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December 23

ASB THE POLYMATH- opc question

What is the chemical composition of OPC drum coating solution i.e. CTL liquid? what can I use to coat OPC drums at home? —Preceding unsigned comment added by 117.242.112.81 (talk) 09:28, 23 December 2010 (UTC)

It would help if you could explain what those abbreviations mean. StuRat (talk) 15:52, 23 December 2010 (UTC)

OPC seems to mean Organic PhotoConductor and CLP should be Charge Transport Layer. --Cookatoo.ergo.ZooM (talk) 21:09, 24 December 2010 (UTC)

I expect the OP is asking about how to make a Xerox copier. Cuddlyable3 (talk) 15:54, 25 December 2010 (UTC)

Two questions about lightning

1. Several years ago, I was in my apartment sitting in front of my computer. To my left was my stereo and to my right was my electric guitar and amp. Everything was plugged in. There was a sort of thunderstorm outside, nothing too heavy, but suddenly, there was a massive explosion of sound, but I never saw any light. As I sat there, time seemed to slow down, and in an extremely slow fashion, my entire body felt like it was expanding. I later described it to people as if every cell in my body had become a balloon and was being filled with a bit of air. I didn't move, either because I couldn't or because I wouldn't, and I honestly thought I was going to explode. But there was absolutely no pain. Just that uncomfortable feeling that lasted a few moments, and then my body "deflated" just as slowly. By the time I realized the situation was over, my computer was shut off. Everything was dead, and only the electric guitar still worked (half of the amp was destroyed, but it still worked on one insert). I've looked at the articles on positive lightning and lightning EMPs, and I've since done some research on Google, but I haven't been able to find any human recounts of physically witnessing an EMP. So my question is, was what I went through a lightning EMP of sorts? What was it doing to my body?
2. Back in the early 90s, I was backpacking through the US southwest during a storm. On the horizon, a strange bolt of lightning appeared. I cannot find an image of what it looked like (I've looked online for years), but imagine a straight bolt of lightning from sky to ground, but every few yards (massive estimation), the bolt expanded into a huge ball. There were three or four balls of light, like Christmas lights on a string, or popcorn on a necklace, within this bolt (or on this bolt), thus: ---O---O---O---O---. I keep running into ball lightning, but this wasn't a single ball of light moving around strangely. This was merely a bolt with a few glowing globs built in. The bolt acted like any bolt would: it appeared quickly, then faded quickly.

Any ideas on what it could be? Thanks for any help on this! Reflectionsinglass (talk) 09:28, 23 December 2010 (UTC)

Something like this: Transcranial magnetic stimulation may be related to what happened to you. This is interesting too: Ball lightning#Transcranial magnetic stimulation (and a nice synchrony with your next question). Regarding #2 the first thought that came to mind was birds :( - the bolt may have traveled from bird to bird before hitting the ground, and each bird burst into flame (I hope they died quickly :( Was the storm very sudden? I assume birds normally take cover during a storm. Another idea: Cosmic rays are hypothesized to stimulate lightning[1] strikes, maybe it was a meteor? It's possible that could do it too (but I've never actually heard or read anything to suggest that, so it's speculation only). Ariel. (talk) 09:47, 23 December 2010 (UTC)

For #2, perhaps it was Bead Lightning? Or perhaps it was more an optical effect, due to over-saturation of your retina? -- JSBillings 14:13, 23 December 2010 (UTC)

For 1), I wonder if it wasn't so much the effects of an EMP on your physiology that you experienced as it was a startle response that you experienced when you heard the massive explosion of sound. Was that thunder, or did it come from your amp and speakers before they blew? WikiDao ☯ (talk) 20:02, 23 December 2010 (UTC)

Simpler causes than EMP for the subjective effects the OP reports might be tentatively confirmed or eliminated by taking an EEG test. In the hospital procedure, strobe light may be used to stimulate a possible abnormal (epilepsiform) response. Cuddlyable3 (talk) 15:51, 25 December 2010 (UTC)

Light

Does light can be used disturb the moving particle be any metal or nonmetal (car, fish, ball,etc) because of its dual character in nature (as particle cum wave)? Please provide me is it possible? isn't it. (or) How it can be possible? (else) Any other suggestions regarding it. Kanniyappan (talk) 10:52, 23 December 2010 (UTC)

Light can move an object because light has momentum like anything else. But it's not because of the dual character of light. Just like if you throw grains of sand at something you can move it, you can do the same with light - but light does not weigh very much, so it barely moves the object. But light does move single atoms quite well, since atoms weigh so little. How well do you read English? I can link to some articles about this, the main ones would be solar sail and Radiation pressure, the others would be Momentum of photon and laser tweezer, but those are harder to read. Maybe this version is easier? simple:Radiation pressure. Ariel. (talk) 11:07, 23 December 2010 (UTC)

One clarification, a photon has no rest mass, so it's not like sand in that way. It does, however, have the equivalent to mass due to it's speed (the speed of light, of course). This is a result of relativity, which is difficult to explain (perhaps someone else will try). And, of course, both waves and particles can do work, so either model of light can explain why it can move objects. StuRat (talk) 15:47, 23 December 2010 (UTC)

(ec) In fact, light weighs exactly zero - its mass is exactly zero. A photon can have momentum, because in the relativistic treatment, momentum is not exactly equal to (mass × velocity) as it is in Newtonian mechanics. In fact, we have an article/section on relativistic momentum which explains this well. In mathematical terms, relativistic momentum is defined by a Lorentz transform; in "laymans' terms", you can simply understand that even a massless particle (such as light) can carry momentum and cause another massive particle to "move" after a collision. The simplest worked example is called Compton scattering, in which incident light hits matter and exchanges momentum and energy with an electron. The equations that define Compton Scattering are explained in our article; depending on the energy of the incident light, it can cause total ionization of an electron. More sophisticated light/matter interactions are described in detail by other processes; the photoelectric effect is one of the more practical uses of light impinging on matter. Nimur (talk) 15:53, 23 December 2010 (UTC)

You said: "in "laymans' terms", you can simply understand that even a massless particle (such as light) can carry momentum and cause another massive particle to "move" after a collision". That doesn't seem intuitively obvious, to me. In fact, I would assume the opposite, based on lighter objects causing proportionally less movement. StuRat (talk) 21:22, 23 December 2010 (UTC)

I make no assertions that any of that is intuitive or obvious - but it is correct and is the way that light interacts with matter in this universe. If you want to get an intuitive feel for relativistic light/matter interaction, all I can suggest is to spend a lot of time working with experimental setups that exhibit this momentum property of photons, and after you see the experimental results turn up the same way a whole lot, they will seem perfectly "normal" and intuitive to you. Or, if you are not the type who wants to independently verify such things, you can accept this fact on faith and trust myself and the many physics textbooks that attest to its veracity. Nimur (talk) 21:46, 23 December 2010 (UTC)

I'm not doubting that it's true. After all, I said as much in my first post. I'm just saying it's not intuitive. StuRat (talk) 00:06, 24 December 2010 (UTC)

BTW there is a reason I did not mention the massless nature of light, and that's because while it obviously has zero rest mass, while it's traveling it does have mass, inertia, momentum and everything else a massy particle has. And except for its refusal to change speed it acts exactly like something with mass. And even the zero rest mass thing is just another way of saying that when it doesn't exist it doesn't have mass. Remember that when light stops the mass doesn't disappear (zero rest-mass) the mass gets deposited onto whatever stopped the photon and the photon is converted into something else. Pretty much the only implication of zero rest-mass is that it travels exclusively at the speed of light, and the implications of that are beyond the scope of the original question. Ariel. (talk) 22:18, 23 December 2010 (UTC)

Thermoelectric

Can u please give me the emf induced and current flowed when thermoelectric couples of zinc and copper wires kept with 5°C of change in junction temperatures between hotter and colder junction kept at a distance of one meter? Please give also any other thermocouples gives more emf or current for the same standards mention above.Kanniyappan (talk) 11:04, 23 December 2010 (UTC)

The Seebeck coefficient of a metal isn't quite constant, but in the 0-100°C range, it's about 3.4μV/K for zinc, and about -1.8μV/K for copper.[2] So from the second equation in the article section Thermoelectric effect#Seebeck effect, a zinc/copper thermocouple with a temperature difference of 5°C will produce an EMF of about 26μV (with no load).

The current produced would depend on the load, as per Ohm's law. For very low-resistance loads, the non-zero resistance of the wires would need to be taken into account, and for that, you'd need to specify the cross-sectional area of the wires used, so that the resistance of the wires can be computed from the resistivity of zinc (59.0nΩm) and copper (16.78nΩm).

For materials that exhibit the thermoelectric effect more strongly, see Thermoelectric materials. Red Act (talk) 17:54, 24 December 2010 (UTC)

Dragon's breath

It's been very cold here in Blighty lately and this has had me wondering. Is there a specific temperature at which dragon's breath appears? (when you can see your breath when you exhale on a cold day). --TrogWoolley (talk) 14:28, 23 December 2010 (UTC)

The short answer is 'it depends'.

The longer answer is, it depends on the current relative humidity, ambient temperature, and local wind. The air that you exhale is going to be fairly close in temperature to your core body temperature (it just came straight from your lungs, after all) and at close to 100% relative humidity at that temperature. What that means is that the dew point for that air – the temperature at which the exhaled air is supersaturated with moisture and capable of precipitating out liquid water droplets as fog or dew – is just a few degrees below your body temperature. So, if that's true, why is it that you don't see a cloud of fog all the time?

First, when air saturated with moisture is chilled, droplets don't form instantaneously; the process takes some time to occur, and often relies on the presence of nucleation sites (little bits of dust and whatnot) in the air to kick the process off. Nucleation and droplet formation are faster when the temperature is further below the dew point and the air is more supersaturated, so visible fog formation is more likely in chillier air.

Second, fog is forestalled if the supersaturated air is diluted rapidly to a non-saturated state. If there is rapid, turbulent airflow (blustery wind!) in front of your face, then the exhaled supersaturated air is mixed quickly with very unsaturated ambient air and no droplets form. Finally, the effectiveness of this dilution is going to depend on how much water there is the air around you. If the ambient air is nearly saturated with water, then you need to mix a much greater volume of it with your breath to dilute the resulting blend down to an unsaturated state — if the ambient relative humidity is high, you'll be able to see your breath much more readily than under conditions of low humidity. (Under low-humidity conditions, any droplets that do form will also evaporate and disappear much more rapidly.) TenOfAllTrades(talk) 15:30, 23 December 2010 (UTC)

Good answer. One other thing I would add is that lighting conditions matter. The ideal lighting condition would be darkness with a sunbeam right on your breath, so that the lighted water droplets stand out against the darkness. On the other hand, if the sunbeam is in your eyes, and not on your breath, you may not see your breath. StuRat (talk) 15:42, 23 December 2010 (UTC)

I wondered the same thing and actually tried to work it out myself. To give a "rough" answer, where I live in Melbourne Australia, under the conditions that were present when i conducted my experiments, I found the temperature to be around 11 or 12 degrees (EDIT: Celsius) when I could begin to see my exhaled breath. I however have no idea how much that could vary depending on the other conditions mentioned above, such as humidity. Vespine (talk) 01:12, 24 December 2010 (UTC)

Resolved

- thanks guys! --TrogWoolley (talk) 11:15, 24 December 2010 (UTC)

is flow of holes called current flow?

flow of electrons is called as the current flow, but whereas the holes are also moving from the p region to the n region. Then why can't we say that the flow of holes is called as the current flow? —Preceding unsigned comment added by 117.197.186.12 (talk) 17:41, 23 December 2010 (UTC)

Hole flow and electron flow are just two ways to look at the same thing. If a hole flows one way, it means that an electron went the opposite way. Some people find it easier to think in terms of hole flow. Some find it easier to think in terms of electron flow. -- kainaw™ 17:46, 23 December 2010 (UTC)

Perhaps see conventional current (which redirects to the conventions section of current but seems to say it nicely). RJFJR (talk) 18:04, 23 December 2010 (UTC)

Climate change and biodiversity

People keep on warning about the "devastating" effects global warming could have on biodiversity, yet the geological past and present of our planet points to the contrary. We should take into account three main things:

• In periods such as the Eocene, global temperatures were much higher than today, just like biodiversity. Biodiversity has been declining ever since the world started to cool in the Miocene. Therefore, warmer climates are more conducive to a high biodiversity.
• Biodiversity hotspots in all the world are concentrated in warm areas, whereas polar areas are much poorer. It's better to lose a small percentage of species to global warming than a large percentage to global cooling.
• It is naive to believe that, if we don't alter the climate, it will stay the same forever. If the climate doesn't warm up, we're headed straight for a new glacial period which really won't do much good to biodiversity.

Why do people continue to consider climate change bad? Are there any factors I haven't thought of (not counting hippyish, kumbayah-irrational arguments). --79.89.248.148 (talk) 19:08, 23 December 2010 (UTC)

I think the problem are the speed of change. I think fast climate change in any direction is one cause for mass extinction events. Diverse ecosystems move very slowly and many will be extinct be cause of the climate change. It is possible that the biodiversity would be greater after some millions of year with higher temperature but most predictions relating to AGW take a shorter time scale of millennias or less. Of course will the climate continue to change what ever we do but the AGW are faster than most natural changes. --Gr8xoz (talk) 19:41, 23 December 2010 (UTC)

In addition to the speed of the change, it's a matter of changing the climate to something we aren't used to, or prepared for. Sure, many plants and animals will thrive, but our coastal cities will all be flooded by rising sea level, and Europe will lose the Gulf Stream and become as cold as it really should be, at that latitude. Much more severe hurricanes will make living near the US Gulf or Atlantic coasts a bad idea, and tornadoes will do the same for the Central Plains states of the US (and soon Canada). So, if we all are willing to move north and inland, then we can survive. But considering the portion of humanity that lives in warm areas or near the sea, that's a tall order. Also, some species, like polar bears and certain penguins, may become extinct, because the climate to which they have evolved will no longer exist. StuRat (talk) 20:29, 23 December 2010 (UTC)

I encounter conceptual problems with Biodiversity#definitions and Biodiversity#Human_benefits. Are we trying to save and promote the diversity of the megafauna (i.e. pandas, which are largely decorative), the microfauna (which we depend on), or the humans? These lead to different notions of "diversity" - for instance, does "diversity" include the diversity of diseases hostile to humans and injurious to our food supply? Do we score the pandas higher than worms because they're bigger, or lower than worms because they're useless (not even doing much good for their own ecosystem), or equal because they're a species? Is preserving an animal in a zoo, or a seed in a seedbank, a valid way of preserving biodiversity, or does the biodiversity have to be active in an ecosystem, and if so, for what reason? So you end up with political and philosophical questions about what sort of world is a good world, and how we view ourselves. Are we concerned about biodiversity because a lack of genetic variation might spoil our plans to turn the world into a massive farm, or because it might spoil our plans to turn the world into a massive garden, or just because we like genes for their own sake? Like Gr8xoz says, are we worrying about the next thousands of years, or the next billions of years? Different agendas produce different definitions of "harmful". 213.122.23.52 (talk) 07:52, 24 December 2010 (UTC)

Why exactly do you say 'we'? What use are you to me? I'm more interested in pandas than I am in you. Dmcq (talk) 10:24, 25 December 2010 (UTC)

drug

are there any stimulant drugs that are not also vasoconstrictors — Preceding unsigned comment added by Kj650 (talk • contribs) 19:43, 23 December 2010 (UTC)

Modafinil, and most of the racetams. Vasoconstriction is a peripheral side-effect of adrenergic drugs, therefore the more readily the drug crosses the blood-brain barrier, the less likely it is to cause vasoconstriction. There are also drugs which act independently of the adrenergic system, such as dopamine reuptake inhibitors, dopamine agonists, certain nicotinic agonists, histamine agonists (or H3 receptor inverse agonists/antagonists) and drugs which stimulate orexin receptors/release. --Mark PEA (talk) 20:12, 23 December 2010 (UTC)

isint cocaine a dopamine reuptake inhibitor and a vasoconstrictor — Preceding unsigned comment added by Kj650 (talk • contribs) 21:03, 23 December 2010 (UTC)

Yes but it's also a noradrenaline reuptake inhibitor, which is probably responsible for this effect. (It also inhibits serotonin reuptake, and these drugs are normally referred to as triple reuptake inhibitors). --Mark PEA (talk) 18:16, 24 December 2010 (UTC)

Beer pong

In beer pong, if the ping pong is spinning along the sides of the cup, blowing will cause the pong to rise out of the cup. Why? And if I take a glass half-way filled with juice and turn it over, with a piece of cardboard covering the top, the liquid won't fall...what's the reason for this? Thanks. 65.92.7.244 (talk) 23:49, 23 December 2010 (UTC)

I think first is bernoulli effect. See the experiments here: [3]. The second is because the piece of cardboard would have to move downward, decreasing the pressure in the glass, and that causes the higher pressure under the cardboard to push it back up. StuRat (talk) 00:05, 24 December 2010 (UTC)

Place a sheet of paper or a playing card on a flat smooth table and blow lightly along the table - you can make the paper float. It's the same principle and it's called Bernoulli's principle and is quite similar to the venturi effect. Ariel. (talk) 00:38, 24 December 2010 (UTC)

I'm still having trouble seeing it. Bernoulli says that the pressure created by fast moving fluid is less than that of slow moving fluid. But where is the fluid traveling faster? If the ball goes up, then it should travel faster above the ball, but why would it? 65.92.7.244 (talk) 02:06, 24 December 2010 (UTC)

Because when you are blowing above the ball, the air is now moving faster above the ball, so the pressure drops above the ball. --Jayron32 03:22, 24 December 2010 (UTC)

But isn't it also moving faster under the ball? And if not, why does blowing air underneath a ping pong ball keep it up? 65.92.7.244 (talk) 04:31, 24 December 2010 (UTC)

You are confusing two slightly different things. Air moving directly at the ball will move it; air is matter, and matter in motion has momentum, and it can transfer that momentum to the ball. Hence, blowing directly under the ball will cause it to move up. However, blowing past the ball, as in not directly at the center of the ball, but such that the air moves past the ball, will cause the pressure to drop. There is an INCREASE of pressure in the direction of airflow, that is in front of the puff of air, and an equivalent DECREASE of pressure perpendicular to the air flow. The trick is to blow NEXT to the ball (i.e. very close to it) but not AT it, so that the air moves past the ball, but not at it. --Jayron32 04:36, 24 December 2010 (UTC)

What!? air pressure, bernoulli's principal!? Try this: take a cup and hold it a couple inches from your mouth, now blow in it. What do you feel? Your own breath blowing back in your face! The air has no where to go but out. if you are still confused put some salt in the cup and do it again. Why didn't the salt stay in the cup?????? —Preceding unsigned comment added by 165.212.189.187 (talk) 14:56, 24 December 2010 (UTC)

December 24

When two metal panels with different work functions approach, what happens?

When two metal with different work functions approach but still is seperate finally, will their surface produce opposite charge (+, and -) when at equilibrium? and will their Fermi levels line up finally?

Another similar case, when a thin oxide is sanwiched by a metal and a semiconductor, if the metal and the semiconductor with different Fermi levels, do their Fermi levels equalize when at equilibrium? --Wkfan (talk) 03:18, 24 December 2010 (UTC)

Why do superstrings "vibrate"?

What causes them to vibrate? Have they always been eternally "vibrating" or does something initially "pluck" the string to get it going? Can they ever stop vibrating? and if so what would happen then? In layman's terms please. (I'm a layman so if these questions doesn't make much sense it's probably because I'm misunderstanding some aspect of the theory :) -- œ^™ 05:17, 24 December 2010 (UTC)

It is better to think of superstring theory as a model used to represent physical reality. Like all models, it is an explanation of reality, and not reality itself. That is, these "strings" are not strings in the literal sense, which need to be plucked in order to vibrate. Rather, the attempt is to represent matter by vibrating strings, insofar as the mathematics of resonance seems to apply to the way in which fundemental particles interact. Using "standing waves" as a model for fundemental particles actually predates superstring theory by some time, for example the Schroedinger equations and wave functions are a much older model used to explain the behavior of the electron cloud in an atom. Superstring theory is in some ways expanding upon these earlier models to a more fundemental level. --Jayron32 05:24, 24 December 2010 (UTC)

A string in a frictionless environment would continue to vibrate forever. They likely existed (and vibrated) since the Big Bang, but all bets are off for what existed before that. StuRat (talk) 06:43, 24 December 2010 (UTC)

Vibration, also known as harmonic oscillation, shows up everywhere in physics. In quantum theories, because of the uncertainty principle, the vibration can never stop completely, so everything vibrates (though this "vibration" is a bit different from what you might think of as vibration in a non-quantum world). String theory is a quantum theory, and because it's possible, geometrically, for string-shaped objects to vibrate, they always do. That property of universal vibration isn't new to string theory, nor is it a particularly important aspect of string theory. The reason it's emphasized in popularizations is that they don't know what else to talk about. Explaining what string theory is really about would be too confusing, so they fall back on showing vibrating violin strings, even though those could just as well illustrate any physical theory from the last few hundred years. -- BenRG (talk) 23:13, 24 December 2010 (UTC)

makeshift loudspeaker

I'm a little confused by this: http://www.youtube.com/watch?v=oGrlz6t28XE

If the sound is being caused by the bottle vibrating, then why is it still making sound when: 1) he is holding it, and 2) when he holds it near the magnet, but not on the table? Thanks. 65.92.7.244 (talk) 08:08, 24 December 2010 (UTC)

At normal frequencies the sound is not from the bottle knocking on the table. The sound is from the bottle directly shaking the air, which causes sound waves that you can hear. Earlier, he ran it at a very low frequency of 5 hz (times per second), which is far too low for you to hear. So what he did is make the bottle knock into the table and you heard a knocking sound each time. Notice how at 5 hz you hear a series of tick, tick, tick, rather than a pure "tone". But at higher frequencies you are actually hearing those tones. Excellent question BTW. Ariel. (talk) 09:52, 24 December 2010 (UTC)

See the Wikipedia article Voice coil.

1. The source of the sound vibration is the wire that is attached to the bottle neck. The vibrations travel through the bottle material at the speed of sound in the plastic. Holding part of the bottle does not prevent other parts of the bottle vibrating.
2. The wire must be close to the magnet to be within its magnetic field for the motor effect to work. The resulting music sound is weaker but less distorted when the bottle is suspended slightly above the magnet so the downward swings of the sound vibration won't cause the bottle to hit the metal plate. Cuddlyable3 (talk) 15:15, 25 December 2010 (UTC)

Heavy luggage in small, light car

Where would the best place be to put heavy luggage (huge bags of books in this case) in a small, light car (Hyundai Atos). I put it in the trunk but it seemed to put tremendous strain on the rear suspension so I was hoping someone with the knowledge on this could help me out. I don't want to break my car but I also want to have the best fuel economy. Would the position of the heavy luggage have an effect on the fuel economy whatsoever? I'm just a student and I need to travel far so that's why I'm so curious as to where to put the bags in order to save money! :O 196.210.239.252 (talk) 11:22, 24 December 2010 (UTC)

For fuel economy I don't think the position will matter much. You use extra fuel because you have to work harder to accelerate the extra weight. But for handing purposes try to balance it evenly front to back, too much weight in the back can severely hurt handling and breaking power, too much in the front is not as bad, but still bad. Also, you will need to add extra air to the tires - besides needing to do it to keep from damaging the tires, this will also help you save money. As for how much air, I can't check the numbers for you right now, but find out how much your car weighs, and how much pressure you normally need, then divide to find pressure/weight, and then calculate that for the extra weight. Ariel. (talk) 11:35, 24 December 2010 (UTC)

Anywhere between the wheels is good. You should avoid putting heavy weights beyond the wheels, as that will cause it to handle poorly. StuRat (talk) 18:08, 24 December 2010 (UTC)

Unladen weight of the Hyundai Atos is quoted as 847 kg. It is a 4-seat car so should be within its limits carrying the equivalent weight of 4 heavy adults. Recommended tyre pressures are 30 PSI front and rear. Do check the car handbook. Cuddlyable3 (talk) 14:46, 25 December 2010 (UTC)

meningiomas (a.k.a. brain tumor;angle tumor)

Periodically I search the internet for any mention of connection between meningiomas (a.k.a. brain tumor;angle tumor)and either estrogen or progesterone receptors. I was surgically treated for such a tumor in 1991. In 1998 I was told of 'recurrence'(that word is significant in my opinion,based on research). I went to Mass Genl for radiation treatment.In making usual/customary rounds for various physical exams, it was the endocrine/ob-gyn doctor who inadvertently and casually mentioned that said tumor in my case had progesterone receptors. She didn't seem to notice my shock when I said 'what?'. "yeah, she said, they see these types of tumors all the time during autopsies, they're very common. They become problematic when they grow too large and progesterone can make one with progesterone receptors grow."

I was prescribed and took progesterone (the so-called "bioidentical good kind from Women's International Pharmacy in Denver, Co.) It was prescribed for reasons not at all 'cosmetic' or superficial. I began taking it in the mid 1980's and contimued taking it after meningioma surgery in 1991. I stopped taking it after I left the informing doctor's office that same day.

While surgeon told me he removed it all, his written record stated that it was "unlikely due to the very vascular nature of the tumor". Ir follows, with some logic I would say, that continuing to take progesterone would cause further growth, hence future problem (these tumors are slow growing). In the late 1990's *Mifeprestone (a.k.a. RU486, the abortion pill;a.k.a. "anti-progesterone") was used in clinical trials to treat meningiomas. I may have misspelled *it. While it met with significant success, there were other strange blocks(of the political and/or greedy types and tones) to making it available to those in need (many with much more frightening alternative choices,if any choice at all). My most recent search (12/23/10 revealed a brief reference to mifeprestone as treatment modality, but required much digging to get to that partial one line reference.

To this day, I cannot find anywhere by anyone any straigtforward, clear mention of this connection as I have described it. I tell every female with whom I cross paths-they 'hear' me with considerable attentiveness; I've written everyone I deem 'should know and disclose'-I know of no response or interest. I have mentioned it to every doctor/healthcare provider with whom I come into contact (most of whom not even visibly moved enough to shrug a shoulder). The kind of empty eyed void or twilight zone experience I have come to call the 'Is it just me? Am I crazy?-game. Or, why isn't 'logic' a required course?

After telling this to my dentist's assistant, she responded by telling me that during a conversation between her mother and Assurant Health Insurance Company, the rep told her mother that she was considered 'disposable'.

Can someone broaden my understanding of this?11:35, 24 December 2010 (UTC)Wastetime4info (talk)

We have a very small article on it Hormone receptor positive tumor. Nothing in the article limits it to breast, but all of the references mention that. Mifepristone may help, but nothing in there mentions cancer. This article seems to match what you wrote - it mentions meningiomas (but I did not read it), maybe it will help you. You can continue searching for articles using this search. Adding meningiomas to the search comes up with lots of stuff. You will not have access to read many of the articles, but your local public or university library probably will have a subscription, so you want to search from there. Ariel. (talk) 12:19, 24 December 2010 (UTC)

Edit: In the article meningiomas I found "Antiprogestin agents have been used, but with variable results." So it could be they did think of it - but it didn't help much. Ariel. (talk) 12:24, 24 December 2010 (UTC)

..and the source used in that article, which you may have already seen says "About 70% of meningiomas express progesterone receptors, while fewer than 31% express estrogen receptors. These observations suggest that progesterone influences tumor growth. A progesterone antagonist such as mifepristone therefore may inhibit tumor growth." This study has something to say about hormonal exposures and risk so it may be of interest if you haven't seen it before. Sean.hoyland - talk 12:47, 24 December 2010 (UTC)

To the OP: background information/observations combined with logic are the first two steps to developing a good hypothesis. However, the field of medicine generally requires more than a good hypothesis to justify treatment decisions (hence, the 'logic' course you mention is not part of the regular medical curriculum). The next step is to generate data that supports or refutes that hypothesis. There seems to have been a reasonable amount of research into whether or not hormone exposures are truly a risk factor for meningioma (see [4], [5], [6], [7], [8], and a meta-analysis of different studies here). The overall result of those studies seems to be that hormone exposure plays a minimal role in the development of meningiomas, if at all.

The next thing you are interested in is whether (based on the progesterone receptor expression in meningiomas) a treatment based on progesterone blockade, using mifepristone (RU-486) would be a good treatment. This is another excellent hypothesis, but one for which there is again no strong evidence. The best I could see was a recent study (here) that looked at long-term effects of mifepristone. The main outcome measures were tolerability and side effects, and I don't think the study was specifically designed to look at treatment outcomes. However, they did mention "minor responses" in a subset of patients (8 out of 28 treated). Altogether, it seems as though (despite the good hypothesis) progesterone blockade hasn't proven to be an effective treatment for meningioma. --- Medical geneticist (talk) 13:44, 24 December 2010 (UTC)

Testosterone levels

Does the Testosterone level in a male human body change after ejaculation? --119.155.10.188 (talk) 11:56, 24 December 2010 (UTC)

Usually, although the extent likely depends on mental health. See PMID 16871136. Ginger Conspiracy (talk) 23:22, 24 December 2010 (UTC)

The PMID reference is about treatment of sexual dysfunction in patients with epilepsy and depression but it does not seem to address the OP's question about change in hormone level after ejaculation. Cuddlyable3 (talk) 21:12, 25 December 2010 (UTC)

So normally would the level increase or decrease in an average human? --119.155.18.241 (talk) 14:50, 25 December 2010 (UTC)

Mercury's mineral status

Is native mercury a mineral? I have a cite [9] to back up my claim that it is a mineral, but nonmineral "uncitedly" states otherwise. Is it a mineral? --Chemicalinterest (talk) 17:28, 24 December 2010 (UTC)

Your reference does not exactly address the question of what is, and is not, a true mineral. According to the mercury article mercury is rarely found as a native metal. I notice your source also lists iron, which afaik, is never found as a native metal. SpinningSpark 18:16, 24 December 2010 (UTC)

I don't know how it is classified, but it is possible to find natural deposits of metallic iron (typically as micron to millimeter sized grains). It can form when iron bearing minerals are heated to high temperatures in the presence of abundant carbon and with very low levels of oxygen. A typical example is when a coal seam is set on fire by lightning or magma intrusion. Not exactly a common scenario, but such things do happen. Dragons flight (talk) 19:11, 24 December 2010 (UTC)

Chemicalinterest wasn't asking whether or not it commonly forms naturally; he was asking whether or not it would be a mineral. According to our article, "A mineral is a naturally occurring solid chemical substance that is formed through geological processes and that has a characteristic chemical composition, a highly ordered atomic structure, and specific physical properties". So the answer is yes. --T H F S W (T · C · E) 21:06, 24 December 2010 (UTC)

Sorry for being so dense! "A mineral is a naturally occurring solid chemical substance". So I geuss no, if you stick to the rules. However, native copper of gold would be a mineral. --T H F S W (T · C · E) 21:20, 24 December 2010 (UTC)

Where's your citation for the "fact" that a mineral is solid? --Chemicalinterest (talk) 22:21, 24 December 2010 (UTC)

Here. --T H F S W (T · C · E) 22:31, 24 December 2010 (UTC)

THFSW, your reference explicitely states "Mercury, however, is recognized as a mineral even though it does not occur in a crystalline state on Earth". And maybe it does occur in a crystalline state sometimes: Temperatures at higher latitudes are sufficiently low - at least in the winter. Icek (talk) 23:44, 24 December 2010 (UTC)

Your source supports my source. It proves that mercury is a liquid mineral. --Chemicalinterest (talk) 00:40, 25 December 2010 (UTC)

Well, from whatever I posted on simple talk, if correct, that's not the case. native mercury = mineral. Liquid mercury = not a mineral. wiooiw (talk) 07:43, 25 December 2010 (UTC)

Native mercury is liquid mercury. Mercury does not exist in a crystalline state on Earth. Look! What needs to be found out is whether mercury (its status of liquid is given) is a mineral. --Chemicalinterest (talk) 13:07, 25 December 2010 (UTC)

Could we agree that mercury is a mineraloid, and a mineral when it is very cold? Dbfirs 20:40, 25 December 2010 (UTC)

As far as Britannica is considered, Native Mercury is a mineral, but liquid mercury does not fit the definition of a mineral, but a mineraloid. wiooiw (talk) 22:25, 25 December 2010 (UTC)

Huh, I found this and this to be quite useful. It reviews older definitions of "mineral". It appears that Brittcanica uses and older version of the definition, thus really is not a valid source to use. So, liquid mercury is now a mineral? wiooiw (talk) 23:46, 25 December 2010 (UTC)

Well, let's look at the official CNMNC guidelines (my italics):

A mineral substance is a naturally occurring solid that has been formed by geological processes, either on earth or in extraterrestrial bodies (Nickel 1995a). A mineral species is a mineral substance with well-defined chemical composition and crystallographic properties, and which merits a unique name. General criteria for defining mineral species are given below. In practice, most mineral species conform to these criteria, but exceptions and borderline cases inevitably arise, and ultimately each proposal to introduce a new mineral species or to change mineral nomenclature must be considered on its own merits.

Now looking at the official IMA-CNMNC List of Mineral Names, we see that native mercury is "grandfathered", that is its "original description preceded the establishment of the CNMNC in 1959, and [it is] generally regarded as a valid species". The only conclusion that one can draw is that the IMA considers native mercury to be an exception to the normal rule that mineral species should be solid. Physchim62 (talk) 00:08, 26 December 2010 (UTC)

Yes. THFSW's reference stated the same thing, but gave native mercury (a liquid) as an exception to the rule. --Chemicalinterest (talk) 12:21, 26 December 2010 (UTC)

Mercury is much more commonly found as cinnabar. ~AH1^(TCU) 17:55, 27 December 2010 (UTC)

December 25

Astronomy question

Approximately what day of the year would the earth cross an imaginary line connecting the sun and the center of the Milky Way galaxy? 76.27.175.80 (talk) 00:33, 25 December 2010 (UTC)

Our Galactic Center article says that it lies in the direction of Sagittarius A*, which is on the border of the constellations Scorpius and Sagittarius. According to our Zodiac article, the Sun enters that region with respect to Earth in the early weeks of December. The Earth would therefore be on the opposite side of the Sun, ie. between the Sun and the Galactic center, half-a-year from then, or in early June. WikiDao ☯ (talk) 04:28, 25 December 2010 (UTC)

Is the Earth on the same two-dimensional access as the galaxy? Magog the Ogre (talk)

Axis, but I think you mean two-dimensional plane.

No, according to our article "The galactic plane is inclined by about 60 degrees to the ecliptic (the plane of the Earth's orbit)." My answer above is just roughly speaking. WikiDao ☯ (talk) 15:18, 27 December 2010 (UTC)

White copper peroxide

Is it true that a white and highly explosive copper peroxide can form on copper if it is exposed to air too long? --Chemicalinterest (talk) 01:46, 25 December 2010 (UTC)

Logically, that can't be true, because lots of copper is exposed to air, and it doesn't turn white or become explosive, it acquires a green patina. So, copper + air alone doesn't do it. StuRat (talk) 02:03, 25 December 2010 (UTC)

Here is a description of how to make copper peroxide: [10]. It seems to be reddish orange, not white, and there's no mention of it being explosive. StuRat (talk) 02:07, 25 December 2010 (UTC)

Hrumph. Section 10: Stability. This as well. There are some others. --Chemicalinterest (talk) 12:57, 25 December 2010 (UTC)

I don't understand. Since copper metal stands outside on roofs and such for long times, why don't they all explode, then ? StuRat (talk) 04:10, 26 December 2010 (UTC)

Maybe the rain dissolves the peroxide to make oxygen and copper oxide. But how did they get this into all their MSDS's? --Chemicalinterest (talk) 21:42, 26 December 2010 (UTC)

Species names by C. Linnaeus

How many names are unchanged since C. Linnaeus: Homo sapiens, Lemur catta, Hippopotamus amphibius, what else? Can we include that somehow in 10th edition of Systema Naturae or it's subarticles? --Eu-151 (talk) 13:05, 25 December 2010 (UTC)

Because of the Principle of Priority, many plants and animals retain the binomial names given by Linnaeus. If you look at the "What links here" page for his article (especially the links to the disambiguation page "Linnaeus"), you will find quite a few such plants and animals among the entries, as you can see by looking at their articles' infoboxes. Deor (talk) 14:11, 25 December 2010 (UTC)

Arun S Bagh question about opc drum

The original post attempted to include an image but failed to upload properly; I have removed the broken wikisyntax. Arun, please see the instructions for uploading an image, and retry posting your picture/question. Nimur (talk) 16:08, 26 December 2010 (UTC)

Are are you trying to post an image using the local file path instead of an image hosting service? That's not going to work. 81.131.30.210 (talk) 13:54, 25 December 2010 (UTC)

Here are many pictures of opc drums in case the drum type you ask about is already posted there. Cuddlyable3 (talk) 14:18, 25 December 2010 (UTC)

earth flip

I heard that the earth flips its axes where the north pole becomes the south pole. My questions are, 1. would this be notice able or will the earth do it slowly. 2. will this cause earthquakes to happen. 3. what would the climate of europe be like particularly around Ireland and britain. 4. Will it cause climate change. —Preceding unsigned comment added by 213.94.236.7 (talk) 19:44, 25 December 2010 (UTC)

I think you have some misconceptions about the switch you're thinking of. I suggest you start off at Geomagnetic reversal (which has a short Geomagnetic reversal#Effects on biosphere and human society) and come back with any questions. Nil Einne (talk) 19:50, 25 December 2010 (UTC)

Yes, the OP is surely thinking of the Earth's magnetic not geographic poles. Geomagnetic reversal#Effects on biosphere and human society notes a few speculations but we can't predict answers to questions 1 to 4. Cuddlyable3 (talk) 20:39, 25 December 2010 (UTC)

To clarify: the Earth doesn't move. The Earth's magnetic field moves. --Tango (talk) 21:16, 25 December 2010 (UTC)

There is also a fringe theory that the Earth's axis itself moves significantly: see Cataclysmic pole shift hypothesis. I don't know of any serious geologist who believes that the pole shifts a significant amount. There is, however, True polar wander: the Earth's axis of rotation wanders about on the surface of the Earth, at apparently no more than 1 degree every million years, or so. Insignificant on human timescales, but important on stellar time scales (it's thought, evidently, that Europa (moon)'s pole has shifted about 80 degrees). There is also Precession and Nutation, where the location of Earth's pole on the ground doesn't change, but the axis shifts relative to the stars. Buddy431 (talk) 23:01, 25 December 2010 (UTC)

No, it's a real worry that it's going to hit us in "about 1.5 billion years" Axial tilt#Long period variations Hcobb (talk) 05:07, 26 December 2010 (UTC)

Oh, well that saves me worrying about the sun becoming a red giant and consuming the earth, because that won't happen for five billion years! Dbfirs 17:09, 26 December 2010 (UTC)

Ungulate reptile/(amphibian/bird/...)

I (by chance) met Stegosaurus ungulatus on the Stegosaurus page. Although it is a nomen dubium and usually united with S. stenops? (or armatus?), it shouldn't have it's specific epithet with no reason. And I read about a "blunt hoof" on Stegosaurine feet. Now my question: 1. Were any reptiles, especially any Dinosauria (improbable: amphibians, birds, synapsids,...), truly hooved? What about genera like Giraffatitan, Paralititan, Argentinosaurus and how the giants are called some had horns (Ceratopsia), but were there any hooved ones? Would hooves preserve in fossils? If they exist, can we cover hooved dinosaurs and their being hooved in a matter to Ungulate? Why are no dinosaurs (except for the one nomen dubium S. ungulatus) namend after being hooved? — Preceding unsigned comment added by Eu-151 (talk • contribs) 21:36, 25 December 2010 (UTC)

A proper hoof is basically a modified toenail; I don't think that any animal group besides the true ungulates walk on hoofs. --Jayron32 22:00, 25 December 2010 (UTC)

Magnet

I got a 250 pound lifting capacity magnet for Christmas. What can I do with it? I noticed that when I get close to my computer with it, the magnet changes the computer's screen color. Why? Also, I noticed that I can screw up AM radio with it. Why? Will this do any damage to the computer? Albacore (talk) 22:23, 25 December 2010 (UTC)

I'm assuming your computer has a CRT monitor? This gives a very detailed explanation for why magnets effect CRT screens. Also take a look at the Degaussing article which is related. Yes, it can sometimes permanently damage the screen. —Preceding unsigned comment added by 82.44.55.25 (talk) 22:57, 25 December 2010 (UTC)

One wonders why you got a magnet that can lift 250 lbs for Christmas if you didn't have any use for it...206.116.252.164 (talk) 01:31, 26 December 2010 (UTC)

A powerful magnet too close to your computer can also destroy your computer's hard drive; see Degaussing#Irreversible damage to some media types. Red Act (talk) 02:24, 26 December 2010 (UTC)

Agreed. Also, any magnetic media, like diskettes or tapes, could be damaged. StuRat (talk) 04:04, 26 December 2010 (UTC)

I'd be mighty careful with that. You may want to store it well away from all of your electronic devices. My dad used to wipe data off of media devices in the course of his work. I recall him saying he used magnets to do so. I'm sure that the magnets in question were nowhere near that strong. Falconus^{p t c} 05:35, 26 December 2010 (UTC)

Credit cards, too. --Mr.98 (talk) 03:19, 27 December 2010 (UTC)

To answer the "what can I do with it" question, here are some fun things you can do with magnets. Red Act (talk) 06:57, 26 December 2010 (UTC)

250 pound lifting force? Hang on! Doesn't that mean you would have to use more then 250 pounds of force to pry something off that thing? I smell a fish. I would be way too scared to play with such a magnet, imagine getting your hand (or worse) caught between a magnet like that and something attracted to it. Vespine (talk) 13:10, 26 December 2010 (UTC)

It would have to be in direct contact with a large, 100% iron object to apply the full force. Even a small offset, like that due to having your hand in between, would significantly reduce the force. StuRat (talk) 14:49, 26 December 2010 (UTC)

Permanent magnet (I assume the OP is not talking about electromagnets) lifting magnets usually have a mechanism for releasing the load when required. Example advert for the kind of size being discussed. See this video of how permanent magnet switching works. SpinningSpark 16:50, 26 December 2010 (UTC)

If you aren't careful, you can wind up pinching your fingers, causing blood blisters.[11]

<- A 250 pound lifting capacity magnet for Christmas, nice! I wonder if they make ones that work in countries that use the metric system. Sean.hoyland - talk 12:13, 27 December 2010 (UTC)

December 26

Fog

What would happen if you boiled fog machine liquid? Would it make a load of fog? 82.44.55.25 (talk) 00:23, 26 December 2010 (UTC)

I know of two types of fog machines, one basically does boil water, so nothing would change. The other uses dry ice (frozen carbon dioxide), which goes directly from a solid to a gas, with no liquid in between (it sublimates). It's not possible to boil carbon dioxide at normal atmospheric pressure. If you pressurized it and heated it, you might get a liquid, and if you suddenly released the pressure, you might get a lot of "fog". StuRat (talk) 04:02, 26 December 2010 (UTC)

I am confused when you say "nothing would change". Do you mean nothing would change with the fog liquid if I boiled it and it would just sit there in the pot, or do you mean there's no difference between whatever a fog machine does to the liquid and just boiling it, so it would make fog? And I'm specificlly talking fog machine liquid, not dry ice. 82.44.55.25 (talk) 10:45, 26 December 2010 (UTC)

From fog machines Typically, fog is created by vapourizing proprietary water and glycol-based or glycerine-based fluids or through the atomization of mineral oil. I don't think boiling would vapourize it particularly effectively, I don't think you'd get a LOT of fog. Vespine (talk) 13:05, 26 December 2010 (UTC)

What is the scientific term for levels of activity by time of day?

An organism is diurnal if it is active during the day, nocturnal if active during the night, etc, but what is the formal term for nocturnality and diurnality themselves? Is there a scientific word meaning "the level of activity of an organism by time of day" that includes diurnality, nocturnality, crepuscularity and all other variants on the concept? I've been wondering this for a long time but haven't been able to find this term despite a hard search. Circadian rhythm seems to be the most closely related concept that I've found, but it seems to be a bit broader than just activity levels. Abyssal (talk) 04:11, 26 December 2010 (UTC)

Chronotype? Clarityfiend (talk) 04:34, 26 December 2010 (UTC)

I don't think that's exactly what I'm looking for. That concept seems to be behavioral, like if a person (a diurnal animal) is a "night owl" (ie chooses to adopt different behavior). I'm more interested in activity levels innate to a species. Abyssal (talk) 07:24, 26 December 2010 (UTC)

Circadian? SpinningSpark 16:22, 26 December 2010 (UTC)

"The time during which an organism is normally active is referred to as the subjective day" - from Pace-Schott & Hobson (2002). NRN. 3, 591–605. Is this what you are referring to? --Mark PEA (talk) 21:39, 26 December 2010 (UTC)

Solar sails

Why aren't solar sails used to propel all spacecrafts? Since they don't require any energy other than to deploy and retract the sails, wouldn't they free up space that would've been used to carry fuel? --75.28.52.27 (talk) 20:31, 26 December 2010 (UTC)

They are difficult to make and deploy, take a long time to build up speed 82.44.55.25 (talk) 20:38, 26 December 2010 (UTC)

"Minimize total energy consumption" is only one objective during spacecraft engineering. While it is true that a solar sail will reduce the energy consumption, and consequently the mass of chemical propellant, a solar sail may incur other costs. Those costs compete against other design objectives - such as "minimize total flight-time"; "minimize flight-mass;" "minimize flight volume;" "minimize risk of failure;" "minimize monetary cost of spacecraft;" and "test specific scientific or engineering design." (With some imagination, you can expand that list ad nauseum). The point is, when you think of spacecraft design, you always have to keep yourself in the mindset of engineering tradeoffs and cost-benefit analysis. With present technology, even though solar sails might reduce the total mass of the propulsion system, they may significantly increase the flight-time - which is usually a tradeoff that the space-flight program cannot afford (because it affects the science objectives, the spacecraft design, and the dollar-budget). They may also introduce signficant risk - because they are both less-tested and less-controllable than a chemical rocket propulsion system. The chance that the propulsion system could underperform (or fail altogether) is altogether unacceptable, and generally outweighs any cost, mass, or other benefit that a solar-sail might provide. You might be interested in reading through the Lecture Notes for AA 222 - Multidisciplinary Design Optimization (a graduate course in spacecraft design from Stanford); you can learn how an aerospace engineer will formally specify the design requirements, evaluate various technologies, and plan the spacecraft. We also have the less-technical spacecraft design article, which mostly just links to articles about related subfields of engineering. Nimur (talk) 20:54, 26 December 2010 (UTC)

To date, Solar sails (skim the article, it's informative) are a basically untested technology. There has been a grand total of one spacecraft to successfully deploy a solar sail and use it for acceleration: IKAROS (Here's a news article about IKAROS, showing the sail). And it's only been up for about 6 months. If it successfully reaches Venus, and there are no major problems with the sail, other solar sail-equipped spacecraft may begin to appear; it's claimed in the IKAROS article that Jupiter is the planned next destination for a JAXA solar sail if this one works out. It's hard to find what exactly IKAROS is carrying (unfortunately, the IKAROS official website is woefully incomplete), but it appears that it's not accelerated solely by the sail: it also accelerates using an Ion thruster. I think it's safe to say that solar sails have a few years to go before becoming common on spacecraft.

It's interesting to note that ion thrusters, now pretty common on interplanetary spacecraft, were not really used in spacecraft propulsion until Deep Space 1, launched in 1998 (ignoring the SERT-1 probe, where one ion engine only ran half an hour, and the other one failed). If solar sails improve at a pace similar to ion thrusters, we may be seeing solar sails used fairly frequently in 20 years. Buddy431 (talk) 22:28, 26 December 2010 (UTC)

After the Japanese Spacecraft IKAROS the idea becomes more accepted. The Jupiter mission will be a lot of fun to see. The talks at COSPAR Bremen showed that JAXA has plans for the solar sail. By the way IKAROS do not use the sail to get faster they use it as a break! It is more efficient close to the sun and getting to venus or mercury are the best places to demonstrate the capabilities. The fact that IKAROS is going to Venus was not because of that, but simply it was the only mission which was launched at the right time with a piggyback capability.--Stone (talk) 22:49, 26 December 2010 (UTC)

Using the solar sale "as a brake" is essentially equivalent to using it to speed up; in space, it's the total acceleration (Delta-v) that's important, not which direction it's in. Buddy431 (talk) 23:14, 26 December 2010 (UTC)

Don't buy your solar sail on sale, or you may find it breaks when it brakes. StuRat (talk) 03:43, 27 December 2010 (UTC)

has any famous scientist ever expressed doubts about the moon landing authenticity?

bertrand russell, a very famous mathematician and philosopher, expressed doubts about the official jfk assassination story. did any famous scientists (like feynman, etc) ever express doubts about the authenticity of the moon landings? 87.91.6.33 (talk) 22:34, 26 December 2010 (UTC)

Why would they? It happened. The moon landings involved tens of thousands of people. Keeping that many people silent on a cover up for 40 years would be impossible. Wikileaks has shown us how keen some government employees are to tell the truth and release embarrassing information to the public. And I'm writing this as an Australian. The landings depended on people on around the world, including Australia, for communication. (Have you seen The Dish?) There would have been hundreds here involved. Nope. we wouldn't have kept America's secret, if there was one. HiLo48 (talk) 22:44, 26 December 2010 (UTC)

There are for sure some very old and very famous scientist expressing doubts about anything. The percentage of expressed stupid thoughts is not smaller because you are a scientist.--Stone (talk) 22:54, 26 December 2010 (UTC)

I would expect scientists to say stupid things less often than members of the general population. It's not never, but I would hope it's less frequent. Of course, they can do a lot more damage when they say stupid things because they have greater credibility (even if their area of expertise is completely unrelated to what they are talking about). --Tango (talk) 23:23, 26 December 2010 (UTC)

I didn't ask about old scientists but famous ones, like Feynman. So, did any famous scientist ever express doubts? 87.91.6.33 (talk) 23:49, 26 December 2010 (UTC)

Charles K. Johnson, president of the International Flat Earth Research Society declared that NASA faked the landings, which were staged by Hollywood with Walt Disney sponsorship and based on a script by Arthur C. Clarke and directed by Stanley Kubrick. The first link attests to Johnson being famous enough to be noted in Wikipedia and the second link is a report about Johnson in Science digest July 1980. Together these links establish Johnson as a Famous Scientist. Cuddlyable3 (talk) 23:52, 26 December 2010 (UTC)

I'm sorry, but calling Johnson a scientist on the basis of the fact that he was featured on a website called Science Digest (which isn't a scientific periodical at all) is utter, total, and unadulterated nonsense. --Mr.98 (talk) 01:37, 27 December 2010 (UTC)

Calling Charles Johnson a scientist can only be construed as a joke. His belief on flat Earth alone is enough to doubt about his mental health.Quest09 (talk) 12:19, 27 December 2010 (UTC)

Another issue is, what kind of scientist? Would the comments of a famous medical scientist mean anything on moon landings? Scientists are specialists. HiLo48 (talk) 23:54, 26 December 2010 (UTC)

WP:OR - The first time I ever met Doug Osheroff, he explained how after winning his Nobel prize for superfluid helium, all kinds of media and political people would call him up to ask his opinion about stem-cell research and space-shuttle disasters and junk. (Somehow even NASA thought he was "expert enough" about Space Shuttles)! But he was only really an expert on helium! He said, as a prestigious scientist, the public automatically trusted him to be an expert on everything scientific, all the time - which was really very silly, and demonstrated how little the public actually understood modern science. The second time I met Doug Osheroff, I didn't get to talk to him very much, but I did get to yell at him because he walked through our "DANGER DO NOT ENTER" barrier at the back parking lot behind the physics building, right into the path of our rocket pyro test (he was just trying to take a shortcut to his car, and delayed our entire procedure). He saw our sign and caution-tape, but he said he "didn't think it would be very dangerous." I guess my point is that even very smart and famous scientists can say stupid things; and you shouldn't always trust their judgement. Nimur (talk) 23:57, 26 December 2010 (UTC)

You just made a preemptive strike against something no one has shown. If you don't think it would be relevant for someone with a Nobel Prize in helium to express doubts about the space missions, you have that right. But me, I care a lot about whether in fact anybody like that did. Your response is like me asking "has any president been antisemitic?" and you saying: what if they were - that doesn't prove that Jews are bad! A president can be very wrong, why Nixon was a crook who would have gone to prison but for a presidential pardon from his successor!!! Why even ask that question??? head asplode. 87.91.6.33 (talk) 00:27, 27 December 2010 (UTC)

I'm sorry. Allow me to clarify. Out of all the famous scientists that I know, none has ever expressed doubt to me about the veracity of the manned moon landings. Nimur (talk) 00:43, 27 December 2010 (UTC)

There's a list of people at Moon_landing_conspiracy_theories#Hoax_proponents_and_their_proposals, some of who are scientists. 82.44.55.25 (talk) 00:52, 27 December 2010 (UTC)

Yes, there's a list of people, but only one of them appears to qualify as being a scientist - Alexander Popov - described as a Soviet physicist and inventor with the degree of Doctor of Physical-Mathematical Sciences. Dolphin (t) 01:16, 27 December 2010 (UTC)

And his area of specialisation appears to be around light - lasers, spectroscopy, etc, so hardly an expert on flying people to the moon. HiLo48 (talk) 02:15, 27 December 2010 (UTC)

Are there any scientists whos field of expertise is "flying people to the moon"? I always assumed the teams of scientists who do these kinds of things have a vast array of different areas of expertise which they apply to the task at hand... 82.44.55.25 (talk) 11:04, 27 December 2010 (UTC)

The evidence available on Wikipedia is very comprehensive regarding high-profile people known to believe the manned moon landings didn't occur. That evidence indicates that no scientist whose field of expertise is directly relevant to manned moon landing believes NASA's manned moon landings were hoaxes. Dolphin (t) 12:27, 27 December 2010 (UTC)

Thank you, although you switcheroo "none of them express doubt" into "none of them believe it is a hoax". I will accept your answer as really reading as the former. (Since there are, in fact, many reasons one could doubt something without expressing it publicly). Thank you. 87.91.6.33 (talk) 15:19, 27 December 2010 (UTC)

You're right, of course. In fact the Apollo program was used a great example of excellent project management for the way it brought together the diverse resources it required. The points made above about specialisations among scientists were simplifications, but still relevant. HiLo48 (talk) 11:22, 27 December 2010 (UTC)

In the case of Popov, he would be an expert for the purposes of evaluating moon landing hoax claims if those claims were based on evidence generated through laser spectroscopy. His pet conspiracy preference, however, revolves around the notion that the launches were faked using Saturn 1B rockets disguised as the (much larger and putatively non-existent) Saturn V. Leaving aside the political propaganda angle (Soviet scientist denies American accomplishment during Cold War, film at eleven), he might be a credible source on this question if he had a background in military reconnaissance, remote imaging, and aerospace engineering. Because his conclusions are based on matters far outside his own specialty, he should be taken as no more credible than any other randomly-picked clever-but-gullible individual. The fact that his day job is as a 'scientist' isn't helpful here, any more than being a 'doctor' is sufficient if a dermatologist were to tell you that you needed heart surgery. TenOfAllTrades(talk) 15:06, 27 December 2010 (UTC)

December 27

Crocodile Dundee II

I know it's "just a movie", but I'm still curious: in "Crocodile" Dundee II, Dundee jumps off a building, holding a rope, and about five or six stories down, the rope snaps taught, and he swings right through a window. Assuming the rope could never break, would this stunt even be remotely possible, without ripping skin off one's hand, etc.? – Kerαunoςcopia^◁_galaxies 08:32, 27 December 2010 (UTC)

It presents a number of genuine difficulties so it would be reasonable to assume this stunt could not be achieved in real life, only in the composite world that can be achieved in film - shoot a number of different sequences, each one entirely ordinary, and then splice them together to give the audience the overwhelming impression that this extraordinary action is not only possible, but that it actually happened. Dolphin (t) 12:04, 27 December 2010 (UTC)

What is interesting is how close one could come, with a sufficiently stretchy rope, careful measuring, and careful training. But if you fall 5 stories down, and the rope "snaps" taught" , there are several g of acceleration involved, and you probably rip of some body parts. --Stephan Schulz (talk) 13:16, 27 December 2010 (UTC)

Is the earth gaining weight?

I couldn't find an answer in the archives. But with my limited knowledge of science, with all the people being born and gaining mass throughout the centuries, shouldn't the earth be gaining mass? Or is the earth losing energy to each living person? I ask, because in the movie Houseboat, Cary Grant explains death to his son in terms of a pitcher of water that is poured back into the earth. I understood where the death of a person becomes the earth, but I don't understand where the mass of a born person comes from. – Kerαunoςcopia^◁_galaxies 08:42, 27 December 2010 (UTC)

Try to reproduce without ever eating, and then ask again. Feezo (Talk) 09:02, 27 December 2010 (UTC)

Yes. We eat plants, or eat animals that have eaten plants. The plants appear to grow from nothing (apart from a seed), but in fact they are grabbing carbon and oxygen from the air, where we don't really notice its weight or size. I always thought this was one of the more amazing things about plants when I first learnt about it. All that bulk in giant trees was once just air. HiLo48 (talk) 11:06, 27 December 2010 (UTC)

Energy that comes from the sun could be converted into mass. Then again, the same energy could be converting the Earth's mass into energy. An interesting idea. If we could calculate the amount of sunlight absorbed by Earth, then we could calculate an upper limit on mass gained. I think my mathematical modeling class would have handled this. ;) Magog the Ogre (talk) 11:28, 27 December 2010 (UTC)

It's a fairly easy calculation. The average insolation at the top of the Earth's atmosphere is 1366 watts per square metre. The Earth's radius is 6371km and its albedo is 0.367. The energy gained in a second is insolation*cross-sectional surface area*(1-albedo). In this case, we get 1.1*10¹⁷W. Divide that by the speed of light squared and we get about 3kg per second. --Tango (talk) 11:54, 27 December 2010 (UTC)

The Earth is also gaining weight through meteorites that are trapped by her.Quest09 (talk) 11:56, 27 December 2010 (UTC)

Magog and Tango's answers are ridiculous, Magog has turned E = mc² on its head and using it in the wrong way, and Tango is encouraging him. Energy radiating from the sun, does not turn into mass on Earth. That equation has to do with nuclear physics, far removed from the concept you're talking about. The Earth loses mass in the form of the lighter gasses in the atmosphere escaping the Earth's gravitational attraction, gasses like helium and hydrogen. On the other hand, the sun is adding the same gasses back by radiating the Earth with solar wind however, I don't know the net gain or loss of these gasses relative to the Earth. In addition to these, as Quest09 has said, space debris, like meteorites, continuously rain down on Earth. Material that makes up the biosphere is continuously being recycled. That, is live does, life takes a chaotic mess of matter, and with the use of energy from the environment, shapes it into something with complexity and order. Death releases the energy back into the environment, letting the order and complexity decay back into a natural tendency of chaos. A simple example of thermodynamic law of entropy. You ask where the mass of a born person comes from? Think of a brick wall, a brick wall does not grow wider by stretching the bricks, instead new bricks, made from fresh clay must be added to the wall. Similiarly, a person does not grow by stretching, new cells must by made by their body. These cells do not appear out of nothing, they are made from what the body can extract from the very food we eat. This applies to whether a person has been born or not. In simple terms, we are build from what we eat, don't take this literally, this is an oversimplification. For the unborn, who not yet eating for themselves, has their mother to eat for them, since they share a body for the time being. I hope this answers your question. --Plasmic Physics (talk) 12:42, 27 December 2010 (UTC)

I agree that there are all kinds of other factors that result in the gain and loss of mass, but sunlight being absorbed does add mass at approximately the rate I said (I think I miscalculated and it's actually more like 1kg per second, but that isn't important). If E=mc² then m=E/c², there is nothing wrong about that. The extra mass is because the total mass of a glucose molecule and oxygen molecule is greater than the total mass of the water and carbon dioxide that they were made from (see bond energy). The other factors may be significantly greater in magnitude, but that doesn't mean that what Magog and I have said is wrong. --Tango (talk) 13:24, 27 December 2010 (UTC)

Actually Tango's logic is exactly correct - but there is a fatal flaw in his arrangement. He only calculated incident radiation - and completely forgot to compute the net radiation - which is (roughly) "amount of input energy from Sun" - "amount of thermal energy radiated by Earth." This amount, called the net energy flux of Earth (or "Earth's energy budget"), is incredibly important as a parameter of planetary and climate science. In fact, when climatologists and planetary scientists discuss "global warming," they are trying to compute an exact value for the net energy flux - i.e., is more energy coming in than going out? (If so, the planet is warming). Most estimates of net energy balance place it around 1 to 3 watts per square meter; though there are huge debates about this. Some scientists even believe the net flux is slightly negative (and that Earth is actually cooling). Many scientists believe that human-created pollution can change the energy flux - mostly by affecting the chemical balance of the Earth's stratosphere (adding Carbon Dioxide, for example, and changing the incoming and outgoing radiation rates). In truth, the exact amount of net energy is hard to determine, and there are a lot of "fudge" factors; and defining the "edge" of the Earth is very hard (i.e., if the magnetosphere experiences a net warming but the rest of the atmosphere experiences a net cooling... has the planet warmed or cooled?) In any case, Tango's approach is valid - if there is a net change in the thermal energy, this will exactly follow the conventional relativistic equivalence between energy and mass - and does affect the gravitational mass of the Earth. But, because of the disparity between incident and net energy flux, Tango's 3 kg/second is off by approximately 3 orders of magnitude. As such, Earth gains far less mass from solar radiation of energy than it does by gravitational capture of micrometeorites. (That is a very real and measuarable effect that you can read about here: The micrometeoroid mass flux into the upper atmosphere... (GRL 2001), describing quantitative RADAR measurements (from Arecibo Observatory) of meteorite rate. Nimur (talk) 13:44, 27 December 2010 (UTC)

voilation of parity in beta decay

question:how parity is voilated in beta decay? — Preceding unsigned comment added by Awanishkt (talk • contribs) 11:13, 27 December 2010 (UTC)

Is that a homework question? If not, can you elaborate a bit for our edification? Magog the Ogre (talk) 11:29, 27 December 2010 (UTC)

I guess voilation is a misspelling of violation. I don't know the subject but the Google search violation parity "beta decay" gives hits, for example Parity (physics). PrimeHunter (talk) 14:33, 27 December 2010 (UTC)

People getting fat

So now it turns out both the British [12] and Australians are getting fat too. It has by no means been limited to the US, premature reports aside. In the US, it's fashionable to blame it on high fructose corn syrup, but I haven't a clue if that (uneconomical but for poor legislation) concoction is even available in Britain or Australia. It's clearly something to do with lifestyle or wealth. What in the world could be the cause of all this? Magog the Ogre (talk) 11:25, 27 December 2010 (UTC)

McDonald's, Subway, Aldi, Burger King, Monosodium glutamate... Always read the criticisms sections. It is ddefinately not only high fructose corn syrup (although I haven't read the article) — Preceding unsigned comment added by Eu-151 (talk • contribs) 11:51, 27 December 2010 (UTC) --Eu-151 (talk) 11:52, 27 December 2010 (UTC)

Why would monosodium glutamate make you fat? Some people claim that it is unhealthy, but it is only a salt, and I suppose with little content of calories. Quest09 (talk) 13:25, 27 December 2010 (UTC)

I agree. MSG may have health implications (I haven't looked into it), but it doesn't make you fat. --Tango (talk) 13:27, 27 December 2010 (UTC)

MSG tends to be in foods that do make you fat, and makes them more appealing. That's the theory, anyway. - Jarry1250 ^{[Who? Discuss.]} 13:51, 27 December 2010 (UTC)

I don't think we use HFCS much here in the UK. It doesn't matter what the source of the calories is. If you consume more calories than you use, you will get fat. It is that simple. People are getting fat because they are eating too much and exercising too little. There is nothing more to it (you can try and explain why those things are happening, of course, but blaming it on particular types of food isn't going to help). --Tango (talk) 13:27, 27 December 2010 (UTC)

Specific kinds of food could be an issue here. If something is a calorie bomb, you can ingest lots of calories with just drinking or eating a little of it. Quest09 (talk) 13:37, 27 December 2010 (UTC)

This article lists some research into it and provides some explination:Division of Nutrition and Physical Activity. Research to Practice Series No. 2: Portion Size. Atlanta: Centers for Disease Control and Prevention, 2006. The UK and Down-under are copying the American food industry -so the problem spreads.--Aspro (talk) 15:04, 27 December 2010 (UTC)

Blister

What is the purpose of Blisters? The article doesn't say —Preceding unsigned comment added by 174.139.241.18 (talk) 14:10, 27 December 2010 (UTC)