Wikipedia:Reference desk/Archives/Science/2008 November 25

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November 25

Frolov (the inventor of the Frolov breathing apparatus)

The Wikipedia disambiguation page for "Frolov" does not indicate which, if any, of the Frolovs listed is the inventor of the Frolov Breathing apparatus (for which Google provides numerous entries, but nothing quickly seen that shows a first name or gives any biographical information). Can the author of the Frolov disambiguation page (or anyone else) provide an answer? I started out on this search to get some sense of the reliability (or value) of the device, for which most of the info readily available on the Web is either out and out hype for the product or testimonials of dubious value. A bio of the inventor would help instill confidence (or lack of it) in various health claims for the device. One related issue: A Russian language article pushing the device claims (rather unbelievably, I thought) that 200 years back earth's atmosphere contained 38% oxygen rather than the 19% it contains today,and that human organisms were intended to live under such conditions. That claim was what first made me skeptical about the whole thing, in part because, even if the claim about atmospheric composition were true, human organisms go back tens of thousands of years, not 200. I would welcome comments on all of this. TIA T —Preceding unsigned comment added by Jkwikijk (talk • contribs) 00:42, 25 November 2008 (UTC)

Yea, the time frame seems way off for the higher oxygen level. It should be more like 200 million years ago. It's hypothesized that higher oxygen levels may have allowed larger land animals to exist. Any animal so large now would have to move slowly or wouldn't be able to get enough oxygen. StuRat (talk) 01:20, 25 November 2008 (UTC)

Czarek Tomczak (talk) 10:16, 2 April 2014 (UTC) See the Buteyko breathing technique that is somehow related to how Frolov device works. This is the only wikipedia page I could find.

Chicken head movement

As in this video, is there a good reason why chickens hold their heads like this? Nadando (talk) 03:11, 25 November 2008 (UTC)

One evolutionary advantage is that by being able to keep its head stationary while walking, the chicken could easily detect movements in its surroundings. This is useful both for avoiding danger and for finding prey. --Bowlhover (talk) 06:54, 25 November 2008 (UTC)

Also, when they walk, they keep their heads completely stationary and then jerk it forward very fast. This allows them to use parallax to provide depth-perception, mimicking other animal's two forward-facing eyes. — Sam 96.237.124.247 (talk) 14:00, 25 November 2008 (UTC)

Its funny, I read the title of this thread, and I thought: its because the guy is going to pay her. Am I alone on this, or did anyone else chuckle at the title?!? --Jayron32.talk.contribs 21:04, 25 November 2008 (UTC)

It appears as though you are alone. 3/23/10

Three colors in a LCD projector

This happened when I was attending a seminar. As a staff, I was sitted on the far side of the projector so I could see the glow of the projectors lens. When I trailed my eyes, I momentarily see the lens's light trailing distinct sections of red, green and blue not blurry and blended like a rainbow. I repeated the eye movement from left to right and right to left and the same result happens. I think that the trailing effect is like making light figures by twirling a flashlight. However, I can't explain the fact that the light "scatters" into sections. I'm pretty sure that I did not eat magic shrooms for breakfast or licked a poison toad so I think I'm sane that time.--Lenticel ^(talk) 05:29, 25 November 2008 (UTC)

What you saw was probably a DLP projector. Single-chip DLP projectors actually use a rotating color wheel to create RGB color, so they're showing the colors not quite at the same color, but one after the other in sequence. If you look past it really quick you'll see a rainbow effect. (In my experience, a small minority of people seem to be really bothered by this effect, but most of us don't notice it in the projected image unless we're moving our eyes back and forth like crazy.) APL (talk) 06:48, 25 November 2008 (UTC)

A good read. I think a learned a thing or two regarding projectors.--Lenticel ^(talk) 08:01, 25 November 2008 (UTC)

What's going on here is actually rather cool. TV's show a sequence of still images - we all know this. A 'conventional' cathode ray tube TV shows the red, green and blue images simultaneously. But a projector (unlike a regular TV) shows an entire image in red, then an entire image in green then an entire image in blue. Then the picture clicks over to the next still picture. The reason this is a problem is the cool part. When our brains see a fast sequence of still pictures, we don't just kinda fail to notice that the images are still - we actually EXTRAPOLATE the in-between images in our heads - we imagine that the image is moving smoothely by calculating where everything would be between the still images we were shown. This is a useful visual trick - imagine the caveman running after a rabbit with a rock in his hand intent on rabbiticide. All the time he can see the rabbit, he can estimate where to throw the rock in order to bring it down. But if you were in a forest with the rabbit darting in and out of the trees, you'd keep in losing sight of it (not unlike the gaps between the still images of the TV picture)...so your brain extrapolates the position of the rabbit so we know (roughly) where it'll reappear and we'll still be able to hit it with the rock.

OK - so we're extrapolating. That means taking the position of the object at time t₁ and the position at t₂ - and from that we can figure out the position at time t₃. But with the projection TV - drawing a new Red/Green/Blue picture every 16 milliseconds, the green colored version of a moving object is at the same position as the red colored version - but about 5 milliseconds later in time. The blue version is also in the same place but 10 milliseconds later in time. So our poor brains can't extrapolate the position of the R, G and B images as if they were one moving object - it doesn't make sense for an object to sit still for 10 milliseconds...then jump forwards within 6 milliseconds...then stop still for another 10 milliseconds. Real world rabbits just don't stop dead behind trees like that. So the best interpretation our brains can come up with is that there are actually THREE completely different objects - one red, one green and one blue - each of them is only visible briefly, once every 16 milliseconds - but that's OK - we've evolved to deal with that.

So - when the object moves quickly - it 'breaks up' into three separate objects and 'reforms' into a single object when it slows down again. You don't notice this when you watch a regular TV image - because the camera has a certain amount of motion blur - so that objects tend to be so streaky/blurry at that speed that you really can't accurately get a position for it - and the color separation is MUCH less noticable.

BUT - if you move your head/eyes quickly across the screen - the object is moving across your visual field very quickly - and you see the 'breakup' effect.

The exact same thing happens in computer games (where there is often no motion blur) if the computer can't manage to update the graphics at the same rate that the monitor repaints the picture. Even if you're viewing it on a CRT monitor. If the monitor refreshes 60 frames a second - and the computer only recalculates at 30 frames a second...then moving object 'stay still' for two 60Hz frames - then jump forwards. Again, it seems wrong and our poor brains see two objects chasing each other across the screen. If the computer falls back to 20 frames a second then you MAY see three objects tracking along...but at about 15 frames a second, our visual system realises what's going on and we see a single object moving jerkily. But the frequency at which this happens varies from person to person and depends on the lighting conditions...and all sorts of other things.

Another problem with 'sequential' color displays is what happens when you blink. If you blink quickly you may miss one or two of the three colors. This can result in the entire screen flashing cyan, magenta or yellow (if you blink really quickly and miss one color) or red, green or blue (if you blink more slowly and miss two colors). I personally find this REALLY annoying...but a lot of people don't seem to notice it at all...perhaps they have slower eyelids?!?

SteveBaker (talk) 01:29, 26 November 2008 (UTC)

you misspelled interpolate —Tamfang (talk) 06:32, 26 November 2008 (UTC)

Are you trying (tangentially) to tell me that you think I should have said 'interpolate' instead of 'extrapolate'? If so, then you need to explain why because I thought very carefully about which word to use - and 'extrapolate' is (IMHO) the correct one in this context. If we were 'interpolating' we'd see the image at t=0 and again at t=1 and from that, figure out where the object was some time in the past at t=0.5 (say). That's not what the brain does because the position at t=0.5 isn't very interesting anymore. Instead we're taking the data from the images at t=0 and t=1 and using that to figure out where the object is right now - at t=1.5...not where it was back in the past. There are some rather subtle experiments that show this. That being the case, the correct term is 'extrapolation', not 'interpolation'. SteveBaker (talk) 20:31, 26 November 2008 (UTC)

If the question is "where the rabbit is now", yes, that's extrapolation. My eye was caught by the emphatic phrase "we actually EXTRAPOLATE the in-between images"; a point beyond the endpoint(s) is not in-between, is it? —Tamfang (talk) 23:59, 4 December 2008 (UTC)

Black holes

Hi, i was just curious as to what would happen if you put a man inside a black hole? I guess the force of gravity might crush a person? but if so, what would happen to the debris?? 79.75.233.111 (talk) 07:19, 25 November 2008 (UTC)

For the love of God, Montresor!!! --Dr Dima (talk) 07:45, 25 November 2008 (UTC)

Literary references will not be tolerated (or understood, anyway) on the Science refdesk. Scray (talk) 11:51, 25 November 2008 (UTC)

Check out Black hole#Effects of falling into a black hole for the gruesome technical details. It looks like spaghettification might get you first. However, if you can avoid that, this describes how to prolong your remaining time. Clarityfiend (talk) 07:50, 25 November 2008 (UTC)

Spaghettifiction is very significant for stellar mass black holes (ie. ones formed when a big star dies). For supermassive black holes (such as are at the centres of galaxies) you can get far inside the event horizon before the tidal forces become significant, eventually they will get you though (infalling radiation that's been blueshifted to very high energy x-rays and gamma rays might get you first, though, I can't remember the details). --Tango (talk) 13:33, 25 November 2008 (UTC)

Fingerprints in electronic devices

Does fingerprint's locks (see here). also work with amputated fingers? Mr.K. (talk) 12:01, 25 November 2008 (UTC)

Yes, and with special rubber-cast copies. There's ongoing research to develop an alternative that uses infrared light and recognizes the unique pattern of blood vessels in the hand instead. EverGreg (talk) 13:19, 25 November 2008 (UTC)

After googling this a bit, it seems there's already blood-vessel readers on the market. EverGreg (talk) 13:22, 25 November 2008 (UTC)

Follow-up question And what would happen is a loose my password? How would I be able to access my data?Mr.K. (talk) 17:14, 25 November 2008 (UTC)

That's not really the worst problem. The difficulty is that making a functional copy of a fingerprint (lifted - for example - from the nice shiney surface of someone's car while they are inside that supermarket with the fingerprint scanner at the checkout). You can grab the print using your cellphone camera for example...you'd never get caught doing it. Edible gelatin fake fingertips can then be manufactured using only the stuff you'd find in a typical kitchen - the instructions are all over the Internet. If it looks like you might get caught using one - you stick the finger in your mouth and eat it! So - the REAL problem is how will you cope with the fact that criminals are using your fingerprint for identity theft! Now you really CAN'T change your 'password'. Fingerprint readers are a dumb idea. I strongly advise everyone to avoid them like the plague! SteveBaker (talk) 00:59, 26 November 2008 (UTC)

Its even easier than that. Mythbusters fooled a fingerprint reader with nothing more complicated than a decent scanner and printer. Lift the print in the standard manner (fine black dust and scotch tape work quite well), copy it onto the computer, and play around with the contrast levels in the copy. They were able to fool the scanner without much problem. Some of the more advanced fingerprint scanners have sensors for temperature and/or pulse detection (to prove its a live person), but the most common ones don't... --Jayron32.talk.contribs 04:06, 26 November 2008 (UTC)

The photographic approach doesn't fool the temperature and pulse detectors - or the ones that measure skin conductivity. But it's easily possible to fool even the super-fancy devices with a thin gelatin-molded fingerprint stuck to your real finger. Temperature, pulse and conductivity readings are close enough to fool the detector into making a reading of the print - and the print matches perfectly so it lets you in. Do a google search for fake fingerprints or something - you'll find sites where people have gotten through the most expensive military-grade fingerprint scanners that way. These devices are practically useless for anything but the most casual use. SteveBaker (talk) 20:08, 26 November 2008 (UTC)

To directly answer, though, if you lose your finger, you regain access the same way as on any other system you lose a password to. Specifics vary by the service in question, but most stuff has some sort of recovery mechanism. — Lomn 14:11, 26 November 2008 (UTC)

Logic Gates

Is there any single Integrated Circuit(IC) which can implement all the logic gates? —Preceding unsigned comment added by 210.212.192.18 (talk) 12:03, 25 November 2008 (UTC)

As an example, this 4011 IC contains four NAND gates.

Yes -- though the question appears backwards from the norm. An IC is a much higher level construct than a logic gate, as anywhere from a few to a few billion gates compose an IC. I'm more familiar with questions like "what's the minimum subset of logic gates required to construct all other logic gates?" or "what's the minimum subset of logic gates that is functionally complete?" (a rephrasing) — Lomn 13:58, 25 November 2008 (UTC)

I think an IC that included all the logic gatss would have to have an AND, an OR, a NAND, and a NOR. —Preceding unsigned comment added by 98.16.67.220 (talk) 22:54, 25 November 2008 (UTC)

NAND alone is a base of propositional logic, as is NOR. Obviously, then, NOT and AND or NOT and OR are also bases. NOT, AND, OR is the standard base. The proof is fairly simple with an induction over the construction of propositional formulas (=digital logic circuits). --Stephan Schulz (talk) 23:09, 25 November 2008 (UTC)

The question asked about gates in an IC. There is no such thing as a NOT gate in an IC. In fact, it is a contradiction in terms to talk about a NOT gate - how can it be called a gate when there are no open-shut conditions? —Preceding unsigned comment added by 98.16.67.220 (talk) 00:34, 26 November 2008 (UTC)

Eh? What?!?! There are plenty of chips that perform the NOT function - we typically call them "INVERTERS" - but the logic function is there - you feed in a 'true' and out comes a 'false'. You feed in a 'false' and out comes a 'true'. That's the definition of NOT! In fact, that 4011 quad NAND chip pictured here is easily used as a NOT gate. Just take your input signal and wire it to BOTH inputs of one of the gates (pins 5 & 6 for example) and the output (pin 4) will be the NOT of the input. SteveBaker (talk) 00:51, 26 November 2008 (UTC)

An inverter isn't a gate. A gate requires at least two inputs. When these inputs meet the required conditions, the gate opens or closes, and the output changes. These conditions are indicated by the name AND or OR. If all the inputs to a gate are connected together, it is no longer a gate - it is an inverter or a non-inverting driver.

That's utter, utter, utter bullshit! To quote from Logic gate: "A logic gate performs a logical operation on one or more logic inputs and produces a single logic output." - the article talks about NOT gates all over the place! We even have an article with the title "Inverter (logic gate)". Check out this data sheet from Integral: www.alldatasheet.com/datasheet-pdf/pdf/126173/INTEGRAL/IN74AC04.html - it's entitled "IN74AC04 - Hex Inverter High-Speed Silicon-Gate CMOS". A google search for "Inverter gate" produces 200,000 hits. I used to be a hardware designer - I built massively complicated graphics chips from the early 1980's into the mid 1990's and I've never heard anyone say that an inverter isn't a gate. What makes something a 'gate' is that the signal has to cross some threshold to trigger it...as opposed to (say) an analog inverter which produces a continuously varying output for a continuously varying input. Pah - you speak nonsense! SteveBaker (talk) 20:23, 26 November 2008 (UTC)

>IN74AC04 - Hex Inverter High-Speed Silicon-Gate CMOS< isn't at all an example of what you're trying to prove. "Silicon-gate" in this case has nothing to do with a logic gate, it's the gate electrode of a field effect transistor. In some CMOS fabrication technologies the gate electrode of a FET is fabricated with doped polysilicon (rather than a metal oxide), hence it's a "silicon gate". While of course FETs can be used to construct logic gates, they can as easily be used to make analog circuits. ([1], [2]) 87.115.77.76 (talk) 22:15, 27 November 2008 (UTC)

And you'll kindly note, Steve, that I've not sneered or belittled or abused you the way you have 98.16.67.220, even though your argument relies on nothing more than a poorly-sourced Wikipedia article and a datasheet you plainly don't understand. Please learn to treat others with some tiny modicum of human dignity. 87.115.77.76 (talk) 22:22, 27 November 2008 (UTC)

Certainly - take any single-chip microprocessor - you can to program it to perform almost any logic function you could imagine! OK - that's probably not what you're asking - but there are lesser programmable parts - PAL's, FPGA's, etc. These are much more like simple 74-series TTL devices - they have a bunch of different basic logic gates inside - and a way to 'rewire' them (sometimes permanently - sometimes in a reprogrammable way). They are very effective at collecting together lots of and's, or's, xor's, nand's and not's, they can implement flip-flops - all of the 'basic' logic functions, certainly - and they have become amazingly cheap. SteveBaker (talk) 00:44, 26 November 2008 (UTC)

If you want to implement AND, OR, NOR, NAND, NOT, XOR functions with the same IC, the easiest way is to use a 4 gate NAND chip as is shown above. See NAND Logic for how to contruct all gates from Nand gates, its also possible to use nor gates.--Dacium (talk) 03:55, 27 November 2008 (UTC)

Thank you for your comment, 87.115.77.76. I ignored the abusive poster. But for others, here is my view on this question of terminology. An electronic gate is either open or closed. An inverter is always open – the output always responds to the input. My viewpoint is based on a rational consideration of the function of the circuit element. As for the authorities quoted, they have sought to establish consistency of terminology where it did not exist in the things referred to. I have never unquestioningly accepted the viewpoint of authority when it seemed to me wrong. If that makes me a heretic,so be it. I always have a shadow of doubt about everything, and am always ready to consider the reasons for opposing viewpoints and change my views if I am convinced. This terminology question is a very small matter, but it has been said that great ideas sometimes begin as heresy. To read of a person who stood by his viewpoints against powerful authority in very important matters, refer to Giordano Bruno in Wikepedia. What a hero that man was. What dedication to truth. Another great thinker was Rene Descartes, who wrote, "... I entirely gave up the study of letters ..., being resolved to seek no other science than that which I might find within myself, or in the great Book of the World.

Inverters are logic gates, I know of no source saying otherwise, please cite one if you do. Perhaps you're thinking of a switch or a tristate gate. By the way you'd need 5 NAND gates so the 4011 wouldn't do the job. You can get hex NAND drivers or some other things to do the job but it would be cheaper to use two 4011s. Dmcq (talk) 18:21, 1 December 2008 (UTC)

Marmosets

Can marmosets be kept as pets? Thanks 124.30.235.62 (talk) 12:26, 25 November 2008 (UTC)

Any animal (including humans) can be kept as a pet. That doesn't mean it will make a good pet or that it is legal where you live. -- kainaw™ 12:52, 25 November 2008 (UTC)

The legality of it will need to be discussed with a local animal control officer or something. Once you've established that it's legal in your area I would recommend talking to local vets to see if you can find one that will treat it. It's no good having a pet that no vets will agree to treat.

But before you do any of that read this : Caring for Marmosets & Tamarins. Here's ominus sample : "Hand-raised, bottle-fed babies are quite charming, but with the onset of sexual maturity, they become unpredictable, aggressive and dangerous to humans - including their owners. Consequently, people should be discouraged from keeping them as pets."

Hope this helps. APL (talk) 13:46, 25 November 2008 (UTC)

Many pets become nasty upon sexual maturity, which is one of the reasons we have them fixed. Can marms be neutered ? StuRat (talk) 14:59, 25 November 2008 (UTC)

What a pity kids can't be charming, especially to those who feed them and care for them. —Preceding unsigned comment added by 98.16.67.220 (talk) 14:04, 25 November 2008 (UTC)

Heh, reading the above comments, the thought occurred to me that kids, like marmosets, may become "unpredictable, aggressive and dangerous" upon sexual maturity. Oh, teenage rebellion... ;) —Lowellian (reply) 04:49, 29 November 2008 (UTC)

Monkeys make tough pets. There is an interesting article on this here. --98.217.8.46 (talk) 14:56, 25 November 2008 (UTC)

A few species of marmosets are endangered or threatened. Honestly, I think it's best to leave them in the wild.CalamusFortis 16:23, 25 November 2008 (UTC)

Don't try to keep a racoon as a pet. When they are young they are alright. They are quite intelligent, and unlike a dog or cat they can pick things up in their front paws. But as they mature they can be hostile to humans and may bite even the person who raised them. —Preceding unsigned comment added by 98.16.67.220 (talk) 23:00, 25 November 2008 (UTC)

There really is a problem with ALL exotic pets and wild animals as pets. Things like dogs, cats and goldfish have been living with humans - and undergone selective breeding (which is essentially a form of evolution) to make them fit into human lifestyles. Pretty much everything else hasn't been through that and is likely to react badly as a result. If you want something a bit unusual - think 'farm animals'. SteveBaker (talk) 01:57, 26 November 2008 (UTC)

Small exotic pets are fine, like fish, since they can't hurt you (with a possible exception for fish with teeth). StuRat (talk) 00:53, 27 November 2008 (UTC)

Opinion Question

Brett Favre aside, most athletes whor etire and try to come back end up doing rather poorly. Indeed, it's often hard for athletes to to retire, from what I've heard, becasue they're so used to the crowds, the cheering, the adrenaline rushes; so much so that I've heard some call it an addiction.

Could this be why people in general "live in the past" at times? Human nature does seem to cause us to need reliable patterns, but the way some do it, it makes me wonder. For instance, our neighbors when I was a teenager had a situation where for at least a few weeks, the woman's ex-husband would drive by the house 1-2 times and honk his horn at them. My dad would just say the guy should "get a life," but I wonder if the fellow could actually have gotten so much pleasure out of it that, he was actually addicted. It's hard to imagine why else he would think about it so much. Just like the athlete who wants to keep playing.

Of course, then there are those who actually think it is the past for a few moments, because of dementia or something, but I'd think such people would be acting upon that in their minds, actually talking to people and imagining things as if it was years ago, not just driving by a house and yearning for the peson to come back.Somebody or his brother (talk) 13:00, 25 November 2008 (UTC)

I'm sorry, but your question appears (after many readings) to be a request to discuss opinions about this topic. This is a reference desk, not a discussion forum. If you are looking for a reference about this topic, please ask again and limit your question specifically to the reference you are looking for. -- kainaw™ 13:15, 25 November 2008 (UTC)

Never mind, then; it's probably a question that psychologists really don't know the answer to.

I would rephrase it as "Could people who are said to be 'living in the past' addicted to former circumstances in the same way that athletes are said to have trouble leaving the applause, cheering, adrenaline rush, etc. of their former playing days." However, looking at the nature of an addiction, it really could be seen as too gray an area.(And there would probably be someone who, without my using an example, would say it was asking for medical advice :-) Somebody or his brother (talk) 13:28, 25 November 2008 (UTC)

There are studies on sports psychology. this is the textbook for one of the classes here. It includes the psychology of leaving the sport - nicely phrased as "career transition." -- kainaw™ 13:35, 25 November 2008 (UTC)

Formula #1 racing driver Jack Brabham doesn't seem to stay still; but on comebacks, some sports people return for financial reasons and it's what they feel they do best. (I'm thinking boxers here.) As psychological flashbacks go, Ian Thorpe recalled exactly re-living a race when swimming in the home pool. Julia Rossi (talk) 01:30, 27 November 2008 (UTC)

Near-death experiences

Why is it that certain mammals, such as small rodents and the Dutch, defecate in certain circumstances shortly before death? the skomorokh 13:10, 25 November 2008 (UTC)

Loss of muscle control caused by whatever is killing them is one possibility. Another is as part of the fight-or-flight response - that article talks about a "General effect on the sphincters of the body", that will include the anal sphincters which control bowel movements. I'm not sure what that effect is, but it could well cause an involuntary bowel movement (cf. the common phrase "shitting oneself" to mean being very frightened). --Tango (talk) 13:38, 25 November 2008 (UTC)

It may be an evolutionary response to attacks by a predator, as some predators will skip prey that smells bad, since this could be a sign of a disease which the predator could catch. StuRat (talk) 14:51, 25 November 2008 (UTC)

Very interesting chaps, thank you very much. the skomorokh 19:43, 25 November 2008 (UTC)

How could it have an evolutionary advantage if the mammal is soon to be dead? Zain Ebrahim (talk) 08:12, 26 November 2008 (UTC)

I didn't say it's a reaction to whatever is killing them, that was what Tango I said. I'm saying it's a fear response that occurs before it's even touched The prey animal's defecation works (sometimes) by convincing the predator, like a bear, not to kill the stinky prey, which it judges may be diseased, and instead it may go off to look for healthy prey. Most predators can smell prey long before they kill it. StuRat (talk) 00:27, 27 November 2008 (UTC)

But the OP is specifically referring to defecation shortly before death, not defecation when being attacked. Could these be related somehow? Zain Ebrahim (talk) 07:00, 27 November 2008 (UTC)

Yes, if this defense mechanism fails to shake off the predator, then the prey is killed, so the defecation had occurred shortly before death. StuRat (talk) 15:06, 27 November 2008 (UTC)

Further to that, though it seems reasonable to use stench as a defence, some animals like to roll in dead, stinky stuff, so would that really work? Julia Rossi (talk) 08:17, 26 November 2008 (UTC)

It certainly doesn't work 100% of the time, it's more of an act of desperation. That rolling in strong smelling stuff is likely to disguise the natural scent. I've seen predators, like dogs, do that, presumably so they can sneak up closer to the prey (before it smells a dog and starts running). StuRat (talk) 00:27, 27 November 2008 (UTC)

Because they get scared-shitless? --Shaggorama (talk) 16:36, 26 November 2008 (UTC)

Also, if a prey animal knows that a predator is tracking it's scent, leaving a big steaming pile may be distracting enough that the predator can't pick up the scent again, or at least it may take a few minutes, giving the prey more time to escape. StuRat (talk) 00:40, 27 November 2008 (UTC)

Hang on one minute, I have to go back to Zain's point: the OP never asked about being killed, the question was about dying (e.g. by natural causes?). Zunaid 12:42, 28 November 2008 (UTC)

Actually, it said "before death". I don't see that this excludes predation, however. StuRat (talk) 14:35, 28 November 2008 (UTC)

windmill turbines

hi, I am a student of electrical engg. Well, induction generators are used (if not, suppose to be) for wind turbines. Then, how does it get the magnetizing mmf? Even though it is singly excited, it requires reactive power to create its magnetic flux. Maybe it feeded on the grid for that, but imagine it directly connected to a load. —Preceding unsigned comment added by 218.248.70.235 (talk) 14:48, 25 November 2008 (UTC)

See induction generator. An induction generator connected directly to a load, with no external source of excitation, doesn't work. 198.29.191.149 (talk) 18:44, 25 November 2008 (UTC)

Quantitative CO2 IR spectrum

Do you know a website where one can get a quantitative infrared absorption spectrum of carbon dioxide? webbook.nist.gov has only relative data (without concentration and light path length information; it has quantitative data for some other compounds). Thanks in advance! Icek (talk) 15:13, 25 November 2008 (UTC)

mouth-to-mouth resuscitation

When did mouth-to-mouth resuscitation begin to be widely used in first aid? I'm reading a manuscript which is about the experiences of an Italian sailor in the Second World war in which he claims that mouth-to-mouth resuscitation was performed on a shipmate who was rescued by the British Navy. Did the British Navy employ this technique in those years? --JAXHERE | ^Talk 16:30, 25 November 2008 (UTC)

Have you seen our article, History of CPR? That may answer some of your questions. --Tango (talk) 16:43, 25 November 2008 (UTC)

Red caviar

When salmon or trout roe is bottled as red caviar, how long will it last and be edible? Does trout caviar usually come from wild trout, or is it harvested in conjunction with trout farming operations? Thanks for any information you may provide. —Preceding unsigned comment added by 80.101.134.43 (talk) 16:49, 25 November 2008 (UTC)

Wow, no replies at all. That doesn't happen here very often. I'm still interested, especially if someone can lead me to info on the shelf life of red (or trout) caviar. —Preceding unsigned comment added by 80.101.134.43 (talk) 09:25, 27 November 2008 (UTC)

• Why not try doing a search for "trout caviar" and "shelf life"? That's what anyone here would do for you. Search engines are your friend. --jpgordon^∇∆∇∆ 16:02, 27 November 2008 (UTC)

What to be done

<medical advice removed>

We don't give medical advice on the reference desk. See a doctor if you have bleeding problems. --98.217.8.46 (talk) 17:25, 25 November 2008 (UTC)

was a wheel (by an axel) distinctly created at a single earliest moment?

so wheel-like things have been used for a while. I heard (or saw in a film) that the ancient egyptians rolled stones on rolling ... rollers. But there was no axel. It seems like the addition of an axel (let alone axle) would have HAD to have been an intelligent choice of at least one EARLIEST, first designer in a FIRST construction somewhere. Is this understanding of mine correct? —Preceding unsigned comment added by 86.217.99.209 (talk) 17:28, 25 November 2008 (UTC)

Are you asking if someone invented a wheel? If so, the answer is yes. In fact, it's likely that several people independently invented wheels. — Lomn 20:15, 25 November 2008 (UTC)

Wheels have been used a long, long, time, but they weren't necessarily used in the way we commonly think of today. Keep in mind that the efficiency of wheels varies directly with the quality of roadways available, so shifting things with wheeled transport wasn't always the slam-dunk improvement we consider it now. It's difficult to prove, but it seems likely that the first wheels were used in pottery making and that other early uses were also horizontal, as in a mill. You are correct (if I understand you correctly) that the invention of the axle was probably nearly as important as the invention of the wheel. Matt Deres (talk) 21:20, 25 November 2008 (UTC)

In a four-wheel vehicle, an important adjunct to its wheels is making the front wheels steerable. In a simple horse-drawn wagon, this is accomplished by having the front axle turn about a vertical axis situated at the center of the axle, thus steering the wheels. By this means, when the driver directs the horse to the left or right, the horse turns the front wheels into alignment with the new direction of travel. The rear wheels follow with no difficulty. The ancient Romans didn't know about steerable front wheels. When a driver took one of their wagons around a curve, a component of motion of the wagon was sideways. This dragging sideways was exhausting for the horse. That has been suggested as the reason the Romans built long-distance roads in a straight line, even when it meant going over a small hill instead of around it. The name of the inventor of steerable front wheels is lost in the mists of antiquity. The use of a tie rod to make front wheels steerable was a later important improvement; it allowed the front axle to be immovably attached to the body of the vehicle with springs for the front axle. An unsprung vehicle is very uncomfortable to ride in, even on today's roads. —Preceding unsigned comment added by 98.16.67.220 (talk) 23:49, 25 November 2008 (UTC)

Flatulence

What foods would LEAST likely cause flatulence in a healthy adult? --Emyn ned (talk) 17:31, 25 November 2008 (UTC)

Our article on flatulence has some good information, including a listing of foods and spices that promote and reduce flatulence. jeffjon (talk) 19:44, 25 November 2008 (UTC)

According to a LiveScience article, swallowing (of air) can also cause flatulence. ~AH1^(TCU) 00:24, 29 November 2008 (UTC)

Relativity

If electromagnetic radiation didn't exist, would the predictions of special relativity still hold true? —Preceding unsigned comment added by 76.68.247.230 (talk) 18:33, 25 November 2008 (UTC)

Well, considering we'd be living in a totally different physical universe, the answer is probably "no" on some level. But if you mean, can you make sense of special relativity without ever referring to EM radiation... you probably could, as it affects more than just EM radiation. For example, time dilation can be easily observed with muons, or really anything that you can accelerate to extremely fast speeds. But it really wouldn't make sense without reference to EM radiation—you can say, "oh, a baseball going .9 the speed of c will have certain effects", and just say that c is an arbitrary number. But it's not—it's the speed of light in a vacuum. It's not a random speed. Removing all EM radiation would make Special Relativity rest on a lot of very arbitrary numbers. And Einstein wouldn't have liked that at all! --98.217.8.46 (talk) 19:54, 25 November 2008 (UTC)

I am having a really hard time imagining a universe without electromagnetic radiation. How would anything at all happen? EM is kinda integral to the whole system that produced it all; it's not like you could just pluck it out of the system and expect ANY aspect of physics, let alone something as specific as special relativity work. Its kinda like asking "what would you have grown up like if your parents never had sex". The question is rendered impossble to answer because it contains internal assumptions which are patently illogical (i.e. it assumes you COULD exist had your parents never had sex). --Jayron32.talk.contribs 21:00, 25 November 2008 (UTC)

Indeed. EM radiation is a natural consequence of electromagnetism, without which you couldn't have atoms, so the universe would just be a mass of electrons, hydrogen nuclei and helium nuclei (possibly with a trace of lithium, if memory serves). In fact, without EM, everything would probably collapse into neutron stars and black holes. --Tango (talk) 23:59, 25 November 2008 (UTC)

And would the said electrons, neutrons, muons etc. experience things like time dialation? —Preceding unsigned comment added by 76.68.247.230 (talk) 06:48, 26 November 2008 (UTC)

Yes - I think so. If you were in a place in our universe that was completely dark, a solid vacuum, almost impossibly cold and surrounded by a few hundred feet of very pure lead - there could (just maybe) be no EM radiation there for a while. There is no reason to think this would make any difference whatever to the laws of nature. Of course you'd be had pressed to test that because inserting anything that's not at absolute zero into our chamber would result in low energy photons being radiated and spoiling the experiment. This makes measuring anything at all completely impossible.

However, if you were thinking of a universe where EM radiation simply wasn't possible because of some weird difference in the fundamental laws of nature - then all bets are off. Different fundamental laws means that all speculation is pretty much meaningless. Ordinary matter probably couldn't exist...nah - we can't even make a sensible guess.

SteveBaker (talk) 00:33, 26 November 2008 (UTC)

True, not having EM radiation would imply completely different laws of physics, and so maybe my question, in the way that I phrased it, becomes meaningless. But the heart of my question is this: does Special Relativity depend on the existance of EM radiation or something akin to it? I mean, most or all of the thought experiments that Einstein used made use of the interesting properties of light, so one would think that the answer is yes. But to think that the very nature of motion is altered by the presence of photons seems ridiculous. —Preceding unsigned comment added by 76.68.247.230 (talk) 04:11, 26 November 2008 (UTC)

The nature of motion wouldn't be dependent on the presence of photons but on the nature of them. Dependence on presence would be asking "does Special Relativity hold in the dark?" — Lomn 14:05, 26 November 2008 (UTC)

But if photons didn't exist period, then it would appear that motion would instead follow Newton's equations, which seems hard to believe. —Preceding unsigned comment added by 76.68.247.230 (talk) 22:06, 26 November 2008 (UTC)

Sorry to sound rude can (I can think of no other way to put this) but your question is meaningless. EM radiation does exist. If we imagine a universe without it we have no way of deciding what laws would pertain in that universe. Martin Hogbin (talk) 15:33, 29 November 2008 (UTC)

Why is refrigeration of tin a bad idea?

I recently heard that cans of vegetables, soups, etc., that are partly used should not be placed in the refrigerator. The person didn't know why, but had heard that, unlike aluminum, it wasn't safe.

Do you knwo why this would be? The article on tin only states that tin itself is harmless, but some chemical reactions with it may be. Does the cold of the refrigeration cause some to leak into the food or something?(Not being a chemist, I don't know if this is it, but seeing that the temperature for conversion to a certain type is only 13 C makes me wonder if that has something to do with it.)

Thanks.Somebody or his brother (talk) 18:47, 25 November 2008 (UTC)

Problem #1: Cans of vegetables, soups, etc. aren't made of tin. They are made of steel, or aluminum. Sometimes, the steel is coated with tin to reduce corrosion. But they are primarily steel or aluminum.

Problem #2: Your refigerator is cold, but its also a rather damp place. There's lots more ambient mosture in your fridge than in the rest of your house. Water facilitates oxidation (aka RUST) and so leaving that half-eaten soup can (which, being opened, has exposed untreated steel to the moist environment in the fridge) will cause it to rust much faster. --Jayron32.talk.contribs 20:26, 25 November 2008 (UTC)

I see, thanks; I guess I always consider them "tin cans" just as a generic term, but that makes sense that they'd be steel by now.Somebody or his brother (talk) 20:38, 25 November 2008 (UTC)

I think there's another factor involved as well. With acidic foods, once the can has been opened, the food, the acid, the metal and now oxygen are available to react. Such reactions can quickly give an off-taste to the unused food. This can happen either in a fridge or out on the counter. Both a) refrigeration and b) storage in a non-reactive container will prolong the life of the food. For example, the instructions on a can of pineapple pieces (a very acidic food) are "After opening, refrigerate contents in glass jar or plastic container."

When dealing with moist foods such as soup or pineapple, the extra moisture inside the fridge may make no significant difference. CBHA (talk) 00:52, 26 November 2008 (UTC)

I think that if anything, putting something in the refrigerator would slow down any chemical processes. Maybe the cause has something to do with bacterial spores landing in your opened can? I'm inclined to think this is just an old wives' tale.69.125.228.48 (talk) 06:49, 26 November 2008 (UTC)

I agree that the refrigeration part is unlikely to be the culprit. The fact that the contents of your can is exposed to oxygen, however, is. I assume that refrigeration gets mentioned, because it delays symptoms ordinarily that would ordinarily keep you from using the food, like a dried out surface, discoloration and the like. That means you'd eat stuff out of a refrigerated can (or tin for BE) that you'd probably no longer consume if it had been left out on the counter for the same amount of time. While the inside of your can may be coated with resin (with it's own inherent health problems) to avoid contact between metal and food, seams are often uncoated. Both uncoated seams and uncoated metal surfaces of your can will react with acidic contents of your food. (Don't nail me to this I very nebulously remember oxalic acid being mentioned in this regard. Maybe someone with a chemistry background can fill in the details.) As I said above you are more likely to keep food for longer in your fridge, there's more time for this to happen and produce undesirable compounds. The processes are aerobic, so while your can is sealed they don't have the air necessary for the reaction to take place. Just pour out the contents into a bowl or plastic container before you put it in the fridge. Alternatively line your can with a freezer bag that's BPA free and then put the contents back into your can. 76.97.245.5 (talk) 09:02, 26 November 2008 (UTC)

Many "tins" now are already lined with a thin plastic coating. Bazza (talk) 15:24, 26 November 2008 (UTC)

It's kind of complicated, but...as was said earlier, once a can is opened, the contents of the can are exposed to the atmosphere, in particular to oxygen and carbon dioxide, as well as to bacterial/mold contamination. Due to the potential for spoilage, it's clearly not safe to keep an opened can at room temperature. It's also not safe to keep an opened can in the refrigerator, even if it is resealed or covered well enough to keep bacterial contamination out. Why this is, however, has NOTHING to do with refrigeration, or temperature at all.

So, what's the concern? The fact that the liquid containing can is now exposed to oxygen and carbon dioxide, but we're not concerned about the tin coating on the steel can, or even about the steel beneath it. What we are worried about is the lead-containing solder that holds the can together. The action of acid and oxygen on the solder can leach the lead into the liquid contained in the can! Consuming the liquid then brings that lead into your body. One cans worth probably won't hurt anyone, but lead never leaves the body, so over time, this could be a dangerous practice. As for a plastic coating on the inside of the can - do you want to take the risk that the plastic isn't scratched? (Sealed cans don't have oxygen or carbon dioxide in them, and are perfectly safe)Bobzchemist (talk) 16:06, 26 November 2008 (UTC)

If you want a reference, British government healthy eating advice from the Food Standards Agency[3] recommends "Don't store food in an opened tin can, or re-use empty cans to cook or store food. This is because when a can has been opened and the food is open to the air, the tin may transfer more quickly to the can's contents." --193.172.19.20 (talk) 10:45, 27 November 2008 (UTC)

If the tin is lined with plastic, note that some types of plastic may contain the cancer-causing agent Bisphenol A which can leach into water when heated, and has been banned in Canada if I remember correctly. ~AH1^(TCU) 00:20, 29 November 2008 (UTC)

Sinusitis

Is there an extreme way to treat sinusitis? Such as using a laser and burning the lining of the sinuses in order stop it from producing muscus all together? Is that possible? What would be the drawbacks of burning away the lining? --Emyn ned (talk) 18:53, 25 November 2008 (UTC)

The treatment of sinusitis, including surgical treatment, is covered in our article. - Nunh-huh 19:45, 25 November 2008 (UTC)

I know. I read the article before I wrote this question. There is no mention of lasers in it thus my question above. Let me know if I am missing something...--Emyn ned (talk) 20:00, 25 November 2008 (UTC)

There's nothing particularly special about lasers; ablated mucosa is ablated muscosa. The article discusses surgical ablation of the mucosa of the maxillary sinus by ordinary means; you'd have to consult MEDLINE to look for recent thoughts on laser treatment; for example J Laryngol Otol. 2006 Dec;120(12):1026-32. "Computer-assisted surgery of the paranasal sinuses: technical and clinical experience with 368 patients, using the Vector Vision Compact system." Stelter K, Andratschke M, Leunig A, Hagedorn H. - Nunh-huh 20:23, 25 November 2008 (UTC)

Type of illusion where one treats Wii sport like regular?

When I went to try my cousins' Wii bowling game, I experienced an illusion, and I've been trying to search what kind it is. I got close to the TV, as I need to, and because it looked enough like a real bowling alley, I moved my hand back and threw as if hefting a real bowling ball - you can probably imagine the force with which that ball went down the alley. :-)

I know what I did involved muscle memory, and my muscles being tricked into thinking it was a real bowling ball. But, it's a little of a couple types. It was optical in the sense I relied on sight, but it was tactile in the sense the neurotransmitters in my brain, while they weren't saying, "This is a bowling ball you have," were saying, "You need to throw it like a bowling ball."

is there a name for this type of illusion? Thanks.Somebody or his brother (talk) 20:35, 25 November 2008 (UTC)

Immersion. We call a virtual experience where you actually do feel you're a part of it "immersive". And (of course!) we have an article about it: Immersion (virtual reality). SteveBaker (talk) 02:04, 26 November 2008 (UTC)

(anthropology/biology) universals that turn women on?

I was reading the line "Penelope Brown and Levinson extended Grice's theory by showing how people all over the world use politeness to lubricate their social interactions", and I was like... I'd like to 'lubricate' my social interactions, if you know what I mean. It's probably not what they meant, but surely politeness turns women on. More generally, what are scientific principles that turn women on? my impression

• secretly be a muscled adonis (though this is just visible through your quality shirt)
• ride a horse (????)
• use tools. like, put up a shelf with a power drill. (???)
• sweat with honest work. (construction workers?)
• have a great sense of humor, make eye contact.
• pay attention, be interested in them in a way no one else is.

but there my 'tips', such as they are, er...run dry. So, does anyone have good, strong, scientific ... moisterizing tips for the fairer race? —Preceding unsigned comment added by 86.217.99.209 (talk) 21:02, 25 November 2008 (UTC)

You could start by not being me. In fact, I can tell by personal experimentation that not being me has always been the best way to get a woman sexually aroused. --Jayron32.talk.contribs 21:07, 25 November 2008 (UTC)

It depends on the woman. But yeah, having a great personality and a great body, those sure can help, I imagine. Some of those things seem unnecessary. I'm not sure all women find horses all that appealing in practice. I think you left off a fairly obvious one:"have a very secure economic situation" (aka, MONEY), as that seems to impress a lot of women (and is one of the few things there that can easily be traced to more "evolutionary" origins). --98.217.8.46 (talk) 21:14, 25 November 2008 (UTC)

The things that attract people to each other are not confined to the evolutionarily advantageous. You can probably think of several real-life examples where a pairing just makes no sense and (perhaps even stranger) where the couple stays together even though it's obvious to all concerned that the match is not a productive one. People get turned on by strange things and there's no accounting for taste. Being good-looking, financially secure, funny and in good health should all seem to indicate a person would make a good mate, yet we all know ugly, unemployed bastards that somehow manage to get dates. Matt Deres (talk) 21:30, 25 November 2008 (UTC)

if you're talking about actual science, there's a decent number of studies attesting to sexual selection on the basis of facial and bodily symmetry. -- Nunh-huh 22:18, 25 November 2008 (UTC)

Ah the eternal question, please notify me if you manage to find the answer.--Lenticel ^(talk) 23:24, 25 November 2008 (UTC)

Political or financial power, or being any kind of leader of men, turns women on. This is undoubtedly a stone age instinct; powerful men and leaders could better ensure the survival of a woman and her offspring. A light-hearted rascal is also attractive to women; I don't know how to account for that. —Preceding unsigned comment added by 98.16.67.220 (talk) 00:11, 26 November 2008 (UTC)

For some reason, being a complete jerk seems to work rather well... Women like to be friends with nice guys and go out with jerks, don't ask me why. --Tango (talk) 00:27, 26 November 2008 (UTC)

Observer bias - the 'other' guy is ALWAYS a jerk! SteveBaker (talk) 04:06, 26 November 2008 (UTC)

Not sure, but perhaps it's some sort of motherly instinct in which the girl will try to "fix" the jerk's attitude in their relationship. Nice guys don't need that kind of help so they ignore them (you might want to make another thread about this section though).--Lenticel ^(talk) 01:15, 26 November 2008 (UTC)

All stereotypes aside for a moment, there's nothing quite like someone who's comfortable in their own skin, who's relatively self-aware and takes an interest in other people. Even unassuming so-called plain guys with these attributes stand out imho. It's like another dimension. Julia Rossi (talk) 02:13, 26 November 2008 (UTC)

Stars and Planets

2 questions really, 1) what is the difference between a planet and a star? and 2) are the lives of all stars and planets finite? I mean i heard that the sun will die eventually, any idea when? does that mean even planet earth is not imune to dieing eventually?! —Preceding unsigned comment added by 79.75.254.37 (talk) 22:09, 25 November 2008 (UTC)

Both are huge balls of matter. The difference is that the amount of matter in a star is so great that nuclear fussion occurs. Yes, the Sun is middle-aged. In about 5 billion years, it will turn into a red giant, possibly engulfing the entire Earth (scientists aren't sure). Even if the Sun doesn't swallow up the Earth, the Sun is gradually getting warmer. In about 1 billion years, it will be too hot and all life on the planet will die off. See the articles on Planet and Star for more information. 67.184.14.87 (talk) 22:26, 25 November 2008 (UTC)

A star is a mass of incandescent gas. A planet is broadly any object which is in orbit around a star. Also see Stellar evolution for more information on the life cycle of stars... --Jayron32.talk.contribs 22:31, 25 November 2008 (UTC)

In a binary star system, is it possible for a star to orbit another star? That is, the center of gravity lies inside one of the stars? 67.184.14.87 (talk) 22:51, 25 November 2008 (UTC)

I don't see why not. It's quite common for one of the stars to be much larger than the other, so as long as they are fairly close together (also not uncommon) one would orbit the other. The only think I'm not 100% on is that both those common things occur at the same time, but I would expect them to. --Tango (talk) 23:36, 25 November 2008 (UTC)

Keep in mind that a billion years is a very long time. The first dinosaurs showed up 230 million years ago — less than 1/4 of a billion years. --98.217.8.46 (talk) 22:49, 25 November 2008 (UTC)

Indeed, it's about 7% the age of the entire universe. When the sun finally dies it will have been around for well over half of the universe's existence. --Tango (talk) 23:36, 25 November 2008 (UTC)

It will still be a sad day though. I wouldn't want to be in my early 20's when the sun ultimately dies. —Preceding unsigned comment added by 79.75.254.37 (talk) 00:05, 26 November 2008 (UTC)

It will take place over the course of billions of years, so it's not really an issue (the Earth becoming uninhabitable may be a little shorter, maybe 1000s of years, I don't know, but still more than a lifetime I'd expect). --Tango (talk) 00:21, 26 November 2008 (UTC)

There's nothing remotely going on to make the earth uninhabitable in a time scale of 1000s of years. Even the worst predictions in the worst possible models of human-caused climate change don't reduce the earth to a barren rock in 1000s of years. Earth will probably not become uninhabitable for life in several hundred million years, probably closer to 1 billion years. --Jayron32.talk.contribs 03:43, 26 November 2008 (UTC)

I believe Tango was saying that the Sun's death will make the Earth uninhabitable over the course of 1000s of years, not that the Earth will become uninhabitable in that amount of time from now. --Sean 15:06, 26 November 2008 (UTC)

Indeed, I was making a wild guess on the amount of time it would take for the Earth to go from being completely habitable to completely uninhabitable (and the wonderful this is, my guess is almost certainly correct before those terms are so vague I can just define them in such a way as to make me right!). --Tango (talk) 21:35, 26 November 2008 (UTC)

Ah... Sorry. I thought you meant "1000s of years from now" and not "1000s of years from when things start getting uncomfortable to getting uninhabitable". Mea culpa... --Jayron32.talk.contribs 02:24, 27 November 2008 (UTC)

Water marbles

http://www.youtube.com/watch?v=vCeAfKCC2ng http://www.youtube.com/watch?v=x_kYkFy5-jI

I know these "water marbles" are real, as I've played with them before, but is this the correct way to make them? And if Calcium bicarbonate doesn't exist in a compound form, then then how does that part work? Furthermore, can I buy it at the store or make it myself with calcium carbonate, or would it need to be bought online? I really want to make these but I want to wait until I know exactly what I'm doing. Thanks! Reywas92^Talk 22:48, 25 November 2008 (UTC)

I've no idea about the answer to your question, but that is really cool! Thanks for the link! --Tango (talk) 23:55, 25 November 2008 (UTC)

Looks like a sham to me. --Scray (talk) 00:42, 26 November 2008 (UTC)

I agree. It's interesting how many of these sham science videos are on YouTube though, no? --98.217.8.46 (talk) 00:45, 26 November 2008 (UTC)

No! It's not a sham! I have played with these balls before. They are really interesting and feel like gel. It's really amazing how they are invisible in water, but they are real! Reywas92^Talk 00:51, 26 November 2008 (UTC)

(after edit conflict)

I'm pretty sure that they're not real. For one thing, these supposedly unrelated videos seem to be taken in the same kitchen under different lighting conditions. But more importantly, look at the how "marbles" themselves look. They're perfectly ridged, all perfectly spherical, all exactly the same size, and pretty strong. (Look at his fingers when he holds one between thumb and forefinger, he's squeezing pretty hard.) Also, in one of the videos, he accidentally drops a marble and it bounces, just like you'd expect a glass one to do. (Look to the right of the screen at 2:32)

Not only that, but the explanation seems like gibberish to me. What does it mean for a substance to "loose its Polar hability"?!?

I would expect real Sodium Acetate to do something more like this. (And get quite hot.) APL (talk) 00:50, 26 November 2008 (UTC)

No! It's not a sham! I have played with these balls before. They are really interesting and feel like gel. It's really amazing how they are invisible in water, but they are real! Reywas92^Talk 00:52, 26 November 2008 (UTC)

I'm only saying that I think that these videos are a sham. I fully belive that you have played with some sort of "water balls" that were really neat. But I don't at all belive that the videos you linked are anything other than a prank.

(I am not at all a chemist, though. So feel free to assume I'm an idiot.) APL (talk) 00:58, 26 November 2008 (UTC)

Here's another video of real Sodium Acetate. Very cool, but nothing like the "water balls" video. APL (talk) 00:54, 26 November 2008 (UTC)

I don't know all the science to it; "lose its Polar hability" may be wrong, but they are not just glass and are real. From all the places I've read, they are two different applications of sodium acetate. Reywas92^Talk 00:56, 26 November 2008 (UTC)

Not just the "Polar Hability", but what is the white powder identified as "Calcium bicarbonate"? Is it "Calcium carbonate"? I suppose it could be, that's a white powder, but it's not the same thing. APL (talk) 01:01, 26 November 2008 (UTC)

Presumably Calcium bicarbonate, precipitated into solid form for the first time by previously unknown science. Algebraist 01:45, 26 November 2008 (UTC)

It's a special kind of science that only works in kitchens that look exactly like that one. APL (talk) 03:09, 26 November 2008 (UTC)

This video Seems a bit more credible, but I still am not sure what he's got there. APL (talk) 01:35, 26 November 2008 (UTC)

Why do you think that's more credible? He gives no instructions - makes no actual claims - and whatever happens is happening off-camera. Those could be blobs of Jello. Extraordinary claims demand extraordinary evidence. SteveBaker (talk) 02:46, 26 November 2008 (UTC)

Oh, That's easy, I think it's more credible because absorbent 'plastic' things that grow to several times their size when left in water for an hour or so are real thing. It's entirely credible that you could make some soft, gooey spheres that way. It's a hell of a lot more credible than the idea that you could mix Sodium Acetate and unobtainium on your stove and get a bunch magic crystal spheres.

Of course, now that I've found those hyrdoponic spheres at deal extreme.com (see below) I'm sure that's what the video I linked to was of. So I was right. The video I linked is probably real. It shows something perfectly mundane, of course. APL (talk) 03:02, 26 November 2008 (UTC)

Here we go!. I'll bet these are what you're thinking of. Very cool. And for the low, low price of $2.58! APL (talk) 01:46, 26 November 2008 (UTC)

So - to summarize the known facts to date:

• There is no such solid as Calcium Bicarbonate - yet BOTH supposedly independent video's claim to use it,
• "polar hability" is a made up term,
• Salt is 'iodized' not 'ionized'...they put iodine in it to stop the grains from sticking together. (Jeez!)
• the two videos (while supposedly submitted by different people) are clearly filmed in the same kitchen
• we see the "water ball" bounce like a very hard solid - despite the claim that these things are slightly squishy.
• The two sets of instructions use totally different methods and very different ingredients to produce this very strange result.
• How could it REMOTELY be possible for such a simple process made with common household ingredients (well - except for the unobtainium-calcium-bicarbonate) not be so well known as to be all over the 'home chemistry' web sites.
• The second set of instructions tell you to heat the vinegar to 550 degrees for 10 minutes. Now - I'm going to be generous and assume he's talking Fahrenheit - but 550F is 288C !! How can you get a liquid composed of water (boiling point 100C) and acetic acid (boiling point 118C) to a temperature of 288C ?!?
• Generously assuming the pot did get up to 550F (and I don't think a stovetop ring would do that) - taking it straight off the stove top and putting it onto the glass shelf of a refrigerator would result in fairly instant shattering of the glass - unless it's a plastic shelf - in which case it's gonna melt for sure.
• None of the usual YouTube wannabies who claim to have reproduced the results have MENTIONED the difficulties of getting their stoves up to 550F or obtaining calcium-bicarbonate. Hence we may deduce that they are lying...so we may discount their stories.

Yeah - this is utter, utter, utter, bullshit - and it's done so ineptly that it falls apart at the first touch of scientific inquiry. I can't tell in what way Reywas is confused/duped/bullshitting-us - but I discount his report. SteveBaker (talk) 02:39, 26 November 2008 (UTC)

I few quick fixes: Calcium silicate is the chemical they use to prevent caking in table salt. It is iodized as a public health measure to reduce the incidence of goiter69.125.228.48 (talk) 06:54, 26 November 2008 (UTC)

Good catch on the temperature. I feel stupid for missing that one.

Please notice that Reywas92 might not be trying to con us at all. He may honestly have played with some spheres at some point, and has mistaken the spheres in these hoax videos for the spheres he remembers. He may be thinking of the plant potting spheres I linked above, or he may be thinking of something entirely different, But I don't think he's claiming that he's ever seen spheres manufactured out of Sodium Acetate. That's why he asked. APL (talk) 03:02, 26 November 2008 (UTC)

Indeed - that's why I said 'confused/duped/bullshitting-us' rather than "OUTRIGHT LIAR" - he could be confusing some other effect - or perhaps he was duped with the plant potting balls - we have no way to tell. It's certainly notable that the refractive index of those plant potting beads is almost exactly the same as water - which makes them seem to vanish. You might even be able to do a bit of kitchen chemistry to make a liquid with an exact refractive index match to enhance the effect. That's undoubtedly the origin of the hoax...combine the interesting (and very real) weird behavior of Sodium Acetate (try Googling "Hot Ice" for some non-hoax examples)...and you have fertile ground for not-so-scientifically-literate hoaxers. SteveBaker (talk) 03:56, 26 November 2008 (UTC)

Yes, the videos are pretty bad. I take no responsibility for anything in them, but I know that the water marbles shown in various videos are the ones I've played with. The balls both bounce and are slightly squishy. You are completely right that the refractive index was the same as water so they are invisible. I don't know how my marbles were made or anything, but these videos are them, and they are likely made with sodium acetate somehow, with unknown veracity of the videos otherwise. What I played with was a toy and not plant potting balls, but they may be similar. Also, I feel insulted by you calling me 'confused/duped/bullshitting-us'. How about curious? Reywas92^Talk 04:19, 26 November 2008 (UTC)

Well - I guess this is how it is:

• The consensus of the ref-deskers is that we don't doubt that there exist squishy hygroscopic balls with a refractive index close to that of water that would closely simulate these mythical 'water balls'. Indeed, we believe you can buy them - and here is a link: [4]
• But we do SERIOUSLY dispute that they can be made in any of the ways indicated in the videos...we dispute that they are some bizarro new phase of water or whatever the heck is being claimed.

So - assuming we're correct about those two facts (which, quite honestly, is beyond doubt at this point) then it logically follows that either:

1. You are telling us that someone showed you some squishy balls in water - and didn't say that they were made with a simple process involving household ingredients - then (because you say that you "know that the watermarbles shown in various videos are the ones you've played with") you must have been confused by those ridiculous videos.
2. You are telling us that someone showed you some squishy balls in water - and told you that they'd made them in the kitchen in ways similar to those in the videos - then you have been duped - the person lied and you believed them.
3. You are telling us that you know for a fact that these balls were made in ways similar to the movies - then you are bullshitting us because there is no conceivable way to even follow the instructions - let alone come up with a product such as they describe!

I don't any way to know which of those things it is - so I said that you are either confused, duped or are bullshitting us. I don't think I'm being unreasonable by saying that...and (since we try to assume good faith around here) - I'd prefer to assume you're either confused or were duped. I'm sorry if that upsets you - but sometimes the truth is hard to bear.

SteveBaker (talk) 06:19, 26 November 2008 (UTC)

Actually, Someone showed me a small container of the balls which was made as a toy and called something like Dinosaur Eggs. I'm asking my friend if he still has it so I can look up the company and product. I know these balls are the ones shown in the movies, so I wondered about their origin. I asked about the videos to see if I could learn anything about what I had played with. Apparently the videos are not completely accurate, but that's why I asked you about them before wasting my time trying to make them. You might call that getting duped, but I don't. I'm not upset, I just didn't learn how to make the balls. Reywas92^Talk 15:39, 26 November 2008 (UTC)

My primary conclusion last time this came up about a month ago, unchanged by the recent revelations is that most of the people posting the videos on youtube (not commenting on the OP) are clearly bullshitting and with one clear purpose. They're trying to fool people into wasting their time and perhaps being laughed at by looking for the non-existant calcium bicarbonate. I guess the people who posted these videos think it's funny, I just think it's lame Nil Einne (talk) 13:15, 26 November 2008 (UTC)

Incidentally, there seems to be rather a lot of blog and forum traffic that about creating "water balls" from Sodium Acetate and powdered calcium bicarbonate, so I can see why that might make someone think that this is a commonly known fact. The problem is, all of that talk, all of it, appears after these videos appear. As far as I can tell this (wrong) idea was completely unknown before these videos came out. In fact, most of the people talking about this effect try to impress each other with the nonsense phrase "polar hability".

I'm sure whoever made these videos is getting a great laugh out of all this. APL (talk) 13:56, 26 November 2008 (UTC)

http://revver.com/video/1004979/invisible-ball/ Here's exactly what I played with. Basically, How do I get it/make it? Reywas92^Talk 16:00, 26 November 2008 (UTC)

I'd bet money that your 'invisible balls' were made from some combination of one or more of these, possibly with another cross-linking agent:

1. Agar
2. Sodium alginate
3. Guar gum
4. Carrageenan
5. Locust bean gum
6. Xanthan gum

and Calcium lactate or calcium chloride

A thick enough gum solution slowly poured into a slowly stirring calcium (lactate or chloride)) solution will break up into large balls of gelled gum that will be firm but squishy and maybe clear. The faster you stir, the smaller the balls will be. Molecular gastronomy uses this trick to make solid/gelled alcoholic drinks, but I can't find the reference.Bobzchemist (talk) 16:38, 26 November 2008 (UTC)