Curlyfilm
When scientists talk about "the universe" they really mean the known universe (the visible universe) which has a start time. Positivists would argue that discussion of events before the big bang, or events possibly occurring outside of the known universe are not questions for science. Despite Clanad's gallant attempts to bring a creation event into the big bang model, it is not known what happened in the brief period after the big bang SINGULARITY when general relativity breaks down. Saying that scientists think it was a creation event is misleading, it is simply not known. Quantum mechanics argues that these or any other events cannot be predicted with complete accuracy and this leads the way to a Many Worlds Theory where, roughly speaking, all possible events that happen form a universe of their own, hell, i may even be successful in one of them.
. It is thought possible (by stephen hawking amongst others) that a theory of quantum gravity may provide a natural limit to measurements and make a theory of everything, explaining what happened at the beginning of our known universe, possible. However, it is likely that there will never be an ultimate theory of the universe because more accurate measurement just brings up new phenomena that needs to be explained. Despite which, a theory of everything wouldn't necessarily tell us what happened before the big bang, just what happened a fraction after it.
The Big Crunch:- Is a hypothesis of what could have happen to the known universe in the past and could happen again in the future, it has not been completely ruled out it is just one of the possibilities.
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