3 ms·
Depends on what level. Historically it was an empirical observation that was taken in as an axiom to classical thermodynamics. So it couldn't be derived from ot
by sharpneli 5y ago
Depends on what level. Historically it was an empirical observation that was taken in as an axiom to classical thermodynamics. So it couldn't be derived from other laws.
If we move to statistical mechanics we can derive the second law from probabilities. In essence it is possible for any system to break it, it's just very very improbable. Just like if you toss a coin billions of times. It's possible for you to get more, or less, than half of the tosses to be heads. It's just very very improbable to get anything more than very tiny deviations.
- meroes 5y agoBut when we apply statistical mechanics to "microscopic" arrangments like a few particles in an idealized rigid box or in a vacuum, there is no arrow of time. The laws of physics themsleves are totally symmetric (CPT theorem), and it is not thought the t-asymmetry of the weak interaction is responsible for the global macroscopic arrow of time. So without some statement of initial/prior conditions, we have no reason to see just the "forward" arrow unless we say something about initial/prior conditions. (Loschmidt's Paradox https://en.wikipedia.org/wiki/Loschmidt%27s_paradox https://en.wikipedia.org/wiki/Loschmidt%27s_paradox)