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Post by abacus9900 on Apr 26, 2011 11:35:42 GMT 1
Why doesn't the zero-point energy of the vacuum cause a large cosmological constant? What cancels it out?
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Post by speakertoanimals on May 4, 2011 13:41:42 GMT 1
Well known problem, but not helped by the fact that there is no EXPLICIT theory that says we should take certain results from quantum field theory, and use them to compute the cosmological constant for a classical theory of gravity.................
Basically , marrying quantum theory and gravity would be the proper theoretical justification for such a move, but we can't do quantum gravity yet.
Mind you, if the naive analysis HAD given a figure in the right ball park it would have been interesting, but having the WORST prediction in all of theoretical physics is interesting as well!
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Post by abacus9900 on May 4, 2011 15:27:31 GMT 1
Well known problem, but not helped by the fact that there is no EXPLICIT theory that says we should take certain results from quantum field theory, and use them to compute the cosmological constant for a classical theory of gravity................. Basically , marrying quantum theory and gravity would be the proper theoretical justification for such a move, but we can't do quantum gravity yet. Mind you, if the naive analysis HAD given a figure in the right ball park it would have been interesting, but having the WORST prediction in all of theoretical physics is interesting as well! I do not believe you are STA because your post was far too measured and civil. Who are you?
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Post by nickcosmosonde on May 4, 2011 19:04:08 GMT 1
Come on, she's measured enough for anyone; as for civility, who cares?
"having the WORST prediction in all of theoretical physics is interesting as well!"
Before the mathematical theorists came to dominate [hysics, this would have been enough to dismiss the whole hypothesis. The dark matter/energy theory is wrong, empirically, by every standard of the hypothetico-deductive method. It's wrong - it's predictions are, as you say, the worst ever. So - we're in a state, a state that occurs every century or so, where we have to admit we don't understand the basic fundamentals. It's good.
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Post by speakertoanimals on May 9, 2011 17:22:41 GMT 1
Except the predictions being made AREN'T based on whatever you think you mean (or even what the rest of us mean), by dark matter and dark energy, but on the FACT that we know that we need to be able to do quantum gravity to correctly join quantum theory (which is the most accurately tested theory in the whole of physics) of matter and interactions, with the classical theory of gravity that describes space and time on the largest scales.
In one way, just says we can't do quantum gravity yet, but we already KNEW that. Says that pseudo-classical rough attempts go horribly wrong when we try to compute the cosmological constant from quantum physics.
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