Where did the universe come from? Atheistic origin science has no answer.

[Anomalocaris]

The thing is dark energy reversing would cause the universe to go crunch, but it won't reduce the entropy of the crunching universe. When the universe finally crunch and rebound, the next universe would start out with higher entropy than the previous one.

So even if our universe is just the rebound after the crunching of the last universe, there could not have been an infinite series of previous universes before ours. The starting entropy of our universe defines the upper limit of how many universes could have existed before ours.

If ours go crunch eventually, the next universe will start with higher entropy than ours. Eventually the next universe will start with such high entropy that nothing of note could happen in it. The universe would keep on its crunch-rebound cycle, but it would from some point on become perpetually sterile.

So all this argues the era when our currently,known laws of physics applies definitely has a beginning. And the progression of crunching rebounding universes cycles in which things like life can happen has an definite end.