Posted: Oct 06, 2011 5:37 pm
newolder wrote:
I don't know what u mean by crazy and/or unproven but dark matter accounts for (amongst other things) the rotation speeds of stars in galaxies (neither crazy nor unproven)
Yes. It accounts for it because we made it up to fit what we saw. It's a great idea, and probably correct, but we have exactly zero evidence for it other than it's existence being inferred by the fact that our calculations are off when we look at very large objects. Obviously something is there, we just have absolutely no idea what is going on. It is the prevailing theory, it fits quite well, and I think it's probably going to be validated very soon. But it is crazy, and it is unproven.
newolder wrote:
and Einstein's (not even a mistake) cosmological constant accounts 4 accelerated expansion.
Almost correct, but not quite.
Einstein postulated the "cosmological constant" as a way to keep the universe static. Basically Einstein disbelieved in quantum mechanics (the discovery of quantum mechanics ironically came as a direct result of Einstein's theories) and tried for most of his life to come up with a way to pretend that "god does not play dice" which is layman for "Quantum mechanics? LALALA I CAN'T HEAR YOU". He thought discovering the universe's laws was a way of seeing the mind of god and didn't like the idea that, on a fundamental level, no one can know an exact result ahead of time or know the exact speed and location of any particle. Einstein's constant was simply a way to keep the universe static while still allow his general relativity equations to work. It was a needless mutilation of his theory and he came to regret it a great deal. So yes, it was a mistake.
The "Constant" we've come up with now is very similar- it's sort of this layer of energy we can't normally interact with that works throughout the universe to push everything apart. That's what we call dark energy.
So it's simply a humorous coincidence that there happens to be a very similar "constant" that does the same kind of thing as Einstein (but in the other direction, so to speak).
And, just like dark matter, dark energy is completely hypothetical with no direct evidence for its existence. Again, it's the best theory and I personally think it will be validated long before I die of old age. But let's not count our chickens before they hatch.