Does the existence of a state with no prior time throw models we use for explaining the existing universe for a loop? Or does it even matter?

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    prior to 'big bang' or prior to state collapse? – Mozibur Ullah Jun 19 '13 at 13:25
  • I am not exactly sure what either would mean, please answer both with each assuming either direction please. I was intending however the big bang. – 0xFFF1 Jun 20 '13 at 21:17

The question is a little confusing. You cannot have a state without time - a state evolves in time.

When a measurement occurs this provokes a collapse in the state through decoherence with the environment it then continues to evolve. Note a measurement is defined to be anything that actually causes a collapse, it doesn't ahve to be a specific measuring device operated by some conscious being.

Hence, at least when physically modelled, there is no prior state.

However one can speculate at what happens at the Big Bang. Since spacetime is held to have started then, a prior state again isn't possible - there is literally no spacetime in which it can occur.

There may be other cosmologies which allows spacetime to continue through this 'singularity'. One could argue since the physical world is uncomfortable with infinite anything, this is only an apparent singularity and spacetime does continue through it. In which case the state should also continue through this singularity. But this isn't mainstream.

So, the answer to your question is no.

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    "a state evolves in time." Not necessarily. See: en.wikipedia.org/wiki/Heisenberg_picture – Alfred Centauri Jun 20 '13 at 22:54
  • "Since spacetime is held to have started then". I don't think that's correct either. See, for example: I’ve written about this many times before, of course, including a great introduction to the Big Bang for beginners, and a couple of lengthy explanations that the Big Bang isn’t, in fact, the beginning of the Universe. scienceblogs.com/startswithabang/2013/06/12/… – Alfred Centauri Jun 20 '13 at 22:58
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    In the Wheeler-DeWitt equation for canonical QG, the entire concept of time is absent altogether. Temporal evolution as we normally conceive of it is nothing more than a local gauge transformation on the state vector. – David H Jun 20 '13 at 23:31
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    @DavidH: If you look at the wikipedia article on that equation you'll note that time is implicit in the equation - it requires decoherence & clock operators to make it explicit. Perhaps an analogy makes this clearer - spacetime in GR is not time+space, as minkowski said space & time disappear into this 4-d concept, it requires taking coordinates to make it explicit again. – Mozibur Ullah Jun 21 '13 at 0:45
  • There is no global evolution in the Hamiltonian because what is labelled by time no longer signifies time: It is the kernel of the Hamiltonian that is Physical. Your assertion that there is no time is only one point in a spectrum of possibilities. Its generally known as the problem of time. – Mozibur Ullah Jun 21 '13 at 1:12

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