheFutureAwaits (talk) 18:34, 29 April 2010 (UTC)

Think about a 2-sphere in 3-space. There's no edge. If you lived in 2-dimension land on that sphere, every point in your world would look the same to you. Rckrone (talk) 18:45, 29 April 2010 (UTC)

See shape of the universe for more details on this issue. --Jayron32 18:50, 29 April 2010 (UTC)

While it can help to think about the universe embedded in higher-dimensional space, it is inadvisable to do so. It's just a way of getting your head around it, it doesn't actually represent anything in reality. (There is the theory of Brane cosmology that includes something similar, but that's not important.) Most likely, there is no edge to the universe in anything meaningful sense. --Tango (talk) 18:51, 29 April 2010 (UTC)

I agree. This is the way I often see it: the laws of physics exist within the universe only. There is no existence without these laws. Therefore there can be no boundary with something that has no existence, because it does not even have dimensions which would be needed in order to say where it is. There is just the universe.--Aspro (talk) 19:09, 29 April 2010 (UTC)

If there is no edge then what if we just continue to go then where are we going to?75.168.119.109 (talk) 22:36, 29 April 2010 (UTC)

There are two possibilities. Either the universe is infinite in extent and you just keep on going for ever and nothing interesting happens or the universe is closed and if you keep going far enough you end up going around in a big circle and end up back where you started. --Tango (talk) 22:48, 29 April 2010 (UTC)

This is no sense how could we go that far then end up going around and back where we started. I think there must be a boundary but you could not go anymore when you get to the boundary or it, the boundary, destroys everything touch it.75.168.119.109 (talk) 22:58, 29 April 2010 (UTC)

That is simply not true. A universe in which you can go all the way round and get back to where you started is possible within mainstream cosmological theories. It is like the surface of the Earth - if you go far enough, you'll get back to where you started. There is no "end of the world" where you fall off into oblivion. The (spacial part of the) universe could be a 3-sphere, so very much like the surface of the Earth, just a dimension higher, or it could be a 3-torus (the 3D equivalent of the surface of a ring doughnut), which still allows you to go all the way around the universe, but the universe would be flat (which fits with observations). (There are more complicated shapes, but 3-spheres and 3-tori are the simple ones worth considering in this discussion.) --Tango (talk) 23:25, 29 April 2010 (UTC)

How could you compare the universe same as Earth? Earth shape is a circle and that's how you could go around it but not the universe. I still think that's nonsense to go around the universe.75.168.119.109 (talk) 23:43, 29 April 2010 (UTC)

Well, you are wrong. That's all there is to say about it (Jayron gave a link to our article which has references to back up my statement). --Tango (talk) 23:44, 29 April 2010 (UTC)

There are two ways that the universe works. One is that it is finite, but with no edges. Sounds crazy, but it does work. Imagine that you are an 2-D ant living on (technically within, but w/e) the surface of a sphere. You can go anywhere you want as far as you want, but you end up where you started eventually. It is a finite surface, but no edge. The sphere is a 2-D surface, just curved. Now scale that up to three dimensions. You get a curved, finite, 3-D space, but with no edges. The other option is that the universe is infinite, but that is a much easier concept to grasp. KyuubiSeal (talk) 02:28, 30 April 2010 (UTC)

Healing of cut

How long (typically) after a minor cut (such as a paper cut) does the skin become impermeable to viruses? Thanks. —Preceding unsigned comment added by 160.109.98.44 (talk) 19:40, 29 April 2010 (UTC)

After a good scab (don't pick it) is developed. If no viruses have gotten in, you should be safe. --Chemicalinterest (talk) 19:49, 29 April 2010 (UTC)

But even if viruses do get in does not mean the end of the world. The human body has a great immune system for dealing with the average virus. It works best though if you let a few viruses in now and again so that it can form and/or maintain immunity against them. Richard Avery (talk) 06:24, 30 April 2010 (UTC)

Unless that virus is Human Immunodeficiency Virus, in which case you can kiss your immune system goodbye. If you're working in a situation where dangerous viruses are likely to be transferred, you should take safety precautions dictated by an authority on the matter, and not take advice from random people on the internet, regardless of whether you have a paper cut or not. Buddy431 (talk) 15:36, 30 April 2010 (UTC)

Dissolution of Metals

Would dissolving of metals necessarily mean the metal was oxidized? For example, Ta dissolves in KOH. Is is being oxidized. --Chemicalinterest (talk) 20:29, 29 April 2010 (UTC)

Yes. Metals do not dissolve as neutral atoms or molecules the way that most nonmetals do (for example, gasseous O₂ dissolves in oxygen as O₂ molecules, neutrally charged). Instead, metals only dissolve if they are oxidized. So when, say, Magnesium metal dissolves in an acidic solution, the magnesium is oxidized from the metal to the Mg²⁺ ion. In such cases, there has to be a corresponding reduction reaction. In the case of magnsium dissolve it will be the formation of H₂ gas from H₃O¹⁺ ions in the acid solution. --Jayron32 20:40, 29 April 2010 (UTC)

If you dissolve the metal in mercury it does not oxidise in that process. The same would be try of metal dissolving in other molten metals. There could be some other solvents that take up metals as complexed neutral atoms. may be liquid ammonia. Graeme Bartlett (talk) 22:44, 29 April 2010 (UTC)

Potassium is sometimes dissolved in liquid ammonia and used as a strong reducing agent. However, people think that the extra electron is removed from the potassium and solvated in the ammonia, so really it's still the potassium ion that's dissolved. Buddy431 (talk) 23:34, 29 April 2010 (UTC)

Here's the appropriate articles: Ammonia#Solutions_of_metals as well as solvated electron. Mr. Bartlett mentioned mercury solutions: those are generally known as Amalgams. Buddy431 (talk) 23:38, 29 April 2010 (UTC)

You can certainly have zero-valent metals (i.e., not "ions") in solution...Tetrakis(triphenylphosphine)palladium(0) is just one example of many hundreds of soluble organometallic compounds. It's just "just atoms" (those ligands are bound to it), but "solvent having specific affinity to solute particles" is how most dissolving works. So all you need is an organic liquid that can serve as a Lewis-base ligand for a metal atom, and you have the same idea as water serving as a Lewis-base coordinating to a cation. One thing I don't know is if you can literally "dissolve the metal". All the organometallics I know are formed by reducing the dissolved metal cation back to zero. DMacks (talk) 01:03, 30 April 2010 (UTC)

I quite accept that it is possible to have a zero-oxidation-state metal, properly coordinated with the right ligands, which is then soluble. The question is can you take a chunk of metal and put it into something, and have it dissolve without any oxidation occuring. I am sure there are some exotic cases (nothing is impossible, per se), but under normal circumstances, for any normal definition of "metal" and "dissolve" then probably not. --Jayron32 02:54, 30 April 2010 (UTC)

Gold in mercury does this. Graeme Bartlett (talk) 09:09, 30 April 2010 (UTC)

Death

After we died then where are we going to? Is reborn one of the possible way?75.168.119.109 (talk) 22:38, 29 April 2010 (UTC)

This is a topic explored by all religions, philosophies, and sciences as long as human has existed. See our articles on Death and Afterlife. Specifically, see reincarnation for the topic on "rebirth". --Kvasir (talk) 22:45, 29 April 2010 (UTC)

Since you have asked on the science desk, I'll give a scientific answer: Once you die, that is it. Your conciousness ceases to exist and your body decays. Pretty much every religions involves some kind of life-after-death, but they are very different in different religions. --Tango (talk) 22:50, 29 April 2010 (UTC)

You mean once we die then that's it. That's mean once we die then we are same as if we are not exist. It is hard to imagine how could that be like.75.168.119.109 (talk) 22:53, 29 April 2010 (UTC)

Your consciousness relies on the electrical signals among the cells in your brain. When you die, those signals stop and your consciousness ceases to exist, as Tango said. 196.38.62.178 (talk) 09:45, 30 April 2010 (UTC)

See http://multilingualbible.com/ecclesiastes/9-5.htm; http://multilingualbible.com/ecclesiastes/9-10.htm.

-- Wavelength (talk) 23:08, 29 April 2010 (UTC)

Remember what it was like to be you before you were born? No? Well, that's what it's like when you are dead.--Eriastrum (talk) 23:11, 29 April 2010 (UTC)

If you are going to give a religious answer on the science desk, please at least give a summary of the various different religious viewpoints. --Tango (talk) 23:16, 29 April 2010 (UTC)

I suggest that the question probably should have been moved to the Humanities desk from the get-go. Kingsfold (talk) 11:47, 30 April 2010 (UTC)

Is what really happen to us after we die?75.168.119.109 (talk) 23:18, 29 April 2010 (UTC)

What is scientific about just saying that the soul goes nowhere when one dies? It is just what people who don't believe in God believe. I believe (an unpopular belief) that people who are saved (believe that you are a sinner, that God can pay for your sins, that you cannot pay for your sins, to trust in God for redemption) go to heaven, and people who are not saved go to hell. Simple. --Chemicalinterest (talk) 23:20, 29 April 2010 (UTC)

You are misrepresenting the scientific view - science doesn't involve a concept of souls at all. It is scientific because it is the simplest answer that is consistent with observations - that is how science works. --Tango (talk) 23:29, 29 April 2010 (UTC)

You are true when you said that science does not involve a concept of souls. It, like origins, is relegated to the realm of philosophy. --Chemicalinterest (talk) 00:38, 30 April 2010 (UTC)

Before you were born you did not exist. But even though your body goes away, your soul never dies. --Chemicalinterest (talk) 23:27, 29 April 2010 (UTC)

That's not necessarily a scientific view or a religious one. References such as Job 38:7, Eccl 12:7, and Jeremiah 1:5 indicate that there was an antemortal existence, or (if you read those scriptures differently) at least that one is possible. Kingsfold (talk) 11:27, 30 April 2010 (UTC)

I could see nobody actually knows the answer for this. But I hope after we die we would not be like never exist, is better to be reborn and become a human again.75.168.119.109 (talk) 23:25, 29 April 2010 (UTC)

Unfortunately, the universe tends not to work in the way that makes us happiest. --Tango (talk) 23:29, 29 April 2010 (UTC)

Well if you hope that, that's fine. This is a question to which there is no scientific answer beyond either "it cannot be known" or "your body decays", depending on whether you consider 'you' to be your consciousness or your physical body. If you had asked on the humanities desk, you would have got versions of Kvansir's excellent answer (the first answer you got here). Being reborn is certainly an option proposed by several religions, and you are free to hope for that. If you find that's what you really believe will happen, that's fine too. But nobody here can tell you which afterlife to believe in. 86.178.225.111 (talk) 23:53, 29 April 2010 (UTC)

I disagree. There is a scientific answer: your conciousness ceases to be. It can't be proven any more than anything else in can in science, but it is still be most reasonable theory. --Tango (talk) 23:58, 29 April 2010 (UTC)

If you are saved, even better. By the way, what is atheism? Just another religion that denies there is a God. --Chemicalinterest (talk) 23:28, 29 April 2010 (UTC)

Strong atheism can be described as another religion, but weak atheism (which is what the vast majority of atheists are - I don't think I've ever knowingly met, online or in real life, a strong atheist) can't. A key (and I would say, defining) feature of religion is that it claims to know absolute truth. Weak atheism doesn't do that. --Tango (talk) 23:32, 29 April 2010 (UTC)

Some might claim to know absolute truth by arguing for evolution in cases where creation clearly has the upper hand. --Chemicalinterest (talk) 00:36, 30 April 2010 (UTC)

First, "arguing for" != "absolute truths", and secondly, you are speaking about the vacuous case here... --Stephan Schulz (talk) 08:17, 30 April 2010 (UTC)

It is folly to presume anything about the unknowable, e.g. post-death realities. Vranak (talk) 00:02, 30 April 2010 (UTC)

Physical body stops working and decays. Spirit/soul/conciousness, nobody knows. People have been working on it for millennia, and we still haven't found an answer yet. KyuubiSeal (talk) 00:32, 30 April 2010 (UTC)

I believe that scientists in the past have actually conducted experiments to look for human souls leaving the body upon death (it's been mentioned here before). Some positive results were indeed reported (see Duncan MacDougall (doctor), for example) but nothing that could be unambiguously reproduced/confirmed beyond reasonable doubt by others. --Kurt Shaped Box (talk) 07:07, 30 April 2010 (UTC)

Its a one-way street. Once you die, you cannot know with human knowledge what is after death. --Chemicalinterest (talk) 00:36, 30 April 2010 (UTC)

I don't believe it's unknowable. A spirit, the afterlife or reincarnation relies on mind /body or Consciousness /Matter dualism. We have been investigating it for millennia and so far there is so far no good evidence to suggest the mind is separate from the brain, but good evidence just keeps piling up that the mind and brain are not separate. I think it can and will be conclusively proved that the mind is a result of the brain, maybe it will take 50 or 100 years until we download someone's mind into a computer brain or something, but it will happen eventually. We're not that far off achieving the raw power, but there'll obviously be a lot more to it then just that.. However, even then I don't believe religion will disappear, they will justify it away just like they have every time science has proved them many times wrong in the past. 203.110.235.1 (talk) 00:45, 30 April 2010 (UTC)

Basically, we have no clue. This isn't a religious debate, and I'm not sure how we got there. Nothing to do with evolution, atheism, God, or religion. We have no evidence for the soul existing in this world after death. Maybe we go to heaven, maybe our soul goes nowhere, we really don't know. On a more humorous note: http://xkcd.com/659/ KyuubiSeal (talk) 01:36, 30 April 2010 (UTC)

Here on the Science desk, you're going to get the science answer, and science demands evidence. Since there hasn't been any evidence there is an afterlife, the presumption is that there isn't one. Comet Tuttle (talk) 03:48, 30 April 2010 (UTC)

Absence of evidence is not evidence of absence. Since there is no evidence for or against, science can have no opinion. There is nothing wrong with having undecidables in a discipline. Ariel. (talk) 05:55, 30 April 2010 (UTC)

Science usually uses Occam's razor as a tiebreaker in these situations, which comes down on the side of no afterlife. As far as science is concerned, there is no problem to solve here. There is no reason to question what happens after death - the answer is obvious. It is just that humans don't like that answer, so choose to believe a different one despite the lack of evidence. --Tango (talk) 06:26, 30 April 2010 (UTC)

I would dispute that there's been no evidence. We're lacking proof, not evidence. Kingsfold (talk) 11:39, 30 April 2010 (UTC)

I would be very interested in seeing any evidence you have for an afterlife. --Tango (talk) 17:28, 30 April 2010 (UTC)

For something that is sometimes interpreted as evidence, see Near Death Experience. It's not a question that they regularly occur, but the explanation for these experiences is hotly debated. Some people will tell you that it's just a scientifically explained brain phenomenon on the verge of death, and others will claim to have evidence to support the claim that it proves that conciousness is not tied with the brain as previously thought. Either way, it is extremely fascinating (at least to me). Falconus^{p t c} 04:30, 30 April 2010 (UTC)

I too find it interesting. By the way, (not really science, per se - but seems like an appropriate thread as any in which to ask) what is the name for the theory that sapience is the result of the presence of a soul? I read someone's take on this a while back and found it good 'food for thought'. --Kurt Shaped Box (talk) 07:13, 30 April 2010 (UTC)

Many scientists think they know the answer. Many laypeople don't want to hear it. 67.243.7.245 (talk) 13:49, 30 April 2010 (UTC)

We cannot take serious any reasoning based on concepts and assumptions that are not well defined/supported. Not only can't we invoke some undefined afterlife, Heaven, Soul, etc. etc. but we shouldn't make other hidden assumptions e.g. about the nature of time, about whether or not information is exactly conserved by the laws of physics. Any assumptions should be made explicit.

So, if I assume that time does not really exist, in the sense that there is no physical pointer that points out the present moment relative to the past and the future, which makes that only the present moment really exists, then you don't really die. All the past states in which you "were" alive simply exist. One has to note that this idea of time is far better motivated than the naive interpretation in which only the present moment really exists. In fact, the naive notion of time violates special relativity, see e.g. the Andromeda paradox article for a clear illustration of why the physical status of yesterday should be the same as the status of today.

Another assumption one could make is that information is exactly conserved in the universe. Both in classical physics and in quantum physics information does not get lost. However, in the Copenhagen interpretation of quantum mechanics, this is only true in a probabilistic sense, while in the Many Worlds interpretation this is true in a more exact sense. So, this assumption is quite well motivated.

So, even if time were to somehow exist in the naive interpretation, the past would still exist in the present moment, albeit in a scrambled form. Yesterday then exists inside today in a sphere of one light day diameter. But to see it, you would have to apply the exact time evolution operator to it. If you belive in the strong artificial intelligence assumption, the way you are are implemented does not affect your consciousness. So, the fact that the copy of you in yesterday's state is scrambled within that one light day sphere, should not be relevant to his consciousness. Of course, his entire physical world is scrambled with him in it, so he subjectively experiences being alive in yesterday world. But the point is that it all exists within today's world. Count Iblis (talk) 15:03, 30 April 2010 (UTC)

(ec) Just like the ghost question asked by the same OP, the answer to this one is pretty much that there is an overwhelming scientific consensus that counter-indicates the presence of rebirth, afterlife, and so on. If the religious folks want to weasel up some contorted definition about the afterlife, and play like it's not subject to scientific reason, then ... by the same logic, those religious people are all pink aardvarks who are not subject to rational, scientific reason. The instant you make a claim about some kind of tangible, extant soul - or afterlife - we can start questioning the logical consequences that would follow from such a claim. If there is a heaven, then where is it? If there is a soul, what is it made of? If the answers to these are "nowhere" and "nothing", then we have a resounding victory for the "sorry, OP, there is no afterlife" camp. If the religious folks want to start digging their hole deeper, they can make shit up to explain the soul and the afterlife. Every single detail they explain will be subject to the same demands for observational evidence as any other scientific claim. If the soul is made of some luminiferous ether, we have already shown that to be inconsistent with our observations of the universe. If heaven is located above the clouds, I have some bad news for you, because we've been there, and it's pretty drab and empty (though it sure does excite the plasma physicists). As the technologies and thought processes available to humans expand, we become better able to explain all of the things we are experiencing without the need for vague and hand-wavey answers. And as for User:Chemicalinterest - while I respect your right to hold your beliefs, I have no qualms telling you that your beliefs are simply moronic, and do not stand up to even the slightest scientific inquiry. The Resurrection of Christ could be explained by an ascent to heaven - or the body might have been eaten by coyotes or jackals. Which is the scientific explanation? If you want to stick to your guns and tell me about heavenly ascent, I have some very simple questions about how a body can levitate, pass through solid rock, and then fly to a place above the clouds, and so on. Do you really feel that there is a scientific ANY explanation for those details, or do you want us to just resign to the idea that "a pink aardvark did it for the lulz"? Nimur (talk) 15:18, 30 April 2010 (UTC)

Coyotes, to my knowledge, did not even live in Palestine during Roman times, so they must be ruled out as a scientific explanation for the disappearance of the body. We should not introduce explanations that are inconsistent with known historical fact. Nimur (talk) 15:20, 30 April 2010 (UTC)

The concept of an afterlife is based on faith, not proof. If you could prove it, there wouldn't be any debate about it. Science demands scientific evidence, and there isn't any. That doesn't mean there's no afterlife, it simply means science has not figured out a way to detect and/or measure it. So anything science says about it is also based on "faith". ←Baseball Bugs ^{What's up, Doc?} carrots→ 16:33, 30 April 2010 (UTC)

The concept of an afterlife is not needed to explain any observed phenomena - so there is no need to test for it. It's also not falsifiable - so we couldn't if we wanted to. The only reason anyone would want to test for it would be to shut everyone up. All the evidence as well as common sense says that when we die our brains shut off permanently and our consciousness ends - I don't know why anyone would want more than that. Zain Ebrahim (talk) 17:02, 30 April 2010 (UTC)

It's the faith, or hope, that there's something more than just this. ←Baseball Bugs ^{What's up, Doc?} carrots→ 17:44, 30 April 2010 (UTC)

Reduction of Iodate

What is the half equation for the reduction of iodate $({IO_{3}}^{-})$?--115.178.29.142 (talk) 23:06, 29 April 2010 (UTC) Reduction to what? I₂? I^-? HIO?

Reduction to HIO is: IO3− + 5 H+ + 4 e− ⇄ HIO(aq) + 2 H2O (+1.13V)

Reduction to I2: 2 IO3− + 12 H+ + 10 e− ⇄ I2(s) + 6 H2O (+1.20V) --Chemicalinterest (talk) 23:24, 29 April 2010 (UTC)

(edit conflict) Reduction to what? At Standard electrode potential (data page) we have two reactions where iodate is reduced, one to HIO and one to I₂ (+1.13 V and +1.20 V, respectively). The half reactions are given on that page (I see I've been beaten... must still post) Buddy431 (talk) 23:29, 29 April 2010 (UTC)

I had it on my computer, so I had easier access. --Chemicalinterest (talk) 00:24, 30 April 2010 (UTC)

Why do birches grow in clumps

I've often seen 2-5 birch trees growing out of one compact spot like in the image at right. Other trees like oaks and pine trees I usually see growing individually. Is there a term for this clumping? Does it stem (pun intended) from birches being considered shrubs, like the Birch article states in the first section? Why does this not happen with other trees? Or is this all observation bias on my part? Dismas|^(talk) 23:50, 29 April 2010 (UTC)

Well, it can be the result of coppicing (there may be a single very short trunk that all the other trunks come out of, but it can be cut so low that it ends up getting covered with soil). It could also be a natural occurrence similar to coppicing - a tree may have died back to a stump and then had many shoots regrow. Our article does mention birch as one of the trees that can be coppiced. If it is intentional coppicing, then you'll probably see lots of clumps like that nearby. --Tango (talk) 00:04, 30 April 2010 (UTC)

I've used this memory crutch for decades, to help tell the difference between Aspens and Birches:

Aspens alone, Birches in bunches.

Ergo, it has to be more than just an accident. DaHorsesMouth (talk) 00:32, 30 April 2010 (UTC)

Well, since aspens can form into clonal colonies some consider the largest organisms on earth, you're either very right (the aspen is alone because it's the whole freaking forest) or you're very, very wrong. Matt Deres (talk) 00:50, 30 April 2010 (UTC)

Just from personal observation, birches will seed even in deep shade so their seedlings will become a forest. It is possible that aspens need more daylight for their seeds to sprout, which means they will only be single specimens. --TammyMoet (talk) 15:00, 30 April 2010 (UTC)

April 30

Rust metal quickly.

I'm trying to make a chess set of nuts and bolts, and one side needs to be rusted. How would you rust steel quickly? There is a zinc coating that needs to be removed. I'm thinking of using a strong acid or base to remove it, and I'd prefer not go out and buy it, so are there any good household chemicals that react well with zinc? I can leave it in a safe area, so toxic gases shouldn't be much of a problem. As for rusting the steel, I know that salt water works, but are there any other factors I can manipulate to make it rust faster? Also, should I spritz the solution on or soak it in a bath? Cost is the main worry here, time isn't as important. KyuubiSeal (talk) 00:14, 30 April 2010 (UTC)

If you have some lye, it is a fairly strong base (NaOH) assuming it hasn't been diluted too much. If you have some (applied and pure) chemistry knowledge, you could try battery acid, but that is kind of very dangerous so don't mess with it unless you know what you're doing! The fastest way to oxidize something is to burn it, though the temperatures needed to burn steel probably are outside your price range. 76.229.165.96 (talk) 00:28, 30 April 2010 (UTC)

Dissolve some baking soda in water. Find a power supply (6-18V, do not go higher electrocution hazard). Attach all of your components to the positive electrode of the power supply. Use either stainless steel clips that would not be dissolved, or use junky ones. Attach any piece of metal to the negative electrode. Turn on the power supply. Hydrogen will be emmitted at the negative electrode. If the zinc plating is thick, you will see a white film coming off the positive electrode. After that, ferrous hydroxide (green rust) will be formed. If you let it sit it will be oxidized by air to ferric oxide (brown rust). Let it go for about 10-120 minutes (the higher the voltage, the shorter the time) and take it out. It will be rough and unshiny. If you keep it moist, it should rust in a couple of days. If you want it faster, you can place it in sodium hypochlorite solution to turn it brown. Keep it in there for a day. Remove it and it should be nice and rusty. --Chemicalinterest (talk) 00:30, 30 April 2010 (UTC)

BTW, battery acid isn't very dangerous. If you get some on your skin, you will feel a burning sensation. Quickly pour baking soda on it and wash it thoroughly in water. NaOH is not as dangerous unless it is concentrated (more than 10 molar). It won't dissolve zinc, though. --Chemicalinterest (talk) 00:31, 30 April 2010 (UTC)

So after it forms green rust, does it need to be in contact with air, or can it be left in a bucket of water? KyuubiSeal (talk) 00:39, 30 April 2010 (UTC)

Either. It just needs water vapor, which is present in small quantities in the air, and oxygen, which is present in small quantities in the water, to rust. You could leave it in salt water (probably the fastest), under moist cloths, or in humid air. --Chemicalinterest (talk) 00:47, 30 April 2010 (UTC)

I wonder if you could set up a basic Cathodic protection system and make the parts you want to rust into Sacrificial anodes? The article says they use zinc for sacrificial anodes on steel pipes.. No idea off the top of my head how you'd set it up, you'd need to work out how to attach the components and what kind of current and how to run it, but it might be a fun project if you are into that kind of thing. Vespine (talk) 00:59, 30 April 2010 (UTC)

Yes you could but it wouldn't rust much faster than ordinary corrosion. Ordinary iron contains areas of more stress, which are eaten away and function as anode, and areas of less stress, where oxygen is reduced and functions as cathode. --Chemicalinterest (talk) 11:17, 30 April 2010 (UTC)

Would there be any effects on the glue used to hold the pieces together? KyuubiSeal (talk) 01:49, 30 April 2010 (UTC)

If the glue is made to bond to metal, it might behave differently with the metal oxide. Just experiment on a few before making your set. --Chemicalinterest (talk) 11:17, 30 April 2010 (UTC)

I don't know about the zinc coating, but bleach is very effective at rusting iron and steel. Dragons flight (talk) 01:59, 30 April 2010 (UTC)

Bleach does sounds like a good idea, it is a strong oxidizer, such as Hydrogen peroxide. As for glue, you need a good electrical connection between the components so glue probably isn't the best solution, maybe clamping them between two pieces of steel would work, but the contact surfaces would probably not rust.. Thinking about it, might be more complicated then it is worth, I'd try the bleach idea first. ;) Vespine (talk) 02:17, 30 April 2010 (UTC)

3% hydrogen peroxide rusts too slow. Bleach, as I scientifically called it sodium hypochlorite, does rust iron (and zinc).

If you want it to rust fast, spray it with water, then dry it on low heat in an oven (as close to, but under 212f). It'll fully rust in no time. I learned that the hard way when foolishly thinking I should quickly dry water from a brake rotor by heating it. To remove zinc I would just sand it. The hotter the metal the faster it rusts. Don't soak it in water - it needs lots of air. Just spray water on it. Ariel. (talk) 06:02, 30 April 2010 (UTC)

Another idea for you: Zinc likes to react with sulfur. Buy some sulfur at a [compounding] drug store (or online), sulfur is pretty cheap. Shake some sulfur all over the metal parts, add ... Actually I'm not sure what the next step would be. I would experiment with heating it, with and without water, and trying to ignite it with a blowtorch. I'm also not sure if the result will stick to the underlying metal. But it should be cheap to experiment. Ariel. (talk) 06:13, 30 April 2010 (UTC)

I tried it, but it didn't affect it. The iron tends to carry heat away too fast. --Chemicalinterest (talk) 11:17, 30 April 2010 (UTC)

Your call Death -what colour!

An easy to obtain acid that will dissolve off zinc and help it to go rusty, is commonly sold in stores as 'Spirit of Salt' better known as hydrochloric acid and used domestically for cleaning drains. When you are ready to make the pieces rusty, use a 10% solution of hydrochloric to remove your 'invisible' but greasy finger prints! That way, you will achieve a more even oxide coat in less time. As mentioned above: a moist warm atmosphere is excellent for rust formation. Be advised though: This form of natural rust is very loose. It will come of as soon as you start playing with them and may make the board feel gritty(you are not the first to think of rusty chest pieces). The acid in sweat and friction will make the metal edges shiny again. It might be better to oxidise the surface to form a Iron(II,III) oxide. This is much more durable. The colour can be adjusted from a grey to a nice black , through brown to a somewhat reddish tone. This coating is often used as a durable finish on military equipment. A professional sculpture would probably choose to send it away and get it done by a sub-contractor. As an example, here is one such firm in Canada.[28]. Another option, very attractive, (only not quite so durable) is Bluing which can be toned all the way down to black. Often used on guns, in order to avoid signalling to the enemy on sunny days “Hay, I 'm over here - hiding in the bushes!”. The bluing solution can be bought from your local gun emporium, for you to do at home. These sort of coating will make it a more practical chess set. After all, you never know who may come to be your opponent !--Aspro (talk) 09:06, 30 April 2010 (UTC)

Yes, if you heat it until it is red-hot, it will form iron(II,III) oxide. --Chemicalinterest (talk) 11:17, 30 April 2010 (UTC)

noble barrier

What is meant by a "noble" barrier, as in a coating to protect iron?--115.178.29.142 (talk) 00:51, 30 April 2010 (UTC)

"Unreactive" or "inert" (like the noble-gas elements). DMacks (talk) 00:57, 30 April 2010 (UTC)

There is a patent covering the idea here. Perhaps that would be of some help? SteveBaker (talk) 00:58, 30 April 2010 (UTC)

It is typically an unreactive oxide coating which prevents further corrosion, such as the one aluminum forms. Another term is passivation. --Chemicalinterest (talk) 01:00, 30 April 2010 (UTC)

Noble gases (like argon) by definition cannot form coatings on metals. Noble metals (like gold or platinum) could be used, though, but they would be prohibitively expensive (although gold coatings are sometimes used on electronic components). FWiW 76.103.104.108 (talk) 07:54, 30 April 2010 (UTC)

Passivation layer may be of interest. Nimur (talk) 15:25, 30 April 2010 (UTC)

Solar sail

How fast would a spaceship propelled by a solar sail go? --75.33.219.230 (talk) 01:34, 30 April 2010 (UTC)

If the sail was powered by a laser, in theory, it could come close to the speed of light. However, to do this, A sail several kilometers across and about 0.001 mm thick would be needed to push a probe the size of the lunar capsule, and micrometeorites would be a major problem. I don't think it's possible. --The High Fin Sperm Whale 02:23, 30 April 2010 (UTC)

Our solar sail article is pertinent, with the first proposal having been to use batteries of Earthbound lasers powered at gigawatt strength for years or decades. I must mention, as always, The Mote in God's Eye as a science fiction novel in which this occurs. Comet Tuttle (talk) 03:13, 30 April 2010 (UTC)

Spaceship propulsion

Would this method for propelling a spaceship work?

1. Uranium is fissioned, releasing energy to power the spaceship.
2. At the same time, an equal amount of anti-uranium is fissioned in a separate chamber, also releasing energy.
3. The two fission chambers are separated by a barrier with holes slightly smaller than a uranium atom. The uranium and anti-uranium atoms can't pass through, but the fission products can, and they annihilate with one another, releasing even more energy to power the spaceship.

In step 3, the same amount of energy is released as if that mass of antimatter had been annihilated immediately, but the preceding fission releases more energy. --75.33.219.230 (talk) 01:34, 30 April 2010 (UTC)

Energy is a conserved quantity. You can't convert a given amount of matter into energy in two different ways and get different amounts of energy. The amount of energy you get by fission will be lost when you collide the fission products, in comparison to colliding the original uranium and anti-uranium. Looie496 (talk) 01:49, 30 April 2010 (UTC)

(ec) I'll leave aside the obvious technical hurdles which prevent such an engine being built, and address what I presume is your central question — do you get more energy out of fissioning the uranium nuclei and then annihilating their fission products than you would from pre-fission annihilation? Instead of giving you the answer outright, I'll ask you a question of my own — Are the products of nuclear fission equal in mass to the original uranium nuclei? Answer that, and you'll be able to answer your question. TenOfAllTrades(talk) 01:54, 30 April 2010 (UTC)

(also ec seems we were on the same page) I'm not a physicist but I suspect that the energy you gain in your fission reaction (and hence the mass you lose) would be the same as the energy you lose by reducing the amount of mass in your matter/anti-matter annihilation. In other words, skip the fission and just annihilate the whole anti-uranium. That's just a guess ;) Vespine (talk) 01:55, 30 April 2010 (UTC)

There are two other points missed by the OP besides the obvious conservation of energy

• Uranium atoms are not smaller than their fission products
• The anti-uranium atoms would annihilate with the container walls.

Dauto (talk) 02:34, 30 April 2010 (UTC)

Ignoring all of the OTHER problems with this scenario, your second problem can be ameliorated with either magnetic or electric fields. For example, if the anti-uranium was ionized, electrically charged walls could repel the anti-uranium atoms... --Jayron32 02:46, 30 April 2010 (UTC)

U-235 + n -> U-236 -> Kr-92 + Ba-141 + 3n

Both sides have a total mass of 236 AMU, so where's the mass loss to correspond with the energy released? --75.33.219.230 (talk) 12:01, 30 April 2010 (UTC)

The AMU is not a sufficiently precise measure of mass here - see binding energy. Gandalf61 (talk) 13:58, 30 April 2010 (UTC)

As gandalf pointed out, you need to be more precise than that. For instance, the mass of Uranium-235 is M²³⁵U=235.0439299 u. Dauto (talk) 14:16, 30 April 2010 (UTC)

OK, here are the values you will need

• M²³⁵U=235.0439299 u
• M¹n=1.0086649156 u
• M⁹²Kr=91.926156 u
• M¹⁴¹Ba=140.914411 u

So, the masses of the left side of your equation add to 236.0526 u and the right side adds to 235.8666 u. Not exactly the same thing.

Dauto (talk) 14:31, 30 April 2010 (UTC)

chrome plating

is there a way to tell if the layer underneath chrome plating is nickel or brass? —Preceding unsigned comment added by Tom12350 (talk • contribs) 02:19, April 30, 2010

Try using a magnet, nickel is magnetic, brass is not. If you have the tools to do it, you can also try measuring the density of the metal. Ariel. (talk) 06:54, 30 April 2010 (UTC)

would the chrome plating interfere with the magnet? —Preceding unsigned comment added by Tom12350 (talk • contribs) 03:29, April 30, 2010

No, chrome is non-magnetic (not under normal conditions, anyway). FWiW 76.103.104.108 (talk) 07:56, 30 April 2010 (UTC)

does it have to be any special type of magnet? —Preceding unsigned comment added by Tom12350 (talk • contribs) 06:44, April 30, 2010

Tom12350, please sign your posts with ~~~~. Just a regular magnet, a stronger one is better I guess. Flexible fridge magnets are pretty weak. Ariel. (talk) 11:48, 30 April 2010 (UTC)

If it is something you do not care about ruining, squirt some concentrated hydrochloric acid on it. If it is nickel, it will slowly fizz hydrogen gas and form a green-blue solution. If it is brass, it will barely fizz at all. --Chemicalinterest (talk) 11:19, 30 April 2010 (UTC)

Even through the chrome coating? Ariel. (talk) 11:48, 30 April 2010 (UTC)

No. --Chemicalinterest (talk) 14:03, 30 April 2010 (UTC)

this item has some greenish rust on it does that tell if it is nickel or brass?

The greenish rust could be patina, not ferrous hydroxide. It would be a copper-containing alloy such as brass, copper, or bronze. Ferrous hydroxide would spontaneously oxidize to brown ferric oxide. --Chemicalinterest (talk) 14:03, 30 April 2010 (UTC)

How to remember names?

I could easily identify people's faces but it's hard for me to remember their names. Any tips on improving name recall?--121.54.2.188 (talk) 07:56, 30 April 2010 (UTC)

Saying their name out-loud whilst looking at them helps. E.g. if someone says "Hello i'm Trevor" you say "Hi trevor" whilst looking at them (similarly if you use their name to start with when referring to them it helps). 194.221.133.226 (talk) 08:15, 30 April 2010 (UTC)

Those that attended the Open University will all know of Tony Buzan. He gave really good advice on how to study effectivly. See Speed Memory – Remembering names and face. Chapter 9 page 59 [29].--Aspro (talk) 09:57, 30 April 2010 (UTC)

How do you learn best? Reading? Hearing? Doing? Whichever it is, do that with the name. Are you good at songs? Make a small ditty out of the name. Or imagine a dance. Or write it down. Or repeat it to yourself a few times. Whichever works best for you. What kinds of things are you good at remembering? Lets say you are good at remembering trees, then in your mind 'link' a kind of tree with the face and then the name. Just think of all three at once. Then you'll see the face, think of the tree, and then think of the name. Ariel. (talk) 11:49, 30 April 2010 (UTC)

amines and hydroxide ions

I have reacted amines with hydroxide-sensitive electrophiles quite a few times now, most of the time due to solubility reasons I used a non-protic organic solvent anyway. But funny enough I haven't really thought of this ... if I had water-soluble reactants, if I dissolved bunch of amine (say a good Nu: like a secondary or primary amine) into water with my electrophile (not terribly sensitive to neutral water but sensitive to OH- on paper), would amine or hydroxide have the preference in adding to my electrophile? (Let's say, use a Michael acceptor as a convenient example.) John Riemann Soong (talk) 12:47, 30 April 2010 (UTC)

Can you provide any links where I can understand your terminology? --Chemicalinterest (talk) 16:42, 30 April 2010 (UTC)

magnetic question

If nickel is magnetic, why is a US 5 cent coin, made of 75% nickel, 25% copper not magnetic? Googlemeister (talk) 14:08, 30 April 2010 (UTC)

An alloy is not "pieces of one metal and pieces of another", but rather a single material with its own material properties not necessarily preserving all electronic and physical properties of each component. Our ferromagnetism article talks about the magnetic issue. DMacks (talk) 14:28, 30 April 2010 (UTC)

You have it backward, it's 75% copper, 25% nickel. Ariel. (talk) 14:28, 30 April 2010 (UTC)

Yes, rare earth metals aren't ferromagnetic, but alloys of them are. --Chemicalinterest (talk) 14:38, 30 April 2010 (UTC)

Neither nickel nor copper are rare earth elements. Every alloy has its own properties; it is invalid to say that "alloys of rare earth metals are ferromagnetic", because it depends on the particular alloy. Every part of you answer is wrong, Chemicalinterest. Please do not make things up before posting them to the reference desk. Nimur (talk) 15:28, 30 April 2010 (UTC)

I did not say that copper and nickel are rare earth metals. I was using that as an example that alloys are sometimes magnetic while the individual metals are not magnetic (or vice versa). Sorry if I confused anyone. --Chemicalinterest (talk) 16:27, 30 April 2010 (UTC)

Samarium-cobalt magnets are very strong, while samarium is nonmagnetic at normal temperatures and cobalt is much weaker. --Chemicalinterest (talk) 16:35, 30 April 2010 (UTC)

Why the "niger" in Sciurus niger ?

Hello all,

Not sure if it should go here or on the language desk, but...

I was wondering why the scientific name of the Eastern Fox Squirrel is Sciurus Niger. Niger, both in Latin and in scientific nomenclature usage, has to do with the color black (cf. Niger_(disambiguation)#Species). But the Eastern Fox Squirrel is in fact not black at all, with the exception of some melanistic individuals, as with black panthers). So... why does their scientific name translate as "black squirrels" ?

Thanks, --Alþykkr (talk) 15:55, 30 April 2010 (UTC)

Some names are misnomers. -- Wavelength (talk) 16:26, 30 April 2010 (UTC)

Rattus rattus

This is the sort of question that is bound to come up again. The Type specimen ( the poor critter that ended up picked in a jar and sits on the shelf of some institution) which was used to first describe the species was – black!. As simple as that. Thinking you might not believe such an answer here is a PDF describing Sciurus niger niger.[30] Likewise if you look at the very broad range of Rattus rattus you can probably guess how that came to be the first type specimen as well.--Aspro (talk) 16:43, 30 April 2010 (UTC)

Thanks to you both. Aspro, I had thought of that, but somehow I thought that before naming a species and establishing a "type", you'd take more of a sample than just one individual. Oh well, guess hard sciences are not that hard. --Alþykkr (talk) 17:02, 30 April 2010 (UTC)

I imagine Charles Darwin and others look for a good 'typical' specimen but it's 'that' unique individual, the actual critter in the jar that is the reference specimen that zoologist always return to for comparison. I don't know if anyone can elaborate further on that? If they can, I'll add it to the WP article.--Aspro (talk) 17:13, 30 April 2010 (UTC)

transformer

when a transformer is on load its starting current is 12 times of its full load current called inrush current.then what is the starting current of a no load transformer and how.

The amount of current that passes through the coils of a no load transformer? None on the secondary side. --Chemicalinterest (talk) 16:37, 30 April 2010 (UTC)

Yeah this question is pretty bizarre even by our standards. A transformer typically will inrush some multiple of it's stated max current, like you said (and depending on the transformer's design). If there is no load then ipso facto there is no current on the output, and the input will only draw current according to the inrush characteristics as you already described. --Jmeden2000 (talk) 17:54, 30 April 2010 (UTC)

Expansion of the universe

Has it ever been hypothesized that the expansion of the universe is within each subatomic particles' growth from one instant to the next. in other words if you compared an object with mass = X at time = t to that same object with mass = X at time = t + y, it could actually be mass = 2X at time = t (in the past)?

No, it hasn't been hypothesized, since it doesn't make sense. If the mass at time t is X, then the mass at time t is X. It can't both be X and 2X (unless it is massless). --Tango (talk) 17:30, 30 April 2010 (UTC)

No let me rephrase: the mass of an object at two different times is two different masses: if you could go back in time and compare the future object to the past object. In other words we are all expanding through spacetime at the exact same rate so relative to each other we are not expanding but relative to our past selves we are.

increase the likelihood of having dreams

I asked a question here about dream recall, and someone suggested that eating lobsters would "increase the likelihood of having dreams". Is this true? What chemicals or substances do lobsters contain that might induce dreams? I must add I have no intention of ever eating lobsters myself because I'm a vegetarian. 82.43.89.71 (talk) 18:15, 30 April 2010 (UTC)