Could the Big Bang Be the Middle of the Universe?

[Chalnoth]

Yes, so it is applicable to 2 moments of time in our universe (if the number of time dimensions is still 1 and 2nd law is still valid - which is not guaranteed at plank times, but let's ignore it now)

But it can not be used to say something about the INITIAL conditions because they are INITIAL.

Hmmm, no. You can't just pick out a specific time and say that this time is special, and the rules don't apply to it.

 

[gruff]

Hmmm, not quite. Granted, the original argument presumed this, but it isn't necessary to do so. Notice that my last post didn't actually make any reference to a pre-existing state, as it's merely pointing out that the early universe had lower entropy than the current universe, and that essential fact absolutely requires explanation.

But doesn't Boltzman's argument assume an existing (albeit timeless) physical universe in order to determine likelihood of fluctuations in it?

 

[Chalnoth]

But doesn't Boltzman's argument assume an existing (albeit timeless) physical universe in order to determine likelihood of fluctuations in it?

Well, yes, but it only requires that all possible microstate configurations are equally likely for the argument to hold. This statement holds trivially in the case of a thermal fluctuation from equilibrium, but that isn't necessarily the only way.

So another way to state the argument is that there must be some sort of physical law that makes it so that it is more likely for microstates that make for inflating regions to appear than for microstates that make for universes like those we observe appear, despite the vastly larger number of microstates that can replicate a universe like the one we observe. And preferably the physical process that causes this wouldn't be ad-hoc, and would be testable by other means.