Wikipedia:Reference desk/Archives/Science/2010 June 11

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June 11

hollow core door

is the vanear of a hollow core door made from solid real wood or plywood or MDF ? —Preceding unsigned comment added by Alexsmith44 (talk • contribs) 02:36, 11 June 2010 (UTC)

It could be real wood or it could be some sort of plastic material. There's lots of different types of construction. By definition, a veneer is usually a singly ply, so something like MDF (basically high quality particle board) wouldn't hold up, and ply wood is basically multiple veneers pasted together. But there are real wood veneers, and there are plastic veneers made to look like wood to various degrees. --Jayron32 03:06, 11 June 2010 (UTC)

its not plastic its some kind of wood. how do i tell if its MDF or plywood or solid real wood —Preceding unsigned comment added by Alexsmith44 (talk • contribs) 03:19, 11 June 2010 (UTC)

If it's a hollow core door, it will not be "real" wood in the sense that it's a series of sliced pieces of wood in a single layer. Rather, it can be plywood, MDF or hardboard. Most flush hollow-core doors are faced with plywood with Philippine mahogany, or "lauan" as the face sheet. It will show a slight texture and grain . MDF or hardboard will be smooth and grainless, with hardboard being, well, harder and slicker. The interior of the door usually contains a cardboard homeycomb spacer. Acroterion _(talk) 03:28, 11 June 2010 (UTC)

so if it is a single ply plywood does it have formaldehyde resin on it ? —Preceding unsigned comment added by Alexsmith44 (talk • contribs) 04:02, 11 June 2010 (UTC)

There are no single-ply plywoods - plywood has at least three plies. That said, it might have formaldehyde resin in it,depending on when and where it was made. Recent plywoods in North America usually don't use formaldehyde resins for interior applications. Acroterion _(talk) 13:51, 11 June 2010 (UTC)

Katla eruption VEI

Hi. If Katla were to erupt in the near future, what scale would it fit on the Volcanic Explosivity Index? Would the effect of a subglacial eruption increase its explosivity? Also, would it release more ash than Eyjafjallajokull did? Thanks. ~AH1^(TCU) 02:43, 11 June 2010 (UTC)

It is literally 100% completely impossible to predict. Scientists have been able, for 25 years or so, to roughly predict when some volcanoes will erupt to within a few weeks, once they start showing signs of activity. However, there is no reliable way to predict the size of an eruption before it happens, especially for volcanoes which are not currently active.. We can look at the relative sizes of past eruptions, but for a completely inactive volcano, it is someone less accurate to predict than throwing darts at a board blindfolded. Indeed, recent eruptions of Katla have been so small as to be barely detectable, according to the article and its sources. --Jayron32 03:02, 11 June 2010 (UTC)

Sure they are impossible to predict with any certainty, but I think that they are 100% impossible to predict is a little strong of an argument. I'm sure a thorough geologic and seismographical study of the area could at least make some conclusions about how it would erupt (VEI potential, mode of eruption, etc.); someone correct me if I'm wrong though. -RunningOnBrains^(talk) 04:40, 11 June 2010 (UTC)

I see your motivation, as listed in the article, being that Katla is extremely active and Icelandic authorities are already preparing for a sister eruption. In that case, I'd suggest that they're preparing for something similar to, say, the 1918 eruption and other historical eruptions, which are detailed in one of the citations for the main article. See the left-hand menu for a list of further information on historical Katla eruptions. SamuelRiv (talk) 05:21, 11 June 2010 (UTC)

Energy numbers to open a black hole

I'm not a physicist by any means, so I might be completely wrong here, but I know if enough energy was collected, a black hole could be created (a lot of time travel stuff I've heard talks about this). I recall a friend of mine once said that they would at least need the energy inside the sun to achieve this sort of thing. But how much energy would you need to actually accomplish this? If I had a giant battery the size of a planet, how many watts or horse power or some other measurement would I need to fill it to do this?  ?EVAUNIT^{神になった人間} 05:16, 11 June 2010 (UTC)

Hi there, this is a terrific exercise for a student. You may have heard of escape velocity, which the moon rockets had to exceed to break free of Earth's pull. There is something called the Chandrasekhar limit which determines the mass and radius of a black hole after its formation. That is, when a star explodes, if it's remaining core is way too heavy (about 3 times the mass of the sun), then it collapses into a black hole. A black hole is so dense that light cannot escape.

Now here's where we get to do real physics. In the escape velocity article, we see that the velocity is ${\sqrt {2GM/r}}$, where G is the gravitational constant (the strength of gravity in human units), and M and r are the mass and radius of the object we're escaping from.

What you want is the energy density needed to make a black hole. Density is just mass over volume, energy density is energy over volume, and in the world of outer space, we can always say E=mc^2 to tie them together. For a black hole, the "blackness" starts where light can't escape - that is, where the escape velocity = c, the speed of light, so let's rearrange the escape velocity equation to solve in terms of energy (mass*c^2): $E=rc^{4}/2G$ and $e_{density}=3c^{4}/(8\pi Gr^{2})$. The energy density is just energy divided by the volume of a sphere, 4/3 pi r^3.

Almost done now. We want to create an extremely small black hole with a usable amount of energy. Note that we'd need a lot less energy density to make a big black hole, but a lot more energy itself to make it big. We want to find a nice stable point in there, and unfortunately not a whole lot of Earthly machinery can reach that point. We can create a lot of energy but it needs too much time - we can't cram it all in there. Big colliders like the LHC are able to pack energy into extremely small spaces by colliding beams of particles at each other. The energy level in the impressive-sounding TERA-electron-volt collider is actually comparable to that of a bug accidentally flying into a window, and so plugging that into the equation for energy, we see the size (radius) of the black holes they'd like to obtain: r = 10^-39 meters. So that's a wee bit impossible (see Planck length), but the nice thing about quantum mechanics is that on those scales, impossible things always have a chance of happening. Anyway, you now have the numbers to plug in to see how much energy you need and how much you need in one place at one time (density) to have a similar possibility of creating a black hole as the pride of physics, the LHC. Does it help? Probably not. Is it neato? You betcha! SamuelRiv (talk) 06:03, 11 June 2010 (UTC)

Oh, actually, I can answer your original question without going through the last steps above. Take that first equation for energy. Power is energy per time (like watts are joules-per-second), and on these scales we can make a neat little guesstimate that the speed needed to make the hole is the speed of light (makes sense), so time = radius divided by c. Therefore, we take energy over radius*c, and get $P=c^{5}/2G$, which is a constant so P = 2.5 * 10^18 W. That's 2.5 billion billion watts, or 3.3 million billion horsepower. That's a lot of horses! SamuelRiv (talk) 06:18, 11 June 2010 (UTC)

SamuelRiv, what you wrote makes little sense to me. It's well known that you get the Schwarzschild radius if you set the Newtonian escape velocity equal to c, but it makes no sense theoretically to do that, so it doesn't seem like a very good exercise. You can combine c and G to get a quantity with units of power, but the relationship to making black holes is unclear to me. (Incidentally, c⁵/2G = 1.8×10⁵² W.) The people who talked about making black holes at the LHC were assuming large extra dimensions, which would make calculations involving G meaningless in that context (and the whole thing is wildly implausible anyway).

To the original poster: I think you're confusing science fiction with reality. Realistically, we can't make black holes. Unrealistically, I suppose the energy required would be the energy of the black hole, and black holes can have any energy... -- BenRG (talk) 21:01, 11 June 2010 (UTC)

Oh come onnnn Ben, using escape velocity is a common exercise for this kind of thing and gives a back-of-the-envelope guesstimate (a word that I used right in the beginning). And... black holes can't have any energy? I mean, my GR isn't great, but there is an equivalence to how mass and energy change the metric. SamuelRiv (talk) 07:50, 12 June 2010 (UTC)

BenRG's point is that yes, there is a relationship between mass and energy, and since there is no minimum mass necessary to form a black hole than there is also no minimum requirement of energy to form a black hole.

I also second his point that your answers weren't very helpfull.

174.58.105.234 (talk) 21:47, 12 June 2010 (UTC)

The problem here is not the energy but rather how to compress matter or concentrate energy to within its Schwarzschild radius. So, if you have a 10 km diameter asteroid, then how are you going to compress it to its Schwarzschild radius of about 10^(-12) meters. The energy contained in the asteroid comes free of charge, just pick one up. Count Iblis (talk) 01:01, 13 June 2010 (UTC)

if someone is scared into not riding in automobiles OR scared into not smoking, which would improve their mortality more?

So here is a scenario where someone is both a light smoker and an regular car driver/passenger: if they could be scared, by looking at car accident OR tobacco-related illness statistics, into either TOTALLY refusing to step into a car anymore (instead living locally, riding the metro, trains, etc) OR totally quitting the light smoking, respectively, then which one would improve their mortality rate more? We are talking about the average everyman, and I don't have an answer or am not pushing an agenda: I would just like to know how the two mortality rates compare. Thank you. 92.224.207.140 (talk) 09:00, 11 June 2010 (UTC)

I did a bit of fishing around for statistics. Obviously it depends where you live, but in the USA, for instance, it seems that in 2003-2004 the death rate in car accidents was about 14.75 per 100,000 head of population [1] whereas death from smoking-related illness ran at 263 per 100,000 [2]. This is a very crude comparison and doesn't take into account, for example, deaths among passive smokers or pedestrians hit by cars, which are still a risk for those who have themselves given up car travel or smoking. However, it would appear that stopping smoking is a more dramatic risk-reduction strategy, on paper anyway. Karenjc 11:27, 11 June 2010 (UTC)

If you stop driving in cars, you'll probably still have to get yourself to and from places. So you'll switch to riding the bus, the subway, a bike, walking, etc. All of these carry different degrees of risk. (I imagine that in an american city riding the subway is basically 100% safe, while biking can be quite dangerous, but biking is a lot safer in most European cities.) These risks would be very hard to estimate and would vary dramatically based on the specific setting. Quitting smoking doesn't involve "switching" to other risky behavior (unless you start overeating or drinking or etc). So this'll make it even more beneficial to stop smoking. Staecker (talk) 11:57, 11 June 2010 (UTC)

Your personal driving risk will also depend on the number of miles you drive, and where you are driving. Someone who drives 4 miles, once a week is going to be in a lot fewer accidents then your sterotypical rural salesman who might drive 500+ miles a week. The same thing can be said with smoking. Someone who smokes 4 packs a day is going to have a higher risk level then someone who smokes 1 cigar every night. Googlemeister (talk) 13:07, 11 June 2010 (UTC)

Infra-terrestrial species

Lets first start with what I mean by 'infra-terrestrial'

An 'infra-terrestrial' species, is :

• An inteligent non human-species (although the inteligence need not be comparable) that has developed complex social patterns (such as worker specialisation. ) within it's own species and it interaction with the wider ecosystem.

Which species on earth could qualify for 'infra-terrestrial' status, or do I need to provide a better definition?

Sfan00 IMG (talk) 09:05, 11 June 2010 (UTC)

Eusociality mentions ants, bees, wasps, termites naked mole rats and Damaraland mole rats. Staecker (talk) 12:01, 11 June 2010 (UTC)

It all depends on definitions. You could include, for example, lions. They are pretty smart, they live in complex social groups (prides) and have a division of labor when it comes to hunting - which is an interaction with their wider ecosystem. Rockpocket 13:14, 11 June 2010 (UTC)

Well, it's going to depend on what you mean by "intelligent". Dolphins are probably your best bet - they are generally considered to be one of (if not the) most intelligent non-human species and they live in very complex social groups each with their own language and culture. --Tango (talk) 19:34, 11 June 2010 (UTC)

Meerkats have pretty clear specialization of roles in their 'mobs' - sentries, child-care workers, tutors, foragers, etc. SteveBaker (talk) 15:56, 12 June 2010 (UTC)

Euscociality, Thanks , I knew there must be a term for it... The question was prompted by someone asking about SETI a couple of days ago. I wondered what the 'Aliens' already on earth might be  :) Sfan00 IMG (talk) 20:46, 11 June 2010 (UTC)

Gyromagnetic ratio of mesons

Hello all. Would anybody know where I can find data on gyromagnetic ratios/magnetic moments/g-factors of mesons? I find everything about nucleons, electrons and muons, but that's about where it stops. Even the Particle Data Groups is silent about it. Or is there any reason why it is not possible to measure/define this? MuDavid (talk) 09:12, 11 June 2010 (UTC)

Sentience/consciousness

Besides humans, which animals are sentient/conscious? --76.77.139.243 (talk) 12:59, 11 June 2010 (UTC)

I think this question pivots on how consciousness is defined. Bus stop (talk) 13:04, 11 June 2010 (UTC)

How do you know that humans are sentient/conscious? You know that you are, but I don't know that you are (cogito ergo sum). Would a sentient race massacre their own kind for no reason other than they are different, or pump poison into the planet that supprots them, or build weapons that could kill billions of ppl? 76.230.7.123 (talk) 13:06, 11 June 2010 (UTC)

Sentience#Animal rights and sentience and the links therein may give you some idea on the different opinions out there. Rockpocket 13:09, 11 June 2010 (UTC)

We don't have a good scientific test for Sentience. However, "Self Awareness" is usually thought to be a requirement of sentience. So you might want to check out Mirror Test, which is the best test for Self Awareness we've got. (However it is far from perfect.)

Humans, Elephants, Bottlenose dolphins, Great Apes, and possibly magpies and Orcas all pass the Mirror Test APL (talk) 14:31, 11 June 2010 (UTC)

That's mirror test. Interesting/thought-provoking aspects of this test are that human babies under about 18 months of age fail it, whereas pigeons can be trained to pass it. Gandalf61 (talk) 14:45, 11 June 2010 (UTC)

Yes that is interesting, Pigeons seem to be good at those sorts of visual processing games. I've heard of experiments where they're used to visually inspect manufactured items for quality control purposes. And they can be trained to pilot missiles at enemy ships!

I wonder if all birds can do that sort of thing, or whether it has to do with pigeons' extraordinary homing ability. APL (talk) 15:14, 11 June 2010 (UTC)

Pigeons have to be trained to pass it. The test of sentience is whether an animal can pass the mirror test without training. --76.77.139.243 (talk) 15:57, 11 June 2010 (UTC)

Of course. To prove 'self awareness' it has to be intuitive. But it's still interesting that pidgeons can be trained to pass. APL (talk) 16:00, 11 June 2010 (UTC)

Indeed. If pigeons can be trained to pass the mirror test, whereas sentience is usually assumed to be innate, then it calls into question whether the mirror test is actually testing sentience. It's like the question of whether IQ tests actually test intelligence or simply test aptitude at passing IQ tests. Gandalf61 (talk) 16:04, 11 June 2010 (UTC)

You can train most animals to do just about anything in their physical capacity, similarly to Chinese room. The test of sentience would be whether you can do the task successfully without preparation of any kind; the same is true of IQ tests and intelligence. --76.77.139.243 (talk) 16:14, 11 June 2010 (UTC)

But, in that case, are toddlers self-aware? They've spent 18 months being casually trained ("Who's that in the mirror? Can you see Daddy? And Mummy? And Billy?") until the point they start responding as we expect. Is that really intuitive? 86.164.69.239 (talk) 22:06, 11 June 2010 (UTC)

Toddlers are probably not self-aware. They fail other cognitive tests, so why not tests for self-awareness? But you seem to be asking if they grow up to be self aware. Yes, because not all human being grow up around mirrors, but adults can figure out how they work without too much trouble. Because humans have an understanding that we ourselves are a human being living in the world, just like everyone else. As opposed to, say, a dog, which might have an understanding what a dog is, but doesn't comprehend the idea of a self, so it doesn't even understand the possibility that he himself might also be a dog.

Training something to specifically pass the test is much easier. The pigeon doesn't have to understand that it is a pigeon, or that it is seeing its own reflection. You just have to teach it that if the bird in the mirror has a spot on its beak, you perform some pre-defined action. You could probably train it just as well with pre-recorded videos of a baboon. Teaching a pigeon to pass the mirror test is like teaching someone the answers to an IQ test. You haven't made them smarter, you've just increased their score on the test. APL (talk) 22:21, 11 June 2010 (UTC)

Actually... In my anthropology class, we learned that there was evidence that a dog could be aware of the fact that not only is it thinking, but the dogs/people around him are too. I don't know how to explain that concept better, but that awareness of self and others is a theory as to why humans are compelled to communicate thoughts whereas chimpanzees are not. Interestingly, wolves are not believed to be aware in the same way that a dog is. I am thinking this is relevant to the discussion, because to identify sentience of oneself would (I would think) have to be a prerequisite for identifying the sentience of others. 65.87.167.166 (talk) 00:19, 12 June 2010 (UTC)

, What evidence? I'd be interested in knowing, I thought that the mirror test was the only widely accepted test for this sort of thing, even with its flaws. The Wikipedia article supports that view, but perhaps it's missing whatever research you're talking about? APL (talk) 04:26, 12 June 2010 (UTC)

To be clear, the Mirror test does not test sentience. It tests "Self awareness" which is a component of sentience. APL (talk) 18:29, 11 June 2010 (UTC)

It's a pretty terrible test - if it works and the animal passes the test - then it shows...something. But if an animal "fails" the test, it could just be that the animal doesn't care - or that the animal has other senses that are not fooled by the mirror. Think of this from the point of view of (say) a dog: The blurry monochrome image doesn't smell like a dog...the end. From the point of view of a shark: The blurry image doesn't emit electrical pulses from muscular activity that can be picked up from your lateral line...so it's not relevent. Those animals could easily be self-aware, but simply not care about your wildly unrealistic tests. On the other hand, I could easily write a computer program for a robot that could detect it's own reflection - measure changes between images taken on consecutive visits past the mirror and react to differences accordingly. The robot would clearly not be "self-aware" in any interesting fashion...so even a positive reaction to a test doesn't actually 'prove' anything. Since neither a positive nor a negative result actually proves anything much - the test should be treated with appropriate amounts of skepticism. SteveBaker (talk) 15:38, 12 June 2010 (UTC)

Well, computers could pass just about any cognitive test if the specific criteria of the test are designed into the software, that doesn't prove anything. If I knew the questions on an IQ test, I could program a computer to fill in the scantron ovals flawlessly. That proves nothing about either computers or IQ tests.

And, obviously, the test will give false negatives, even after you augment the mirror with olfactory cues. It's the positives that are interesting. (Although some animals clearly fail. Parakeets, for example.) APL (talk) 01:08, 14 June 2010 (UTC)

P.S. Don't dogs have bichromic vision?

Assuming the validity of the strong AI assumption, the answer is in principle contained in the algorithm that describes the animal. Count Iblis (talk) 16:12, 12 June 2010 (UTC)

I think all animals are sentient. Just that we, in our limited intelligence dont realise it. —Preceding unsigned comment added by 78.100.32.20 (talk) 10:50, 13 June 2010 (UTC)

Spoof SETI

How hard would it be to spoof SETI? I mean something like putting a satellite in geostationary orbit (or approximately anyways since the SETI equipment is not at the equator) and sending extremely low power transmissions back to them? Googlemeister (talk) 13:25, 11 June 2010 (UTC)http://en.wikipedia.org/w/index.php?title=Special:UserLogout&returnto=Wikipedia:Reference_desk/Archives/Science/2010_June_11&returntoquery=action%3Dedit%26section%3DT-9

It would be trivial to determine the origin of any transmission from an object orbiting Earth. It would be only slightly less trivial to determine the origin of any signal from within tens of light years. So no, nobody is going to spoof SETI. — Lomn 13:30, 11 June 2010 (UTC)

I should explain a little bit. Any local signals can have their origin determined by parallax. In the case of Earth-orbit signals (and probably for anything within the main solar system), two receivers on opposite sides of the Earth create sufficient parallax to determine where a signal comes from. That would take a matter of hours, at most, to determine. For large distances (up to 1500 light years, give or take) you need up to six months, allowing the diameter of Earth's orbit to serve as the baseline. The only way you could "spoof" SETI would be to recreate the Wow! signal, which didn't last long enough to allow for more than one observation -- but since there wasn't more than one observation, SETI doesn't treat that as anything approaching a positive hit. So no spoof. — Lomn 14:08, 11 June 2010 (UTC)

Also, to be clear, large radio telescopes and arrays of telescopes have a small beam—they only "see" a small part of the sky at once, just like a large optical telescope only sees a small part of the sky at once. They're not going to detect any random signal sent to them, like a transistor radio would. They have to be pointed at the transmitter. -- Coneslayer (talk) 14:21, 11 June 2010 (UTC)

As an aside, anyone who has the enormous money and means to try place a satellite and attempt to fool SETI has a whole lot of more interesting things to do with their time and treasure. Richard Avery (talk) 16:05, 11 June 2010 (UTC)

That's not as true as it once was. Some tiny satellites are theoretically within the range of a middle-class individual. They wouldn't go into geostationary orbit, though, they'd be in much less desirable low-orbit locations. (You couldn't really run a con with a geostationary satellite anyway. They're too high-profile.)

If you can fit your SETI hoax into a satellite the size of a coke can, here's a launch option that might even fit on your credit card : [3] APL (talk) 22:34, 11 June 2010 (UTC)

Yes - but let's be really clear: SETI have comprehensive procedures that allow them to easily eliminate signals coming from airplanes and spacecraft within roughly the orbital distance of the moon. Beyond that - if a believable signal came from further away, they'd need to observe it for a while to be utterly sure that it was not something within the solar system, etc. Their processes are really meticulous - you couldn't 'spoof' them - it's just not remotely reasonable. (On the other hand, those coke-can sized satellite thingies are awfully interesting.) SteveBaker (talk) 15:24, 12 June 2010 (UTC)

You could fool them for a while if you know those comprehensive procedures well enough, though. Pick a SETI listening station and find out what station they use to corroborate signals and check the parallax. Then you use two unidirectional transmitters sending the same signal, with the appropriate phase difference, from two different blimps (or similar). The difference in the locations of the blimps would (if you calculated it right) look like the parallax from a signal several light years away. It wouldn't fool them for long (they would just need to check with a third listening station, which they would do very quickly), but you would cause a bit of excitement for a few minutes. --Tango (talk) 02:25, 13 June 2010 (UTC)

For the sake of answering this question, let's lump all of SETI into one category: "radio signal analysis." (Needless to say, there are other branches of SETI, but this is the most relevant to the question). Now, as you probably know, one of the most fundamental, oldest, and simplest techniques for analyzing radio signals is to detect the range and location of the source. Give the SETI guys some credit - if they detect a signal, don't you think they will attempt to determine where it came from? There are a lot of spoofs you could play - you could, for example, throw some electronic countermeasures technology on your satellite, (like a stealth aircraft), and try to fake your position - but it's much harder than you might think. Once the signal is analyzed from two or more stations, it will become obvious that your spoof signal is being injected from here on Earth. Nimur (talk) 01:37, 12 June 2010 (UTC)

I think the main problem is that no object in the solar system can stand still because of gravity (except maybe a solar sail), so seen from the earth it would have the wrong apparent angular velocity. This is especially true for earth orbiting satellites (for example an geostationary satellite will appear to stand still in the sky, any real signal is expected to rise once each 24 h just like the stars.). It will is a litebit harder if the source is in solar orbit, for a real world example see http://www.youtube.com/watch?v=WPprykBiIgg at 4:00 to 5:40, they are confused by signals from the SOHO solar orbiting space probe for 16 h.(He calls it a satellite but it is not.)

I think it would be very hard to spoof signals from outside the solar system by a transmitter in the solar system without manipulating the equipment used by several independent research groups. Of curseee it is easier to spoof extraterrestrialialial probe (http://en.wikipedia.org/wiki/SETI#Probe_SETI_and_SETA_experiments) but probably the spacecraft will be traced from launch so it will not be able toNASAl Nasa and others.Gr8xoz (talk) 20:21, 14 June 2010 (UTC)

Etching on the cheap

I'm an artist and I want to experiment with etching, so today I've been rounding up some equipment. I bought some ferric chloride from an electronics shop (they use it for etching circuit boards). Finding a cheap source of suitably-sized pieces of sheet metal was difficult: my current best option is some baking trays. These are "traditional tin plate", so I presume they're the same as tin cans, i.e. made using a tinning process. My plan is to paint the tray with "ground", engrave the image, pour in the ferric chloride, and when it is beautifully etched, print off a few copies by means of ink and paper and rubbing with the back of a spoon. What I want to know is:

1. Am I making a stupid chemical mistake which will create a cloud of poison gas?
2. What's a cheap supermarket-bought substance that might work as a "liquid hard ground"?

213.122.46.177 (talk) 15:53, 11 June 2010 (UTC)

1. No poison gas - (I'm not sure if ferric chloride will etch tin - but probably will). I'm nearly 100% certain than baking trays are not tin plated though.. You can get brass or copper sheet online (prices seem to be ~5£ (8$) for a small sheet). There's probably a cheaper way of getting etchable metal sheets - maybe "copper clad board" for pcb making would be suitable - they're cheap.

2. As a guess - nail varnish , don't forget the nail varnish remover - again online you can buy the remover very cheap as acetone. Possibly other forms of varnish ( eg wood varnish/lacquer) may be suitable.87.102.13.41 (talk) 17:21, 11 June 2010 (UTC)

You'll probably like this http://www.ganoksin.com/ftp/edinburg-etch.pdf not only does it describe ferric chloride etching - but has instructions on making grounds too. Acrylic paint might also be good - you can dissolve this using methanol, or acetone, or MEK amongst other methods.87.102.13.41 (talk) 18:01, 11 June 2010 (UTC)

Windmill on a car ?

How feasible is the idea of fixing a windmill like arrangement on a car, to generate some electricity, so as to say charge up the battery a little or power up the AC ? Is the idea worth giving an experimental trial ? Rkr1991 ^{(Wanna chat?)} 16:32, 11 June 2010 (UTC)

The laws of thermodynamics say it's not practical, assuming you mean you want to use the "wind" of the air staying in place as the car moves forward to spin the windmill. The extra energy needed to overcome the drag produced by the windmill and move the extra weight would be greater than the power produce because of inefficiencies. If you mean parking your car in a windy area and doing something for a while, then coming back and folding your windmill into your trunk or something before you leave, that's a different story. 76.229.205.199 (talk) 16:37, 11 June 2010 (UTC)

(ec)It depends. Putting a small windmill up there to take advantage of the wind when the car is not moving might be useful, to keep a battery topped up or even that car cold or warm without burning fuel. But if you want to utilize the air flow generated by the cars own movement, then no, its a waste of energy. Its less efficient than directly using the car's alternator. --Stephan Schulz (talk) 16:39, 11 June 2010 (UTC)

Your windmill idea is used already by airplanes, though — see Ram air turbine — but this is to generate power if all the engines fail, not to try and boost efficiency. Comet Tuttle (talk) 16:42, 11 June 2010 (UTC)

A turbocharger essentially uses the "wind" generated by expelled exhaust gases to improve the efficiency of the car engine by generating additional compression. The turbine in a turbocharger is not functionally different than a windmill. It just sits in the exhaust path inside the car rather than in the air outside of the car. --Jayron32 19:29, 11 June 2010 (UTC)

These are often used on yachts. It may harvest energy from the wind, as I expect cars spend most of 24 hours stationary, even though it would increase the drag of the car and hence increase the amount of fuel used. 92.15.25.9 (talk) 21:18, 11 June 2010 (UTC)

I actually saw on the freeway south of San Francisco a car with what seemed to be a wind turbine attached to the roof. Later I saw several of them in a parking lot at Google's Mountain View campus. I didn't investigate further, but now I wish I had because my web searches aren't turning anything up. My immediate reaction when I saw it was "that's ridiculous", but after thinking about it some more I'm not so sure. A turbine can obviously give you a net gain when the car is parked and there's a breeze, and it's not clear to me why that would cease being true if the car was moving. The air-ground speed differential exists independently of the car's motion. -- BenRG (talk) 22:40, 11 June 2010 (UTC)

Here's a proof of concept: a purely wind-powered vehicle that can travel downwind faster than the wind. -- BenRG (talk) 23:17, 11 June 2010 (UTC)

Going faster than the wind is used on sailboats, by the way, basically by keeping constant wind at an angle to the direction of motion so that some wind is always hitting your sail on the side. SamuelRiv (talk) 07:58, 12 June 2010 (UTC)

Thanks for a fascinating link. It proves that energy can still be obtained from the wind when moving downwind faster than the windspeed, but I would question whether the small amount of energy that can be obtained in this way will significantly affect fuel consumption. I would guess that most of the extra energy would be lost in an inefficient transmission and in extra drag from the supporting structure. Has anyone done any trials? Dbfirs 08:29, 12 June 2010 (UTC)

There actually is at least one example of a vehicular power system that used the energy of the vehicle's motion to produce electricity (for lighting etc.) as a normal mode of operation. The generator was driven by the wheels, not a windmill. I'm talking about passenger train cars. Today the electricity they need is generated on the locomotive ("head end power") and a set of wires runs through the train. But the steam locomotives that trains used to use didn't have generators on them, so the cars were provided with the wheel-powered generators instead. (There were batteries that provided power when the train was stopped and recharged from the generator when it was moving again). Similarly, train heating was provided by steam from the locomotive -- if these cars were used with a diesel locomotive, the train had to carry a boiler to generate steam for heating. --Anonymous, 10:40 UTC, June 12, 2010.

• Correct me if I'm wrong, but I think some of the above answers seem to be a little confused..... There is most certainly going to be a drag as the car moves forward, and with respect to the car, a breeze flowing in the opposite direction. My idea is just to use that breeze to power a battery, energy which would have been wasted otherwise. I don't see why any laws of Thermodynamics would prevent me from getting useful energy out of this, despite the inefficiencies, and I also don;t see how the situation changes when the car is still or in motion..... With respect to the car, it's just the same, right ? As an extrapolation, how would the idea work, if applied to say trains, with rows of windmills on behind another on top of the train, all generating a little electricity ? Rkr1991 ^{(Wanna chat?)} 12:06, 12 June 2010 (UTC)

The breeze you feel when you move through still air, and the force that breeze might exert on a windmill, are examples of drag. It's just another way that your car would be less aerodynamically shaped. The more sources of drag there are, the harder the engine has to work or the slower the car would move than it would otherwise...i.e., your car becomes less energy-efficient at driving. So you use more fuel to drive the same speed--there's your added energy cost. The gain is that you can get some energy out of the windmill. But you will get less energy from the windmill than you put in as extra fuel (the engine->rolling-friction->air-turbulence->windmill->generator-friction all involve losses of efficiency). DMacks (talk) 14:53, 12 June 2010 (UTC)

Rkr1991, haphazardly adding windmills to a moving vehicle is unlikely to help matters, because it will add a lot of drag. But DMacks, I don't think there's a straightforward thermodynamic argument that windmills must be a net loss, and I don't even think it's true. For one thing, if the air is moving relative to the ground then energy can be extracted from that differential by a vehicle moving at any speed in principle. And even if the air is stationary relative to the ground, I see no reason why adding windmills coupled to the drive train in some way couldn't reduce your net loss to friction. Drag doesn't add linearly. I can't even see how to prove that adding a windmill in a carefully chosen location couldn't reduce the overall drag, even if you don't recover any power from the windmill—it seems very unlikely, but not obviously impossible. In fact, wouldn't a proof along those lines be worth a million dollars? -- BenRG (talk) 21:30, 12 June 2010 (UTC)

Per "with respect to the car, a breeze flowing in the opposite direction", I assumed the air current we're talking about--the air motion that would drive the windmill on the car, relative to its frame of reference--was due to that car motion. If there's additional air motion (actual weather/wind) relative to the ground, then you could recover that just as for a stationary windmill mounted on the side of the road. DMacks (talk) 22:11, 12 June 2010 (UTC)

Let's say I am able to somehow position the windmill such that it doesn't add tp the drag. First of all, is this possible? Second, If I do, will I now be able to get useful energy out of it ? Rkr1991 ^{(Wanna chat?)} 03:03, 13 June 2010 (UTC)

No, it's not possible! That's exactly the point. In effect this is converting the vehicle's kinetic energy into electricity, and that means it is consuming that energy, and that means it causes drag. --Anonymous, 05:10 UTC, June 13, 2010.

Have a fold-down windmill, to reduce drag when the car is moving (except with a tail-wind). Oh, and you've forgotten to mention adding a kite or sails to the car to pull/push it along. 92.28.252.46 (talk) 13:36, 13 June 2010 (UTC)

No. If you managed to position the windmill so that it didn't add drag (say, in the trunk) then it would not turn. The drag is how it works. The propeller spins by slowing down the air around it. (Or, from another perspective, slowing down a car going through still air.) APL (talk) 01:00, 14 June 2010 (UTC)

That is not true, of cursee the windmill will have drag but the combined drag of the car and the windmill are not necessary greater than the car alone, the turbulence from the windmill could delay the separation of airflow on the car, see for example http://www.youtube.com/watch?v=nufXpDBELdQ from 1:50. Of curse for this to work the windmill will need to be very small and will not produce any significant power.

Gr8xoz (talk) 20:55, 14 June 2010 (UTC)

On a still day, If the windmill turns the energy to turn it is coming out of the car's forward velocity. APL (talk) 14:16, 15 June 2010 (UTC)

With a tail-wind, the wind would have to be going faster than the car to get any energy out of it. A 50mph wind is - I guess - a storm wind or worse. With a front-wind, you could get some net energy if the wind was fast enough to overcome the loss in energy to drag. 92.15.28.6 (talk) 17:35, 15 June 2010 (UTC)

Protein breakdown for energy... trigger?

What's the trigger for your body starting to break down protein for energy? I know this happens with long-distance runners who have no other alternative energy source. I'm looking for an exact mechanism; I assume it's triggered by a lack of glucose being detected, but what happens on the molecular level for this process to begin? Regards, --—Cyclonenim | Chat  17:07, 11 June 2010 (UTC)

This is not an area of expertise for me, but the "Regulation" section of the gluconeogenesis article gives some information. It says that the main activators are acetyl CoA, which is produced by metabolism of fatty acids, and citrate, which is produced in the basic Krebs cycle. Of course the availability of the substrate (unused amino acids) is also important. In fact any protein you eat that your body can't use will be converted to energy, because there is no other way for the body to get rid of it that isn't harmful. Looie496 (talk) 18:33, 11 June 2010 (UTC)

Looking at this again, I realize that I didn't actually address the question -- but the answer seems to be that the causes of protein catabolism aren't all that clearly understood. The breakdown of protein in lean muscle cells apparently results mainly from the ubiquitin pathway, but that's an extremely complex process that is affected by many factors. It seems, though, that low levels of insulin in the bloodstream are one factor that upregulates it. Looie496 (talk) 21:20, 11 June 2010 (UTC)

Right Handed Dominance

So, why is it that a majority of the population is right-handed? Why are there such things as right and left hand dominance and what purpose does this serve? Is this an evolutionary trait or what? Thanks! Stripey the crab (talk) 18:57, 11 June 2010 (UTC)

There is no proof that we know the answer, but the general story is probably that there are certain brain functions (most notably language) that don't work well when both sides of the brain participate in them, probably because of the time delays involved in sending signals from one hemisphere to the other. Thus, a number of functions get segregated mainly to just one hemisphere, some to the right, others to the left. This segregation would have to be controlled by genes, and it would be hard to design a genetic scheme that would, for example, place the language system on one side but be neutral about which side it is. It happens that fine motor control of the hand is segregated to the left hemisphere in most people (which controls the right hand). I realize that this explanation is a bit hand-wavy, but I don't think it is possible to be more specific based on what we currently know. Looie496 (talk) 19:23, 11 June 2010 (UTC)

(edit conflict) There is some discussion of the issue in the article Handedness, but the actual reasons why right handedness dominates are likely arbitrary. There's probably a good reason why one hand dominates, and it arbitrarily became the right hand. It likely could have easily been the left hand (cats, IIRC, are left-paw dominant usually), but it ended up being the right. There are some sketchy connections to "divisions of labor" in the brain (i.e. the "right handed people are analytical, left handed people are artsy), but these sorts of connections are VERY tenuous and have little scientific support behind them, they are mostly bullshit. The real reason is likely just random chance chose the right to be the dominant one in most humans, and it stuck. --Jayron32 19:24, 11 June 2010 (UTC)

it is because the physical environment is predictable and not at all postmodern, artistic, and emotional. if people were raised in a pure emotional environment in which repeating the same action did not result in the same effect from the physical environment, but rather depended on its "mood", you would find children would end up left-handed. This is my original research, so as with my other reply, if the nobel committee needs to contact me you will have to reply here as I am not allowed to include my email address. 85.181.50.245 (talk) 20:32, 11 June 2010 (UTC)

A related question involves amino acids. Philosophy of chemistry#Foundations of chemistry (permanent link here) says "Left-handed amino acids and right-handed sugars are the basis of the chemistry of life." -- Wavelength (talk) 21:47, 11 June 2010 (UTC)

Note for the gullible: 85's answer above is purest bullshit and should not be treated as even vaguely science. 86.164.69.239 (talk) 22:01, 11 June 2010 (UTC)

I've heard that the reason for right-handedness being more common in humans is that women will tend to carry their babies with there non-dominant hand, and carrying the baby on the left will make it closer to the heart, which makes the environment feel more like the womb. This makes the baby happier, less likely to cry, and I assume less likely to attract predators. Of course, this raises the question for why nearly all humans have their hearts on the left. (See Dextrocardia). — DanielLC 06:12, 14 June 2010 (UTC)

Have humans been historically right handed? I mean, if you look at ancient Egyptian and Babylonian paintings, do the warriors seem to show hand preference? Googlemeister (talk) 15:41, 14 June 2010 (UTC)

energy harvesting is so stupid

OR without a question, with a solicitation to the Noble/Nobel Prize Committee.
The following discussion has been closed. Please do not modify it.
i think the current ways of harvesting energy are really stupid, they should just build a couple of wormholes, one to the surface of the sun, and one to someplace cold, and use the heat differential to get energy. the wormholes don't have to be very big since you are not really transferring much through it. the text above told me not to include my email address so please reply here if you need to contact me. (nobel committee). 85.181.50.245 (talk) 20:26, 11 June 2010 (UTC) Reply to what? ---Sluzzelin talk 20:32, 11 June 2010 (UTC) to what I've written here. They might need it more fleshed-out before they go handing out the prize, which of course I understand. 85.181.50.245 (talk) 20:33, 11 June 2010 (UTC) Yeah, but were not secretarys for the noble prize comittee - you need this webpage http://nobelprize.org/ I know geniuses have difficulty dealing with everyday things but this is ridiculous.77.86.125.56 (talk) 20:44, 11 June 2010 (UTC) Were not secretaries for the noble prize committee what? What were they? 92.15.25.9 (talk) 21:23, 11 June 2010 (UTC) There's a missing apostrophe - it should read "we're not" - most people would have been able to work that out.. you're obviously not of the same mental calibre as the original poster.77.86.125.56 (talk) 21:31, 11 June 2010 (UTC) No one knows how to build a wormhole, and there are good reasons to think that wormholes may not actually exist. If you can demonstrate a way to create wormholes, you might well get a Nobel prize, but speculating about how hypothetical wormholes might be used isn't going to get you anything. Dragons flight (talk) 20:43, 11 June 2010 (UTC) I recommend building a working prototype, and selling the electricity back to the power company. Your profits could easily exceed the Nobel prize money, and any additional surplus could be used to buy one of those nifty Nobel medallions used. APL (talk) 22:40, 11 June 2010 (UTC)

Ant stamina

I've had the opportunity over the last few days to watch ants crawling over my kitchen counter. I notice they don't stop to rest for any reason. In fact, they never stop moving. Do they get tired the way we mammals do? Or, do they go back to the nest to sleep? Hemoroid Agastordoff (talk) 21:10, 11 June 2010 (UTC)

There seems to be very little science relating to ant sleep, but this paper (published last year) reports that fire ants do sleep, but only inside their nests, and only in short bouts. Looie496 (talk) 21:27, 11 June 2010 (UTC)