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marcus
#24
Oct13-03, 09:44 AM
Astronomy
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I assumed bettysfetish was female and he says to chroot:

"You may be suprised
To know that I am A longhair bass guiter player with a wife 4 kids(still at home) and I'm 48 years old and can play STAIND, NICKLEBACK, GODSMACK, or THEORY OF A DEADMAN better than anyone you've met in a while."

so now that little misunderstanding is cleared up.

Earlier in the thread (October 7) Nereid asked:
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BTW, to what extent would a successful LQG...be able to address at least some part of the first 10-34s?
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Nereid, part of your question you asked gets over into how LQC deals with the universe right around timezero. It predicts inflation (you dont have to put inflation in "by hand") and it removes the singularity.

There'v been a bunch of papers by a bunch of different people that you can get from arxiv by search with keywords like

loop quantum cosmology

inflation loop quantum gravity

To save the trouble of searching and choosing which articles to read, here are a couple of September ones:

Quantum Gravity and the Big Bang
http://arxiv.org/0309478

Quantum Gravity and Inflation
http://arxiv.org/0309045

the meaning of time becomes an interesting question around timezero and whether one can ask about time-evolution in steps smaller than Planck time (0.539E-43 second)

Loop cosmology is a radical simplification of the full theory of quantum gravity (Friedmann eqns of cosmology are much simpler than the Einstein eqns of the full GR theory). So its much easier to develop LQC and it has happened very quickly----now LQC can help guide solutions of the more difficult problems of the full LQG theory. This was reflected in the "conclusions" part of one of the papers

"With new developments in quantum geometry, quantum gravity has become a theory whcih can make concrete predictions about the very early stages of the universe. Results include possible solutions of old conceptual problems, as the singularity problem and the problem of initial conditions and also new phenomenologicial proposals which can be confronted with cosmological observations. The models currently available are most likely too simple, but more complicated ones with less symmetries [ref] and more realistic matter content are being developed. An advantage of the formalism is that the relation between models and the full theory of loop quantum gravity is known, so that lessons learned for models can be taken over to the full theory. In this way we will be able to guide developments in quantum gravity by cosmological observations."

There will be a talk on loop quantum cosmology by Bojowald at this month's "Strings meets Loops" symposium at the AEI, so this should give an even more timely summary of the state of research in that area.

There was a stringy part to your question too but I cant respond to that part because I dont know of any concrete predictions that string theory makes---seem to be an infinite supply of versions of the theory all saying different things and no way to choose