Possibility that the universe has existed infinitely far into the past

Determine whether the universe has existed infinitely far into the past with no beginning, i.e., whether it is possible that the universe "was always here" rather than time starting at the Big Bang.

Background

Complementing the question of whether time began at the Big Bang, the author explicitly raises the alternative possibility that the universe has no past boundary and has existed infinitely far into the past.

This uncertainty motivates the paper’s proposal to distinguish and analyze temporal behavior using both A-series and B-series structures, and to explore models in which the Big Bang can be finitely earlier in the B-series yet infinitely far in the A-series past.