General > Biology
Crows are pretty damn smart
Peter:
--- Quote from: gymsum ---If you lower pressure like in a vacum, you can boil water which releases its energy and thus freezes.
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Just read this line a few times yourself, what is wrong?
--- Quote ---The loss of the mass of the sun has to do with energy consumption during light emission. Recall E=mc^2; well say 4 million metric tons is lost a second. We haev calculated the amount of energy produced by the sun in ergs, about 4 x 10^33 ergs/sec. We know the mass loss is equal to 4 x 10^33 ergs/sec, and we have our original equation so divide the energy out by the speed of light squared, or (3 x 10^10 cm/sec)^2 and you now have an equation to calculate the loss of mass due to energy-light crap. (sorry for lack of jargon).
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I haven't heard of 'ergs/sec', meaning it isn't a standard, means I ignore it, please use SI-standards(you know them like, meter, gram, Joule and so on) I am not going to calculate back. Oh and please write down exactly what you do. I don't follow you.
--- Quote ---Taken from the suns total mass and radious, at this rate evry 160 billion years the sun will lose 1% of its current mass. So to produce 4000000000000000000000000000000000ergs/sec it must consume/alter the state of 4 million metric tons of (fuel I guess) per second, or 1 onehundred-sixty billionth of its entire mass a year. I think thats correct, if my notes are still acurate.
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How did you come by the '1%' loss of mass in 160 billion years of the sun. How did you come by the '4 with much zeros ergs/sec'.
Oh and I agree with Numsgil, I'd like to get the anwsers to the questions.
--- Quote ---Didn't check out your math (math is boring). But this part you glossed over is the interesting bit, IMO. What fuel is used (what was that mass before it was converted to radiant energy), what reaction takes place, etc.
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--- Quote ---That the universe is expanding has been known since at least Hubble (the scientist, not the telescope). If you had two objects in space, and neither object is accelerated, after billions of years they would end up further apart, because the actual space between them is expanding. See wiki. This makes sense when you consider the fact that the universe literally exploded out from a single point. The more interesting bit is that this expansion is accelerating. This is where the whole idea of dark/vacuum energy comes from.
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It stays a theory that the universe will keep expanding, a strong one but it stays a theory. There are other theorys like the steady state, altrough it isn't really a competitor anymore.
Numsgil:
There's a great deal of data to support the theory that the universe is expanding, though. Basically supernovae have a known color. Distant ones from us are are all red shifted, which indicates that their sources are moving away from us. It's possible that space is not expanding, and is constant, but then that would mean that everything in the universe is moving away from us (so we'd be at the center of the universe, quite literally). It would be a remarkable coincidence for us to be in the center of the universe, given that Earth could have been anywhere in the universe, so that idea didn't catch on. Instead we assume that all points in the universe are moving away from all other points.
In science, a theory doesn't mean "educated guess", like it's used in everyday life (that's called a hypothesis in science). Theory means "something that explains all known data on the subject." And even after it's proven, it tends to keep the "theory" label (eg: Pythagorean Theorem). Basically science doesn't deal in absolutes. It doesn't say "this is the way the universe works", it says "if you use this model, you can predict outcomes to events within the tolerance of measuring instruments." See Theory vs. Hypothesis. A theory is like a best-fit polynomial. You use it to fit the data you have, and make predictions about future data you will receive. If those predictions are wrong, science (slowly) will revise the theory until it takes the new data in to account as well as the old data. That way theories are rarely "wrong", they're usually just incomplete (ie: Newton's laws of motion under relativistic speeds).
Many times theories don't seem to make much sense, but they still manage to explain all the observed data. The reality of the event is probably more complex than we currently understand, but the end data behaves like it would if it were doing our simplified model. For instance the wave/particle duality of light. The truth is probably really neat and complicated, but we don't really understand it. However we can predict what sort of results we would expect to see in any given experiment by pretending that light is made of particles some of the time, and waves at other times.
Testlund:
I don't trust the Big Bang theory any longer. See this video:
http://www.youtube.com/watch?v=nl3Uj2UJjPA
Numsgil:
Um, don't trust "scientists" that post on youtube. You tube is for dogs on skateboards. Here's another tip: if they say something like "what was before the big bang" or "why did the big bang happen then instead of before or later", they don't know what they're talking about. Time itself started at the big bang. There was no "before", because there was no time. There also wasn't a "somewhere else", because space didn't exist either.
Peter:
--- Quote from: Numsgil ---In science, a theory doesn't mean "educated guess", like it's used in everyday life (that's called a hypothesis in science). Theory means "something that explains all known data on the subject." And even after it's proven, it tends to keep the "theory" label (eg: Pythagorean Theorem). Basically science doesn't deal in absolutes. It doesn't say "this is the way the universe works", it says "if you use this model, you can predict outcomes to events within the tolerance of measuring instruments." See Theory vs. Hypothesis. A theory is like a best-fit polynomial. You use it to fit the data you have, and make predictions about future data you will receive. If those predictions are wrong, science (slowly) will revise the theory until it takes the new data in to account as well as the old data. That way theories are rarely "wrong", they're usually just incomplete (ie: Newton's laws of motion under relativistic speeds).
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I that a hypothesis is a speculation, I know a theory is well though out, it is not like there are theorys brurted out. But wait, it does not explain how the universe works?, it does not?
--- Quote from: Testlund ---I don't trust the Big Bang theory any longer. See this video:
http://www.youtube.com/watch?v=nl3Uj2UJjPA
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My soundcard doesn't work on this computer, so I think I would miss the message.
--- Quote from: Numsgil ---Um, don't trust "scientists" that post on youtube. You tube is for dogs on skateboards. Here's another tip: if they say something like "what was before the big bang" or "why did the big bang happen then instead of before or later", they don't know what they're talking about. Time itself started at the big bang. There was no "before", because there was no time. There also wasn't a "somewhere else", because space didn't exist either.
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Dog.. skateboard.... , but why not. Why can't those scientists be trusted. You are posting links to wikipedia, well it isn't like that can be universal trusted, I have found some mistakes in it, just a few but still, can you trust wikipedia fully.
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