Wikipedia:Reference desk/Archives/Science/2007 February 12

=February 12=

dark eye shadows
To whom it may concern- Why does the area around our eyes getting darker when we don't sleep? I have heard theories, the best one is that it is venous congestion from prolong eye opening. Thanks —Preceding unsigned comment added by Salim19 (talk • contribs) 02:39, 12 February 2007


 * See eye circles &mdash; Kieff | Talk 03:06, 12 February 2007 (UTC)

Phase angle
Can someone please explain phase angle and why capacitors and inductors and such change from it in layman's terms? I know the math but don't understand it or the concept really.69.29.62.73 02:43, 12 February 2007 (UTC)

I mean, what is actually going on in RC, RL, RLC circuits


 * In an AC circuit without L or C components, the voltage and current are "in phase" or, at all times proportional. The introduction of L or C components in a circuit will cause the voltage and current at various places in the circuit to be other than exactly proportional. The "phase angle" is a measure of the disproportionally with respect to time where 360º = 1/f. hydnjo talk 03:43, 12 February 2007 (UTC)


 * In fewer words, phase angle (in circuit phasor notation) is merely a representation of time delay. A phase angle of zero with respect to some point represents no time shift, while a phase angle of 360 degrees (2 pi radians) represents a time shift of one whole period of the phasor frequency. -- mattb

so, because inductors and caps store energy, the wave at any given time "come out" of them at a time delay?


 * Yes. Because these lump elements store energy, they introduce a delay. -- mattb

thank you. I figured that was what was going on but I wasn't for sure
 * I always thought of a capacitor as a device which hates to see the voltage change. If the voltage starts to change, the cap will absorb current (charge) or pay out same to try and keep the voltage constant. The voltage change lags behind the current change in a capacitor. On an oscilloscope, with AC going through a capacitor, the peak of the current waveform leads the peak of the voltage waveform by 90 degrees. An inductor hates to see the current change, and produces a counter EMF to oppose the current change, so the  current change lags behind the voltage change. On a scope, the peak of the voltage waveform leads the peak of the current waveform by 90 degrees for an inductor. In either case, the presence of resistance decreases the lead from 90 degrees. Edison 16:57, 12 February 2007 (UTC)

Total oxygen-producing capacity of the Earth's vegetation
Have there been scientific studies to estimate the total oxygen-producing capacity of the Earth's vegetation? If so, what do we know about it? If the current trends of population growth and deforestation continue, at what point will we be in danger of not having enough oxygen? --71.175.23.226 04:11, 12 February 2007 (UTC)


 * It's likely that the Earth would become unlivable due to excess carbon dioxide long before the oxygen started to run out. The fact that minerals like coal and diamond are buried are the reason that oxygen is so available on the Earth's surface; it was all CO2 to begin with.  The other question to ask is: what do we use oxygen for?  Well, we use it to oxidize fuel, and we breathe it to oxidize food.  Food and biofuels like wood or whale oil get their carbon and hydrogen from CO2 and water that were (in geological terms, anyway) recently split by photosynthesis.  If we can produce enough food for our population, we will, by default, have produced enough oxygen to metabolize that food.  Fossil fuels, as I mentioned earlier, were separated from their oxygen much longer ago.

We will never mine all of them, though: most just aren't accessible. If accessibility weren't a problem, we would be stopped from digging up coal (and from living) by a greenhouse effect like the Earth hasn't seen in a very long time: we're worried about the effects we've seen while going from 280 to 380 parts per million of atmospheric CO2, but using up half the world's oxygen would bring the concentration up to 10.5%, or 105,000 ppm.
 * I hear that the developers of the first nuclear bomb worried that it might ignite the atmosphere, forming nitrogen oxides and using all the world's O2 in one fell swoop, but that obviously didn't happen (we now know that it's impossible). I haven't heard any other serious scenarios where we might use up all the oxygen without the side effects of such a process killing us all first.--Joel 09:12, 12 February 2007 (UTC)
 * The "igniting the atmosphere" scenario was actually about igniting a nuclear reaction such as fusion of two nitrogen atoms to form aluminum. Such a reaction would be exothermic and therefore potentially self-sustaining, and it was thought that the blast might be hot enough to start it. Calculations using a more detailed model showed that it would not. --Anonymous, February 13, 2007, 04:14 (UTC)>
 * (Or worse still, warming the oceans could result in frozen methane deposits in deep ocean trenches melting and bubbling to the surface. Since Methane is a vastly more effective greenhouse gas than CO2 and it doesn't get metabolised away by plants, this scenario would be close to 'game over' for humanity). SteveBaker 00:49, 14 February 2007 (UTC)


 * CO2 is pretty poisonous actually - If there is 5% of CO2 in the air, humans will die - irrespective of how much oxygen there is. (Prolonged exposure to air with more than half a percent of CO2 is considered hazardous...again, irrespective of the amount of oxygen).  So the key thing about plants is not so much that they are producing oxygen as that they are removing CO2.  Incidentally, plants only consume CO2 when they are exposed to sunlight - in the dark, they consume oxygen and actually produce CO2 - just like animals do.  As for how much they produce - I have no clue...but green phytoplankton in the oceans are another major way that CO2 gets absorbed out of the atmosphere so it's not just "plants" in the usual sense of the word. SteveBaker 20:38, 12 February 2007 (UTC)
 * An interesting point I see quite often is that fitoplancton is responsible for 90% of the oxygen produced on Earth. --Taraborn 22:13, 12 February 2007 (UTC)

See Carbon cycle. Heating the oceans may create more plantlife (i.e. absorb CO2) or it may release CO2 that is stored. Both answers have different climate impacts. --Tbeatty 06:08, 13 February 2007 (UTC)

Also see Overpopulation and question what you know about human population patterns. (SEWilco 18:56, 14 February 2007 (UTC))

Also see biomass - some subfields of ecology and environmental science use macroscopic models for "total amount of living things" and then do simple stoichiometry (probably approximate, but "order of magnitude" sort of stuff). Nimur 19:55, 14 February 2007 (UTC)

Helicopter
If a helicopter pilot turns the motor off (in flight), will the helicopter just plump down like a stone or glide like a gyrocopter? Mr.K. (talk) 11:12, 12 February 2007 (UTC)
 * Autorotation --Zeizmic 12:56, 12 February 2007 (UTC)


 * Thanks! Mr.K. (talk) 12:59, 12 February 2007 (UTC)


 * Autorotation is indeed the answer - but it's something that takes skill to learn - and it's very nerve-wracking. When the engine dies, you have to tilt the blades of the rotor so that as the helicopter plummets down ("like a stone"), the blades turn like a windmill in the airflow.  This does two things.  Firstly, the rotor acts like a parachute - slowing down the rate of fall of the helicopter - secondly, the blades start to spin faster and faster (because it's acting like a windmill).  At some appropriate height - just before you hit the ground - the pilot has to reverse the pitch of the blades again so they are back the way they'd be if the engine was still running.  That causes them to start pushing air downwards - just like they'd do if the engine was still running - but because it's not, the rotors lose energy and slow down dramatically.  But (ideally) that last downward push is just enough to let the helicopter gently settle the last few tens of feet onto the ground.   The nasty part for the pilot is judging his height just right for that final manouver.   If he does it too soon then you're still way above the ground with the rotors not spinning anymore and the helicopter surely will plummet like a rock.  If he leaves it too late then that last burst of energy that would have slowed you down doesn't happen in time and you'll still hit the ground too fast.   This is a tough skill to learn and it's very, very nerve wracking to do 'for real' because if you get it wrong - you're probably dead.  So most helicopter pilots only do it once or twice in a real helicopter - and hope to heck that they never have to do it in a real emergency.  The best way to learn is in a flight simulator where you can practice as many times as you need to learn the skill well. SteveBaker 20:28, 12 February 2007 (UTC)
 * An old Navy pilot told me that any landing you walk away from is a "good" landing. I would think that, by analogy, any landing that leaves the aircraft even repairable would be a "near perfect" landing. All this from the perspective that it is an amazing feat to get anything heavier than air to fly at all. Edison 05:39, 13 February 2007 (UTC)
 * Airforce pilots tell me that Navy pilots only say that because they have to swim away from so many of their "landings". :-) SteveBaker 00:45, 14 February 2007 (UTC)


 * Civilian pilots tell me that military pilots sit in uncomfortable chairs wearing oxygen masks and watch their computer fly their aircraft. Nimur 19:58, 14 February 2007 (UTC)

arun's ques.
does human urine contain sperm?


 * Only if the human in question has ejaculated recently so that their urinary tract has left-over sperm paddling around.


 * Atlant 17:03, 12 February 2007 (UTC)

arun arun arun ques about chemistry
what is the actual meaning of 'spd''f' in periodic table


 * Atomic orbital gives a fairly thorough explanation. --Ed (Edgar181) 13:57, 12 February 2007 (UTC)

How to keep something cold
Is it possible to keep something - such as a mattress, cold or chilled without electrical power? Is there a cooling gel or system that could keep something cold for hours?

THANK YOU!!!
 * A water bed can act as an enormous heat sink, such that if you don't heat it, it can actually be dangerously cold (e.g., to an infant or bedridden person). In general, anything that can absorb and radiate heat away from your boday faster than you can produce it, will stay "cold" indefinitely. --TotoBaggins 14:39, 12 February 2007 (UTC)


 * evaporation or gas expansion comes to mind. Tbeatty 14:42, 12 February 2007 (UTC)


 * Also see this, for ancient ACs. Mr.K. (talk) 16:04, 12 February 2007 (UTC)


 * Without consuming power, it can only stay as cold as the environment it's sitting in - this is dictated by the second law of thermodynamics - so we're pretty sure there is no 'get out clause' that would allow you to build something that can cool itself without power. Even a large water mattress will eventually settle down to somewhere around room temperature.   However, that will feel cool to your skin because we are much warmer than room temperature and heat flows from warm things into cooler things.   But - our perception of coolness is not strictly one of temperature.  If you take a chunk of metal and a chunk of plastic that are at exactly room temperature - and place your hand on the metal, it will feel cooler than the plastic.  That's because our perception of temperature is the amount of energy our skin loses or gains from whatever it's touching.  Since metal conducts heat away quite efficiently while plastic doesn't, we feel more heat from our skin flowing into the metal than into the plastic - so plastic feels warm to the touch and metal feels cold - even when they are at the same temperature.  So if you take a nice cuddly blanket (which is a great insulator...like the plastic) that's been sitting in the same room as a waterbed (which conducts heat away like a chunk of metal) - then the water bed will FEEL as if it's colder than the blanket - even though it's not.  So your FEELING of cold can indeed be kept up without electrical power - although the temperature cannot.  Providing the water bed can lose heat into the room faster than your body can feed heat into it (which it easily can) - then you'll feel cool all night.   BUT if the air temperature ever gets above body heat (which can happen here in sunny Texas) - then the opposite would happen.  Because the room temperature is above your body temp - and the water bed will eventually come to be the same temperature as the air, a water bed will conduct heat INTO your body much more efficiently than a blanket would - so you'd feel a lot hotter in the water bed.  But the second law of thermodynamics is what prevents you from making a refrigerator that doesn't use any electricity.  The laws of thermodynamics are such kill-joys! SteveBaker 20:13, 12 February 2007 (UTC)


 * Without consuming some form of energy you will not be able to keep something cold. But this doesn't mean that it must be electrical power. If you take a metal plate for example and let alcohol drop on it at a steady rate, you will keep this metal plate cold for a while. Similar experiment with different materials (ether, amonia) are also possible. Just keep in mind that some form of liquid must evaporate to become a gas (i.e. absorb energy). The second law of thermodynamics doesn't prevents you from making a refrigerator that doesn't use any electricity. Indeed due to the second law of thermodynamics you can make a refrigerator that doesn't use electricity. For more information look at Einstein refrigerator  Mr.K. (talk) 13:19, 13 February 2007 (UTC)


 * Yeah - I didn't say you needed electrical power - just that you need power of some kind. In your example, you're using chemical energy...but it's still consuming power of some kind or another in order to stay cool.  There are refrigerators that you can buy for mobile homes that run on propane - so for sure you don't need electricity. SteveBaker 00:42, 14 February 2007 (UTC)


 * Of course you said that. Read at the end of your post: " But the second law of thermodynamics is what prevents you from making a refrigerator that doesn't use any electricity. " 132.231.54.1 10:25, 14 February 2007 (UTC)

Astronauts Pills
I heard a while back that there was a pill given to Astronauts to relieve sexual tension or urges once in space. Is there any information on this or was this just a rumor?


 * You might read anaphrodisiac for general information and consult Snopes for specifics. Walter Siegmund (talk) 18:13, 12 February 2007 (UTC)


 * In any case, one suspects they have more important matters on their minds. There is no better anaphrodisiac than having to pay close attention to your survival. They are considered members of the elite 100km high club without going that bit further.--Shantavira 09:15, 13 February 2007 (UTC)

I read somewhere that there was a pill in which the Astronauts would have "sex" on their dreams while they are sleeping. And then the drug dealers got a hold of this drugs and where selling them. Has anyone heard of this story?


 * OT but I just thought of this. I suspect a lot of companies are dying to make porn in space. Think of the possibilities. Nil Einne 14:31, 17 February 2007 (UTC)


 * I doubt the story is true. -- Beland 01:52, 18 February 2007 (UTC)

Oribit
Is it a valid comment to say that “an aeroplane orbits the Earth, if the aeroplane circumnavigates the Earth?" i.e. one complete flight around the earth = one orbit. I am of the opinion that this is not an orbit (in a scientific sense), but I just want to get the general consensus. Thanks RaGe 16:23, 12 February 2007 (UTC)
 * Once you start altering the meaning of a word, it could mean anything you want:) Is a person standing on the ground "orbitting", given that he is circling the earth's rotational axis once a day? DMacks 18:35, 12 February 2007 (UTC)


 * "Orbit" is correct according to the dictionary, (an approximately circular or elliptical path traced by something in motion OED) but it's never used in that specific sense in practice. "Circumnavigation" is the right word in that situation. --Shantavira 18:33, 12 February 2007 (UTC)


 * If this is just a question of dictionary definitions - then indeed, standing perfectly still for 24 hours would imply you were orbiting the earth. But this is the Science Desk - not the English Lit. Desk and scientists very often have different meanings for words than the general public...so we need to talk about the true distinction between what a circumnavigating aircraft does compared to something like a satellite that is 'in orbit'.   When we talk about something being "in orbit" around the earth, we generally mean "in a stable orbit".  That means that without firing any rockets, you'll keep going round and round the earth pretty much forever.

That's clearly not what our airplane is doing. As soon as it shuts off it's engines...kersplat...no more "orbit" - it's in a highly unstable orbit. To be in a stable orbit, you need to be going around the earth at a speed such that "centrifugal force" (a term most physicists hate - but which none the less serves our purpose) exactly equals the force of gravity. That's a rather precise speed that depends on your altitude above the earth. SteveBaker 19:59, 12 February 2007 (UTC)


 * Steve goes wrong at the end: what he's describing are the conditions for a stable circular orbit. An elliptical orbit accommodates a wider range of speeds, and the speed of the object will vary continuously -- fastest when lowest, slowest when highest -- but this is still stable, so long as the lowest point is for practical purposes above the atmosphere.  For an orbit that isn't circular, the speed at the lowest point will be faster than for a circular orbit at the same height (so you still need a minimum speed to be in orbit), and the speed at the highest point will be slower than for a circular orbit at that height.  --Anonymous, February 13, 2007, 04:24 (UTC).


 * Thanks for the responses people, just what I wanted RaGe 19:41, 13 February 2007 (UTC)

relativity and light
The speed of light is always the same-however fast you are moving, light always passes you at 3x10^8ms^-1. So if you were on a photon travelling at 3x10^8, and another photon passed you it would be travelling at 3x10^8 relative to your speed. However from the other photon, you would pass it at 3x10^8. This seems to mean two photons can pass each other, both going at twice each others speed. How the **** does this work?Hidden secret 7 17:27, 12 February 2007 (UTC)
 * See special relativity. If you're looking for a quick "how this works" in layman's terms, I don't believe anyone's ever come up with an explanation like that.   Friday (talk) 17:43, 12 February 2007 (UTC)

From one photon the other would appear to be moving at 6x10^8, so could this be extrapolated out further to suggest that a photon could travel at infinite speed relative to one travelling at infinity-3x10^8, which was relative to one travelling at infinity-6x10^8&c:)HS7


 * It is misleading to phrase the question in terms of photons, because, in a sense, photons don't "experience" time at all. No photon could "pass" another photon. So let's instead consider an astronaut moving at 0.9c relative to the Earth. A photon passes her, and she observes its speed to be c relative to her. Would an observer on Earth then have measured the speed of the same photon to be 1.9 c? No, the Earth observer would also measure a speed of c. It will appear to the Earth that the relative speed of the photon to the astronaut is 0.1 c, but that the astronaut measures a relative speed of c because of the strange things that relativity does to the astronaut's measuring devices: the astronaut's clocks appear (to the Earth observer) to go too slowly, and her rulers appear (to the Earth observer) to have shrunk.


 * If we instead consider a second astronaut that passes the first one, at a relative speed of 0.9 c, and a third astronaut that passes the second one with a relative speed of 0.9 c, and a fourth astronaut that passes the third one etc., then all of these astronauts will move at less then c relative to the Earth observer. Even if there is an infinite series of such passing astronauts, their speed relative to Earth will only approach c, never exceed it. --mglg(talk) 18:52, 12 February 2007 (UTC)


 * Photons don't have a rest frame of reference. That means that there is no relative velocity to even speak of.  Imagining yourself as the photon and being "at rest" with respect to other photn, while a thought experiment, is simply not a physical reality.  Tbeatty 20:26, 12 February 2007 (UTC)


 * Yeah, you can't have a photon pass another photon. Think about what you mean by "passing" here — you mean that one photon, going c, is surpassed by a photon on a parallel path going at a speed greater than c. You're basically saying, "the speed of light is constant (in a vacuum), but what if light could go faster than the speed of light?" Which is a nonsensical question and one which doesn't really appreciate what the "speed of light" means. You might as well say "if the top speed of a certain model of car is 50 mph, and another of the exact same model of car goes by it at 100 mph"... see the logical problem? --24.147.86.187 23:13, 12 February 2007 (UTC)

But the speed of light is always the same, relative to the speed of anything it passes:) If you travel at close to the speed of light, you will still see light passing you at the speed of light:) Therefore if light passes everything still going at the speed of light relative to whatever it passes, it would be able to go faster that the speed of light:) Based on the answers here this seems to possibly have something to do with time dilation:( But really the entire universe could be going backwards and light would still pass us at the speed of light:( I think I got a bit confused, and am not sure if any of this was what I was trying to say, but it looks close enough:(HS7 14:21, 14 February 2007 (UTC)


 * The speed of light is the same. IT has the interesting phenomena that the frequency is modulated by the relative velocity of the source and receiver (not the medium like sound waves).  So if you were moving close to the speed of light and approached a regular flashlight, the light would still be coming at you at the speed c, but the frequency of the light might now be Xrays or different than the resting light frequency.  `Think of it this way: you cannot impart kinetic energy to the velocity of light (I'm sure there some fancy relation to how kinetic can be imparted based on some quark property such as spin).  But it has to go somewhere so it goes into the frequency.  All of it.  --Tbeatty 06:54, 15 February 2007 (UTC)

Alleles identical by descent
No disease model is given, nor is the information about the genotypes of parents and a child in a family. Is it possible to tell the IBD score from father to son?

In another case, we have a family in which father and the second child are affected, mother and 1st child are not affected. what would be the IBD score?


 * You have give insufficient info to answer your question. alteripse 00:31, 13 February 2007 (UTC)

Just curious...
I've just finished taking a course of Rifampicin after a breakout of meningitis at my school, and was just wondering what causes the bright orange/red urine? MHDIV ɪŋglɪʃnɜː(r)d ( Suggestion? | wanna chat? ) 20:48, 12 February 2007 (UTC)


 * That's pretty much just the color that Rifampin is (reddish) +/- some additional yellow from urine (--> reddish-orange). You're excreting the drug in your urine (mostly) and also in every other bodily fluid, which is why you were warned (or should have been) to avoid using soft-contact lenses if you wanted them to stay clear instead of red. - Nunh-huh 21:38, 12 February 2007 (UTC)

Is table salt the same as the salt in tears?
Okay, so my friend says the salt in your tears is the same as table salt. My other friend (who is nerdy) says the two are completely different because table salt contains iodine, but this isn't the only difference. I need you guys to settle this once and for all. NIRVANA2764 20:59, 12 February 2007 (UTC)
 * Try this article. ColourBurst 21:02, 12 February 2007 (UTC)
 * The main salty component is the same in both (sodium chloride). But as your nerdy friend pointed out, table salt also contains small amounts of some other compounds like iodine, and anti-caking aids. Tears, of course, also contain many other things: many other salts, a large number of different proteins, etc. But, again, their salty taste comes mainly from the same chemical compound as is in table salt. --mglg(talk) 21:09, 12 February 2007 (UTC)
 * By the way, there is just one salty tasting known substance. It is sodium chloride. If something tastes salty, there is sodium chloride inside. Mr.K. (talk) 13:29, 13 February 2007 (UTC)
 * Really not true. Chemically "salt" is a generic name for a large class of ionic compounds.  Not surprisingly, several of the common mineral salts also taste "salty", which is how the group originally got its name.  Calcium chloride and potassium chloride are ones you might encounter as a sodium chloride substitue in food.  A large numbers of "salts" will also taste bitter, and some organic salts even taste sweet.  Dragons flight 17:12, 13 February 2007 (UTC)
 * Don't forget MSG! --Wirbelwind ヴィルヴェルヴィント (talk) 18:26, 13 February 2007 (UTC)


 * MSG tastes savory and not salty. Potassium chloride tastes bitter, although it is a salt substitute for sodium chloride for preserving food. Calcium chloride is a equally a substitute for Sodium chloride for preserving food. See this article and this for more information about the taste of calcium chloride. In the first article the authors try to overcome the taste of calcium chloride through "an oily solution of calcium chloride, which reduces the bitter taste of the salt." The second also points to the bitter taste of calcium chloride: "Calcium chloride is not the ideal calcium salt to use in food fortification because of its high bitterness ratings". The only source about salty taste of calcium chloride that I found was wikipedia itself. MThis is due mainly to the anatomy of our taste_buds for saltiness, which work through ion channels. Specially Na+ is able to pass through this channels.Mr.K. (talk) 19:42, 13 February 2007 (UTC)

A drug categorization dispute
Would anyone be willing to participate in settling a dispute? Please read Wikipedia talk:WikiProject Psychedelics, Dissociatives and Deliriants. I know this is hardly the place to ask a question like this, but I've been trying to enlist help from users in WikiProject Psychedelics, Dissociatives and Deliriants] to help, and not a single Wikipedian has made any comments, and we're a far cry from reaching a consensus on a debate we're having. The debate is over the definition of "psychedelic," as Wikipedia currently uses the word to describe a very specific class of serotonergic and cannibinoid drugs. I argue that the definition is too stringent. The defender of that definition and I have cited many sources to defend our respective views, and they're well referenced, so simply reading through and leaving your two cents would help us reach a consensus. Thanks! Jolb 21:20, 12 February 2007 (UTC)


 * I looked at the page Hallucinogens and the other links and saw the way they have been broken up into three classes, I also looked at the points you both made. I have no dissagreement with either..
 * I honestly couldn't make a decision. so personally I'd stick with it as it is. 87.102.16.197 22:35, 12 February 2007 (UTC)


 * I have commented on the above and asked at the WikiProject Drugs talk page for input, pointing them to the WP:Psychedissocialiriants discussion. − Twas Now ( talk • contribs • e-mail ) 00:00, 13 February 2007 (UTC)

The Watchmaker analogy
Hello, I'm the anonymous user who posted "Science and the supernatural" on Feb 9th. I have another, related question. Creationists and Intelligent Design proponents sometimes argue that "Just as a the existence of a watch implies that there must be a watchmaker, and it would be perverse to suggest that the watch came about by random chance, so a complex universe [or "irreducibly complex" structures in that universe] shows that there must be a God." Thus, science would prove the existence of God. I have read people like Isaac Asimov try to refute this argument, insofar as it is offered as a scientific proof, pointing out that the whole point of science is to find blindly operating natural causes and that "to surrender to ignorance and call it God is premature and it has always been premature." Yet, when we find a watch (or even some kind of machine we do not recognize), we do assume that there is an intelligent designer. The existence of humans is an accepted scientific fact (I think), as is the fact that watches are intelligently designed. So where is the flaw in the analogy? Are humans supernatural beings? Or is the analogy valid? Cause I'm not entirely sure that ID is a bad idea. EDIT-made my Question more clear 69.223.156.241 22:37, 12 February 2007 (UTC)
 * I see no real flaw in your arguments - it's just that very little is 100% certain - that's the only problem.
 * Also it is possible that humans are supernatural beings - I've often wondered this - but it's neither provable or disprovable as far as I can tell.
 * There is no real explanation for existance - as you have noticed I think - but if we say that it must have been made by something eg god (as per the watch) the problem continues ie who made the god.. I can tell you I found the whole question fundamentally unanswerable, though I admit I still think about it.
 * Lots of people are fairly certain that god either exists or doesn't exist, who however can be certain? - everyone thinks about it don't they?87.102.16.197 22:53, 12 February 2007 (UTC)
 * By the way I'd like to point out that it's not actually scientific method you are describing but more logic and reason that you are using to prove/disprove the existance of things. Better than science in my opinion. You might want to start reading philosophy articles - though there's a lot to wade through you've got till eternity to do it! Good luck - remember that the 'greatest minds' of world history haven't really cracked this one.87.102.16.197 23:04, 12 February 2007 (UTC)


 * The reason the watchmaker analogy is used by creationists is that it's emotionally appealing rather than because it's intellectually sound. It's appealing because in our experience, all watches are made by humans. Therefore if we find one, we assume it was made by a human. But this is not because the watch is "complex", it's because all the watches we know were made by people. One might with equal (or equally little) justification say that the presence of a rock implies a rockmaker.  And there is no analogous experience that all humans are made by gods. The statement presumes the same thing that it seeks to prove, so it's not intellectually sound; its purpose is to persuade, not enlighten. It also fundamentally misrepresents evolutionary theory, as no evolutionary theory claims that any complex structure ever arose "by chance".   - Nunh-huh 23:07, 12 February 2007 (UTC)


 * Irreducible complexity is a different concept than just complexity — I just want to point that out. Paley's original watchmaker argument was not about irreducible complexity (irreducible complexity only becomes required later when you have an alternative method — gradualistic evolution — to argue against). Irreducible complexity is an entirely different thing and should be regarded quite separately from your question (IC says that some structures could never have naturalistic/evolutionary explanations because removing one element of them would be useless, ergo any sort of evolutionary process would never have been able to create it. This is quite different from the argument that complexity implies a designer, in general).
 * As for the problem — it depends entirely on whether you consider the explanations of naturalistic "design" (design without a designer) to be valid. The main argument against it is that there are some principles which we generally call naturalistic which seem to, without any additional intelligence, give rise to incredible complexity. But whether or not you consider those principles to be evidence of further interaction by a God or not — i.e., maybe he set forth the principles in question — or whether you consider them to be "truly" naturalistic will depend primarily on your prior philosophical/religious convictions, because there is no compelling logical reason to choose one explanation or another. The "scientist" would perhaps say that the introduction of superfluous concepts seems unnecessary and illogical but that is an aesthetic, not a logical, preference. --24.147.86.187 23:08, 12 February 2007 (UTC)
 * Comment - (note to self) 'watchmaker' or not, what is still needed is an explanation of why anything exists at all.87.102.16.197 23:31, 12 February 2007 (UTC)
 * Which is actually an argument that works easier in Paley's favor than against it. For Paley it is clear that if you agree that there is a watchmaker God then you will find plausible that existence itself is at the discretion of such a God. Which is not necessarily any larger of a logical jump than saying that things "just exist" for the sake of it, which is pretty much the closest answer you would get from modern science (officially science would actually just refuse to give an answer, as it is not really a question within its purview, but to me that doesn't really help much). --140.247.242.75 18:07, 13 February 2007 (UTC)

The is the dumbest argument in the world! Let me explain why.

"A watch implies a watchmaker, therefore a human implies a God". The biggest problem is this "How do you recognized a watch (a thing that is designed) when you see one?" Because of your experience of a watchmaker(designer) or stories of a watchmaker(designer). Now ask yourself this question, if you had never had the experience of God or stories of God, will you conclude that finding a human implies the existence of God. Of course not.

What you are saying is:

Things that are designed are "complex looking" therefore things that are "complex looking" are designed. QED.

202.168.50.40 00:46, 13 February 2007 (UTC)


 * It isn't the "dumbest argument in the world", and generally when one encounters an argument which has been discussed up and down by dozens of philosophers for hundreds of years assuming that it is simply "dumb" is more a statement about yourself than it is one about the argument. Paley's actual argument, which you likely have not read, is much more specific about what he considers this complexity to be, and he appeals to the very general experience one has with things like mechanical clockwork, which you'd be a fool to think doesn't imply a designer (Paley's argument is in many ways a very pragmatic one, appealing to what "any reasonable person would believe" rather than attempting to define everything from first principles). The only reason Paley's argument doesn't really work is that we do, now, have explanations of how highly complex things can come about without intelligent intervention. Paley's argument simply says that authorship and complexity seem connected in the human technical world, and there is no a priori reason not to think they would be connected in a biological world. It's someone like Darwin who gives you a possible a priori reason for doubting that. --140.247.242.75 18:07, 13 February 2007 (UTC)


 * To the original poster: I can specifically recommend Richard Dawkins's book, The Blind Watchmaker, which as its title implies addresses Paley's Watchmaker fallacy directly.


 * Why is the analogy fallacious? My own answer is that you can come at it from two directions.  One is that, although life is undeniably complex, hypothesizing the existence of a watchmaker -- a god -- implies much more and even more unimaginable complexity.  Life may be improbable, but an omnipotent god is even more so!


 * The other answer, the other direction to come at it from, is that evolution and natural selection actually work much, much better and with much more finesse than you might at first imagine. It's very hard to believe at first; it seems nearly impossible that (to cite everyone's favorite example) something as magnificent as the eye just happened to evolve, by random accident.  Again, read Dawkins for a better understanding of this -- he explains it very eloquently and convincingly.


 * If I were an omnipotent god and I wanted to create life, there's no way I'd have the patience to muck around with individual eyeballs and irises and ribs and stuff; instead I'd invent evolution and natural selection, and let life design itself for me. —Steve Summit (talk) 02:35, 13 February 2007 (UTC)
 * That's a good point. You know, this sort of topic came up in my biology class. In this post, however, I will give my personal opinion on the matter.
 * If there is a God, which I firmly believe as a Roman Catholic, that wanted to create a diverse and free race, then he would have created a system to do so. Let's take into the perspective of Nazism. The Nazis attempted to acheive a Master race by means of experimentation with women in the concentration camps. In this case, Hitler tried to play god by means of manipulating the human population (selective breeding? eugenics?). As we know now, trying to create your own race by means of using your own power might not be the best thing for the human population right now. It would strip us of our individuality and uniqueness. Now in the case of human society today, generations of children are produced by natural process such as fertilization.
 * In conclusion, I believe that God created the human race along with a means of naturally producing further generations of humans to create a completely diverse population, with creatures of different backgrounds, unique characteristics, and individuality.-- Ed  ¿Cómo estás? 03:19, 13 February 2007 (UTC)


 * See Teleological argument. Emmett5 03:07, 13 February 2007 (UTC)

There are so many ways around this watchmaker analogy. For example: Suppose you have the components to make a watch - a bunch of gearwheels and springs and stuff. You shake them up and dump them at random onto the floor...what are the odds that there will be a complete, functioning watch just sitting there on the floor? Almost zero...really, astronomically small. But evolution has been operating for three billion years - hundreds of thousands of teeny-tiny viruses and bacteria have been breeding in every drop of water in our 1,340 million cubic kilometers of ocean - reproducing every few minutes for all of those billions of years. If every single one of those events were you tossing the watch parts onto the ground - does it seem so improbable that one of those would turn into a functioning watch just by chance?

But things are much, much better than that in the world of living creatures. They have DNA - this allows the sucesses of one generation to be passed onto the next generation. Watches don't have that. It they did then if by chance two gear wheels happened to assemble themselves together, then they will be ready-assembled for the next watch-tossing event. This speeds things up no end.

A better example is Richard Dawkins one of asking what the probability of a million dice being rolled and all coming up sixes. The odds are far, far too long. If you rolled dice from the big bang until the end of the universe - the odds are slim that you'd ever see a million sixes. However, if you roll the dice once and are allowed to keep the sixes you rolled - then on the first throw, one sixth of the dice come up sixes - on the next throw, we roll only the remaining five sixths - and already nearly a third of our dice are showing sixes. If you did this for real, a few dozen tosses would suffice to get all of the dice to show up sixes...and that's the way it is with evolution. Each successful mutation pushes the 'design' of the creature a little closer to what we have today.

Evolution is not a theoretical thing. Take a disease like Turburculosis. Treat patients with whatever wonder drug you have - and almost all of them get better. But the mycobacterium that cause the disease EVOLVE - in each generation, just a tiny, tiny few of the bacteria somehow manage to survive the drug. The ones that survive have some kind of gene that lets them avoid the worst effects of the drug. Over years, the drug gradually loses it's effectiveness because the bacteria evolve to survive in it's presence. We can see this happen in the DNA of the bacteria - there is no magic, no mysterious 'designer' - it happens through simple, easy-to-understand mechanisms that are easy to study. The bacteria can evolve resistance to a particular drug over just a matter of years - it doesn't take millions or billions of years - it happens in no time flat. Evolution is a FAST process. Drug resistant diseases are very commonplace - and they result from evolution - pure and simple.

SteveBaker 03:38, 13 February 2007 (UTC)


 * Mutations also tend to speed up the evolution process.-- Ed  ¿Cómo estás? 03:47, 13 February 2007 (UTC)


 * I don't believe watches are made by watchmakers because they're complex. I believe watches are made by watchmakers because a large number of people are glad to describe, in detail, how to make a watch.  If God comes down here and announces on television that it was him who created Earth, I will believe in him.   --Bowlhover 03:53, 13 February 2007 (UTC)
 * Paley's argument does not depend at all on knowing how watches are made. It is made from the standpoint of one who can judge something as being more likely to be authored intelligently than not, even if they do not know for sure how or why it was made. I think you'll find that in most cases you'd be taking a pretty silly position if you couldn't believe in the intelligent authorship of a technical object without knowing exactly how it was made, or expecting someone else to. You can infer without too much difficulty in the technical world that intelligent authorship exists, which is part of the crux of Paley's argument. --140.247.242.75 18:07, 13 February 2007 (UTC)


 * Paley's argument may not involve how watches are made, but mine does. We know in general how everything is made and what materials were used.  For example, iron, steel, wood, and plastic are very common materials.  I know humans like building with them, so if I see a device that has these materials, I'll know it was made by humans.  I won't go up to the Grand Canyon and claim it was built by humans or God just because it looks complex.  --Bowlhover 04:29, 14 February 2007 (UTC)


 * Well what I did was first I made the earth dodecahedral in shape and I placed continents on some of the pentagons of the dodecadhedron, you call them africa, north america, south america, europe, central asia, east asia, india, and antartica. I also drew some little islands and australia was an afterthought. Then I made the biggest mountains at the bondaries between the pentagons, that's were all the volcanos are as well. Then the pentagonal surfaces were distorted a bit to make the earth look rounder, I made the moon out of silver and the sun of gold. Are you listening? User:God.83.100.254.40 11:55, 13 February 2007 (UTC)

In the book IRobot, by Issac Asimov, the robot QT uses logic to prove that he was created by god instead of by people, even though he saw that people could create robots, and that the earth didn't exist as he had never seen it:) This shows that logic could prove almost anything if you want it to:)Hidden secret 7 13:04, 13 February 2007 (UTC)
 * According to SCIFIPEDIA, QT-1's argument is as follows: QT-1 does not believe that humans...created him, since to him it is obvious that no inferior (biological) being can create one greater than himself (made of metal, more efficient, etc). They show him the view port, where QT-1 can see the stars, the planets, and outer space, but QT-1 says their explanation is ridiculous; that there is simply a black mass just beyond the glass, with small white dots in it. QT believes that a “master” created the station, the humans, and then the more efficient robots, to serve him. He convinces the other robots on the station of this, who make QT their spiritual leader (“There is no master but the Master, and QT-1 is his prophet”). QT-1 banishes the humans from the beam control room. ... They try to demonstrate to QT their ability to create a robot, but he points out that they assembled, not created; he thinks they know instinctively how to do that.
 * QT's problem is the same as that of the creationists. It has postulated an unfalsifiable hypothesis.  In a universe where a literally omnipotent being exists with no limits whatever on his/her powers, anything can happen, no scientific laws have any value whatever - no conclusions can be made, no mathematics, philosophy or anything else has any meaning because an omnipotent being can easily fake evidence, cloud our senses, tweak our neurons...whatever.   Religious people say that God is Good - but how do they know that? God could just as easily be totally evil - he might just tweak your brain to make you think he's good.  So, you have a choice - take the unfalsifiable hypothesis and say it's true.  This results in zero information, zero ability to reason, make valid decisions, zero, zip, nada.  Or you reject the unfalsifiable hypothesis and use science to try to make sense of the universe.  Either of these views is a valid position - but (IMHO), only the scientific view is of any use whatever.  What isn't valid (IMHO) is to take the unfalsifiable hypothesis and to use this zero-information situation to start trying to run people's lives on the basis of arbitary theories that are completely unprovable. SteveBaker 00:08, 14 February 2007 (UTC)


 * The problem with "intelligent design" is not that it is false, it is that it us unfalsifiable. A virtually identical argument could apply to any part of human scientific endeavor.  Take fire for instance.  Fire looks pretty scary and complicated.  If all early people just threw up their hands and said "this is complicated, dangerous shit - God must have made it, let's just run away", we'd still be in the stone age.  Or, disease.  Just because it was not immediately obvious how pathogens could reproduce and transmit didn't mean it was the work of supernatural powers out of the realm of human understanding.  Basically, the "god did it" theory is the most boring, overused excuse in the history of human nature.  It's so boring I'm tired of writing about it.  The only interesting part is that the intelligent design movement against evolution (and science in general) is a great example of a societal evolutionary effect.  Eventually the united states will be so scientifically exhausted from generations of pseudo-scientific education that we'll be extinguised as a culture.  --18.19.0.41 19:24, 13 February 2007 (UTC)
 * This is heading towards the God of the gaps realm. DMacks 20:38, 13 February 2007 (UTC)
 * No - not at all. God of the gaps says that God does all the things that science can't explain - and basically implies that science is valid for everything else. But serious, thinking scientists can't tolerate that version of reality since if God is omnipotent, we can't tell whether any particular phenomenon is a 'gap' or not.  We might THINK this is something that science understands - but in fact it's a 'gap' that God has chosen to disguise as a scientific fact by deliberately fudging the evidence.  This is the argument that some creationists use to explain fossils - "God deliberately created all of those fake stone bones in order to test the faith of those scientists."...If there is an omnipotent being then we don't even know that 1+1=2.  Any attempt to reason about anything becomes totally pointless because we can't trust our instruments, our senses or our reason. SteveBaker 00:34, 14 February 2007 (UTC)

While the argument has been thrashed out to death already (and the original poster should really read "The Blind Watchmaker" (richard dawkins) who totally destroys the original argument (he gets a little silly in later books).. anyway you say (or a creationist would say) it is "perverse to suggest that the watch came about by random chance". Humans coming about is not "random chance", they came about through Natural selection. Which is a mechanism which is unlike "random chance". And it is a mechanism that is well understood. Creationism is a massive waste of everybody's time. Heck, read Darwin's original The Origin of Species (which is very readable) too.—Pengo 09:22, 14 February 2007 (UTC)

Opal and flint
Have looked at flint, chert and opal

Is there an overlap between rocks labelled flint and rocks labelled opal.

I'm specifically thinking of rocks found in association with chalk, sometimes in nodules with a white surface, dark gray/muddy brown with underlying colours or white/yellow/grey sometimes with graphite coloured dendritic structures.

I assumed flint but have seen in a minerology book similar rocks described as 'common opal' and 'dendritic opal' - it was not clear if they were found as nodules in the book.

Can anyone help?87.102.16.197 22:46, 12 February 2007 (UTC)


 * All these stones are Chalcedony. If opal has no colour you would call it chert .  So yes there is an overlap

. The chert atricle says that flint is chert found in chalk. It also suggests that chert is a rock, and that chalcedony is the mineral.

So to reword - if you have colours (blue green red - not black grey or white) then you have opal, else if its in chalk then its flint, and if its not in chalk its chert. Got that! The graphite coloured dendrites may be manganese dioxide or pyrolusite. GB 05:55, 15 February 2007 (UTC)
 * I'm going to have to ask you to clarify or someone else answer since you don't seem to be completely right. See Chalcedony "It is, however, crystallographically identical to quartz" - opal is nothing like identical to quartz in terms of crystallography. Also opal is coloured due to 'opalescence' - some sort of diffraction or scattering effect - the base colour can be colourless - the opalescense depends on angle of view - so it's difficult to define the colour due to it often.213.249.237.49 14:06, 15 February 2007 (UTC)
 * Also (to clarify) the dendrites in this material are seemingly of the same material as the rest of the rock - but darker (due to some impurity I guess).213.249.237.49 14:09, 15 February 2007 (UTC)
 * From the Opal article: Precious opal shows a variable interplay of internal colours and does have an internal structure. At the micro scale precious opal is composed of hexagonal or cubic closely packed silica spheres some 150 to 300 nm in diameter. . But this article also says that Opal contains water - presumably between the spheres.  The spheres would be on the same order of size as the wavelength of visible light.  The Opal article also says that colourless opal is amorphous.  You can ignore my comment about black dendrites as yours are obviously different.  It looks like I am wrong about colourless opal being the same as chert. GB 01:57, 19 February 2007 (UTC)

Bats
Do bats only spiral left when they leave caves?

David Winkelaar
 * I did a nice long search on this piece of trivia, and it turns out that it has been asked and answered with silliness, many times. The big bat caves of North America always seem to have counter-clockwise exit spirals, but nobody has systematically confirmed it with every cave.  There was even an unreferenced suggestion that they have different directions in the north and south hemispheres, just like bathtubs! (not!). --Zeizmic 01:11, 13 February 2007 (UTC)


 * The air in a cave tends to be at a different temperature than the air just outside. If this air is warmer than the outside air, it generates a thermal.  One of the best ways for flying animals to gain altitude is to spiral around in a thermal -- and guess what happens if a swarm of bats don't all spiral around in the same direction? --Carnildo 22:13, 13 February 2007 (UTC)

Gravitational effect of planetary size/density
This is sort of a theoretical question, but I can't find the appropriate articles on my own searches:
 * Assume a smaller planetary diameter than Earth (6300 km for example?);
 * Assume a roughly equivalent mass, and therefore gravity, compacted into that smaller area;
 * What, if any, known limits are there on planetary density/accretion/survival? Feel free to disregard the problems of having a core of sufficient density, although not anything related to angular momentum, loss of atmosphere, or other habitability.
 * Any articles to point me at would be great as well. -- nae'blis 23:40, 12 February 2007 (UTC)


 * Disregarding your disregard, it may be possible to have a planet made mostly from iron from a supernova, or possibly from lead, as ther are some lead stars who's main metal is lead, they tend to be very low in metals, and high in neutrons. What  elements are there are converted by the s-process up through the periodic table, and the heavy elements decay back to lead.


 * Another possiblility for a planet is white dwarf degenerate matter or neutron star material. If you had a black dwarf orbiting another star, would you call it a planet? GB 02:04, 13 February 2007 (UTC)


 * I'm interested in stars whose main metal is lead. Could you show me some references (or maybe wikipedia articles) on this? 193.171.121.30 12:16, 14 February 2007 (UTC)


 * Planets are formed from a stellar disk from points with slightly greater density than others, then snowball into larger and larger planets, sweeping up more and more with its growing gravitational field. Densities of planets can and do vary widely; the terrestials (Mercury-Mars) have a much greater density than the gas giants (Jupiter-Neptune), the fairly small variation in your "what-if" (a planet with a density about 1% more than Earth's) is easily feasible, say if the dust cloud that became our Sun had a tiny bit more iron instead of silicon.  On formation, whether or not a planet forms in a particular orbit depends on where other planets have begun to form.  A large mass like Jupiter will disrupt nearby planets, preventing them from forming, capturing them, or ejecting them (related to Clearing the neighbourhood).
 * Check out Protoplanetary disk, and Debris disk, which are also related. As I recall, some of my recent Scientific Americans from the past year have also had articles on planetary formation, see if your library has them to browse through. (I don't have mine with me, so I can't tell you what issues) Atropos235 02:41, 13 February 2007 (UTC)
 * Interesting, and thank you; that was a lot more information than I was able to pull together myself. -- nae'blis 18:02, 13 February 2007 (UTC)

The surface gravity of a planetary body plays a large role in determining whether it can hold on to an atmosphere. Beyond certain limits (determined by such things as the bodies relation to it's star and the amount of gas available), the planet will start trapping hydrogen and helium and grow into a gas giant. So for a given mass, decreasing its size will increase the probability that it will be able to retain a H/He envelope. However, if enough gas is available, it may then greatly increase in size by gobbling up gas, and in the process the net effect would be to decrease in density. So there is probably some upper limit on the density of an object that can form in a gas rich proto solar system. Aside from that, there is no physical limit on achievable density till you get much much denser and start seeing nuclear reactions. People and animals living on a planet with higher surface gravity would probably have thicker limbs and shorter heights to provide added support for their own weight. Dragons flight 18:22, 13 February 2007 (UTC)

More on the Lead Star
In response to an anonymous poster's question. see these references for papers about lead stars. Lead can be enriched over 1000 times the solar abundance:

 Sara Lucatello et al: ''Stellar Archaeology: a Keck Pilot Program on Extremely Metal- Poor Stars From the Hamburg/ESO Survey. III. The Lead (Pb) Star HE 0024−2523'', AJ aug 2002

 S. Van Eck et al: More lead stars Feb 2003

 T. Sivarani et al: ''Elemental abundances of metal poor carbon rich lead star: CS29497-030'' December 2002

GB 05:46, 15 February 2007 (UTC)


 * Thank you. I want to add that, according to the numbers in the papers, iron is still the more prevalent metal in these stars, although the lead/iron ratio is much larger than in the sun. 193.171.121.30 12:49, 12 March 2007 (UTC)