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August 7

Human race

If the human race felt no emotions, would civilisation have developed to the stage it is at now? Why or why not? Clover345 (talk) 00:52, 7 August 2014 (UTC)

Please read the introduction to this reference desk above, especially the sentence that says "We don't answer requests for opinions, predictions or debate." If that sentence in general, or any specific words within it, are confusing to you, let us know and we can provide references to definitions of those words that may help you understand it better. --Jayron32 01:35, 7 August 2014 (UTC)

I agree with the above. However I also think the answer is very obviously no. For one, I doubt it's even possible to feel "no emotions", even psychopaths feel emotions, just differently no "normal" people. No one would be motivated to do anything without emotions. Vespine (talk) 01:51, 7 August 2014 (UTC)

Perhaps have a good read of Emotions, might clear it up for you. Vespine (talk) 01:52, 7 August 2014 (UTC)

I refute both of your statements by pointing to your computer. It has no emotions, and it is clearly doing something. --Bowlhover (talk) 01:56, 7 August 2014 (UTC)

I don't believe that refutes anything, whatever computers do/did they didn't "build" our civilization. Can we build (or have we already built) computers that could possibly grow our civilization from THIS point, that's an argument you could have; Could we have got THIS far? That's the question I'm answering with a definite "no". 04:28, 7 August 2014 (UTC)

And just one more point, a computer these days clearly does not have any motivations or desires of its own, any computer that IS capable of making a decision is programmed with the motivations or desires of the programmer / designer. IF we one day create a computer that does actually possess its own motivations and desires, it's quite possibly sufficient to say that computer has emotions, though how you would actually work out IF that was true, might not be possible, see Philosophical zombie Vespine (talk) 04:35, 7 August 2014 (UTC)

• I'm unhatting this, because even if the question is speculative, it can be answered in a non-speculative way, by pointing to relevant literature. One particularly relevant item is a book by Antonio Damasio called Descartes' Error. He covers the neuroscience of emotion (such as it is), and argues that emotion plays an essential role in human decision-making. There are several aspects of the book I'm not keen on, but it does directly address this question. Looie496 (talk) 02:27, 7 August 2014 (UTC)

Yes we'd call ourselves Vulcans though. --DHeyward (talk) 18:31, 7 August 2014 (UTC)

"Nothing great in the World has been accomplished without passion." Hegel, Philosophy of History, III § 26 John Z (talk) 18:42, 7 August 2014 (UTC)

Vulcans are not emotionless, they simply have a high level of control over their emotions. ←Baseball Bugs ^{What's up, Doc?} carrots→ 18:44, 7 August 2014 (UTC)

Biodiversity of suburban gardens vs farm fields

Quite a while ago, I'm sure I read the abstract of a research paper that said suburban gardens had generally higher biodiversity than intensively farmed fields. I can't remember the details though, and I haven't been able to find it again. Did this research ever really happen, or am I misremembering some rant I once read on a blog? 129.67.119.181 (talk) 13:08, 7 August 2014 (UTC)

This claim is generally true, for most common interpretations of 'suburban garden', 'biodiversity', and 'intensive farming.'

However, there are lots of complicating details. For starters, how is diversity quantified? Alpha diversity, beta diversity, and gamma diversity are a few metrics, but we also have things like evenness and other diversity indices that could be considered. Also we have to consider whether we are thinking of "total diversity" of all present taxa (soil microbes, insects, birds, plants, etc), or perhaps we are just interested in e.g. plant diversity.

So, if you consider e.g. a field of roundup ready corn, doused with insecticides and herbicides, compared to a small plot of mixed veggies grown organically (and in the same biome), the latter will almost surely have higher total species richness per area. However, if the "intensive farming" happens to be organic, and a good habitat for insects and birds (e.g. some forms of permaculture), then the monoculture of plants may well have higher total or insect diversity than a small mixed veggie plot that has been treated with sevin. The organic 'monoculture' could even have higher plant diversity, if the weed richness is high, and the home garden has been thoroughly weeded.

As for the specific research article, I don't think I know specifically what you are talking about, but here are several articles that address similar issues: [1], [2], [3], [4], [5].

If you're interested in these issues in general, you may also like to read about Integrated_pest_management, agroecosystems, and Ecological_effects_of_biodiversity#Effects_on_community_productivity. SemanticMantis (talk) 16:35, 7 August 2014 (UTC)

I expect it was a joke, but just to avoid misleading anyone, the technical meaning of "almost surely", as explained by the linked article, is not the same as the informal meaning in SemanticMantis's comments. The probability of a of a lower species richness for the organic farm may be small, but it is not zero. --Trovatore (talk) 03:12, 8 August 2014 (UTC)

Meh, I thought I qualified the claim sufficiently to make it mostly true in the technical sense, if perhaps hyperbolic. I did also think it was a humorous claim. I suppose you could argue that "almost surely" should never be applied to anything in the real world, and reserved for formal abstract systems, but that's a debate for a different day... Still, my intent was not to mislead, so your clarification is useful. Also good to know someone's paying attention :) SemanticMantis (talk) 16:52, 8 August 2014 (UTC)

I see no reason a priori why there cannot be a real-world event that is possible yet has probability 0. However I cannot think of an example of such an event. --Trovatore (talk) 17:37, 8 August 2014 (UTC)

Here is a link to a BBC News story about this subject, and here is the Sheffield University project referred to in the BBC story. DuncanHill (talk) 17:26, 8 August 2014 (UTC)

Automatic, non-poisonous mosquito deterrent

I'm getting a bit tired of mosquitoes waking me up at night. We have door and window screens that work pretty well, but barriers like that can never be totally effective because sometimes we need to open them. Also tried a poison vaporiser thing that plugs into a power socket, and it works 100% but the gas gives me a headache and a sore throat. It can't be exactly healthy....

Is there any automatic, reliable, non-poisonous-to-people way of either killing mosquitoes, or making them want to leave a particular room? What about the blue-light fly killers that restaurants have in their kitchens - do those work on mozzies? 129.67.119.181 (talk) 13:15, 7 August 2014 (UTC)

The Dynatrap DT2000 XL may be just the ticket, if it's a "worth $200" sort of problem.

I generally use this kind of mosquito coil, and don't mind the smell, but your nose may be different. InedibleHulk (talk) 13:26, August 7, 2014 (UTC)

If you'll pardon a slightly random tangent, I have a column with the same sort of name (TSK-G3000_SWXL). Guess it's all marketing anyway, regardless of the audience. (+)H₃N-Protein\Chemist-CO₂(-) 14:55, 7 August 2014 (UTC)

No problem, but personally, I don't think I've ever been so confused by that many different words at once. I can honestly say I've never seen such a fair price on TSKgel SWxl Top-Off for SWxl/QC-PAK. If I ever need one/some, I'll keep you in mind. InedibleHulk (talk) 12:25, August 8, 2014 (UTC)

There is actually an accredited American Mosquito Control Association with some useful information (for example, the "ultrasonic mosquito replants" don't work)   —71.20.250.51 (talk) 16:26, 7 August 2014 (UTC)

If they are only a problem at night, you might consider mosquito netting for your bed. That's a very old, non-toxic solution. StuRat (talk) 16:36, 7 August 2014 (UTC)

You might consider Citronella oil, (or plant lemon grass near the door and/or windows) but dogs don't like it (and may be toxic for them) -otherwise it seems to be safe and effective (see article and refs); however, the smell alerts everyone to the fact that you have a mosquito problem; and some people find the odor annoying [e.g.:71.20.250.51 (talk) 00:24, 8 August 2014 (UTC)]. Note that in the UK, the control freaks are uncertain, so they banned Citronella for this purpose. —Or, if you prefer "licorice-mint scented foliage" you could plant some Texas Hummingbird Mint (a.k.a. "Mosquito Plant")   —71.20.250.51 (talk) 01:32, 8 August 2014 (UTC)

The linked HSE article makes it clear that the HSE did not ban citronella, but rather that citronella producers chose not to supply evidence that it is effective and safe. And one can still legally buy, sell, or use citronella products, however they must not be marketed as a biocide - because the manufacturers have not supplied evidence that such use is safe and effective. DuncanHill (talk) 17:47, 8 August 2014 (UTC)

OK, here's a new thing to be irritated about (new to me, anyway). The linked citronella oil article says that citronella is considered a biopesticide by the United States EPA. But it doesn't kill anything! It just repels.

To me, if it doesn't kill, it's not an -icide of any sort. But the various articles I just clicked through on such topics make no mention that -icides have to kill. Is this linguistic shift really complete? Who let this happen?

By the way, our drowning article is also flat wrong in the first sentence. If you didn't die, you didn't drown. --Trovatore (talk) 18:52, 8 August 2014 (UTC)

That is why I worded thus: "...for this purpose" —It can still be sold as "perfume" or whatever. -Although we are drifting off-topic (mosquito deterrent), , I believe there is something on WebMD relating to citronella oil used to treat athlete's foot fungus, presumably as a -cide (as in "fungus killer"), but I currently don't have time to cite sources.  —71.20.250.51 (talk) 21:21, 8 August 2014 (UTC)

Mosquito control should always start outside. There are things like abandoned tires and stagnant pools on man-made trails that can breed them in great numbers, which you can reasonably destroy. Mosquitoes don't travel all that far after hatching, so eliminating nearby hazards can really pay off. Wnt (talk) 01:05, 9 August 2014 (UTC)

Not really viable in cities though, where most if not all the surrounding area is someone else's property. It only takes one lazy resident or negligent landlord... 95.246.128.149 (talk) 14:04, 9 August 2014 (UTC)

Well, there are rules on nuisances though, and not many people really want their mosquitoes if asked, and if they can't be asked (abandoned) they can't complain... I wish we had a knowledge base on this sort of issue somewhere, but I can't believe there aren't options. Wnt (talk) 09:52, 10 August 2014 (UTC)

Antagonistic interactions

Another editor above has said "it is well known that there is an antagonistic interaction between pain and substances that induce global anesthesia. It's particularly clear in the case of opiates such as morphine: doses that induce stupor of unconsciousness in most people might not substantially impair alertness in somebody in severe pain. It also holds for alcohol -- but it should be noted that even though pain improves alertness and arousal in somebody who has consumed alcohol, it doesn't improve motor control or decision-making." Could anyone provide any reliable references for this? Particularly for what mechanisms are involved? Thank you. DuncanHill (talk) 13:23, 7 August 2014 (UTC)

In old times before the ether surgeons would give patients alcohol and then cut the tissue. --AboutFace 22 (talk) 23:44, 7 August 2014 (UTC)

This question involves "decision making" and "judgement" which pain, opiates, alcohol, and alertness all affect in different ways. 104.128.96.117 (talk) 09:39, 8 August 2014 (UTC)

Mythbusters did at least one relevant experiment; I seem to remember that Adam was measurably less drunk after Jamie slapped him. (Perhaps someone else remembers the episode better than I do.) —Tamfang (talk) 03:50, 10 August 2014 (UTC)

dog sense of taste

It's well known that the dog's sense of smell is far greater than that of humans. In humans, smell and taste are closely intertwined (see http://www.entnet.org/content/smell-taste). Would it be true, then, that dogs also have much greater sense of smell than humans? --Halcatalyst (talk) 15:49, 7 August 2014 (UTC)

There is a good answer to your question here:

“ Humans win the sensitivity contest for taste, with around 9000 taste buds as compared with only 1700 for the dog. ”

—Stanley Coren, Ph.D (April 19, 2011). "How Good Is Your Dog's Sense of Taste?". Psychology Today : Canine Corner. Psychological Enterprises Ltd.   —71.20.250.51 (talk) 17:35, 7 August 2014 (UTC)

Yep their sense of taste is fairly basic, smell does the job of checking the food out and then they just want to gulp it down quick-- you don't see them savoring their food. By the way as far as smell is concerned [6] says elephants have twice as many genes for smell as dogs, I'm also a bit surprised that humans seem to have more than the monkeys and apes they tested. Dmcq (talk) 17:43, 7 August 2014 (UTC)

Thank you! Makes a great deal of sense (no pun intended). --Halcatalyst (talk) 21:31, 7 August 2014 (UTC)

But isn't the sense of smell a large aspect of taste? I am curious as to how that plays into it. Justin15w (talk) 14:41, 8 August 2014 (UTC)

Strictly speaking, in the relevant areas of science, taste refers purely to those sensations which are delivered on the tastebuds. Flavour is the thing we often mean when we casually refer to taste, and that is a combination of taste and smell (and often things like Pungency ("hotness") as well). Your experience of flavour also depends on your psychological expectations based on what it looks like, and on mouthfeel. When a manufacturer wants to change the taste of a food, they change the proportions of things like sweeteners, salty ingredients, fat, monosodium glutamate, caffeine, and such like. When manufacturers want to change the flavour of a food, they change the flavourings they add, which typically alter the smell of a food. Skittle (talk) 16:26, 8 August 2014 (UTC)

What test?

Hi, I've taken some statistics classes in my time but long since forgotten most anything useful... I've some ecological data, recorded at a number of sites. Each site is a single row of data: name, a binary (A/B) classification, and the remaining columns are a specific measurement for each of a number of species. I'd hypothesise that the B sites have lower values for this measurement. These measurements are not normally distributed, and the two groups are of different sizes (there are more A sites than B). I considered e.g. taking the mean of the rows and using the Wilcoxon signed-rank test, but I wondered if there were any tests that would gain power from/allow me to compare the two sets of rows directly (rather than collapsing each into a single row). Thanks! 82.13.241.56 (talk) 19:17, 7 August 2014 (UTC)

Without more info, I would guess that the counts are Poisson distributed. There exist tests to compare means of Poisson distributed variables, e.g., Tests for Two Poisson Means. --Mark viking (talk) 19:32, 7 August 2014 (UTC)

We have articles: Wilcoxon signed-rank test & Poisson distribution, which might refresh you memory. Further inquiries might get better results over at the mathematics desk. —71.20.250.51 (talk) 20:36, 7 August 2014 (UTC)

Sci fi vs real science

How much of the science in Star Trek is actually scientifically plausible (I.e. Not flawed in some way)? Ignoring the fictional life forms. I'm referring more to the engineering, science and technology of the universe, starships etc. 94.14.151.66 (talk) 22:56, 7 August 2014 (UTC)

The article: Technology in Star Trek is rather skimpy, but the 'Further reading' section has several sources on the subject.   —71.20.250.51 (talk) 23:05, 7 August 2014 (UTC)

For one thing, teleportation and faster-than-light travel are scientifically implausible (violating the Heisenberg uncertainty principle and the special relativity theory, respectively). 24.5.122.13 (talk) 02:27, 8 August 2014 (UTC)

Also food replicators, upright deck artificial "gravity generators," and everything about "subspace" is as implausible as transporters (or any other form of mass teleportation). 104.128.96.117 (talk) 09:23, 8 August 2014 (UTC)

I believe some form of food replicators are possible now. That is, a machine can include raw ingredients and produce the requested food by combining them together. For example, a pizza machine could add the requested toppings, or a smoothie machine could blend the requested ingredients. Now, replicating a turkey isn't possible now, although perhaps we could grow some Quorn around an artificial bone and call it turkey. Also, food replicators could be tailored to each person's nutritional needs. For example, a menstruating woman might get extra iron added to her food to replace the iron lost in blood. StuRat (talk) 14:05, 8 August 2014 (UTC)

There are 3D printers for food already. These could be considered to be a crude first step toward a food replicator. It's not a stretch to imagine eventually being able to "print" a steak or a chicken leg from meat cells that were grown in a vat.--Srleffler (talk) 02:05, 9 August 2014 (UTC)

Although it wouldn't violate any physical laws per se, manned interstellar travel at even sub-light speeds still looks vastly out of reach technologically for the foreseeable future. See Interstellar travel#Challenges. Red Act (talk) 03:46, 8 August 2014 (UTC)

Not really. The Star Trek sleeper ships such as Khan Noonien Singh's SS Botany Bay and in The Emissary are completely plausible with current technology, except for the fact that they had implausible means of artificial gravity. 104.128.96.117 (talk) 09:23, 8 August 2014 (UTC)

Well, for starters, as the sleeper ship article you linked to says, "There is currently no known technology that allows for long-term suspended animation of humans." Red Act (talk) 13:24, 8 August 2014 (UTC)

Still plausible per e.g. recent advances in cryopreservation. 104.128.96.117 (talk) 08:43, 9 August 2014 (UTC)

Almost everything about FTL in the show is bogus, and sometimes not even wrong. This includes not only the ships (which travel at the Speed of Plot), but torpedo munitions, transporters (they include a "Heisenberg compensator" component, which is a major conflict with the uncertainty principle), and subspace communications (which generate "chicken vs. egg" issues in a moving frame of reference).

Chemistry and metallurgy are way off, too. For starters, it's highly unlikely that even one element not yet discovered is stable enough to observe visually, and it's unlikely that there are any elements beyond 180.

About the alien life forms, even if they are of common origin, it is quite a stretch that all of these evolve into near-human beings. It's even more silly that those are genetically compatible. ST:TOS is sometimes called ST:KFETM (Star Trek: Kirk fucks everything that moves), TNG gets RFETM (Riker), and DS9, well, ST:HIF (Humanity is fucked).

I am not so sure. A lot of fish look like a lot of completely unrelated fish. Why not hominids for animals gaining space-fairing capability too? The closest competitors on Earth for such capabilities were the lizards that evolved into birds (some parrots and pigeons are very smart, but they can't take selfies with a camera) and octopuses, which can use tools but have very poor communication skills. 104.128.96.117 (talk) 09:23, 8 August 2014 (UTC)

The similarities are just too striking.

Certain similarities are very plausible: a brain somewhere near the mouth would make sense, to save on neural mass and transmission lag. Sensory organs near the mouth make sense, too, and with "larger" lifeforms, a head containing these three will probably develop; moving the head to look around, rather than the entire body, saves time and energy.

Animals on a solid surface will probably have one to six legs; six are easy to use, but large animals have fewer, which are more demanding of the brain (which will still come out ahead with large animals, because the weight penalty of the brain does not increase with size). For more height and carrying capacity (or flight), two legs are even better than four, but even more difficult to use. Some four-legged animals move more on two than on four legs, too. Many kangaroos move around with "one" leg; they don't move their legs independently when bunny-hopping. So we can expect many alien races to have a head and two or four legs; however, most Star Trek species are extremely similar. - ¡Ouch! (^{hurt me} / _{more pain}) 05:45, 11 August 2014 (UTC)

But most of that pales in comparison to Star Trek engineering. They have "manual" controls which need power; they can't even open the average door without redirecting power to it. Used as a plot device, but utterly stupid. Also, control panels of death.

Star Trek is not the "Science in name only" end of the sci-fi hardness scale, but it can see it on a sunny day. And still a better love story than Twilight. - ¡Ouch! (^{hurt me} / _{more pain}) 07:37, 8 August 2014 (UTC)

Are real life scientists currently researching ways around Heisenberg uncertainty and special relativity? And can someone explain in simple terms how Heisenberg makes teleportation impossible? 94.14.151.66 (talk) 11:40, 8 August 2014 (UTC)

I believe transporters are possible, although they will take on a slightly different form. In ST, the person's atoms are disassembled, sent to the target, then reassembled there. This is somehow even possible with no transporter pad at the destination. In reality, a scan of the body would be done, at high enough resolution to see each atom, then the information would be sent to the target location, where a transporter pad would be assemble a copy of that person, atom by atom, from raw materials (we can currently assemble DNA like this). The assembly is the trickiest part, as you have to keep liquids in place, keep air out, etc., during the assembly process, which probably means it needs to be extremely fast, which would generate lots of heat. Or perhaps once we figure out how to make cryogenics work in humans, we can slowly assemble a frozen human, then thaw them out and give them CPR to revive them. The original would then have to be destroyed, or else you've cloned a person and copied over his memories. Think Like a Dinosaur (The Outer Limits) had an excellent treatment of the moral issues, although they avoided getting into the details of the assembly process by having that take part in an unseen location. They did send the information faster than the speed of light, too. StuRat (talk) 13:57, 8 August 2014 (UTC)

It has been pointed out that teleportation of living things would require knowing not only information about each atom, but also the quantum state of every subatomic particle (or at least the electrons) simultaneously, since those are critical for the function of living things. It would be less than useful to be duplicated at a remote location without memories or consciousness. I'm not sure how much data that represents, but it's orders of magnitude higher than atomic-level resolution. Acroterion (talk) 14:33, 8 August 2014 (UTC)

One of the points which Star Trek actually mentions; bulk transport cane be done using "molecular resolution", but to teleport personnel, they need "quantum resolution". - ¡Ouch! (^{hurt me} / _{more pain}) 05:45, 11 August 2014 (UTC)

Yes, there are more than a few hurdles there. My guess is that, if meaningful teleportation is ever possible, it will be in a form completely unlike that and/or be completely unrecognizable with current science. Perhaps some kind of worm-hole creating machine. Something like that is only impossible (i.e. outside our realm of understanding), while ST teleportation is wildly improbable to ever be feasible (i.e. understood, but completely beyond us technologically). Matt Deres (talk) 15:18, 8 August 2014 (UTC)

One rough bandwidth and power calculation is found here [7], and it doesn't even address quantum states, which would have to be measured within the bounds of Planck time to be accurate. I don't see transporter technology as it is described by Star Trek as practical: it will require a completely different method that doesn't involve making a quantum-state catalog. Acroterion (talk) 15:31, 8 August 2014 (UTC)

The shuttle craft seemed quite plausible to me, at least those without warp drive. Indeed, I would expect more use of shuttle craft in our future, to transport people, supplies, and equipment between ships. Currently a lot of EVA is used to do that, or the main ships dock together. Shuttles that land on planets with Earthlike gravity and take off again would require a much more efficient energy and propulsion source than current fuels. Perhaps a matter/antimatter reactor accelerating particles (ship waste, atmospheric molecules, etc.) to the speed of light would give them that ability. Of course, such a shuttle would be rather dangerous, should it have an antimatter breach. Even the light speed matter stream would destroy whatever it hits. So, I'd only use this to explore uninhabited planets (which, unlike in ST, seems to be almost all of them). StuRat (talk) 14:27, 8 August 2014 (UTC)

Supposedly, the reason Roddenberry came up with the matter transporter was to avoid having to use the shuttle all the time, i.e. to speed up the story. By the 23rd century, they had developed the transporter sufficiently as to avoid the kind of glitches seen in The Fly. ←Baseball Bugs ^{What's up, Doc?} carrots→ 16:46, 8 August 2014 (UTC)

Small craft are an important part of any navy; they would indeed see a lot of use. For short stints, even fusion-powered shuttlecraft would be extremely useful. The capabilities of small craft are particularly ill-defined in ST, too. Sometimes they are just shuttles, and sometimes they seem to occupy the niche of big vessels. ST:DS9 and VOY (trans-warp shuttlecraft!) had some ugly inconsistencies about shuttles.

Sadly, StarTrek screws up even the simplest of stuff. We had a discussion a few weeks ago about the communicator badges...even though we have the technology right now to make a badge that would act as a voice-dialling cellphone - the ones in StarTrek are flat out impossible for a variety of stupid reasons that could easily have been fixed if the script-writers had taken the time to think through how they'd have to work. They also fail badly in predicting technology even a couple of years ahead of the show itself. In one episode when someone wishes to give the captain a big stack of work to do ("crew reports" or something), they'll hand him a pile of things that look and act like a circa 1990's PDA's or tablets. That's not bad for a show premiering in 1987 when the first commercial realization of such a thing arguably wasn't really around until the Apple Newton in 1992. But the idea of transferring data by handing someone a tablet computer rather than sending the data to a tablet that they already have...and needing one of them for every chunk of data you need to impart seems ludicrous in light of how these things are actually used.

It's actually hard to find ANY piece of tech in the StarTrek universe that's remotely plausible...they are either utterly impossible from a science perspective - or kinda useless when compared with what we actually have. It's hard to imagine why com-badges don't have cameras in them - or why a simple radio transmission fails to carry even a voice signal in situations where their transporters can get a lock on someone to beam them out. If the badge can send detectable position information - then why not morse code? SteveBaker (talk) 17:37, 8 August 2014 (UTC)

One of the problems with Star Trek, from a narrative perspective, is that if the technology actually worked as well as you described, it'd suffer from "superman syndrome". One of the things that makes Superman the most boring of all superheros is that he's almost literally invincible. Without the possibility of failure, the story has no narrative tension, and thus has nothing entertaining about it. They literally had to invent Kryptonite as a plot device (almost a decade after the character was created) just to make the stories interesting. With Star Trek, it may not be that the script-writers make all the stupid science mistakes you note because they don't understand it; they do it because they have to "kryptonite" their technology to add interest to their stories. Perfect science where everything works may annoy people who expect perfection because they understand the science, and have a problem with suspension of disbelief with science-related topics, but from a narrative perspective, it makes sense. Asimov, for example, understood this with his three laws of robotics. He invents these ironclad behavioral principles about how robots are supposed to behave, and then proceeds to violate those laws in every story. Why? Because it's in the violation of the laws that the stories are interesting, if everything worked perfectly, there's no story there. In Star Trek, we can scream at the TV "If all that shit worked right (i.e. followed the rules of science and engineering that we all understand), the characters wouldn't get into all this stupid trouble!!!!" The problem is "stupid trouble" is what makes the story worth watching in the first place. --Jayron32 21:02, 8 August 2014 (UTC)

Do you have any examples of Asimov's violations of the three laws? I just flipped through my copy of 'I, Robot' and I'm pretty sure every story contains an apparent contradiction or violation, but the conflicts are almost universally resolved by the engineers understanding how the interaction between following the laws exactly cause unexpected robot behavior. SemanticMantis (talk) 21:48, 8 August 2014 (UTC)

I was thinking the same thing. There was also a new Outer Limits episode (Resurrection) that posed an interesting dilemma for the robots. They all worked according the the laws, but then the people went and killed themselves off via biological weapons, leaving the robots without purpose. They split into two factions, one of which argued that their duty to serve man was discharged, now that mankind no longer existed, and they should find their own purpose, with the other faction dedicated to first finding cures for the bioweapons and then cloning dead people to bring them back. StuRat (talk) 23:32, 8 August 2014 (UTC)

Even if Superman can't die, he can certainly fail, because he cares about things and people other than himself. You not only don't need self-interest to make drama, it doesn't even make for very good drama. Superman stories are boring because writers don't like killing off sympathetic secondary characters and because he's been in 75 years' worth of comics and the writers run out of ideas, neither of which has anything to do with him personally. (And because many of the writers just aren't very good.)

And as SemanticMantis said, I, Robot was only interesting because the robots didn't ever violate the three laws. Asimov was basically a mystery writer who happened to use a science-fiction setting for many (not all) of his stories. Every story in I, Robot is a puzzle of the form "how does this robot behavior, which seems obviously inconsistent with the three laws, actually follow from them?" -- BenRG (talk) 00:13, 9 August 2014 (UTC)

Not all of the robots in I, Robot followed the three laws. Little Lost Robot featured a robot with a modified first law (permitting it to passively let a human come to harm), and Runaround had a robot with a strengthened third law, permitting it to ignore some orders that would cause damage to it. --Carnildo (talk) 02:27, 9 August 2014 (UTC)

Aside from those two stories about robots with subtly tweaked laws, Asimov is trying to demonstrate how, even with three seemingly well-thought-out laws - each being *perfectly* obeyed, things can still go horribly wrong. But Asimov is a little 'off' in places too. A robot vacuum cleaner who was truly following "A robot may not injure a human being or, through inaction, allow a human being to come to harm." - would immediately seek to discover whether there was some human somewhere whom it might (by inaction) allow to die. If it could pick up an audio feed from your TV set, it would likely head off to Africa at full speed in an attempt to do something to help with the Ebola outbreak...because even the smallest chance of being able to avoid a human dying would be of higher 'potential' than vacuuming some lazy human's carpet. Robots that truly followed those laws would be entirely useless. In a car factory, it would only be a matter of time before one of the robots got to hear of a fatal car crash someplace and deduce that NOT making any more cars is the only way to obey the first law. Your entire factory would be shut down within days of turning it on.

So, yeah - the stories are about failure of the technology - what makes them clever is that they are showing how a fully perfect implementation of a seemingly reasonable set of rules can result in failure of a device to meet expectations.

SteveBaker (talk) 14:28, 9 August 2014 (UTC)

One more detail (the reason one of the shows exists, no less): a single vessel stranded in the Delta Quadrant will never out-tech the rest of the Federation. Sure, they could meet a lot of new species (does that sound like the ST:TOS intro?) but with one ship, they could never put all the new technology they see to good use.

Actually, the writers wrote one episode where reality ensued: they found an extremely long-ranged teleporter tech (yeah, teleporters again, so much for "reality"...) which could teleport them to the Alpha Quadrant (where the Federation is) in a single bound. When they tried to connect it to their power grid, they almost blew the warp core. - ¡Ouch! (^{hurt me} / _{more pain}) 06:18, 11 August 2014 (UTC)

August 8

Bone marrow biopsies

Is the procedure highly painful? I would guess so, and story (below) makes me wonder more, but the "After the procedure" section of bone marrow examination mentions soreness and "worsening pain", but it doesn't address routine pain. Story: I have a friend with leukemia; he had a bone marrow biopsy recently, soon after he was told that chemotherapy had destroyed his cancer. If I understood rightly, they did this biopsy to see what was hanging around in the marrow still, and his extreme reluctance to undergo the procedure (basically a mindset of "I'm doing it because it's good for me, but I really really really don't want to") makes me wondering if there's a major pain issue (or other side effect) that patients frequently experience. I kept forgetting to ask my friend whether it were deeply painful, or otherwise I wouldn't have to come here. Nyttend (talk) 04:58, 8 August 2014 (UTC)

According to Roswell Park, yes, it can hurt. I am of course offering this answer purely to assuage your "'satiable curtiosity" and not in any sense at all as any kind of advice. DuncanHill (talk) 05:25, 8 August 2014 (UTC)

This depends on the skill of the anesthesiologist and dumb luck about whether you can remember the pain. Because if a tree falls in the forest, it makes a sound, but if nobody hears it, then it might as well not have. 104.128.96.117 (talk) 09:36, 8 August 2014 (UTC)

Thank you. This actually wasn't to assuage my curiosity; I'm about to improve the article somewhat. Duncan, it would help if you'd check my addition ("Site of procedure" section) to ensure that it follows the source. It shares some little bits of wording with the source, e.g. "cannot be anesthetized", but only at points when I couldn't think of an alternate wording. Nyttend (talk) 11:17, 8 August 2014 (UTC)

I will do so shortly, Nyttend. My comment about "for information only" was an attempt to fend off any misguided attempts to remove a perfectly reasonable question. DuncanHill (talk) 16:31, 8 August 2014 (UTC)

And your edits look good to me :) DuncanHill (talk) 16:41, 8 August 2014 (UTC)

Transport careers

Is a career in transport management and operations similar to event management? — Preceding unsigned comment added by Clover345 (talk • contribs) 15:48, 8 August 2014 (UTC)

This question sounds like the "Operations Sector" question from July 26. Nimur (talk) 15:57, 8 August 2014 (UTC)

The following is my un-referenced personal experience and opinion, for whatever you think that's worth. My grandfather was a transport manager and I have worked in companies which use transport to support their main activities (and still do). I have also been involved in amateur event management over a couple of decades (Fan-run Science Fiction Conventions and CAMRA Beer Festivals, if it matters).

I would say the two types of activity are very different, beyond the very basics of needing an organized and 'businesslike' approach and the flexibility to deal with the unexpected. Similarly, careers in them seem to me likely to differ markedly. However, professionals in either field would be better placed to advise on specifics. If none show up here to answer (as seems likely) you might try researching some leading companies in either field (local to yourself) and contacting their recruitment/personnel/human resources/whatever offices directly. All companies have to recruit new staff (on account of those pesky workers keep moving, retiring or dying) and should be eager to help genuine enquirers. {The poster formerly known as 87.81.230.195} 212.95.237.92 (talk) 19:15, 8 August 2014 (UTC)

Wood-burning cars and steam engines

This probably would have been equally at home at the humanities desk, but I'll add an additional component to make it more RDS-friendly...

In the book O Jerusalem!, reference is made to a "wood-burning Mercedes," without further elaboration (I don't have the book in front of me, but I distinctly remember being puzzled by the phrase and irritated that it was mentioned in such an offhand way). Does anyone know more about wood-burning models of Mercedes? Also, what exactly does "wood-burning" mean in this context? Surely these weren't steam cars, or were they? The idea of having a wood fireplace to heat a large car seems almost as absurd, though, so what's going on there?

And the more sciencey bit: what are the energy efficiency implications of using a steam engine in a car, or steam engines in general? Obviously using gasoline to heat water to boiling is going to be far less efficient than using the gasoline to drive the pistons directly, but what about with other fuel sources? There are still locomotives that use steam engines, but is it really more fuel efficient to use coal to drive a boiler than it is to liquefy that coal and use its energy directly? Evan ^{(talk|contribs)} 20:30, 8 August 2014 (UTC)

there's some information here that may be of use/interest. DuncanHill (talk) 20:34, 8 August 2014 (UTC)

We also have some info at Wood gas. --Mark viking (talk) 20:36, 8 August 2014 (UTC)

Notable is the Mercedes 35 hp, the very first car produced by Daimler to bear the "Mercedes" name was gasoline (petrol) fueled from the start. However, reading the Wood gas article, it says "Wood gasifiers can power either spark ignition engines, where 100% of the normal fuel can be replaced with little change to the carburation" The article Wood gas generator would also be a good read; it converts wood cellulose directly to wood gas to feed internal combustion engines; so literally you could feed wood into the car, and then run it. A wood-burning Mercedes then must be a Mercedes fitted to run with a wood gas generator. --Jayron32 20:49, 8 August 2014 (UTC)

See Steam car for the second part of the question. Most early 20th-century steam cars were oil-fired, although one major advantage of steam is that you can run it on anything flammable. Tevildo (talk) 21:29, 8 August 2014 (UTC)

True, but burning most things results in massive quantities of pollution. StuRat (talk) 23:20, 8 August 2014 (UTC)

During WWII, there were "coal-powered" VWs; see:[8] using the same wood-gas technology (e.g:Holzbrenner “Wood burning” Volkswagen). A 1945 Daimler "woodmobile" can be seen here:[9] — From this interesting article on the subject: [10]. Here is a Mercedes-Benz type 230 with the entire apparatus within the trunk:[11] 71.20.250.51 (talk) 22:20, 8 August 2014 (UTC) & 22:23, 8 August 2014 (UTC)

The German article also has several photos. Rgds ✦ _hugarheimur 03:52, 9 August 2014 (UTC)

Thanks for the replies, everybody. Fascinating stuff. Evan ^{(talk|contribs)} 22:26, 9 August 2014 (UTC)

Abdominal fat

Why is abdominal fat so hard to lose even with exercise and healthy eating? Is it genetics? — Preceding unsigned comment added by 94.14.151.66 (talk) 21:06, 8 August 2014 (UTC)

The tendency to put on weight there, versus other places, does seem to be genetic. Unfortunately, abdominal fat is also the most unhealthy. StuRat (talk) 23:21, 8 August 2014 (UTC)

That last sentence reads awfully like unsourced medical advice. HiLo48 (talk) 23:23, 8 August 2014 (UTC)

Doctors on TV frequently say that folks with belly fat, a.k.a. "apples", are at greater risk than those with backside fat, i.e. "pears". In fact, this doctor makes essentially the same statement: "Belly fat is the most dangerous type of fat." However, he also contradicts the OP's premise: "But I have good news: Belly fat is the easiest fat to lose!" ←Baseball Bugs ^{What's up, Doc?} carrots→ 23:33, 8 August 2014 (UTC)

No 11 of my 'Rules of Life' says "Never believe anybody who is selling you something". Richard Avery (talk) 12:48, 9 August 2014 (UTC)

Probably a random TV show isn't the best source but there is a fair amount of research in to fat distribution and the correlation with different health outcomes. See e.g. Body shape#Fat distribution (we also have a Android fat distribution but it's totally unsourced). E.g. of research articles [12] [13] [14] [15] [16] [17] [18] [19] [20] [21] [22]. (A mix of stuff relating to the health outcomes and research on factors associated with different distributions since I was lazy to seperate them.) A quote from the first source which may be helpful for the confusion

There is little controversy that upper body/visceral obesity increases the risk for dyslipidemia (8), hypertension (9,10), type 2 diabetes (11,12), sleep apnea (13), etc. It is also recognized that increasing amounts of lower body fat are independently associated with a reduced risk of metabolic complications (14). Many (15,16,17), but not all (18), studies find that visceral fat mass is more strongly associated with an abnormal metabolic profile than upper body sc fat

Nil Einne (talk) 14:49, 9 August 2014 (UTC)

I wouldn't call The Doctors a "random TV show". It's a popular daily show with several doctors from various fields, exploring different medical issues each day. That doesn't necessarily make it "authoritative", but it's not "random" either. ←Baseball Bugs ^{What's up, Doc?} carrots→ 21:12, 9 August 2014 (UTC)

It depends a lot on what is meant by "exercise" and "healthy eating". If you still end up above a caloric deficit, or in surplus, you aren't going to be losing weight. That's not to say that genetics, and other such, don't play some role - just pointing out that healthy food alone won't cause you to lose weight if you are eating too much.Phoenixia1177 (talk) 03:31, 10 August 2014 (UTC)

Extraction of insulin from animal pancreas

The article on Insulin describes the work of various researcher who by the early 1920's had found means of extracting insulin from the pancreases of beef or pork and purifying it into a form which could be injected subcutaneously into humans to control diabetes. Collip was apparently quite important in devising a way to process the animal tissue into a useful extract, since researchers before his work with Banting, Best and McLeod had made extracts which lowered blood glucose, but which produced infection. My first question is, what would the process be, for making insulin from pork pancreas? This is for intellectual interest only, and certainly I am not looking for medical advice nor do I plan to actually do the process. I just wonder what a "recipe" might be for small scale production, in some hypothetical situation in a novel where synthetic insulin were not available, but animal carcasses were available. Something like "Take a fresh pork pancreas, (or isolate Islet cells from same), maintain it in some specified temperature range, macerate it in a blender with some solvent, filter, remove certain impurities by some process, concentrate the insulin by some process." Citing a book chapter or journal article describing the commercial process before the Humalog etc were invented would be a good response if it would be too long to describe all the processing, equipment and chemicals. The second question is, if insulin is a water soluble peptide, why is it impossible to preserve it as a powder to be reactivated by adding water, similar to the (different) chemical in the "Glucagon emergency kit" sometimes carried by diabetics, or as a long-term stable precursor chemical which could be processed into insulin by adding another chemical. The article Inhalable insulin says " Carl developed a method to preserve peptide hormones like insulin in the glassy state so that they can be pulverized into a powder and inhaled by diabetics as an alternative to self-injection." Such a "glassy state" or powder form might or might not be more stable over time or at more varied storage temperatures than the present liquid forms of insulin. Edison (talk) 21:29, 8 August 2014 (UTC)

Regarding the first question, I should note that this is not of historic interest only; if I recall correctly (based on conversations wih a diabetic acquaintance), porcine insulin was used alongside Humalog etc. until recently, so the details of the purification process are probably not hidden in some obscure pharmaceutical archive.

Also, this 1975 patent for a proposed improved purification method seems to describe the usual purification processes of the time. הסרפד (call me Hasirpad) 21:42, 8 August 2014 (UTC)

Porcine insulin is still used, according to the British National Formulary, as is, but rarely, bovine insulin. (From the July 2014 edition, section 6.1.1). DuncanHill (talk) 21:54, 8 August 2014 (UTC)

There's information here. DuncanHill (talk) 23:59, 8 August 2014 (UTC)

and this patent also has details. DuncanHill (talk) 00:01, 9 August 2014 (UTC)

and Eva Saxl is an article that is also relevant. DuncanHill (talk) 00:03, 9 August 2014 (UTC)

If you just go to PubMed and search for insulin, you can click on the last page (of 321635 results!) and look through a number of the old articles, which amazingly enough someone has actually put online. Here's an early purification [23] - only a partial purification at the time; remember that historically things like "insulin" refer to enzyme activities, not to single molecules per se. It appears that picric acid had a particularly important role; needless to say it is very "old school" biochemistry, though with a somewhat embarrassing degree of familiarity to the modern reader! Wnt (talk) 00:55, 9 August 2014 (UTC)

This looks promising. It does stress that you need fresh glands. DuncanHill (talk) 21:34, 9 August 2014 (UTC)

August 9

Beckman's Internal Medicine

In searching for answers for another editor's question, I repeatedly came across references to the book "Beckman's Internal Medicine", but have been unable to find mentions of this work except in the context of Eva Saxl. Anyone familiar with the book, or know if it's been archived online, had another title etc? Or who Beckman was? DuncanHill (talk) 00:28, 9 August 2014 (UTC)

This forum post is the best I can find - not a reliable source by any means. Apparently, the book exists, but it's not in "English, German, or Spanish" (French, possibly?). Our source for the statement in the Eva Saxl article isn't particularly wonderful (a blog posting from 2002), and I think it's likely that all the other references are derived from our article. I'll keep looking. Tevildo (talk) 20:45, 9 August 2014 (UTC)

Beckman _may_ be Arnold O. Beckman, but he was primarily a chemist. The timescale is right, though, and there aren't any other plausible Beckman's at Beckman (surname). Tevildo (talk) 20:50, 9 August 2014 (UTC)

Incidentally, I don't like that apostrophe, but "Beckmans" looks equally wrong. Apostrophe#Use in forming certain plurals doesn't really help. But it's not critical. Tevildo (talk) 21:21, 9 August 2014 (UTC)

Got it! Gustav von Bergmann, Handbuch der inneren Medizin, Volume 2, Berlin, Springer, 1930. See this bibliography. It presumably is in German, after all. Tevildo (talk) 21:00, 9 August 2014 (UTC)

Thanks! Beckman is a plausible typo/misremembering for Bergmann. DuncanHill (talk) 21:34, 9 August 2014 (UTC)

No problem. Now, we need to fix the Saxl article. Just changing the text would be little more than a guess (not even WP:OR), so we need to find something that says Saxl used Bergmann's book... Tevildo (talk) 22:28, 9 August 2014 (UTC)

There's a copy in the Wellcome Library in London, (and in the British Library) if anyone fancies taking a look. See here. Tevildo (talk) 10:52, 10 August 2014 (UTC)

WARF testing lab

From the article SUPERthrive: "SUPERthrive is a WARF testing lab–certified nontoxic liquid concentrated growth enhancer product for plants".

Does the name "WARF testing lab" mean anything to anyone on the Science Reference desk?

Thanks, C7nel (talk) 00:34, 9 August 2014 (UTC)

You can check out their website here: http://www.warf.org/   —^{71.20.250.51 (talk) 00:45, 9 August 2014 (UTC)}

Sabaton (not the band)

Did the long pointed toe of the sabaton (the shoe, not the band) have any functional purpose? Or was it only a decorative badge of rank? 24.5.122.13 (talk) 02:05, 9 August 2014 (UTC)

I can't imagine they didn't have some intended functional purpose. I've done some searches to find an answer for your question, and couldn't find anything substantial, but remember that medieval armor was absolutely functional; if your armor didn't work for you efficiently, you died. I suspect the idea was to have a weapon to kick with from horseback, a well-planted kick to the ear would ruin someone's day. Notably, the pointed toe did not stay in fashion for long; it may have had too many disadvantages in battle to counter any advantage of being able to use it as a weapon. --Jayron32 02:16, 9 August 2014 (UTC)

The article does point out one disadvantage -- it would greatly hinder the knight when fighting on foot (which is why when dismounting to fight as infantry, they would change their sabatons for sturdy leather boots). As for possible advantages, could the pointed toe have helped the knight stay in the saddle when hit? 24.5.122.13 (talk) 02:22, 9 August 2014 (UTC)

The downward slope of some of them could conceivably provide some protection from a sword blow, deflecting it downward and away from the wearer, instead of upwards and into the ankle and shin. DuncanHill (talk) 02:42, 9 August 2014 (UTC)

Light reflection

My question relates to an older question I found in the archive.

https://en.wikipedia.org/wiki/Wikipedia:Reference_desk/Archives/Science/2007_September_12#Stupid_question_about_light_reflection.

If a flashlight beam is shining on a good mirror and another flashlight beam of equal intensity and color is shining on a white surface, which surface will return more light?

I realize that with the mirror the direction of the light leaving the surface largely follows the rule that the angle of reflection is the same as the angle of incidence while with the white surface the angle of reflection is much more variable. My question is, IGNORING differences in the direction the light is reflected, which surface will reflect more light in total?

I'm not asking about something that might be called "a perfect mirror" or "an ideal white surface". I'm thinking about a good quality mirror compared to a piece of hardboard painted with a good quality white paint.

Thanks, C7nel (talk) 06:02, 9 August 2014 (UTC)

As surprising as it may sound, a surface painted white with the best-quality white paint (titanium dioxide) will reflect more light in total than a mirror made from the best reflective material (silver). 24.5.122.13 (talk) 08:04, 9 August 2014 (UTC)

Agree with that. Ordinary titanium white paint can reflect 90% of the light and good quality stuff may only lose a few percent. An ordinary mirror you buy in a shop may lose nearly half the light. The article on titanium dioxide unfortunately doesn't give figures about paint but it describe its use in dielectric mirrors which only lose a tiny fraction of a percentage of thee light. Dmcq (talk) 08:11, 9 August 2014 (UTC)

There are optical coatings that produce mirrors with 99.9% or better reflectivity, depending on the range of wavelengths desired. See Dielectric mirror. --Mark viking (talk) 08:21, 9 August 2014 (UTC)

Reflectivities of gold, silver and aluminium mirrors

It's close...and the devil is in the details. The exotic aluminium/molybdenum mirrors we use on our laser cutter are 98% reflective in IR and about the same in the visible light spectrum...but the chart at right shows how good a gold, silver and aluminium mirrors can be - and it depends where in the spectrum you are.

For paint, some manufacturers actually print the reflectivity for visible light next to the paint samples you see in the store. So if you see "LVR=90" (or sometimes "LRV=90") would mean that this paint (on a smooth surface) is 90% reflective - averaged over the entire visible spectrum. Titanium white (which I think is the whitest white you can get in paint) is generally claimed to be about 93% reflective - so it's comparable to a silver or aluminium mirror.

The decision as to which is best depends on the frequencies of light present in your light source - and (critically) on how smooth the surface is. SteveBaker (talk) 14:10, 9 August 2014 (UTC)

"and (critically) on how smooth the surface is" So if they were both painted with the same paint, a smooth sheet metal surface would return more light than a piece of hardboard? C7nel (talk) 18:11, 9 August 2014 (UTC)

They would reflect the same amount of light (if the light is incoming perfectly equally from all directions, including within the nooks of the material itself), but the reflected light would be diffuse and/or bounce around in the cracks, losing energy, in the uneven surface. In a home experiment, grab some aluminium foil straight from the roll and carefully keep it completely smooth over a flat surface. You should just barely see the reflection of your hand when you put it close. Now start curving the foil (no need to fold or crumple), and you'll see the image fall apart. The amount of light reflected is the same, but it's no longer aligned with what went in. That's also why water must be quite still to give you a reflection - even tiny slow long waves will diffuse the image (small narrow ripples are local enough to preserve it in places, though). SamuelRiv (talk) 00:50, 10 August 2014 (UTC)

If each time light hits the surface, (say) 90% of it gets scattered away in all directions and 10% if it is absorbed into the material - then a perfectly smooth surface will cleanly reflect 90% of the light and turn the remaining 10% into heat within the material. But if the surface is slightly rippled - then when the material scatters the light everywhere, some amount of it will hit the surface again. This produces a second reflection - also with 90% reflectance - but now it's 90% of the 90% that escaped the first reflection...so only 80% of the light that must undergo two bounces will emerge. The rougher the surface is, the higher the amount of light that will undergo double, triple, quadruple reflections. A matt painted wood surface is likely to be a lambertian reflector - but gloss paint is capable of 'specular' (mirror-like) reflection - and now you have something that's a hybrid of a mirror and a matt painted surface. At this point, the explanations get complicated. Some surfaces (notably copper) reflect light in different colors depending on the angle...diamonds are incredibly reflective even though they're transparent because they have a crazy refractive index and reflect by 'total internal reflection' and easily cleave into near-perfectly flat surfaces. SteveBaker (talk) 02:32, 10 August 2014 (UTC)

Bird id

Who am I?

Can anyone identify this chap for me? He's our neighbour in Bratislava, Slovakia. Possibly a kestrel? Henry^Flower 06:14, 9 August 2014 (UTC)

His name is "Charles", but his friends call him "Karl". -But, seriously... We have a List of birds of Slovakia; this fellow looks as if he belongs in Caracaras and falcons section, but I've checked all 8 listed, and he doesn't seem to be there. The closest is the Red-footed falcon (see female) —but without the red feet. I suspect he might be a she ("Charlene", a.k.a. "Karla"), due the the somewhat demure appearance. It would be useful to see the bird from the front. You might check the 23 species listed in the 'Hawks, kites and eagles' section, but none seem likely.  ~Sorry that I couldn't be more helpful, ~E:71.20.250.51 (talk) 09:52, 9 August 2014 (UTC)

Thanks for trying. :) I have some more angles on my blog, but I suspect they don't reveal anything more. I had thought of the red-footed falcon, but they seem to be rare in Slovakia; I do like the idea of having discovered the even rarer non-red-footed-red-footed falcon, however.

And me?

If I may add a bonus question, is this second bird a Eurasian Buzzard? There were five of them, also near Bratislava. Henry^Flower 13:36, 9 August 2014 (UTC)

Almost certainly - it's not a Honey Buzzard according to this identification page [24]. Mikenorton (talk) 15:31, 10 August 2014 (UTC)

Have you considered asking at WT:BIRDS? Some of the guys there are really good at this. There is usually (but not at the moment) a long 'birds for identification' thread on there... --Kurt Shaped Box (talk) 15:34, 10 August 2014 (UTC)

Vortex rotational profile

Could an expert have a look at this issue?--Almuhammedi (talk) 08:53, 9 August 2014 (UTC)

Thanks, I think it is done.--Almuhammedi (talk) 11:47, 10 August 2014 (UTC)

Rest & relativistic masses

Lately I had a long debate with a quantum physics professor regarding those terms as he was insisting to forget about rest mass & relativistic mass (I don't know if there is a dedicated article/section for this historic argument). He was addressing those who still use such terminologies as non educated or basic level learners. I understand the argument among physicists about this but do we seriously need to get rid of such terms and if we do so, what could be the alternative accounting for mass–energy equivalence principle? On the other hand, does special relativity directly affect the mass of the proton if we know that its individual mass of quarks is much less than that whole mass of the proton?--Almuhammedi (talk) 09:10, 9 August 2014 (UTC)

I'm not exactly sure what the question is about. I would consider the idea of relativistic mass as very useful in many ways. How else does one go around explaining that if you heat up a box of gas it will get heavier? That effect is not observable at normal temperatures but it is most definitely what the physics says will happen. If they are saying you should not use the terms then they should be saying what you should be doing instead, so what have they said? Have you read the relativistic mass article where it explains that relativistic mass is not a property of the object but relates to the frame of reference it is in. Really it is not all that different from a collision between cars. If they are both going in the same direction at the same speed ten they just bump each other, if they are going in opposite directions and crash then it is major incident. Dmcq (talk) 12:10, 9 August 2014 (UTC)

The statement "relativistic mass is not a property of the object but relates to the frame of reference it is in" explains why it's such a dubious and dangerous concept. Dubious because mass really is a property of an object and should therefore be frame-independent; energy and momentum are used to describe an object's state of motion."Dangerous" because it conveys wrong ideas about special relativity as it suggests for instance that the impossibility to accelerate things beyond the speed of light might be due to an increase of mass of those things rather than the fundamental structure of space-time. The mass of a box of gas does indeed increase when it is heated; that's because it's internal structure is changed, energy is pumped into it, and the box's mass includes both the rest masses of the gas particles and their kinetic energies. The mass of the box does not change when it is moved around (no physical change of the box there, only a change of reference frame!), only its energy and momentum change. --Wrongfilter (talk) 17:37, 9 August 2014 (UTC)

A question that comes up with this is whether rest mass is a property of an object, or its interaction with the Higgs mechanism. Related question: if individual Higgs particles have a position and momentum in space, why does the Higgs mechanism give the same rest mass to a particle regardless of its frame of reference? Wnt (talk) 20:11, 9 August 2014 (UTC)

The Higgs mechanism actually accounts for only a small part (~1%) of the rest mass/energy of ordinary baryonic matter. Most of the rest is from the strong force (and kinetic energy of the valence quarks).

The vacuum isn't filled with real Higgs particles (which would indeed have a state of motion, breaking Lorentz symmetry), but with a uniform Higgs field. -- BenRG (talk) 22:00, 9 August 2014 (UTC)

Yeah, come to think of it I suppose it's not so mysterious with an electric field that is the same regardless of frame of reference, and this is sort of the same idea, apart from the whole mysterious uniform throughout space yet prone to change over time part. As for the 99% of rest mass that is "kinetic energy of valence quarks", you do mean the relativistic mass of the valence quarks, right? :) Wnt (talk) 01:13, 10 August 2014 (UTC)

Alright, suppose I have an electron sitting in a conductor at -10,000 volts. It therefore has 10,000 electron volts of energy it would like to get rid of, which could be used to run a transformer or electrocute a hapless captive. This potential energy has mass, which I assume we call rest mass because the electron has it at rest. So the electron's mass is whatever the physical constant is, plus 10,000 eV of mass. Is the way that the electric field has given the electron extra mass the same as the way the Higgs field gives a particle mass? Wnt (talk) 01:24, 10 August 2014 (UTC)

Relativistic mass is a useless concept, because it is synonymous with the totale energy of an object. The mass-energy equivalence says that the inertia of an object at rest is equal to its total energy content at rest. So, the whole concept of mass is redundant. But the rest energy of a particle is an invariant property of that particle which is useful in physics. It's conventional to use the word "mass" instead of "rest energy". Count Iblis (talk) 20:24, 9 August 2014 (UTC)

Do I detect a certain prejudice/judgementalness? Just to put a cat amongst the pigeons: it is essentially impossible to define rest mass in a consistent way that is not equivalent to "relativistic mass as measure in a center of momentum frame. And since such a frame is only well-defined for an isolated system (even in special relativity), it certainly puts a question mark over whether the concept of rest mass is in any sense fundamental. BTW: "Relativistic mass is a useless concept, because it is synonymous with the total energy of an object" implies that the total energy of an object is a useless concept ;-) —Quondum 21:14, 9 August 2014 (UTC)

What was the argument for getting rid of rest mass? I don't think I've heard that one.

The best argument for getting rid of relativistic mass is that you should write everything in a manifestly covariant form, with tensors (and/or spinors). Rest mass stays because it's a scalar (= rank-0 tensor), relativistic mass goes because it isn't. You still have the four-momentum, which is a rank-1 tensor whose time component is the relativistic mass, so you haven't really lost anything, you're just writing everything in a consistent notation where it's easier to avoid mistakes (such as forgetting to apply the correct transformation law between reference frames). -- BenRG (talk) 22:00, 9 August 2014 (UTC)

That is no argument at all, if it is intended to support the abolishment of the term "relativistic mass". It would have us get rid of names for any non-tensor quantity that you care to mention, such as momentum, energy, velocity, the stress tensor, charge density, current density, electric field... It is clear that it is simply how we describe one component of the energy–momentum tensor in a given frame, scaled by c² to give a meaningful mass, which also translates as inertia, etc. At least it is always well-defined in special relativity, which is not the case for rest mass. There is another quantity associated with a field that might rightfully claim to be a scalar: e.g. the m in the Dirac equation. But I strongly suspect that it will be very different numerically from what we normally call the rest mass of an electron. And the rest mass of a quark probably needs very special interpretation, since a free quark probably has infinite rest mass... All I'm trying to point out is that the claim that I've seen periodically to the effect that rest mass is king, and relativistic mass is a term reserved for the confused is not as obviously true as some seem to think. I've even seen WP articles being written to say that E=mc² refers to rest mass and that's how Einstein intended it since "mass" means "rest mass", but then, obviously he only meant it to apply in the comoving frame of the particle, because otherwise it's invalid. Or perhaps he meant the rest energy too... You tell me who's getting confused in this scenario?

We are side-tracking from the OP's question, so I'll add this: the rest mass of a proton is considered to be made up by: the rest mass of the quarks (which constitute only a tiny percentage), the mass contribution of their kinetic energy (which, if I remember correctly, makes up the bulk of the total energy –or mass– of the proton due to the relativistic velocities of the quarks), plus a contribution from the gluon fields. —Quondum 00:25, 10 August 2014 (UTC)

Rest mass/energy is the length of the momentum four-vector, so it's defined whenever relativistic mass/energy is (the t component of the same four-vector).

I think we are better off without the things you listed when doing relativistic physics, but they're useful in the Newtonian limit. Relativistic mass isn't, and that could be why it's singled out for special dislike.

Relativistic mass is not straightforwardly interpretable as inertia (see also transverse and longitudinal mass) and it doesn't gravitate either (fast-moving objects don't collapse into black holes). -- BenRG (talk) 05:10, 11 August 2014 (UTC)

Yes, tensors are to be preferred. So, I take it you believe that the general consensus is with Okun on this? And that the COM frame is unique for distributed, nonisolated systems? —Quondum 06:40, 11 August 2014 (UTC)

Thank you all Wiki-contributors. Just to have a root cause analysis to my question, please refer to Okun's criticism:

When doing relativistic physics (and often when teaching relativistic physics), particle physicists use only the term "mass." According to this rational terminology the terms "rest mass" and "relativistic mass" are redundant and misleading.

Of course there were also some critics replying to his article at the time but I thought physicists should have resolved this argument since then.--Almuhammedi (talk) 11:05, 10 August 2014 (UTC)

Scientists don't tend to resolve matters like this and come to a unified conclusion about how they should think about something. What normally happens is that the old guard just eventually gets replaced. Dmcq (talk) 11:30, 10 August 2014 (UTC)

I'd rather describe it as that there is nothing to resolve in this instance, since every discipline tends to define its use of terms. —Quondum 16:04, 10 August 2014 (UTC)

To give another simple example comparable to the quarks, what is the rest mass of the Earth-Moon system? You take the frame (center of gravity) where the relativistic mass is lowest, add the rest mass of the Earth plus the rest mass of the Moon minus the mass-energy released by their decrease in potential to their current positions plus the relativistic mass of their current motion, right?

But the goofiest case of this was a thread we had here (I think) about black holes here a while back. To the limited degree I understand it, the matter falling into a black hole can potentially release all its mass value of energy on the way down. Leaving the hole full of, what, massless particles and the ghost of a gravitational field? (I guess the stuff inside the event horizon couldn't emit gravity anyway...) There was some physicist arguing on arxiv about whether the black hole really had twice its mass or 1x but I didn't know if he was a crank or not. Wnt (talk) 20:35, 10 August 2014 (UTC)

I should emphasize that this debate is purely semantic, and has absolutely nothing to do with how the universe works. Every physicist agrees on what happens to a proton when it's accelerated to 99.99% the speed of light. If you ask any competent physicist what a certain instrument would measure, they would give you the same answer. The universe doesn't care what we define "mass" to be; we define mass in whatever way appears convenient.

An analogous situation is the "debate" over whether Pluto is a planet. Pluto couldn't care less whether humans call it a planet or not. Whether Pluto is a planet or not doesn't increase or decrease our knowledge of it by one iota. It's purely a linguistic issue, just like the definition of "mass". --Bowlhover (talk) 04:16, 11 August 2014 (UTC)

If two metals contact in space, do they blend, simply as that?

Does the oxygen in the air prevent metals from melting together - or some layer of oxygen on the metal? Can we simulate the process on Earth? (in vacuum) OsmanRF34 (talk) 14:51, 9 August 2014 (UTC)

Are you thinking of Cold welding? Nil Einne (talk) 14:57, 9 August 2014 (UTC)

Right, this is the article I needed.OsmanRF34 (talk) 15:33, 9 August 2014 (UTC)

Explosion welding is an extreme example of "push metals in contact and they blend". Maybe not quite the same process at heart because it sounds more like the two pieces deforming into each other rather than just contacting. DMacks (talk) 15:57, 9 August 2014 (UTC)

If you could make two perfectly smooth, perfectly clean, metal surfaces and bring them together in a vacuum - then you'd immediately have one piece of metal - you don't need pressure or anything. The atoms don't know that they 'belong' to one piece or the other. So it's the microscopic roughness and the presence of thin layers of impurities that prevent that from happening in our normal experience. SteveBaker (talk) 02:11, 10 August 2014 (UTC)

So, if a rub two metals together in the vacuum, I should expect that they will 'click' at some point and weld together, specially softer metals? OsmanRF34 (talk) 15:54, 10 August 2014 (UTC)

You don't even need to rub them. If a) it is a true vacuum and b) the metals are scrupulously smooth, clean, and free of oxidation or other impurities, ANY contact will cause the metals to fuse together. This has been demonstrated to work between like metals (two pieces of the same metal) and dissimilar metals (with, say, one piece of gold and another of silver). This has to do with the nature of metallic bonding, which features highly delocalized electrons. In non-metallic substances, all electrons have a high degree of "association" with a specific geometric region around a specific atom or molecule (this is called an orbital). In quantum mechanical terms, we say that each electron has a region of space where it has a VERY high probability of being found (see almost surely for how probable this is...) What makes a metal a metal, at the quantum mechanical level, is this lack of association between electrons and specific geometric regions. When I take, say, two pieces of plastic into vacuum, and let them touch, nothing particularly interesting happens: the electrons stay in their orbitals around the molecules they always have been in, because of this high degree of association. The plastics retain their individual identity BECAUSE the electrons retain their association with SPECIFIC orbitals. In metals, which LACK this association, once two metals touch (and TRULY touch, without any gas or impurities between them), the electrons from piece "A" don't know the difference between the nuclei in piece "A" and the nuclei in piece "B", since they weren't really tied to any one part of piece "A" anyways, so they just sort-of all jumble up and become one piece. --Jayron32 17:46, 10 August 2014 (UTC)

Isn't sintering related to this? Think of it as a very large number of microcrystalline metallic particles in contact with one another. At low temperature, there is a high ratio of surface area to volume, but the void ratio is also high, so instead of bonding, the particles can only clump together in a weak association. When the temperature is raised sufficiently, the particles soften, allowing the voids to be filled in. As a consequence, more surface area of individual particles in contact with each other, thus allowing them to weld together into a superstructure. Plasmic Physics (talk) 00:33, 11 August 2014 (UTC)

See Friction welding for joining 2 pieces of metal by rubbing them together.--Wikimedes (talk) 02:42, 11 August 2014 (UTC)

Earth gravity and animal speeds

I started to think that, for example, the peregrine falcon in his 300+km/h hunting stoop is significantly assisted by the gravity of Earth (essentially enjoying a free fall), which imparts him the acceleration and affects the bird's own speed. Cheetah, to the contrary, generates his hunting speed on his own, without g acceleration. So perhaps it's incorrect to declare the peregrine falcon the fastest animal among all, since birds, aquatic and terrestrial animals face different conditions when generating their speeds? Now if a hungry peregrine falcon is put into weightlessness and then sees his prey, what theoretical speed he would show? Brandmeister^talk 16:21, 9 August 2014 (UTC)

The article List of birds by flight speed lists another bird that's capable of straight-line speeds over 100 mph, i.e. faster than the cheetah. As to what's "correct", or what straight-line speed the birds of prey can attain, that would depend on what the sources have to say. ←Baseball Bugs ^{What's up, Doc?} carrots→ 16:39, 9 August 2014 (UTC)

I wonder whether the diving bird speed is controversial due to Earth acceleration. If yes, then looks like the Oscar goes to Golden Eagle, rather than peregrine falcon, according to that list. Brandmeister^talk 17:18, 9 August 2014 (UTC)

It doesn't appear so, just that it's "qualified". You could google the subject, perhaps "bird speed controversy" and see if it hits anything. ←Baseball Bugs ^{What's up, Doc?} carrots→ 21:10, 9 August 2014 (UTC)

One might naively attempt to correct for the dive speed by subtracting, say, the terminal velocity of the diving falcon, which I calculate to be approximately 100m/s or 360kph. However, TV takes many seconds to reach, while the falcon's dive is from relatively low altitudes, so by the 3-second half-growth rule of thumb of TV, we'd be subtracting maybe 150-200kph from the record time. Again, I emphasize that this is a very naive back-of-the-envelope estimate, but it could be a method to compare dives to horizontal flight. SamuelRiv (talk) 01:57, 10 August 2014 (UTC)

I agree that handing the title fastest animal" to something that can fall really quickly is a flawed thing. Is the terminal velocity of a sperm whale greater than a bowl of petunias? Does either of them beat a falcon? Unless someone knows - or specifies "fastest animal when engaging in it's normal behavior"...all bets are off (and even then, humans have the falcon beat too). Records are things that are mostly of interest as trivia quiz questions - they have little value beyond that - and just like most trivia questions, if you pull them apart and stick them under the microscope - they all have more than one answer. Sure, it might be of practical interest to examine which birds can dive faster than others in order that we may learn something about their aerodynamics - but ranking a bird against a cheetah and arguing about which one is fastest is kinda silly.

I have the same problem with people who claim that jai alai is "the fastest sport in the world" (presumably because of the ball speed) - when it's clear that placing a ping pong ball inside a formula one race-car would have it beat - and claiming formula one as the fastest is kinda silly when you have air-racing listed as a sport - and even that's broken compared to rifle shooting. Come to think of it, playing flashlight tag entails speed-of-light constraints, so maybe it gets my vote for "fastest sport".

From a science perspective, you just need to be a lot more specific about what you're measuring. If you aren't then it's not apples-and-apples comparisons and all bets are off.

This is more a question about linguistics and human nature, not science.

SteveBaker (talk) 02:04, 10 August 2014 (UTC)

"A Yugo has impressive acceleration. But, of course, this is only the case when pushing one off a cliff, which is an excellent idea, BTW." StuRat (talk) 00:44, 11 August 2014 (UTC)

Speed of magnetism

Watching Donald and Pluto makes me wonder — what's the speed of magnetism? Not mentioned in magnetism, and all I found in Google was Q&A websites and passing mentions in things such as this book. Nyttend (talk) 20:36, 9 August 2014 (UTC)

The only sensible interpretation that I could give to it would be as a field. Since magnetism is part of electromagnetism, any disturbances in this field propagate at the speed of light. —Quondum 20:44, 9 August 2014 (UTC)

Your basic magnetic field is just a special relativistic effect of the electric field (speed of light). In field theory, it's a field with a vector potential, while the electric field is a scalar potential, but I don't think that could possibly make a difference to propagation speed. And just in case this other thought crossed your head, ordinary permanent magnets are approximately magnetic dipoles, but in spite of their curvy look and 1/r³ field strength, the force is still based on the charge carriers in the material itself and that still propagates by photons at the speed of light. SamuelRiv (talk) 02:07, 10 August 2014 (UTC)

Could you add something of this to the magnetism article? Nyttend (talk) 04:32, 10 August 2014 (UTC)

I've added a brief sentence to this effect. —Quondum 06:20, 10 August 2014 (UTC)

Thanks; I don't understand enough to write this sensibly. Now created a Speed of magnetism as a redirect to this section. Nyttend (talk) 13:52, 10 August 2014 (UTC)

August 10

Blackbody propulsion

Take a sheet with one side silvered and the other black, warm it up, and put it in space with zero external light. It will emit more blackbody radiation on the black side than the silvered side, which produces thrust without any propellant and needing no exotic theory. Am I missing something? Note that I'm not talking about any type of solar sail that uses an external light source. This was also asked on reddit with one poster providing the thrust (2.04μN at 300K) and the rest confusing it with a solar sail. SamuelRiv (talk) 14:02, 10 August 2014 (UTC)

The principle is sound: emitting electromagnetic radiation predominantly in one direction produces a reaction force that acts as propulsion. This is a photon rocket. The earlier responses in the linked reddit discussion make sense. To maintain the radiation at a level above ambient, you will need a source of power. Once it cools to ambient (reached thermal equilibrium, e.g. with the microwave background radiation, the pressure of incident thermal radiation on the reflective side will balance the force from incident absorbed radiation and emitted radiation on the black side. In terms of impulse per unit energy, if the radiation is all in one direction like a in laser, I expect that this is theoretically the most efficient rocket-like propulsion possible. —Quondum 15:02, 10 August 2014 (UTC)

What is the specific impulse of photon rockets with the best available current lasers for the job? Laser propulsion#Photonic Laser Thruster (PLT) has information on thrust but not specific impulse. 104.128.96.117 (talk) 20:32, 10 August 2014 (UTC)

Who needs lasers? It would take forever to justify the additional mass. Since we're not actually building this thing, let's makes some idealizing assumptions:

• Assume a black cavity or surface (as proposed by the OP), heated to emit radiation. The radiation is not collimated as with a laser, but the intensity (and hence momentum) is proportional to cos θ, where θ is the angle from the direction the cavity faces. This gives a momentum of cos² θ in that direction per unit angular area. Integrate over the hemisphere, and we end up with an efficiency due to lack of collimation. I seem to get 1/3; anyone who is interested can verify this.
• Assume heating by annihilating fuel composed of matter and antimatter: total conversion of mass to heat energy.
• Assume non-relativistic speeds to simplify calculations.

The momentum of a collimated photon beam with energy equal to annihilating mass m is energy E = mc², and the momentum is E/c = mc. Applying our efficiency factor for the non-collimated radiation, we get a specific impulse I_sp = (mc/3)/m = c/3. —Quondum 22:12, 10 August 2014 (UTC)

That seems to be in distance/time. Specific impulse is measured in units of time. I love the idea of a heated blackbody thruster though. I wish I had the math skills to follow... Can you get Newtons per Watt? How about using electrical current heating a resistor instead of antimatter annihilation? 104.128.96.117 (talk) 22:38, 10 August 2014 (UTC)

To quote from Specific impulse: If the "amount" of propellant is given in terms of mass (such as in kilograms), then specific impulse has units of velocity. Measuring the quantity of propellant by its weight seems particularly inappropriate in the context of space propulsion, whence the units of velocity that I gave. But if you insist on measuring impulse in terms of the weight of the propellant in terms of Earth gravity, this translates to c/3g ≈ 10⁹ s. —Quondum 00:32, 11 August 2014 (UTC)

Sorry, missed some questions. In terms of thrust per unit power, it is the same as momentum per unit energy, which is mc/(3mc²) = 1/3c ≈ 10⁻⁹ s/m ≈ 10⁻⁹ N/W. This might seem miniscule, until you realize that to compare apples with apples, you need to include the mass–energy of propellant in the "power" in a conventional rocket, and that is worse by many orders of magnitude. Ignoring the mass of your on-board power storage does not make sense. Electrical heating does not particularly make sense – where are you going to store the energy? In some chemical form? Matter–antimatter annihilation seems almost perfect for the job here. One kilogram of propellant would propel a one-kilogram craft to a significant fraction of the speed of light. —Quondum 00:59, 11 August 2014 (UTC)

Wow, thank you. I think that is impressive, but ... antimatter? Is there any way to get Newtons per Watt from less exotic sources of heat? 104.128.96.117 (talk) 01:01, 11 August 2014 (UTC)

You need to be more specific about the context. Newtons per watt would usually be used in the context of a power source working with an external mass to act on, such as with a jet or turbo engine. Or from an external power source in space, such as the sun – or a phenomenally powerful laser beam – with a solar sail. (Oh, and the N/W figure is the same for this type of thruster, regardless of the source of heat.) —Quondum 01:17, 11 August 2014 (UTC)

Deep ocean internet lines

How are deep sea internet lines laid at the deepest part of the oceans. Is it just dropped in or is it lowered down using specialised deep ocean diving machinery? And when these lines get near a coast, does it just go under the sea bed since I'm assuming the cables wouldn't just be on show in shallow water or on a beach. How does it get underground without water also getting int this underground area where the cable goes into? And what happens to the cable when it reaches a deep ocean trench? Does it follow the trench right down and back up again following the seabed terrain exactly or is it bridges across the trench? — Preceding unsigned comment added by Clover345 (talk • contribs) 20:15, 10 August 2014 (UTC)

Underwater cables have been around a lot longer than the internet - see Transatlantic telegraph cable, the first of which was laid by ship in 1858. Mikenorton (talk) 20:31, 10 August 2014 (UTC) See also Submarine communications cable, which has more details. Mikenorton (talk) 20:34, 10 August 2014 (UTC)

Wall plugs that look like a nail/screw hybrid

In Romania, before the fall of the communism, instead of using the plastic wall plugs invented by Fischer, we were using some nails with screwing thread on one end. They look like this (scroll). They were locked into the wall using a pistol that pushed them into their place. My question is if they have a distinct name or they are simply named "wall plugs". Who invented them and when? I am also curious if they were used in the West or maybe only in the communist countries? Thanks. —  Ark25  (talk) 23:47, 10 August 2014 (UTC)

I think just nail guns are used for that purpose here, although I don't understand what was screwed into the ends of those. StuRat (talk) 00:32, 11 August 2014 (UTC)

I haven't seen them in the UK either, and, like Stu, I'm puzzled about how they were used once the pistol had put them in place. Dbfirs 09:08, 11 August 2014 (UTC)

In England there's a similar product called a "threaded nail", which serves much the same purpose - the spiral means the nail rotates as it's hammered in. They're not common, and usually have to be bought from specialist building shops rather than general hardware stores. I'd guess that their relative rarity in Western Europe compared to Romania is due to differing construction techniques - wood isn't a common building material here, and a wall in Britain, France, Germany etc is usually plaster over brick, meaning the additional strength of the plastic plug is necessary to hold a nail or screw in place without cracking the plaster. 89.242.88.157 (talk) 09:26, 11 August 2014 (UTC)

August 11

Locking pin

What is a locking pin? Is it the same thing as "Split pin" ? From the google images it looks like it is. If I translate from Romanian ro:Splint (which means "split pin") into English, then I get "Locking pin". If it's not the same thing, then can anyone start a stub about it or at least help me with some info so I can start such a stub? Thanks. —  Ark25  (talk) 00:15, 11 August 2014 (UTC)

In the US we call it a cotter pin, although that seems to mean something else in the UK. StuRat (talk) 00:19, 11 August 2014 (UTC)

I don't think there is much difference in usage, except that cotter is the connecting pin in the UK, with the word "cotter" (on its own) not normally used for the locking pin that keeps the cotter in place. The locking pin (cotter pin in the US and sometimes also in the UK) can be a split pin or a locking device of a different design (R-clip or split ring). Dbfirs 08:45, 11 August 2014 (UTC)

I've never heard of a cotter pin being referred to as a cotter in the UK, and I've never heard a split pin called a cotter pin. DuncanHill (talk) 09:39, 11 August 2014 (UTC)

A cotter pin in britenglish is quite different to a split pin. The most familiar example used to be the cylindrical bolt with a tapered flat wedge section used to tighten the crank of a bicycle to the front chain wheel's axle. Similar but more elaborate devices were used to hold steam engines together. A split pin is merely a D shaped cross section of wire wrapped around to form a cylindrical, but split, pin. I suggest the OP post a photo or find one online to show us, as there are many options. In engineering terminology I would be quite happy to call many wedge type fixtures cotters. Greglocock (talk) 09:47, 11 August 2014 (UTC)

Footprints in streambed

If someone leaves footprints on the bottom of a small stream (as was the case in Fenimore Cooper's The Last Mohican), how long would they typically last before they're washed away? (No need for high precision here -- a ballpark figure will suffice.) 24.5.122.13 (talk) 07:41, 11 August 2014 (UTC)

That would very enormously depending of the flow rate and material in the stream bed. For a fast flow over light silt, the prints might vanish within a second or two whereas for a gentle stream over a clay bed the footprints might remain for months. Dbfirs 09:04, 11 August 2014 (UTC)

How might footprints (e.g. from dinosaurs) last so long as to end up petrified? ←Baseball Bugs ^{What's up, Doc?} carrots→ 09:09, 11 August 2014 (UTC)

See ichnite.--Shantavira|^{feed me} 10:38, 11 August 2014 (UTC)

I see. Hardened enough that being silted over did little or no damage to the print, and resulting in preserving it and eventually becoming rock. Thank you! ←Baseball Bugs ^{What's up, Doc?} carrots→ 10:43, 11 August 2014 (UTC)

White Kidney Bean extract - is it cooked?

I'm talking about the famous Phase2(tm) extract... It seems powderish for in my check, and I try to understand if it's actually cooked beans than dried and grinned, or just grinned beans (I ask this because I've heard that eating non-cooked beans can be toxic, and therefore it's not very likely that Phase2(tm) extract is made from uncooked beans). thanks for you elaboration, Ben. Ben-Natan (talk) 11:15, 11 August 2014 (UTC)

Kidney activity

Does the kidney as a whole or in part, function at a constant rate or in peaks and troughs? If the rate varies, what are the variables that influence the rate?