Inflation without a beginning: a null boundary proposal

[Jehanne]

Professor Sean Carroll, in his debate with William Lane Craig, asked Dr. Craig the following:

I will repeat – the quantum eternity theorem, a sensible analysis of the history of the universe, might be with the rules of quantum mechanics. He claims that someone else said there might be a singularity in quantum gravity but he gives us no understanding, he simply repeats his previous analysis. So, I want to draw attention not to my model but to the model of Anthony Aguirre and Steven Gratton because this is perfectly well defined. This is a bouncing cosmology that is infinite in time, it goes from minus infinity to infinity, it has classical description everywhere. There is no possible sense in which this universe comes into existence at some moment in time. I would really like Dr. Craig to explain to us why this universe is not okay.

Dr. Craig never replied, but here is the paper that Professor Carroll was referring to:

https://arxiv.org/abs/gr-qc/0301042

[Jehanne]

Are there any theists in the House?

[Mystic]

I will give it time tomorrow. Too tired tonight.

[Jehanne]

Just read the preamble:

We develop our recent suggestion that inflation may be made past eternal, so that there is no initial cosmological singularity or "beginning of time". Inflation with multiple vacua generically approaches a steady-state statistical distribution of regions at these vacua, and our model follows directly from making this distribution hold at all times. We find that this corresponds (at the semi-classical level) to particularly simple cosmological boundary conditions on an infinite null surface near which the spacetime looks de Sitter. The model admits an interesting arrow of time that is well-defined and consistent for all physical observers that can communicate, even while the statistical description of the entire universe admits a symmetry that includes time-reversal. Our model suggests, but does not require, the identification of antipodal points on the manifold. The resulting "elliptic" de Sitter spacetime has interesting classical and quantum properties. The proposal may be generalized to other inflationary potentials, or to boundary conditions that give semi-eternal but non-singular cosmologies.

[Minimalist]

Dr. Craig never replied

Of course he didn't.  Asking a bible-thumping shit like Craig about actual science is as silly as me trying to explain radar to my dog.

[LadyForCamus]

Curious to hear Steve and RR’s responses here.

[Minimalist]

What's to hear?

Goddidit.


Always the same shit with those two when you boil it down.

[Jehanne]

Curious to hear Steve and RR’s responses here.

Yeah, I was wondering about that, too!