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August 9

Direct observations of evolution of multi-cellular organisms

I recall an article that listed several observation of species forking in plants, but I can't find it. This is but a part of an attempt to make a comprehensible list of direct observational proofs for evolution. Can someone please lend a hand? אילן שמעוני (talk) 07:39, 9 August 2015 (UTC)

The article was probably Evidence of common descent#Evidence from speciation, which mentions Arabidopsis thaliana (which is branching into two species due to the fact that the two branches have incompatible immune systems), Senecio cambrensis (a hybrid species created when an infertile hybrid (the equivalent of a mule) suddenly became fertile) and Brassicoraphanus (similarly, fertile hybrids of cabbages and radishes), as well as plenty of examples from the animal kingdom. Smurrayinchester 08:02, 9 August 2015 (UTC)

(If your goal is to have evidence to use in debate with creationists/intelligent designists, I will warn you that they will probably dismiss all of these as "microevolution", since they will argue that one type of cress turning into a different type of cress merely produces a new species within the same "baramin". Rather than using the fact that cabbages and radishes have been seen hybridizing into a new species as evidence of evolution, creationists will move the goalposts and just argue that it shows they are part of the same baramin.) Smurrayinchester 08:12, 9 August 2015 (UTC)

Thanks, very much! I take it one step at a time. They usually claim no evolution was witnessed for large organisms, well that is clearly wrong. Cheers! אילן שמעוני (talk) 08:19, 9 August 2015 (UTC)

Lactase persistence. Bam. Great example of human evolution. With that said, you're extremely unlikely to change any creationists' minds, so don't waste your time if that's what you're expecting. I'm quite fond of the statement, "You can't reason someone out of something they were never reasoned into in the first place." It's not like there's a shortage of information about evolution on the Internet. I will give a quick shout-out to RationalWiki, which I edit occasionally. --108.38.204.15 (talk) 09:43, 9 August 2015 (UTC)

Also I should definitely mention the venerable TalkOrigins Archive. Slipped my mind. --108.38.204.15 (talk) 09:52, 9 August 2015 (UTC)

The most straightforward proof of evolution is simply the discovery of fossils that can be shown by radioactive dating to have a certain age. We can measure the rate at which an isotope decays and extrapolate how long it takes to break down. The limit of this idea, of course, is that an omnipotent being could have altered the fossil record; indeed, we can't rule out last Thursdayism. Deciding what is 'real" is easy if we only consider the methods of natural science, but once one allows for the supernatural, all bets are off. And we really can't rule out such interference, either at the truly divine level or at something as trivial as some sort of simulation, Holodeck etc. Wnt (talk) 00:37, 10 August 2015 (UTC)

Certainly the existence of an omnipotent, omniscient and actively-intervening being puts scientific statements about evolution in doubt...but also all other statements - without any exceptions. Are you reading what I'm writing - or are you having words implanted in your brain by an omnipotent being while you stare at a blank screen? Does the room you're in exist? Who knows? Did you have a decent lunch today or were you chewing on dried moss in a dank cave someplace? There is literally no way to know. So if people wish to take that position, then there is no way to convince them of anything whatever - and (if they are rational) they might as well give up on life since anything and everything they try to achieve or understand in the world is in doubt.

If you deny the omnipotence - or agree that any god(s) out there are not active in the world - then you can once again reason about the way the universe works - and then all of the arguments for evolution come in to play - and the argument is unassailable to people with open minds and a modicum of intelligence. SteveBaker (talk) 01:55, 10 August 2015 (UTC)

Well, you start with a reasonable statement, but I think you go off the rails. If you can't know for sure you really know the truth, does that mean that you should give up on life, or you should have faith? And the belief in the "rational" that asserts that only what you can remember is real is actually a serious logical error, since memory is not merely imperfect but fundamentally limited. A fundamental basis for moralistic decisions may be the existence of atman, which is to say, that all human sensation is actually perceived by the same being, which is merely implemented and manifested in different brains; by supposing that rational behavior is to assume that only what one remembers in one is real, one hurts oneself over and over.

The assumption that God intervenes incessantly or not at all is also difficult to defend. Is it really that implausible that an author might grant his characters but a brief peek at the notes on the cover flap, while leaving them mostly to live according to the rules of the novel?

I will note the reconciliation I prefer is one that supposes that the universe is a work in progress - from beginning to end, all past and all future is revised repeatedly, so that there are two independent dimensions of time. The sort of history quoted by the Abrahamic religions can be seen as a sort of Dreamtime, not necessarily privileged in status above other faiths or even some of one's own dreams, but offering a limited view of the parallel universes that preceded this one. Wnt (talk) 12:26, 10 August 2015 (UTC)

The "I have faith" answer is pretty weak. It generally means one of two things:

1. I have made up some guesses in my own mind about what is true - and now I have "faith" and therefore it's true.
2. I defer to a book that was written a couple of millennia ago by a bunch of fanatics and edited and generally hacked around by a hundred generations of people with their own particular axes to grind. But I have "faith" in it and this makes it true.

Neither of those perspectives on life permit any kind of reasoned discussion that might result in their minds being changed on the basis of observations and experiments. "Faith" is just a word meaning: "I've made up my mind on the basis of zero evidence and I'm never going to change it.".

Solid, comprehensible, convincing evidence for evolution/global-warming/big-bang/whatever is out there for anyone to examine - but those who have already decided on their world view on the basis of no evidence whatever, and locked themselves into that position due to "faith", are never going to so much as look at the wealth of contrary information with an open mind.

...which is why our OP is probably wasting his/her time trying to find a convincing argument. There are plenty of great arguments, mountains of evidence - but that's not the problem here.

SteveBaker (talk) 16:28, 10 August 2015 (UTC)

I think you misread my answer. The issue isn't whether "I have faith" - only that you haven't shown me evidence why someone should "give up on life" rather than having faith when faced with the reality that someone could be messing with our experimental perspective on the world. This is an open question, depending on a lot of sort of Emmanuel Kant philosophy that, I must admit, I haven't actually read, which puts me at considerable disadvantage. We can say that the world is certainly meant to look like it works a certain way, and that appears to be something meaningful and useful to learn; but we overreach when we tell people that this rules out God, or that we know there is nothing that we haven't been able to examine scientifically. Wnt (talk) 00:17, 12 August 2015 (UTC)

Translate in italian

Sorry, i'm italian, and i don't speak english very well. Someone of you can translate this in italian, the definition about the wavelengths i intend. Thank you so much anticipatly. --95.232.155.109 (talk) 13:59, 9 August 2015 (UTC)

Have you read the Italian Wikipedia article, spettro elettromagnetico, which contains a very similar picture? Nimur (talk) 14:35, 9 August 2015 (UTC)

The pictures are similar, but not the captions. --79.51.163.197 (talk) 18:09, 9 August 2015 (UTC)

These captions explain how the energy for each wavelength is absorbed by the human body. This information is explained in Italian at: trasparenza e traslucenza: assorbimento della luce nei solidi, and penetrazione della radiazione ionizzante nella materia, and Radiobiologia: effetti delle radiazioni ionizzanti.

Nimur (talk) 01:48, 10 August 2015 (UTC)

August 10

How much would an archaeologist know about dinosaurs?

I know that it's a common misconception that archaeologists look for dinosaur bones - but would an archaeologist typically know more about dinosaurs than your average layman? IOW, do their studies include dinosaurs at all? Because they might encounter dinosaur bones in their work... Just thinking about how it's sometimes said that many veterinarians could probably perform surgery on humans, in an emergency and wondering how it compares. --87.114.247.205 (talk) 00:55, 10 August 2015 (UTC)

The holder of a B.A. in Archaeology from Stanford might have taken zero classes in paleontology; there are electives offered in zooarchaeology and related scientific areas; but it's up to each individual to choose those optional classes.

"Archaeologist" is not a very clearly-defined term; generally, I would not call somebody an archaeologist unless they held at least an accredited undergraduate degree from a major university in the field of archaeology; but a wider definition might include holders of degrees in biology, anthropology, zoology, forensics, any of a variety of liberal arts fields... or even a non-degreed individual.

At Stanford, the Anthropology department also grants degrees (in anthropology, not archaeology); the departments are split into cultural anthropology and physical anthropology. Students in the latter department would have more formal scientific training. The Cultural Anthropology department is less likely to entertain undergraduates who seek specialization in archaeology; but they offer a graduate program. (Correction - these two departments merged a few years ago, so another important item that determines an archaeologist's formal education is when that person studied to become an archaeologist!)

Taking an even broader perspective, some experts in ancient history lack any formal schooling or credentials. A long time ago, I studied archaeology in the Middle East. Occasionally, I encountered exceptionally knowledgeable experts who were not formally educated at all - they were simply the locals who were enthusiastic enough to stick by the sites of historical interest during some very hard times. I would feel comfortable calling some of these individuals "archaeologists," irrespective of any formal education. I doubt they would know the first thing about the paleontology of ancient animals. Even the professors at the American University Archaeology Department probably did not have a strong background in palaeontology: but they spoke more languages than I could hope to!

Moral of the story: in modern times, it's difficult to generalize about a person's expertise, even if you know their credentials. Within the walls of a single institution, there is such a wide spectrum of different pedagogical ideas and formal curricula that it's fairly futile to speculate about the specific skills and expertise of any individual degree-holder.

Nimur (talk) 01:25, 10 August 2015 (UTC)

While the above is a good answer, I think it could be pretty much summed up as: "on average, yes". Archaeology states paleontology as a cross discipline. So of course some archeologists would have nothing to do with dinosaurs, but compared to "lay people", the group "archeologists" would, on average, know more about dinosaurs. Vespine (talk) 06:30, 10 August 2015 (UTC)

Having watched TV programmes such as Time Team it would appear that most archaeologists tend to specialise in a particular niche and become an expert in that area. So one may be an expert in dating fragments of ancient pottery whilst another may concentrate on a particular period. They then tend to consult someone else when they find something out of their area of expertise. Richerman (talk) 09:32, 10 August 2015 (UTC)

Yes, in two (overlapping) ways. First, as educated people, they likely know a little more about dinosaurs than the general population (though the same could be said for people with degrees in art history, quantum physics, or structural engineering. Second, there are areas where a background in archaeology provides context missing from most lay people's lives (an understanding of geologic time scales, stratigraphy, fossilization, provenience, and the scientific method, among others). However, while obtaining my degree in archaeology we never once mentioned dinosaurs. However (again!), see also some of the writings of Adrienne Mayor for very specific overlaps. 64.235.97.146 (talk) 13:59, 10 August 2015 (UTC)

Not Completely Off-Topic

This discussion reminds me of the periodic comment by Bones (Dr. McCoy) on Star Trek, "Dammit, Jim! I'm a surgeon, not a psychiatrist!" Because he had as much knowledge as he did, he knew the limits of his own knowledge. A competent archeologist should know the limits of her own knowledge of dinosaurs. Some years ago, I, as an information technology engineer with a degree in chemistry, was given the task of classifying various sorts of hazards to American servicemembers to which the system was tracking exposure. Sometimes I discovered that the terminology of industrial hygiene was different from that of chemistry. "Dammit, boss! I'm a chemist, not an industrial hygienist!" Know the limits of our own knowledge, and be aware that sometimes terminology is field-specific. Robert McClenon (talk) 14:55, 10 August 2015 (UTC)

Also relevent is the Dunning-Kruger effect (or really the anti-Dunning-Kruger effect here): Your own understanding of your knowledge on a subject means you also know more about how much you DON'T know. --Jayron32 16:42, 10 August 2015 (UTC)

It is also worth making an emphatic pitch for breadth in education - whether that takes the format of an out-of-field elective during university studies, or an informal hobby educational pursuit. Richard Feynman's chapter, Bringing Culture to the Physicists in his autobiographical work Surely You're Joking, Mr. Feynman, talks all about how he, an amateur (and a physicist) presented a lecture about archaeology on behalf of Otto Neugebauer, and eventually became a reknowned expert on Mayan mathematics. Someone can choose to specialize in some area - say, physics or computer theory or nuclear weapon design - for a variety of reasons; that primary specialization doesn't preclude the development of knowledge, and even expertise, in other areas. Nimur (talk) 16:59, 10 August 2015 (UTC)

Feynman once took a holiday and spent it working in a Biology lab. He also spent time investigating whether there was some reason that there are six consecutive 9's in the decimal expansion of pi after just 760 digits. "Common sense" says that this is a suspiciously astounding coincidence. It turns out that it's not really that unlikely - see: Feynman point. But, yeah - he definitely excelled outside of his core subject. SteveBaker (talk) 04:15, 12 August 2015 (UTC)

Cheapest source of icaridin insect repellent?

Is there are cheaper source of icaridin (it has a few other names listed in the article) in the UK than regular consumer insect repellents? I tried and failed to find a chemical company that stocks/sells it. I just don't want to get ripped off if the same product is available elsewhere at a fairer price. --129.215.47.59 (talk) 12:28, 10 August 2015 (UTC)

Well, you can buy 100% picaridin from a Chinese company called Simagchem. Their minimum order is 25 kg, which goes for 8000 US dollars. That's probably a typical scenario if you want to buy it in non-consumer form. Looie496 (talk) 14:58, 10 August 2015 (UTC)

Scientific notation for inverse units (like per unit area or per second)

When I was in high school (England, UK, 2003), I was told that the old notation of m/s (metres per second) and kPa/m² (kilopascals per square metre) were going away and the correct notation would be m.s^-1 and kPa.m^-2. Is this correct? Who decided this? Was it just the UK department of education or something bigger? --129.215.47.59 (talk) 13:47, 10 August 2015 (UTC)

You know what, I asked this same question last decade: [1]. Sagittarian Milky Way (talk) 14:02, 10 August 2015 (UTC)

In my experience, which was a long time ago, but was in the US, both forms were accepted. I think that they still are. There are times that the use of the negative exponents is clearer, but anyone who can use scientific notation can transform the notation. In the case of meters per second, I think that the division form is clearer, because it really is meters in a second. In the case of energy, I think that the negative exponent is clearer. Robert McClenon (talk) 14:48, 10 August 2015 (UTC)

It seems like it doesn't matter - and for simple things like kilometers-per-hour, it probably doesn't - but there are units for things like molar entropy (m².kg.s^-2.K^-1.mol^-1) that would be impossibly horrible if expressed with slashes and words like 'per'. Acceleration (meters per second per second) trots off the tongue easily enough - but electric field strength (meter kilogram per second per second per second per amp) does not! So, while it's not unreasonable to continue to use the slash notation for simple informal stuff like m/s, the approach that uses negative superscripts is more practical for complicated cases.

I was unable to find who started using it or when - or whether some standards organization started mandating it - or some educational department head started demanding that it be taught. Those are all good questions! SteveBaker (talk) 16:03, 10 August 2015 (UTC)

I believe many style guidelines still allow the use of the solidus, but require that you only use one without brackets, and use brackets to avoid ambiquity where needed in any case. Some may suggest it's simpler or better to use negative exponents in complicated cases (without any specific definition of what's mean by this). I think some also allow a horizontal line instead of a solidus, but this often doesn't work well when typesetting.

See for example BIPM, US NIST, IAU.

Simpler student guidelines may recommend the negative exponents throughout to avoid mistakes and so they get in to the habit of understanding what they mean.

Nil Einne (talk) 18:46, 10 August 2015 (UTC)

Dogs

Why are dogs so interested in (and will sometimes eat) human faeces and other human body fluids?--86.176.8.152 (talk) 16:09, 10 August 2015 (UTC)

Read this or this or this. Also, for future questions you may have on any topic: Instead of coming here and waiting for answers, just type your question (whatever it is) into the search bar at the website http://www.google.com It will give you lots of answers for your question, and you can do it on your own, without anyone else's help, and faster than it would take to wait for someone else to do. Everyone here will do that as a first step when answering your questions, and you can get them answered faster if you just do it yourself. Not every question can be answered like that, but this one clearly could, as the links I gave you above are the first three answers when I typed "Why do dogs eat poop?" into Google. --Jayron32 16:37, 10 August 2015 (UTC)

It's not just human poop they like, any poop will do. The real Q is why evolution hasn't given them the instinct to avoid poop, since it's an obvious source of disease, which would seem likely to prevent them from passing on their poop-eating genes. Cats, for example, quite sensibly bury theirs. So, any evolutionary benefit to eating feces would have to outweigh this rather substantial negative. (Another negative is that humans may not want to adopt dogs that have poo-breath, leave steaming piles in the house, leave a turd as a present on the master's pillow, etc.) StuRat (talk) 18:30, 10 August 2015 (UTC)

Humans "adopting" dogs is an extremely recent phenomenon. Just a couple of hundred years ago dogs were kept almost exclusively for work, hunting, droving or guarding, how proficient a dog was at those things would have outweighed how sweet their breath was. Having a dog purely as a companion was almost unheard of. Vespine (talk) 22:54, 10 August 2015 (UTC)

So, Stu, do you have any references to back up the statements you are making here, or should we just accept what you say because you're better than everyone else, and we should just trust you? --Jayron32 19:30, 10 August 2015 (UTC)

Have a link then: evolution. StuRat (talk) 19:42, 10 August 2015 (UTC)

So, the answer is "no", then. --Jayron32 20:16, 10 August 2015 (UTC)

No, the answer is "If your really need a source to show that evolution occurs when there's evolutionary pressure for or against something, then read the damn article and stop trying to make trouble already". Or do you require a source to prove that cats bury their poop ? You keep pretending to know absolutely nothing and I might just start believing you. StuRat (talk) 22:48, 10 August 2015 (UTC)

Actually, it's a really dumb idea to talk about evolution, in something which has been as messed up by artificial selection as dogs. Nil Einne (talk) 12:47, 11 August 2015 (UTC)

Are you arguing that dogs have been bred to eat feces ? If so, why ? If not, then they evolved that way on their own, or inherited that trait from wolves, who evolved it or inherited it, etc. StuRat (talk) 22:31, 11 August 2015 (UTC)

We have a decent article on coprophagy. SemanticMantis (talk) 19:25, 10 August 2015 (UTC)

• Is there a British version of the humane society or health and human services where a person feeding his dog human feces or leaving it and other excrementa about can be reported? μηδείς (talk) 20:44, 10 August 2015 (UTC)

RSPCA Dbfirs 22:11, 10 August 2015 (UTC)

The police!DrChrissy ^(talk) 22:36, 11 August 2015 (UTC)

Effects of gravity vs. simulated gravity

On space missions we research the effects of gravity on cells, tissue, atomic matter. Since the space missions aren't really at a distance that would remove gravity, we use the method of "falling around the planet" that simulates gravity. Are there theories or research on the possible different results when investigating in one condition over the other? — Preceding unsigned comment added by 99.57.49.187 (talk) 22:35, 10 August 2015 (UTC)

An object in orbit experiences weightlessness. There is no difference between that weightlessness and the weightlessness of being far from any massive objects or even being the only object in the universe. Simulated gravity is different, though. The type where you spin a spaceship can indeed cause side effects, like nausea. StuRat (talk) 22:45, 10 August 2015 (UTC)

There is no difference between acceleration caused by a gravitational field and equivalent acceleration caused by anything else. This is the central insight behind general relativity. Orbital trajectories don't simulate gravity; rather, they cancel out its acceleration. When you're in a stable orbit, you're in freefall towards the body that you're orbiting, but you're on a trajectory such that you keep missing the body you're falling towards. Douglas Adams was actually deeply correct when he said that the knack to flying is to throw yourself at the ground and miss. I suggest [2] and [3] for some more insight. You're right that space missions don't "go beyond" the reach of gravity; the Earth's gravitational force in low Earth orbit is only slightly less than that at its surface. So when laypeople say "there's no gravity in space", they're wrong. Just think: what keeps the Moon orbiting the Earth, or the Earth orbiting the Sun? Also, to expand on what StuRat said, the side effects of simulated gravity aren't because it's somehow "different" from "real" gravity. Remember what I just stated above: there is no difference. Rather, it's because rotating around an axis can cause motion sickness if the difference in velocity between parts of your body is significant, as would happen in a small spacecraft rotating fairly quickly. This is because your inner ear is involved in your sense of balance and tells your brain about the motion it's experiencing. But if this information conflicts with other information from your eyes and other parts of your body, your brain can freak out. This is the same mechanism behind car sickness, seasickness, etc. --108.38.204.15 (talk) 23:43, 10 August 2015 (UTC)

(edit conflict)The equivalence principle hypothesizes that there is no fundamental difference between actual and simulated gravity. I should note that "falling around the planet" does not simulate gravity - this is freefall, and this is why there appears to be no gravity within the space station or other space vessels. Despite this theoretical basis, there are practical differences between actual and simulated gravity. For instance, if one were in a spinning spaceship, the apparent acceleration of gravity would vary based on distance from the axis of rotation. This could result in a situation where you regularly experience rapid changes in gravitational acceleration as you move about the ship, something you would never experience walking around on Earth. If there are windows in the ship, or you can see beyond your immediate vicinity, you could become nauseous from disorientation. There are also subtle differences between freefall and actual weightlessness. For instance, imagine you are in a large cubical room in freefall around the earth. You and a friend are floating above the ground on opposite sides of the room. While the room orbits the earth, you and your friend actually experience slightly different gravitational acceleration vectors, and will ever so slowly move toward one another, though this may be too slight to be perceptible. Finally, there is all manner of weirdness when you are orbiting an object that is spinning - weirdness that is imperceptible to mere humans, but has been measured by Gravity Probe B. None of this is in conflict with the equivalence principle, just a consequence of spacetime curvature being not-quite-uniform. Someguy1221 (talk) 23:48, 10 August 2015 (UTC)

Tyre pressure

The recommended tyre pressure for my caravan (trailer if you're American) is given as 36 psi for a maximum speed of 100 kph and 33 psi for a maximum speed of 140 kph - why the difference? Surely if the maximum speed allowed is 140 kph you are going to be travelling at 100 kph for some of the time anyway. Also, the tyre pressures for the rear tyres of the car (VW Passat) should be about 4 psi more than the front with light loading, but with a full load you need to increase the rear pressures a little and the front tyres a lot so that they have a higher pressure than the rear tyres. As the extra load is likely to be at the back (especially when towing) why do you need to add so much more to the front tyres? BTW I'm sorry about the mix of imperial and metric units (psi/kph) but that's the way they're given in the manual. It shows our schizophrenic relationship with metric in UK :-) Richerman (talk) 22:46, 10 August 2015 (UTC)

Softer tires might tend to absorb vibrations which could be a problem at high speeds. StuRat (talk) 23:02, 10 August 2015 (UTC)

I kind of get the feeling they had one of their engineers calculate the "optimal pressure" for various speeds and then just threw that in the manual, likely because they're required to give different pressures for different speeds by law or something like that. The reason you want a lower fill pressure when the tire is being driven at higher speeds, everything else being equal, is because the temperature of the tire increases as it is driven faster, which increases the pressure of the gas in the tire (per the ideal gas law). You always want the tire to be as close to the ideal pressure as possible when in service, to get the best balance between traction and fuel efficiency, and of course to prevent damaging or destroying the tire from too high a pressure, so it makes sense to deflate the tires a little if you expect to spend more time driving them at higher speeds. As for why you fill the front tires more than the back tires with a heavier load, my guess is it's to keep the trailer balanced. The load at the back is going to push the back of the trailer down, and the front up, which decreases the traction on the front wheels. Jackknifing is a real problem with loaded trailers, especially at higher speeds. --108.38.204.15 (talk) 23:19, 10 August 2015 (UTC)

To be clear, the higher pressures for the car tyres are given for a fully loaded car rather than specifically for towing. Does higher pressure in the tyre increase the traction? You would think that lower pressure would mean more of the tyre surface is in contact with the road. Richerman (talk) 23:42, 10 August 2015 (UTC)

Setting tire pressures for cars is a rather adhoc process, there is a push to transfer the job to the tire companies, which will be interesting. Mainly the reason we specify higher pressures for high loads and speeds is to reduce sidewall flexure which causes the tire to heat up, and possibly deflate. The higher pressures are pretty safe at lower speeds and loads, but they give a horrible ride. There are other considerations for a car, but that's the main hitters. Greglocock (talk) 07:45, 11 August 2015 (UTC)

(speculation) The faster you go, the hotter the tyres become, which increases the pressure. The recommend tyre pressure is for cold tyres. LongHairedFop (talk) 20:03, 12 August 2015 (UTC)

August 11

Can stimulating the brain really cause an orgasm?

Amy Farrah Fowler said in the Big Brain Theory: "Does volunteering for a scientific experiment in which orgasm was achieved by electronically stimulating the pleasure centres of the brain count?" Is it possible to stimulate the brain to orgasm? Or is orgasm more complex than that? What about release of oxytocin? Wouldn't oxytocin be required in an orgasm? What would cause the release of oxytocin? 71.79.234.132 (talk) 00:26, 11 August 2015 (UTC)

Minor nit. It's the Big Bang Theory, not 'Brain'. Dismas|^(talk) 00:42, 11 August 2015 (UTC)

A scientist simulated various parts of mouse brains with electrodes to see what each part does. When he found the rodent pleasure center he gave the mouse the on switch and it pressed the lever until it starved to death. Sagittarian Milky Way (talk) 00:43, 11 August 2015 (UTC)

These were experiments by James Olds and Peter Milner in the 1950s, involving rats not mice. None of the rats starved to death, though they did self-stimulate to the point of exhaustion. They were disconnected as it was thought they would starve to death if left attached. Additionally, females ignored their pups while males ignored potential mates, and both genders became willing to endure pain in exchange for stimulation. I haven't been able to find any online-resource that discusses the experiment in detail. Someguy1221 (talk) 00:54, 11 August 2015 (UTC)

Then I must've forgotten that they only found out rodents likely would stand on the lever till death but it didn't happen. And also that they were rats. Sagittarian Milky Way (talk) 01:10, 11 August 2015 (UTC)

You most likely remembered accurately something you read online, possibly even at a normally reputable source. Unfortunately, this experiment has been reported and re-reported so many times with no one checking the original publication (because oh God, you'd need to visit a library), that the version of the experiment remembered in popular culture is not quite what really happened. I also found we have an article on Brain stimulation reward that discusses some of these experiments. Someguy1221 (talk) 01:25, 11 August 2015 (UTC)

There was indeed an experiment in which rats starved, but it is important to understand the details. The experiment was set up so that for an hour each day a rat had access to two levers, one of which delivered food, the other brain stimulation reward. However, a rat needed to press the food lever so many times for each food pellet that it essentially had to spend all its time on the food lever to get enough food to maintain weight. It was found that in this situation some of the rats nevertheless spent most of their time pressing the brain stimulation lever, and starved. Reference: http://psycnet.apa.org/journals/com/60/2/158/. Looie496 (talk) 13:13, 11 August 2015 (UTC)

That's mean. I do remember that now, there's no reason there could be one famous experiment and one famous follow-up (besides tightening ethics rules). Sagittarian Milky Way (talk) 13:50, 11 August 2015 (UTC)

We have decent coverage on Orgasm and Oxytocin#Synthesis.2C_storage.2C_and_release. Here is a nice review article summarizing the science of the human orgasm [4]; it has information on psychology, biochemsitry, neurotransmitters, and hormones. Lots of refs therein. Here is a more specific article that discusses brain imaging and sexual response [5], and it discusses all kinds of things about what regions light up (and how, and when) in the sexual response cycle. In a sense, all orgasms come from stimulating the brain. I take it you mean without other tactile stimulations and relying solely on electrical stimulus in a laboratory context? I can't find any record of that, but WP:OR it's not an insane claim. It would probably be available in a mouse model before it got tried on humans. SemanticMantis (talk) 00:50, 11 August 2015 (UTC)

Pleasure center#Human experiments describes a few accidental experiments of this on humans. These were people that were already getting electrodes implanted into their brains for other medical reasons. In the three cases listed, it seems the doctors just happened to land the electrodes in such a position that stimulation caused pleasure. I should note that the actual scientific literature I've read describes the experience as "orgasm-like" rather than "orgasm". Someguy1221 (talk) 00:57, 11 August 2015 (UTC)

This idea was explored in a highly believable, futuristic movie in the early 1970s.[6] ←Baseball Bugs ^{What's up, Doc?} carrots→ 01:54, 11 August 2015 (UTC)

I haven't seen a reference to this, but I keep thinking there are philosophical problems when stimulating the brain. How do you know that the person really feels pleasure and isn't just displaying positive reinforcement? Couldn't the treatment simply create a compulsion to seek out stimulation (including claims of pleasure) without actually being pleasant? I suppose at some point after the fact you just take someone's word for what he felt, but ... could positive reinforcement deceive even his memory of the sensation? Wnt (talk) 11:41, 11 August 2015 (UTC)

You can't know that the person feels pleasure as feelings are a private experience and cannot be measured directly. A person might tell you that they are experiencing pleasure, but what does this mean? Don't forget that whereas one person being whipped or caned might report this as being unpleasant, others might report it as being pleasurable. This is where the concept of positive reinforcement is of benefit as this refers to a change in observable behaviour, rather than the feeling of pleasure which (as above) cannot be measured directly.DrChrissy ^(talk) 13:33, 11 August 2015 (UTC)

Do it in an fMRI machine. But this is worse than giving humans crack. Not ethical. Sex has a ramp up and ramp down (however short it can be, it's not 200 milliseconds) and temporary satiation for a reason. Sagittarian Milky Way (talk) 13:36, 11 August 2015 (UTC)

Even with imaging technology, the issues which Wnt and DrChrissy touch upon remain in play; what you gain from these observations is that you can correlate the neural activity to a self-reported state of mind or to stimuli, but the experience itself has no empirical quality, is subjective, and can never be directly compared against what we assume to be a similar experience in another individual. This is a recurrent theme in the cognitive sciences that continues to baffle researchers armed with the most advanced investigative technology to basically the exact same extent it did philosophers amongst the ancients. Epistemologically speaking, we still have no (and I mean "no" in as literal a sense as we can ever know) understanding of what an "experience" (or consciousness broadly) is, why or how it results from physical mechanics, or whether it is a "real" phenomena at all, cogito ergo sum presumptions or no. ([7], [8], [9], [10], [11]).

As to the ramp up you speak of, there are many forms of experience that actually simulate various pleasure centers of the brain much more broadly and powerfully than orgasm and can be triggered much more immediately. Orgasm as a unique experience is not defined just by pleasure; it actually has many features which set it apart neurophysiologically and experentially from the general notion of pleasure and other forms of experience which are often classified as pleasurable. Which is not to counter your root argument--that there are deep ethical implications of allowing a person to have direct access to their own neural architecture with regard to pleasure--as these are numerous and, as you imply, significant. Snow ^{let's rap} 05:30, 12 August 2015 (UTC)

This would be reinforcement stronger than anything than anything physically possible in life, and people have let their pre-pubescent boy be routinely anally raped to afford crack. Sagittarian Milky Way (talk) 13:43, 11 August 2015 (UTC)

• There are a variety of drugs that sometimes cause women to experience spontaneous orgasms, including Prozac. The drug clomiprazine sometimes produces orgasms that are triggered by yawning. Also orgasm can be triggered directly by brain stimulation, as described in http://www.violence.de/heath/jnmd/1972paper.pdf, one of the most remarkable (and remarkably unethical!) papers I have ever read. Looie496 (talk) 13:28, 11 August 2015 (UTC)

Jeeeeeeeezus. That has to be seen to be believed. We have a small article on Robert Galbraith Heath that says the work was (surprise!) financed in part by the CIA and US military. If this is remarkable... imagine what research they must have funded that wasn't made public. Wnt (talk) 13:58, 11 August 2015 (UTC)

The specifics of studies with electrode stimulation with regard to orgasm have already been referenced above, but there is a more general brain-in-a-vat point here that ought to be made for the OP. That is to say, not just orgasm but indeed the vast majority of all physical sensations and physiological responses that the brain is capable of generating could in theory be produced by similar methodology of direct neural stimulation. There are forms of physiological feedback between the brain and the rest of the body which cannot presently be reproduced, or even vaguely approximated, by artificial stimulation, but, in theory, any conscious experience the brain is capable of experiencing through the medium of the rest of a body's physiology could be experienced without a body, given the right (and in many cases, highly hypothetical) circumstances. The number of sensations which have been experimentally generated (compared against the overall possibilities) are actually quite small, but orgasm is actually incredibly easy to achieve (compared against, for example, generating a specific hallucination), since it does not depend on replicating a highly specific sensation; you instead need only generally stimulate certain pleasure centers of the brain in order to cause a cascade of signals which approximate the sensation of sexual climax. Remember too that some people (either naturally or through experimental processes) have been known to have orgasms as a result of stimulation that decidedly non-sexual for most people. On an off-topic side note, I would definitely need numerous electrodes buried in very specific locations of my own brain to ever stand a chance being entertained by The Big Bang Theory, so heavily does that show miss the mark with regard to both comedy and science. Snow ^{let's rap} 22:44, 11 August 2015 (UTC)

Invertebrates

I lifted this from Pain in invertebrates. It has been shown that snails will operate a manipulandum to electrically self-stimulate areas of their brain. Balaban and Maksimova surgically implanted fine wire electrodes in two regions of the brains of snails (Helix sp.). To receive electrical stimulation of the brain, the snail was required to displace the end of a rod. When pressing the rod delivered self-stimulation to the mesocerebrum (which is involved in sexual activity) the snails increased the frequency of operating the manipulandum compared to the baseline spontaneous frequency of operation. However, when stimulation was delivered to the parietal ganglion, the snails decreased the frequency of touching the rod compared to the baseline spontaneous frequency. These increases and decreases in pressing are positive and negative reinforcement responses typical of those seen with vertebrates. DrChrissy ^(talk) 13:54, 11 August 2015 (UTC)

References

How were these videos made?

At several points in this video there are shots of the night sky where... well, I'm not sure what to call it, but I guess it's the Milky Way that is clearly shown with gas clouds and such. Complete with purple and blue hues. I've been out in nature quite a bit in my life but I've never seen anything like that with my naked eyes. The most evidence of the Milky Way (yes, I know we're in it) I've seen is a 'band' of stars across the sky. So, is this achieved with some telescopes and some post-processing? Dismas|^(talk) 00:41, 11 August 2015 (UTC)

This website has some weird formatting issues, like it was copy pasted from somewhere, but it includes detailed instructions for pulling that off. Simply googling "photographing the milky way" pulls up lots of other sites with instructions, including complete details about appropriate camera settings for different camera models. Someguy1221 (talk) 00:45, 11 August 2015 (UTC)

I don't see any formatting issues. Thanks for the link! Dismas|^(talk) 01:16, 11 August 2015 (UTC)

That's because there's few places in the East half of the US or Europe or industrialized Asia that are dark enough. If it's a video it's unlikely to be much more sensitive than the human eye even with today's tech. It's probably more grayscale in real life, though. But it's been described as veined marble and casting shadows. Sagittarian Milky Way (talk) 00:53, 11 August 2015 (UTC)

Yes, I'm reminded of the lyrics to Kodachrome: "...brings out the greens of summer, ... makes all the world a sunny day". That is, certain films can enhance the colors dramatically. StuRat (talk) 03:18, 11 August 2015 (UTC)

If it's a video it's unlikely to be much more sensitive than the human eye even with today's tech. This premise is incorrect. This is not technically just a "video", at least not in the naive sense: recorded "live". This is a timelapse, clearly because the rotation of the sky. I have a friend who takes exactly these kinds of "videos". What you do is take a series of long exposure photos in widefield, with probably a DSLR not a video camera (my friend uses a 6D, the same camera I have), over the course of several hours. By long exposure I mean up to 30-40 seconds is possible before stars start to "streak" in widefield. This is FAR more sensitive than the naked eye. Then you just "stitch" those exposures into a "video". I am somewhat of a hobby astronomer and I have been to very remote dark skies and it never looks anything like that, it can be extremely impressive, but not like that video. Vespine (talk) 05:31, 11 August 2015 (UTC)

In that case it could be more sensitive. If the sky much over 15 degrees from the MW centerline is not almost black when no moon than it's either more sensitive or light polluted. Otherwise, it's as or less sensitive. Reciprocity failure of course was a problem before digital. The Moon and Sun is very bright though, they can make the sky bright enough to detect with the naked eye up to 7 and 18 degrees below the horizon respectively. Venus and Jupiter are bright enough to affect dark adaption. And maybe the solar cycle and the hours long decay of sunlight-induced mesosphere phosphorescence. Where's the darkest sky you've ever seen though? Even if you went to the California desert or mountains you probably had enough light pollution to affect the naked eye view, only an unusually off-the-beaten-path part of Death Valley and small corner of the Sierra Nevada doesn't have enough. 6-9 thousand feet altitude and looking at the galaxy's center the minimum possible distance out of the atmosphere (only possible at 30°S) are even more impressive. Night vision is one of the first things to go with hypoxia though so more than 3,000 meters should hurt the view even with acclimatization. (w/ some variation from individual hypoxia-tolerance of course) Sagittarian Milky Way (talk) 15:42, 11 August 2015 (UTC)

Perhaps I'm missing something but I don't see the relevance of places outside the US in your earlier comment. Sure you could see better in places with less light pollution than anywhere in the US, and you could produce better videos too, but the description for this video strongly implies that this particular video was shot entirely within the US. It's possible that the parts of the video being referred to were all shot in the Death Valley or a small corner of Sierra Nevada, but I'm not sure about that either (but I know little enough about US geography that I can't reliably say). Nil Einne (talk) 17:49, 11 August 2015 (UTC)

P.S. When I originally wrote the comment, I mistakely believed you wrote above "few places in the US", which implied that it would be difficult or impossible to see anything like this in nearly all of the US (or Europe or industralised Asia), whereas this video was obviously shot in the US so the US is the best comparison. I later realised you actually said "few places in the East half of the US", which changes things a fair amount. I tweaked my comment slightly since no one had replied to it, but it really needs significiantly more substanial modification or just deletion. But it's been there for long enough I'm not sure this is fair, so I'll leave it be. I do think there remains an open question, namely are all the scenes being referred to really shot in the places you consider necessary for such observations? If they aren't then that seems to counteract the notion you need such places, even if you may very well need such places for naked eye observations. Nil Einne (talk) 18:01, 11 August 2015 (UTC)

The OP's user box say he's from Vermont, so unless he's traveling far something closer to the video than what the OP's seen exists. You shouldn't need utter darkness if you use a camera, but I never said that. It could have more dynamic range than the eye and a huge lens and a custom filter that blocks the bigger emission lines of streetlights.

[12] combined with Bortle scale and the next link show that very small amounts of anthropogenic light really do prevent the eye from seeing everything (even telescope vs. same telescope). And that the zone where you can see everything is only about 10% of the land area of the West and 0.016% of the East if you go by "real East" maybe 52/48 instead of naive bisection. About the California example, that is not the darkest state. It's only dark by my Eastern standards. It still has much desert and tall mountains. And the highest mountain in the non-Alaska US (14.5 thousand feet), the hottest weather ever measured (Death Valley, 134°F), which are pretty far from populous areas so I was surprised how little pristine area it had. (minor nitpick: I thought Mt. Shasta and stuff are more east than they are so that must be Sierras but Sierra Nevada (U.S.) says I'm wrong, my bad). Arizona is the most famous state for darkness and it's like 95% spoilt by land area. Montana might be the second most famous state for darkness and it's not much better. Utah, Colorado, almost every state it's the same, none is more than about 1/3rd pristine besides Alaska. So it's slightly hard to vacation in the pristine zone by accident, [13], but certainly easy to do it on purpose (with a surprisingly large choice of scenery). I wasn't in any way saying that it must be Death Valley or the Sierra Nevada if it's the US.

I guess I wasn't clear. The 150,000 square miles of utterly dark sky in the Lower 48 is surprisingly diverse though (high mountains, flat plains for hundreds of km radius, plateaus, low mountains, hills, geysers, lakes (natural and artificial), forests, deserts, endless sand, major rivers, short grass, mixed grass (no 100% tall grass), geothermal stuff like hot springs and sulfurous pools, 1 Florida atoll where 40°F is the all-time cold, peaks that are almost ice caps (or even true ice caps?), and at least one dry salt lake of the kind they try to break land speed records in). Sagittarian Milky Way (talk) 23:26, 11 August 2015 (UTC)

Well I don't think anyone doubts the OP has only seen whatever they say they've seen. My point was that the video suggests there are many different locations in the US you can image (whether or not you can see with the naked eye) what's seen in the video, so you don't need to go to the specific locations you mentioned in your earlier reply to image what's seen in the video. I'm not BTW suggesting imaging equipment is magic and can somehow counteract all the effects of light pollution, simply that it's foolish to assume you're going to see exactly what you can record (including with post processing) using decent equipment in the same location. Cameras and the eye each have their own advantages so you should expect significant differences, particularly when you consider post processing of the camera out put. In other words, while the OP could surely see better night skies if they visit a place with a lot less light pollution, this doesn't actually answer their only question of how to record what was recorded in the video. Nil Einne (talk) 13:35, 12 August 2015 (UTC)

Even in terms of normal real time video, I doubt it's true that they aren't more sensitive than the naked eye with todays tech. Of course comparing naked eye to what's produce from a camera can be misleading. If you've ever watched a sport broadcast in the evening, say a cricket match in a stadium without lights, you often wonder or hard to see when it doesn't look that much darker than before. But there are other ways to measure sensitivity e.g. [14] [15] Nil Einne (talk) 12:43, 11 August 2015 (UTC)

Then why do Hollywood movies not film in moonlight and use fake lights. I think they still do that, right? Even civil dusk still has orders of magnitude more illumination than moonlight and people can see in moonlight just fine. And no one will play sports where you have to hit a 100 mph cricket ball from 66 feet away after civil twilight. During civil twilight there can be a lot of contrast between sky and ground, the eye tries to keep the brightest things in view a light color when physiologically possible so it might make the pitch seem harder to see than it could be (in the day the Sun adds brightness to the ground without being in view itself (cause it'd hurt the eyes) so there's less contrast. The blue sky is still brighter than the ground but close enough for the eye to handle). Besides being huge and professional quality, the camera doesn't care if it'd lose detail in the sky at this setting and instead cares about making the pitch easiest to see. Maybe you could dark adapt at least 30 minutes like a skygazer would and then look at the ground at civil dusk before you could see the sky for even a fraction of a second. Maybe push paper towel tubes into your eye sockets, close your eyes, open your window, and don't open your eyes until the tubes are facing the ground. It should look a lot brighter than any ground you've ever seen at civil dusk before. Sagittarian Milky Way (talk) 15:42, 11 August 2015 (UTC)

I think you're conflating different things. My point about videos of sports at night is that comparing what you see on video with what you see in real life is not a good way to compare the sensitivity because you probably aren't comparing sensitivity but instead different things. And BTW, there was one famous game where parts of it were controversially played in what's normally described as almost complete darkness 2007 Cricket World Cup Final although with only spinners and the stadium did have limited lighting. However I'm not sure if it was after civil twilight. Video of that is actually a good example of what I'm thinking about as these generally don't make it seem that much worse than a typical Day-Night game. But again, my main point is that this doesn't really tell us much about sensitivity of cameras.

BTW, I agree that there's a difference between dark adapted and non dark adapted eyes. That was part of the point I was making about comparing videos with what you see.

Second, we're talking about the absolute sensitivity of cutting edge cameras. These cameras may be expensive and targeted at specific usages. They will often produce fairly noisy, low resolution and low frame rate results. People shooting video professionally for television and movies generally want high resolution, sometimes high frame rate, which looks very good (so has good contrast, highlights etc) and that looks something like what people would expect for the time it's supposed to be.

Good lighting with good cameras gives that. No lighting but with specialised cameras doesn't (and probably never will) but it doesn't mean that there aren't cameras out there which are significantly more sensitive than the human eye. Notably just because we have very sensitive cameras (and as I remarked earlier, it can be confusing sometimes precisely how dark it is), it doesn't mean a moonlight scene can be made to look like daylight and for various reasons professional shoots do sometimes happen at times when it is dark even if it's meant to be light.

The specific cameras used for the precise video we're discussion which are all listed may or may not be significantly more sensitive than the human eye when used for real time video. I don't know but I never commented on the specific cameras simply on what's out there since you implied it was impossible for videos to be shot with significantly more sensitivity than the human eye "with today's tech" (rather than the specific cameras used for this video).

It's probably fair to only include commercial products, so I'm not sure if those earlier links were entirely fair as it may not be a commercial product, but I don't believe it's something that much higher than what exists out there already and there's nothing in the discussion to suggest it is.

Ultimately what matters is resonably objective measures of sensitivity of "today's tech", not how people feel stuff looks like, or should look like, or may be capable of. My sources weren't the best, but they did seem to imply there are and I'm fairly sure there are people here who know far more about this than me, so I couldn't be bothered looking for better ones for what was intended to be a quick comment.

Nil Einne (talk) 17:44, 11 August 2015 (UTC)

Maybe I underestimated the growth of video camera sensitivity. The eye is still logarithmic though not linear and has up to 10,000:1 contrast ratio so you'd need a big advancement in camera tech to make a moderate difference. There were only 5 classifications of star brightness per 2 orders of magnitude before the 1850s. A star could be right next to one that's 9.6% brighter and even an expert variable star observer could tell only with great difficulty.

I said it's been described as veined marble and bright enough to cast shadows (maybe that's only if the galactic nucleus is up and not low though?) so I'm wondering if he's seen a pristine sky if "a band of stars" is his description. I've heard that the center of the galaxy looks like steam pouring out of the Teapot (some stars in Sagittarius look exactly like teapot) and the summer Milky Way looks like a gigantic vulva (30 degrees wide) with cloudy bright labia and a long black rift in the middle. This is what the Central American civilization thought it liked like. It's a lot more than just the band of visible stars (the star clouds (technical name) are made of stars too dim to see individually). Sagittarian Milky Way (talk) 23:26, 11 August 2015 (UTC)

But again, you seem to be conflating different things. Cameras may very well have a poor dynamic range compared to the eye (although I think this is more the brain than the eye), but that tells us little about their best achievable sensitivity.

In fact I'm fairly sure the most sensitive video cameras would generally be used for other night scenes (like footage of nocturnal animals), and probably not used for recording the milky way (if they are used for the night sky, only for very dim stars). Incidently I suspect one big advantage they have is their ability to record wavelengths the human eye can't see.

The poor dynamic range does actually limit how you can use cameras including I think in the night sky case and the more you talk about it, the more it sounds like this is what you're referring to. And as I said the most sensitive cameras probably aren't even that useful for recording most night sky cases. But your original post seemed to imply that cameras aren't likely to be much more sensitive than the human eye which having researched and thought about it even more (albeit without finding any links I would consider great RS for this discussion), I'm fairly sure is wrong. You didn't initially say the eye had a poorer dynamic range or whatever else.

Also, I'm fairly sure you could improve the dynamic range of even real time video (as opposed to time lapse I mean, not as in viewed in real time) either by using multiple very close cameras with different sensitivites and post processing to combine them or by more complicated processing of specialised sensors.

This is already fairly common for daylight with photos and time lapse video, see High-dynamic-range imaging. It's a fair amount more complicated for realtime video. You can use specialised sensors and processing (e.g. [16] although this seems to be trying for real time in both sense), but I'm not sure this will give you the desired dynamic range, particularly for night sky situations where you may need different cameras since we may be looking at highlymore sensitive specialised ones. (Although as said earlier, I'm not sure how useful extremely sensitive cameras would be for record the night sky, I suspect they won't be that useful in the vast majority of circumstances. It may very well be more normal cameras with appropriate settings would be the best choice, particularly when recording the Milky Way.)

Using several cameras is likely to add even more complexity since they won't be in the exact same location (and if they are different cameras, their output may be different resolutions, sizes etc). [17] is one daylight example which used a beam splitter and the same kind of cameras. Alternatively, if you know the precise spacing of the cameras and ensure they are all angled correctly, you could probably develop you processing to account for this and still produce high quality videos.

AFAIK this is rarely done, probably amongst other reasons since time lapse with long exposured makes much more sense for most night sky situations. (Which is probably another reason why you'd rarely use the most sensitive cameras for recording the night sky.) But this doesn't tell us much about what you can do if you really wanted to. In any case, poor dynamic range is still seperate from sensitivity.

Nil Einne (talk) 13:55, 12 August 2015 (UTC)

Is there any way to isolate Citrulline from Watermelon ribs?

I understand that Citrulline is found in decent amounts on the Watermelon ribs.\

1. Can I isolate it somehow to make a powder or at least some kind of a concentration.
2. Can I do this in the house's kitchen? Thank you, Ben-Yeudith (talk) 20:01, 11 August 2015 (UTC)
3. What will be the best way to preserve it after I made it?

Thank you Ben-Yeudith (talk) 20:01, 11 August 2015 (UTC)

The modern watermelons here don't have "ribs". Do you mean rinds ? Or do you mean something like this historic watermelon that did have ribs: [18] ? StuRat (talk) 22:20, 11 August 2015 (UTC)

1. Yes 2. Probably not. 3. No clue. See Process for the production of L-citrulline from watermelon flesh and rind: http://www.google.com/patents/US8173837. Also interesting is Method of producing citrulline by bacterial fermentation: http://www.google.com/patents/US3282794 Justin15w (talk) 22:24, 11 August 2015 (UTC)

Yes, I meant to the rind...

Thanks, Ben-Yeudith (talk) 03:14, 12 August 2015 (UTC)

August 12

ROVs

What types of ROVs are used in maritime rescue work? 2601:646:8E01:9089:2C02:9BB5:5007:AC7 (talk) 00:43, 12 August 2015 (UTC)

The US Navy developed the Submarine Rescue Diving Recompression System for rescuing the crews of sunken submarines. Not sure if there are any other drone rescue craft actually in operation. A number of countries have been discussing the use of unmanned aerial vehicles to locate, but not rescue, victims of maritime disasters. Someguy1221 (talk) 02:00, 12 August 2015 (UTC)

Thanks! Any ROVs out there for saving drowning people? I'm making a game document for a co-op multiplayer rescue simulator, you see, and I want to know what types of vehicles I should include. The SRDRS will definitely be included, along with it's manned counterpart the Mystic-class DSRV (hey, where the hell did that article go -- it was there just the other day?!) -- any others I should put in there? 2601:646:8E01:9089:2C17:EABD:3104:7BA2 (talk) 05:43, 12 August 2015 (UTC)

DSRV-1 Mystic. Someguy1221 (talk) 07:17, 12 August 2015 (UTC)

NATO is working on the ICARUS search-and-rescue vehicle, and Israel has developed the Silver Marlin. The Silver Marlin was primarily developed as a weapon system, but is also advertised as a search-and-rescue vehicle. Googling "unmanned rescue boat" turns up a great many pages describing similar vehicles in development by public and private organizations, but I assumed you only wanted ones that actually existed. Someguy1221 (talk) 07:25, 12 August 2015 (UTC)

Thanks a million, once again! Yes, I want ROVs which either exist in real life or at least have their detailed designs finalized, and it doesn't really matter if they are designed for something else, as long as they have a solid search-rescue capability. Now, one last question: On How It's Made, in the "Underwater Robots" episode, they showed the manufacture of a robot which can actually submerge and recover drowning victims from underwater -- anyone happen to know the model name? 2601:646:8E01:9089:2C17:EABD:3104:7BA2 (talk) 07:40, 12 August 2015 (UTC)

Regarding how it's made, I'm not sure what the model number was, but the submersible they showed was built by SeaBotix. Maybe that will help you track it down. Someguy1221 (talk) 07:55, 12 August 2015 (UTC)

Thanks once again! 2601:646:8E01:9089:2C17:EABD:3104:7BA2 (talk) 10:51, 12 August 2015 (UTC)

Chemical composition of liquid paraffin (medical type)

I'm trying to find out the chemical composition of liquid paraffin. Apparently the medical type is distinct from the type used as a fuel. In particular I'm interested in the range of lengths of the carbon chain. --78.148.104.21 (talk) 17:18, 12 August 2015 (UTC)

Our article on this substance-application is Liquid paraffin (medicinal). DMacks (talk) 17:29, 12 August 2015 (UTC)

...and neither it nor the parent Mineral oil article on the family of substances covers typical chain-length for various purposes:( It's certainly a pretty large chain, given vapor pressure is negligible and flash point is >180°C (per its MDS). If you have a list of alkanes, knowing the density is 0.845g/mL might give you an approximate length. DMacks (talk) 17:35, 12 August 2015 (UTC)

This links says chain lengths between C14 and C30. https://books.google.com/books?id=vPUOgqtxd-kC&lpg=PA778&ots=iQyfO1eFFe&dq=paraffinum%20liquidum%20carbon%20chain%20length&pg=PA777#v=onepage&q&f=false Justin15w (talk) 22:00, 12 August 2015 (UTC)

How big was the Chernobyl explosion?

How big was the Chernobyl explosion? E.g. in terms of TNT tonnage or something else? I know it wasn't a nuclear detonation. --78.148.104.21 (talk) 23:19, 12 August 2015 (UTC)

Doesn't look all that big considering it was nuclear. According to this site (which has a little bit of a commercial interest), maybe 300 tons of TNT. This source and this source both says about a tenth of that. 30 to 40 tons seems a safer bet, with 300 being exaggeration or a typo. Ian.thomson (talk) 23:27, 12 August 2015 (UTC)

EDIT: Double checking, the source I've scratched out is self-published. That said, the one I've bolded is from Infobase Publishing, so I'm gonna say that their figure of 40 tons (36 metric tons) is accurate. Ian.thomson (talk) 23:29, 12 August 2015 (UTC)

It was not "nuclear" at all in the sense of being a nuclear explosion. It was a steam explosion of the reactor. The idea that nuclear reactors can explode like nuclear bombs is an extremely common misconception. The effects of the Chernobyl disaster were from the breach of the reactor and the resulting fire, which spewed the radioactive fission products around. --108.38.204.15 (talk) 23:59, 12 August 2015 (UTC)

Actually our article (Chernobyl_disaster#Experiment_and_explosion) gives a 10 ton-equivalent nuclear "fizzle" as one of four possible causes for the second explosion. Rmhermen (talk) 03:12, 13 August 2015 (UTC)

This is a photo of the power plant from two years ago. There are so many trees now that it is hard to see it. You can see that there was certainly no 300 megaton explosion because it is not reasonable to believe that the woodland animals rebuilt all the power station buildings after the humans left. 209.149.114.32 (talk) 13:47, 13 August 2015 (UTC)

Who knows? Maybe the radiation exposure created a race of hyperintelligent squirrels who are rebuilding the plant to power their civilization...--Jayron32 15:03, 13 August 2015 (UTC)

August 13

Melanin and light absorption

According to melanin, it's able to dissipate over 99.9% of absorbed UV radiation. However, dark colors absorb more light compared to light colors. To what extent melanin offsets more intense light absorption by dark skin and dark hair when compared to light skin and light hair colors? And to what extent black hairs and skin heat up more than their light colored equivalents? Brandmeister^talk 13:31, 13 August 2015 (UTC)

Some good info in these freely accessible articles - "Optical properties of human skin" [19], "The evolution of human skin coloration" [20], "Spectroscopic characteristics of human melanin in vivo" [21]. SemanticMantis (talk) 14:00, 13 August 2015 (UTC)

(edit conflict) "dark colors absorb more light compared to light colors": This is true, but UV is not visible light, and low absorption at visible wavelenghts does not always coincide with low absorbtion of UV. According to this article: (Reflection of ultraviolet radiation from different skin types) "Skin types with moderate sensitivity to solar radiation, neither too pale nor too tanned, reflect the greatest UVR."

Also of interest: The Optics of Human Skin (freely available as pdf). It has a remittance spectrum of two different skin types (light and dark). You can see for UV wavelenghts (below 400 nm) total remittance is always below 30%, so at least 70% of UV light is absorbed, even for Caucasian skin type. Hence I think we can safely say that dark skin is more effective at dealing with UV radiation, even considering that it does not reflect as much as light skin. - Lindert (talk) 14:17, 13 August 2015 (UTC)

If an alien contacts you and ask what's a kg

How would you tell an alien, who's not on Earth, how to measure a kg?--Scicurious (talk) 14:08, 13 August 2015 (UTC)

5.97470 x 10²⁶ hydrogen atoms. Looie496 (talk) 14:13, 13 August 2015 (UTC)

And why don't we uses Looie's definition above, instead of still defining the kg according to an artifact?--Scicurious (talk) 14:26, 13 August 2015 (UTC)

Because while that's a good definition for some purposes, it also has many problems. Because the CIPM is very careful, and these things take time. We don't want international standards to change quickly. Metrology is hard, and there are seldom easy answers.

Anyway, see Proposed_redefinition_of_SI_base_units, and here [22] particularly on the current work to redefine the Kilogram. They are actually hoping to do it in terms of the Planck constant, see here [23], involving a Watt balance. For more on this, search /electronic kilogram/, which also leads us right back to NIST - [24] SemanticMantis (talk) 14:40, 13 August 2015 (UTC)

What school is this homework coming from? It is MUCH more interesting than my physics homework! 209.149.114.32 (talk) 15:10, 13 August 2015 (UTC)