Hacker News Reader

Yes, that assumption is called the Ergodic Hypothesis, and generally justified in undergraduate statistical mechanics courses by proving and appealing to Liouville's theorem.

[1] https://en.wikipedia.org/wiki/Ergodic_hypothesis

View on HN

It's worth noting that there's more than just ergodicity at play, although that's a fundamental requirement. For instance, applying the Pauli Exclusion Principle gives rise to Fermi-Dirac statistics.

Isn't that more about enumerating the microstates? The Pauli exclusion principle just ends up forbidding some of the microstates (forbidding a significant fraction of them if you're in the low-temperature regime).

It is about enumerating the microstates, but in a way that takes into account how the particles interact with each other (aka making assumptions about the dynamics).

If we didn't take into account any interactions, we'd be unable to do anything with statistical mechanics beyond rederiving the ideal gas law.

Reply on news.ycombinator.com