What is that "something" that is happening all at once? In my naive understanding of cosmological theories is they seem to end in probabilities (e.g., eternal inflation) that emerge from a kind of (oxymoronic) "chaotic static", but what does that mean for this to "happen all at once"? That statement seems to imply there's no degree of freedom through which something can occur (at least casually).

I suppose the question comes to, what is time? I imagine "time" to be a degree of freedom through which something can change. I understand some see time to be related to entropy, and that it's an emergent property of this thermodynamic property but this seems too limiting. It would seem entropy is more-so an explanation for the arrow of time, but not time itself.

If time is defined as the dimension through which something can change then should time not be fundamental to any cosmological theories that extends beyond the Big Bang?