Temperature and Time.

[devonin]

If such a thing were to happen, we couldn't think anything about it anyway. If the temperature of the universe were to somehow instantaneously reach absolute zero (And it would have to be both instantaneous and come from some magical impossible outside force [In order for it to happen naturally, my intuition is that we'd need every particle of matter to be infinitely far away from every other particle of matter, which would both take infinite time, and happen long after humanity ceased to exist] in order to actually happen instantaneously)

In such a case, to a magical outside observer who isn't bound by the laws of our universe, everything would appear to be frozen. To anything inside the universe, nothing would appear to be anything, because, well, everything would be frozen, which includes the various chemicals in our brains necessary for thought or awareness.

If things were then to go back to normal, not only would we not notice that anything had happened, from the perspective inside the universe, it would be the true case that nothing had happened. These stops and starts could be happening constantly and we have no way whatsoever to percieve them.