Entropy is a measure of a number of distinct possible configurations that result in an equivalent outcome.
It’s pure statistics. Given time symmetric laws of nature and a state that can be achieved by a relatively small number of configurations, in the absence of potential barriers, the system inevitably approaches a state that’s achievable by a larger number of configurations. Simply because an elementary change is more likely to fall into the latter mode. Thus, arrow of time emerges.
CapeWearingAeroplane@sopuli.xyz 10 months ago
There seems to be a slight misunderstanding here: If you imagine the “moment before” the big bang that is a state where the entire universe is compressed into a singularity, which necessarily has no entropy, because it can only have one state. Once the universe started expanding, you get a whole lot of disorder, because, while you are forming particles (introducing order) those particles are moving away from each other at relativistic speeds. The available volume for the particles (the volume of the universe) increases extremely rapidly, meaning you have more possible microstates than if all particles were compressed into a point.