Wikipedia:Reference desk/Archives/Science/2008 August 7

Welcome to the Wikipedia Science Reference Desk Archives
The page you are currently viewing is an archive page. While you can leave answers for any questions shown below, please ask new questions on one of the current reference desk pages.

August 7

Please try to disprove this theory

In the Alaskan Psychic Newsletter recently there was an article stating that George W Bush was an alien from 20 million light years away implanted here on our earth to cause havoc. How can this theory be disproved? —Preceding unsigned comment added by 79.76.167.200 (talk) 00:06, 7 August 2008 (UTC)

Maybe if he starts behaving hisself? Julia Rossi (talk) 00:17, 7 August 2008 (UTC)

It can't. Essentially you're saying, "How do I prove that Bush is not an alien?" (Or maybe, a humanoid Roomba belonging to an alien.) That doesn't mean the article is correct; it just means we have no credible evidence of an extraterrestrial civilization, especially one that would travel 20 million light years to swap babies with George H. W. and Barbara Bush. They've known George W. for quite some time, and don't really seem the Jonathan and Martha Kent sort. Those writing the article either knew it to be complete codswallop, or believe in; in the former case, they're not going to admit the joke, and in the latter, you can't get through the tinfoil.

I could as easily write an article claiming that Vladimir Putin is the illegitimate child of Elizabeth I and Rasputin, conceived as a result of time-travel technology that was hidden in the temple of Hatshepsut until brought to Paris by Freemasons, only later to be pocketed by Peter the Great after his visit to Rheims (and his reading of Anna Yaroslavna's prayer book). Equally difficult to disprove (though possibly more entertaining). OtherDave (talk) 00:24, 7 August 2008 (UTC)

To idly quote those who are wiser than I am: "Logic cannot remove what logic did not put there." SDY (talk) 00:36, 7 August 2008 (UTC)

Surely that is most illogical, Captain: after all I am a Vulcan. You're a mere human! —Preceding unsigned comment added by 79.76.167.200 (talk) 01:14, 7 August 2008 (UTC)

You can't falsify something unless it makes testable predictions. If the aliens in question are bug-eyed, for example, then this claim is falsified by a large amount of eyewitness evidence. Without that kind of detail you can't prove the claim wrong, but it also fails to qualify as a scientific hypothesis (or theory). It's no good to say that the aliens have the technology to hide their evil plot from us; that's still an unpredictive statement. -- BenRG (talk) 01:38, 7 August 2008 (UTC)

When superstitious theories are raised by those who are serious, skeptics often use Occam's razor. For jokes like this one, on the other hand, even Occam would groan. --Bowlhover (talk) 03:06, 7 August 2008 (UTC)

I might be opening up a can of worms, but I have a follow-up question. We know that this ridiculous theory can't be disproved. But isn't it also fair to say George W. Bush isn't an alien? Similarly, isn't also fair to say that god doesn't exist for the same exact reason? ScienceApe (talk) 03:40, 7 August 2008 (UTC)

It would be fair to say "we have no reason to believe that George W. Bush is an alien." which is typically as close as science ever gets to these sorts of unprovables. APL (talk) 06:46, 7 August 2008 (UTC)

What I was disproving was a theory that included "to cause havoc". Without that item, it is impossible to disprove. With that item, it would be "disproved" if he indeed stopped what he's doing and say, made daisy chains instead, because logic does depend on what is put there (or not) -- so there y' go... Julia Rossi (talk) 07:01, 7 August 2008 (UTC)

For a second there I thought you had it Julia, but no. If he was sent to cause havoc and didn't accomplish that, it would only mean that he was incompetent as a from-20 million light year-away alien. Franamax (talk) 08:07, 7 August 2008 (UTC)

Also, how would you know the aliens didn't order him to stop wreaking havoc? --Bowlhover (talk) 08:19, 7 August 2008 (UTC)

I can see only two possibilities. Alien GWB fails at causing havoc, terrestrial GWB causes havoc. Either way, EPIC FAIL. /rant Franamax (talk) 10:07, 7 August 2008 (UTC)>

Actually, I think we can logically disprove this theory. Start from the assumption that there is a lone alien who (a) can flawlessly impersonate a human being; (b) can manipulate human affairs to insert themselves into any desired position of power; (c) is rationally pursuing an objective of causing as much havoc on Earth as possible. Given this, the alien would insert themselves into a position with as much individual power as possible. The head of state or head of government in a democracy has relatively little personal power, so the position of President of the United States is not a rational target for our hypothetical alien. On the other hand, the leader of a military dictatorship in a country with a nuclear capability has a much greater potential for causing havoc ... Gandalf61 (talk) 09:09, 7 August 2008 (UTC)

You're assuming that the alien is omniscient, which may not be the case. --Bowlhover (talk) 09:33, 7 August 2008 (UTC)

Well, let's at least assume they have access to a comprehensive electronic encyclopedia of human knowledge - think I've seen one around here somewhere ... Gandalf61 (talk) 09:45, 7 August 2008 (UTC)

Ahem, you've seen the ceeohk, but have you seen the alien? Let's not assume the alien is godlike, but only acts that way, and who says he looks flawlessly human? and if he was incompetent might that be our secret weapon agaiinst invasion then? Logical presups are proliferatiing like nuclear armaments here... Julia Rossi (talk) 10:07, 7 August 2008 (UTC)

See wishful thinking --Shaggorama (talk) 17:32, 7 August 2008 (UTC)

• The disproof is that there is no evidence space aliens could be that cruel. Edison (talk) 18:31, 7 August 2008 (UTC)

• Since one person's causing havoc is another person's working towards orderliness, accepting proof of the theory seems based on whether you are the hammer or nail. Suntag (talk) 19:39, 8 August 2008 (UTC)

Will going faster than the speed of light create a black hole?

I was having a conversation about the speed of light with someone I knew and he said that according to theory, if you go faster than the speed of light, it will create a black hole. Can someone please explain this theory to me, and if this is even true. Monkeynator03 (talk) 00:11, 7 August 2008 (UTC)Monkeynator03

No, that's not true. (Well, I suppose you could argue that it's vacuously true because you can't go faster than light in the first place.) I've never heard that one before. I have heard people say that something going very fast (but slower than light) will become a black hole, which is also not true. -- BenRG (talk) 01:18, 7 August 2008 (UTC)

I'm going to echo vacuous truth in non-small font, because I think it's the most useful thing you're going to get out of this question. As the first half of the statement ("things that go faster than light [in vacuum]") is an empty set, the second half of the statement can be anything and, from a logical standpoint, the collective statement is true. "If I go faster than light, I create a black hole" is the logical equivalent of "If I go faster than light, Wikipedia tastes like candy".

On the other hand, when that "[in vacuum]" caveat I added is removed, you can make a meaningful statement: when a particle exceeds the speed of light in a given medium, Čerenkov radiation is produced. But not a black hole. — Lomn 02:17, 7 August 2008 (UTC)

That's a misconception. I just tried it. Wikipedia tastes like a LCD screen. See also "Why cant I type?" below. :) Franamax (talk) 08:00, 7 August 2008 (UTC)

I think the misconception may stem from the fact that relative mass increases the faster you go. People confuse relative mass with rest mass. You can travel at 99% the speed of light, and your relative mass will be immense, but your rest mass is the same as it was at rest. Creating a blackhole depends on immense rest mass coupled with immense densityScienceApe (talk) 03:34, 7 August 2008 (UTC)

Black Holes can only be created only if a body possesses a redius less than Scwerckild Radius(2MC/C²). Travelling faster than light won't create a Black Hole.117.201.96.57 (talk)` —Preceding undated comment was added at 20:17, 9 August 2008 (UTC)

TeleDeltos paper

Where can I get it? I need to plot. —Preceding unsigned comment added by 79.76.167.200 (talk) 00:15, 7 August 2008 (UTC)

The authors of this webpage ordered it from Sensitised Coatings in England. --Bowlhover (talk) 07:21, 9 August 2008 (UTC)

Why cant I type?

Why cant I type after 8 pints. I mean, my brain knows what to do, but my fingers just dont obey me? Why is that? —Preceding unsigned comment added by 79.76.167.200 (talk) 01:20, 7 August 2008 (UTC)

Alcohol is a central nervous system depressant, so although your brain sends the signals, they don't quite make it there in good shape. Q ^{T C} 01:34, 7 August 2008 (UTC)

20 20 24 hours a day, I want to be -- typing???

Duuud! I woz sooooo wasted I couldn't even -- type???

O man! She sooooo wanted it but I had to -- type???

Youth is wasted on the wrong people! Saintrain (talk) 04:58, 7 August 2008 (UTC)

Checking my email is the first thing I do when I get in, drunk or otherwise, and I agree typing is a significant challenge. It's not just more typos, it's different typos as well... I don't generally think about it much, though - I'm drunk at the time, after all! (I do have to be careful about *what* I'm typing though!). --Tango (talk) 18:29, 7 August 2008 (UTC)

True. I find I type similar-sounding words rather than the word I want when I'm drunk or tired. Which is frankly bizarre. It's like my fingers are taking dictation from my mind, but are themselves drunk... 79.66.38.215 (talk) 23:05, 7 August 2008 (UTC)

Oh dear... I do that sober... It's terrible, it makes it look like I don't know the difference between "there", "their" and "they're", when I do, it's just my fingers that don't. --Tango (talk) 02:48, 10 August 2008 (UTC)

You might also want to check out short-term effects of alcohol, specifically this bit. —Cyclonenim^T@lk? 11:22, 7 August 2008 (UTC)

If sufficient pitchers of beer are consumed, it may be perceived to be an insoluble problem to pour the next glass from a newly arrived pitcher, because they put the handle on the wrong side of the pitcher! Just saying. Edison (talk) 18:30, 7 August 2008 (UTC)

Helium lifting gas

What isotope of Helium provides the most lift? ScienceApe (talk) 03:35, 7 August 2008 (UTC)

The lightest one, naturally, i.e. Helium-3. The gain isn't much, though, and you'll have trouble getting it in useful quantities. Algebraist 03:40, 7 August 2008 (UTC)

(e/c) I assume you mean "the most lift if you put it in a balloon". Helium-3 would probably provide more lift than Helium-4 because it's lighter, but it's ridiculously rare. Paragon12321 (talk) 03:41, 7 August 2008 (UTC)

Unless we start gas mining the moon or Jupiter. ScienceApe (talk) 04:55, 7 August 2008 (UTC)

Nah - make some tritium and wait for it to decay .. Philip Trueman (talk) 11:29, 7 August 2008 (UTC)

If you wanted to fly an airfoil through a purely helium atmosphere, wouldn't the more massive isotope provide more lift? Nimur (talk) 19:30, 7 August 2008 (UTC)

No. Aerodynamic lift depends on air pressure, not density. So lift should be the same for all reasonably gases (various caveats not discussed to keep it simple). --Stephan Schulz (talk) 03:48, 8 August 2008 (UTC)

And wouldn't hydrogen be even better?, in a purely helium atmosphere there is no chance it would burn. Graeme Bartlett (talk) 02:11, 8 August 2008 (UTC)

Talking about the lift of various gases, water has lift too. I once worked for an aerospace firm that took a government contract to design and build a one-man submarine. They knew nothing about submarines. They were embarassed to find that the submarine kept heading for the surface when it should have gone straight ahead. They finally found out that the shape of the hull caused lift. Water is relatively imcompressible. So I think nearly all the lift on that miniature submarine was due to the wedge effect of sloping bottom parts of the hull, rather that hydrodynamic lift. AndMe2 66.52.8.251 (talk) 05:47, 8 August 2008 (UTC)

Technically, Helium-2 is the lightest isotope. It has a ridiculously tiny half-life, so the result of a balloon full of it would be similar to that of a nuke going off. The convection from the superheated gasses would result in the most lift, although if you're going to do it that way, it might be better to use extremely heavy isotopes of helium, which AFAIK would release more energy for a given volume. It would, of course, be impossible to fill a balloon with a helium isotope other than 3 and 4 before it decays. — DanielLC 00:32, 10 August 2008 (UTC)

Curl of F

If the curl of F is not zero, what does it represent besides the presence of friction? For example the curl of E is the time rate of change of B. So when the curl of F is not zero, what does the quantity represent? —Preceding unsigned comment added by Kissnmakeup (talk • contribs) 04:58, 7 August 2008 (UTC)

The circulation. Have you seen Curl (mathematics)#Interpreting the curl? 81.174.226.229 (talk) 08:33, 7 August 2008 (UTC)

I see that I need to be more specific. According to Keith Symon in his text, Mechanics, if the curl of F (and consequently the line integral about a closed path by Stokes' Theorem) is zero, then the force is conservative. If it is not zero, energy is not conserved. When energy is not conserved does the quantity of the curl of F indicate anything quantitatively about the lost energy? If you do a line integral around a closed path and you don't get zero, is the quantity that you get equal to the energy dissipated by, say, heat from friction? Does the number that you get have a physical meaning specificly with regard to energy not being conserved? (By the way for those of you who are interested, I chose this strange handle after reading some of the discussion pages for articles like entropy.)Kissnmakeup (talk) 11:32, 7 August 2008 (UTC)

No, it doesn't always represent friction. In the example you gave of the electric and magnetic fields, it obviously doesn't represent friction. It represents the EMF induced by the changing magnetic field. You say "energy is not conserved", but of course the total energy of the system is always conserved. For example, if the changing magnetic field produces 1 V of EMF, and I let one electron go once around the loop, it gets accelerated by 1 eV of energy. This energy is exactly the energy that came from the magnetic field. Other non-zero curls of forces similarly represent transfers of energy. 128.165.101.105 (talk) 14:15, 7 August 2008 (UTC)

Cats and their waste

Cats are generally good about disposing of their waste – they dig a hole in loose soil or sand, do their business in it, and then meticulously cover it up. Do big cats, like lions and tigers, do the same? --Bruce1ee^talk 06:07, 7 August 2008 (UTC)

Instinctively domestic cats bury their waste to protect their trail from predators. This usually only applies to subordinate cats however, and sometimes a dominant cat will actually display it's waste as a sign that "this is my territory, keep the hell out". I would imagine that this behavior is the same in big cats, as "the various species of cat are amazingly similar in both structure and behavior." Of course, some cats use other methods, though I'm not sure how a lion would look doing that! 20I.170.20 (talk) 13:24, 7 August 2008 (UTC)

It might be of interest to note that Christian the Lion used a litterbox scrupulously when he lived in London. - Nunh-huh 20:34, 7 August 2008 (UTC)

I have read that cats bury their waste so their prey will not know, by smell, that a cat is in the area. I have also read that cats frequently lick their fur so their prey will not smell the remains of earlier prey emanating from the fur. It's too bad cats are predatory animals - I really like them. They seem to know so much and they say so littls. They are a riddle wrapped in an enigma. AndMe2 66.52.8.251 (talk) 05:38, 8 August 2008 (UTC)

Air brakes

I know that fast cars, especially race car and high end road cars, have spoilers to create massive downforce. Hundreds and hundreds of pounds.

Why do I not see more cars with Air brake (aircraft)? The Veyron has one [1] --mboverload@ 06:22, 7 August 2008 (UTC)

You do. That "something" must be rather large to have a significant braking effect at the low velocity of race cars (relative to jet planes, that is), so a parachute is used, to help stop dragsters at the end of their runs. For race cars that go around a curved track, there's no hurry to slow down, as they could just go around the track a few times and coast to a stop if they wanted to. StuRat (talk) 06:31, 7 August 2008 (UTC)

So the issue is that at even high road speeds air braking would have little effect? And any effect would be mitigated by the increase in weight of the air braking system? --mboverload@ 06:49, 7 August 2008 (UTC)

If you used the same sized mechanism as on a plane it would have little effect, yes. I still say that a parachute IS a type of air braking, however, just one designed to use a much larger surface area and yet still have a low weight. StuRat (talk) 14:49, 7 August 2008 (UTC)

Air brake only makes sence if you are fast 100km/h is not enough to give you the benefit you want. But in racing the technice is old and was established in formula 1 racing through the Mercedes 300 SLR in the 1950s. This modification was forbidden, partly due to the fact that you block the view for all cars behind. --12:46, 7 August 2008 (UTC)

The air brake on that particular Mercedes model was also responsible for a particularly spectacular multi-fatality (80 dead!) crash during racing. Mercedes-Benz 300 SLR, 1955 Le Mans disaster, [2]

Atlant (talk) 20:00, 14 August 2008 (UTC)

Loud booms

I suppose this goes in here. Hello, I'm from Temecula, California, and I've been hearing successive loud booms coming from a west by south-western direction for over an hour and it's freaking me out a bit. From a scientific standpoint, what is causing the booms, and why are there so many of them over a period of about an hour and a half? Camp Pendleton is in that direction, though I think it's too far away for anything to be heard from here if something is going boom over there. And this started around 11:00 PM local time.--十八 07:41, 7 August 2008 (UTC)

You might try reading about the Sonic boom, although I don't know why they would cause such a disturbance that late at night. Kissnmakeup (talk) 11:07, 7 August 2008 (UTC)

Speaking for my area, which is near a military test facility, we're subject to destructive testing. While the base normally tries to blow things up during normal work hours, some tests don't quite go as planned -- we've had unusually large (heard across multiple counties) explosions past 11 PM on occasion. Some similar event could be the cause. However, there's no possible way for us to ascertain the cause from a scientific standpoint, as there's not enough information available. — Lomn 13:11, 7 August 2008 (UTC)

Čerenkov radiation/speed of light/follow on from previous question

Someone said earlier that:

when a particle exceeds the speed of light in a given medium, Čerenkov radiation is produced

How is this possible? I was always taught, albeit I'm only an A-Level student, that things cannot go faster than the speed of light, especially if they actually have mass. Particles have mass, don't they? —Cyclonenim^T@lk? 11:27, 7 August 2008 (UTC)

Things cannot go faster than the speed of light in a vacuum. Čerenkov radiation is seen in media such as water. William Avery (talk) 11:51, 7 August 2008 (UTC)

Let me clarify my point of emphasis: there is c, the "speed of light in a vacuum". c cannot be exceeded, ever. However, much like the speed of sound varies in different materials, so does the speed of light. Light travels through water ("the speed of light in water", if you will) at some rate less than c, and particles can exceed that speed. Exceeding c in water remains impossible. — Lomn 13:08, 7 August 2008 (UTC)

Incidentally, the differing speed of light in different mediums is the cause of refraction, as given by Snell's law, and diffraction. --Bowlhover (talk) 19:36, 7 August 2008 (UTC)

Keeping Cool

How can your body keep itself cool when the outdoor temperature is 37C and there is 100% humidity?

Surely there is no way for the body to keep cooler than 37C and the temperature will therefore continue to rise, how come people do not die? And yet people live in such conditions, not necessarily with air conditioning.

I am going on holiday next week and it is very likely I shall face this problem (although I will have central air most of the time). 62.24.129.68 (talk) 11:56, 7 August 2008 (UTC)

Well, firstly people do die from hyperthermia. The best way to stay alive is simply drinking plenty of water (plenty!) and to use sunscreen to help keep sunburn away. Avoid drinking alcohol and caffeine during the day, these all play games with your homeostatic mechanisms. Oh, and don't do too much vigorous exercise in the heat if you're not well-trained to! —Cyclonenim^T@lk? 12:10, 7 August 2008 (UTC)

The last response didn't seem to address the core issue. Let me try to state it: "If the humidity is 100% and the temperature of everything in the person's environment is significantly hotter than normal human body temp, what mechanisms does the body have to cool itself ?" In such a case evaporative cooling shouldn't work, neither should conduction of heat into a cooler object, as no cooler object is available, and neither should convection of air around the person, as that requires cooler air to replace the hot air. Perhaps radiation can still work, if the person is somehow able to radiate heat more than the objects around them, provided this difference in thermal radiation can overcome the additional heat the body absorbs due to the other forms of heat transfer.

I'd say that the way people are able to survive is that they avoid such environments except for brief periods. In places where such conditions exist, they likely hide from them until they pass, such as in undergound dwellings which remain cooler or in an adobe abodes which retain the coolness of night well into the heat of the day. However, if conditions remained like that, day and night, permanently, I'd say such a place would indeed be uninhabitable. StuRat (talk) 14:41, 7 August 2008 (UTC)

I don't think radiation is going to help - the rate at which you radiate heat depends on your colour (black radiates most), but the same colours which radiate a lot absorb a lot, so the affect is going to cancel out. Even if it doesn't cancel out exactly, it's still going to be far to low to help much. I think people would soon die in such conditions - you have to just get out. The human body can survive in very high temperatures (I'm not sure how high, but certainly much much more than body temperature) if the humidity is very low, but in high humidity, heat can easily be fatal. --Tango (talk) 18:36, 7 August 2008 (UTC)

I'd classify that as "not survivable": the heat index of 37C/100% humidity is 83C, far above what the article gives as the "extreme danger" point of 54C. --Carnildo (talk) 20:33, 7 August 2008 (UTC)

Wormholes and momentum

If wormholes exist, then wouldn't their existance allow one to violate the law of conservation of momentum, ie by placing the two wormhole mouths at a right angle to each other (if you go through one vertically, and then exit somewhere else horozontally, then momentum's not conserved because momentum is a vector). —Preceding unsigned comment added by 76.68.246.7 (talk) 13:09, 7 August 2008 (UTC)

Wow, where to begin? First of all, a real wormhole solution of general relativity is not just some magical portal where you go in one "mouth" and instantly pop out the other. There is no clearly defined "mouth", and every point of spacetime (even inside the wormhole) has a little patch of spacetime around it that looks locally flat. That's one version of the equivalence principle, and it's extremely important for general relativity (it means spacetime is actually a manifold, so it can't have any corners, edges, or abrupt changes of any kind). So it could be that if you go in one end of your wormhole, you have to fire your rockets and turn inside it in order to come out the other end. Conservation of momentum is certainly not violated.

Getting into a little more detail than perhaps you're looking for, momentum actually isn't conserved globally in GR. That statement actually makes no sense, because momentum vectors at different points in spacetime aren't even in the same vector space, so you can't compare them. Instead, if an object with a certain momentum moves through spacetime, its momentum vector undergoes parallel transport, and if the spacetime is curved, you can go around a loop and back to the point you started from, and have the vector be pointing a different direction. See holonomy. So even if you can go through your wormhole and back around to where you started and it seems like momentum isn't conserved, it's actually not a problem. Momentum is always conserved locally, that never changes. —Keenan Pepper 13:31, 7 August 2008 (UTC)

Thanks a lot! —Preceding unsigned comment added by 76.68.246.7 (talk) 20:54, 7 August 2008 (UTC)

Project Management

WHAT IS PROJECT MANAGEMENT ALL ABOUT? WHAT DOES PROJECT MANGEMENT REALLY ENTAILS?

REGARDS, J.J. HARRY —Preceding unsigned comment added by 66.178.116.10 (talk) 14:17, 7 August 2008 (UTC)

First, stop SCREAMING (typing in all caps means you are angry and screaming at everyone) and then try reading project management and come back if you still have questions. -- kainaw™ 14:19, 7 August 2008 (UTC)

Why would a pencil sharpener need microbial protection?

I saw a pencil sharpener advertised in an OfficePro flyer that said, "ACME PENCIL SHARPENER/ERASER COMBO \ With Microban antimicrobial protection." Why would it need this? --205.174.162.243 (talk) 14:43, 7 August 2008 (UTC)

We have an article on Microban. Supposedly, it "inhibits the growth of odor and stain causing bacteria", according to the packaging I've seen. I think it's kind of a pointless exercise unless you really dislike the smell of your pencils and/or don't wash your hands regularly. —Cyclonenim^T@lk? 15:00, 7 August 2008 (UTC)

Control of bacteria is sometimes critical in health care settings with vulnerable patients such as nursing homes. An object that is used by a large group of people is a good way to transmit germs (door handles are the usual suspect for this problem). The ironic twist to this, of course, is that most medical records must be permanent and indelible and are therefore not written in pencil in the first place.

It's also possibly an advertising gimmick, since many pencil sharpeners are used in schools and defending children from nasty bacteria, well... anything for the children. Too bad it increases the risk of things like MRSA. SDY (talk) 15:20, 7 August 2008 (UTC)

What I worry more about, is what do all those "anti-microbial" chemicals do to the environment, if they actually work, and if they don't, it's just snake oil. I can't picture it actually doing any good to have your pencil sharpener treated with some chemical when snot-nosed kids are lined up using it one after another. (I don't mean that in a derogatory way, just realisticly.) On the other hand, how would any of us build up any anti-bodies to harmful stuff if we OCD sanitize everything like Mr. Monk? I think it's wise to be prudent either way. Balance, moderation, and just plain old common sense are in order.Kissnmakeup (talk) 16:17, 7 August 2008 (UTC)

Is it for the benefit of people that suck on the end of their pencil while they think? I think the most likely answer, however, is that it's just a gimmick. I wouldn't buy one. --Tango (talk) 22:47, 7 August 2008 (UTC)

Maybe it has something to do with cutting yourself on the blade? 89.241.242.129 (talk) 11:35, 11 August 2008 (UTC)

111-year-old reptile

Today, I read a news story about a 111-year-old reptile (lizard) that mated for the first time in decades. (See [3].) Also, I have previously read about turtles being 200+ years old. (Question A:) How in the world do "they" (scientists) know the age of such creatures? These scientists do not say "approximately" 111-years-old. They give an exact number, as if the birth were actually recorded somewhere. That was also the case on the oldest documented turtle ... it was like 225 years old or something like that. (Question B:) Is there some article in Wikipedia or on the Internet that compares average life spans of various animals (example: gnat = life span of 3 hours; turtle = life span of 125 years, etc.)? (Question C:) In terms of evolution, can anyone see the reason / purpose that some animals live for such extended periods (100+ years)? Thank you. (Joseph A. Spadaro (talk) 15:59, 7 August 2008 (UTC))

(B) Maximum life span or one of its external links [4], which has a bit more extensive table. Oops, these are max. values, not averages. Clarityfiend (talk) 16:12, 7 August 2008 (UTC)

Getting down to (C) while avoiding notions of "reasons" for evolution, it's quite clear that an extended lifespan gives a creature more opportunity to produce offspring. There will be more turtles with potentially-200-year-old parents than those with potentially-80-year-old parents, all other things being equal. — Lomn 16:36, 7 August 2008 (UTC)

To the question (C): in general, yes, longer lifespan may give an animal an opportunity to produce more offsprings; and/or may allow an animal to afford slower metabolism; and/or provide for better survival rates for long spells of unfavorable conditions; and/or allow an animal to rear its young longer so that the offspring survival rate is high; and/or allow for better selection of the fittest individuals before they have a chance to reproduce. Obviously, only some of these apply to any given long-lived organism. Shorter life-span allows for faster metabolism, higher adaptability for unexpected changes in the environment, higher rate of population increase under favorable conditions, etc. Hope this helps. --Dr Dima (talk) 18:08, 7 August 2008 (UTC)

Thanks. I guess with regard to Question C ... what I was asking was ... why would the period be so long as to be 100+ years? Certainly, these animals can reproduce / survive harsh conditions / etc. in shorter time frames that that? These very long time spans (100+ years) seem excessive, no? (Joseph A. Spadaro (talk) 19:43, 7 August 2008 (UTC))

Geez. I hope that when I hit 100+ years, my lizard still wants to get up and go for a walk. --Drop Dead Ed (talk) 19:57, 7 August 2008 (UTC)

Hi. How is it possible that a lizard could mate over 100 years? Was this a tuatara by any chance, because it did say it was endangered, and related to dinosaurs (sphenodontians, to be exact)? Do they have a slow reproductive rate or something? Thanks. ~AH1^(TCU) 20:08, 7 August 2008 (UTC)

Humans are actually fairly unusual in having a menopause, and even that only affects women. Assuming that the lizards and tortoises don't invest a lot of time and energy in raising young, what would be the advantage in them living that long and not being able to reproduce? 79.66.38.215 (talk) 22:56, 7 August 2008 (UTC)

Astro, yes I'm pretty sure Joseph is referring to a tuatara. In response to the question, it's possible as others have suggestedm Henry's year of birth is known. However I'm not so sure... This (slightly older) source says he was born in the 1880s [5] which doesn't gel with an age of 111. This even older source says he was ~130 in 2001 [6]. It's possible some records were unearthed which showed Henry's likely true age. It's also possible that as part of the PR for the story, the team decided that since according to their estimates, he was at least 111 they might as well say he's 111 since it sounds better. (Or maybe even some in the press did it and it stuck.) Note that these sources describe his mate's age as 70 to 80 [7] & [8] something we may expect if the age is simply an estimate Nil Einne (talk) 14:37, 9 August 2008 (UTC)

Again, the "why" is problematic. Evolution isn't concerned with motivation. For this case, though, so long as the critter isn't going sterile, its lifespan is tied to a competitive edge in offspring quantity, and thus those genes make up a larger portion of the gene pool. — Lomn 20:45, 7 August 2008 (UTC)

Living longer is obviously better, all else being equal, since it gives more time for reproducing. The real question is: Why do other animals not live as long? Take a look at Senescence for some possible reasons. --Tango (talk) 22:56, 7 August 2008 (UTC)

As for part A, the exact ages of many animals are known because they are pets handed down from one generation to the next and the date of birth (or hatching) was noted. There may be older creatures of that species in nature, but maybe not, as they aren't as likely to be taken care of in their old age and live as long. StuRat (talk) 01:18, 8 August 2008 (UTC)

There's a joke about a fossil being 152 million and 43 years old. Why? Because the museum had been told it was 152 million years old 43 years ago. Maybe the keeper of the lizard was told that the lizard was 50 years old 61 years ago. --Kjoonlee 02:14, 8 August 2008 (UTC)

Tu'i Malila, Adwaita and Harriet might be helpful for information on old turtles/tortoises. --Kjoonlee 02:20, 8 August 2008 (UTC)

(C)They're in for the long haul so the tortoise wins the race. Julia Rossi (talk) 03:23, 8 August 2008 (UTC)

Yes, but only by a hare. StuRat (talk) 20:12, 8 August 2008 (UTC)

Thanks to all for the above info. It was helpful. Thank you. (Joseph A. Spadaro (talk) 15:47, 9 August 2008 (UTC))

Why are their bellies cut open?

 ?? —Preceding unsigned comment added by ScienceApe (talk • contribs) 19:34, 7 August 2008

See exploding whale. --Carnildo (talk) 20:49, 7 August 2008 (UTC)

Well, as the picture is about whaling, that's done because that's what you do with things you're killing for food. Gutting is a pretty necessary process if you're going to eat an animal or prepare it for eventual eating; when you take out the bowels and internal organs, you also take out a lot of the bacteria that'll make the fish (or any animal, really) spoil more quickly. Most of that stuff is inedible anyway. Also, as Carnildo points out, not cutting in a couple of holes for ventilation can also result in the build-up of gases, but I think at that point the animal is going to be pretty much unfit for consumption anyway. -- Captain Disdain (talk) 20:55, 7 August 2008 (UTC)

Slight correction: They're not fish. —Pengo 22:43, 7 August 2008 (UTC)

No, I know. I was trying to say that just like fish have to be gutted, so do whales, but that particular point didn't really come through here. -- Captain Disdain (talk) 23:29, 7 August 2008 (UTC)

Well, there's a Chinese saying:

We eat everything with four legs, except for tables and chairs. We eat everything with wings, except for airplanes and helicopters. We eat everything with fins, except for submarines.

And there's also a Korean saying:

There's nothing to waste from a bovine.

If you try hard enough, almost anything is edible. Whale intestines are consumed for food in Korea. --Kjoonlee 01:53, 8 August 2008 (UTC)

"You can eat every part of a pig except the squeak" DuncanHill (talk) 10:04, 8 August 2008 (UTC)

Sure. But you're still going to want to remove the bowels ASAP, what with them being filled with shit and all. Even if you clean them up afterwards and use them in sausages or whatever. Leaving them in isn't going to do the carcass any favors, as far as avoiding food poisoning and parasites goes. -- Captain Disdain (talk) 13:30, 8 August 2008 (UTC)

I recall hearing about a Hmong dish translated as "doodoo soup" that has apparantly uncleaned bowels. But, then again, I hear a lot of wrong things about the Hmong diet where I'm from. — Ƶ§œš¹ _{[aɪm ˈfɻɛ̃ⁿdˡi]} 22:04, 8 August 2008 (UTC)

Well, hell, some people really like their dumplings, but I didn't think there'd be enough demand for an actual cuisine based on that. Guess it wouldn't be that much of a surprise, though, all things considered... -- Captain Disdain (talk) 23:58, 8 August 2008 (UTC)

Vectors

When dealing with vectors (ie displacement, velocity, acceleration, etc.), is it always needed to write the arrow above it? Now I know probably few people do always bother; my question is more asking if there are certain times (ie when dealing with vector components) when writing the arrow would be improper. —Preceding unsigned comment added by 76.68.246.7 (talk) 21:02, 7 August 2008 (UTC)

As long as you use consistent notation, then technically you can write it however you want. However, marking vectors (with a small arrow, or a boldface font, or a squiggle, or whatever you want to use) can be helpful especially when they're used in expressions with scalar quantities to make sure that you only perform vector operations on vectors and scalar operations on scalars. For example, writing v = xi + yj + zk is much clearer about what's going on than v = xi + yj + zk. Confusing Manifestation(Say hi!) 22:37, 7 August 2008 (UTC)

Personally, I underline vectors, but whatever notation you use, it's important to use it consistently. You could not mark vectors at all, but if you're going to mark some, you need to mark all, otherwise it will certainly cause confusion. If you don't mark any, people can probably work out from context when something is a vector and when it's not, but it's a waste of effort when you could just have marked them in the first place, and there is a risk of confusion. Also, marking them allows you to use x and x as two different variables - x often means position as a vector and x is the x-coordinate, so x=(x,y,z). If you didn't mark them, that would be extremely confusing. --Tango (talk) 22:52, 7 August 2008 (UTC)