Big Bang singularity: can we say anything about its size?

[iantresman]

TL;DR

Has the Universe been anything other than infinite? (ie finite)

The Big Bang is sometimes described as started from a singularity, which I have interpreted as meaning that its characteristics are undefineḍ. If that is the case, can we not even say that the Universe as a singularity was still infinite? Otherwise we are implying that the singularity was finite, and at some point after the Big Bang, there must have been a point in time when there was a transition from finite to infinite.

Cosmological inflation suggests that the Universe is expanding. Is this by volume? That doesn't make sense to me. If the Universe is infinite in volume, at no point during the inflationary period could it have been anything less than infinite? Or does this suggest that spatial expansion is not related to volume?

 

[berkeman]

Have you read the numerous Insights articles about the Big Bang and some of the questions you are asking?

https://www.physicsforums.com/insights/?s=big+bang

 

[iantresman]

Thank for that, the article "Intro to Big Bang and Infinity Concepts" is useful.