> I always thought that W in k ln(W) was the number of possible states. That formula - Boltzmann's entropy - is only applicable when all the microstates are eq

> I always thought that W in k ln(W) was the number of possible states. That formula - Boltzmann's entropy - is only applicable when all the microstates are equiprobable. The question of what does it mean in general is subtle. If we have a gas in a container in thermal equilibrium with a heatbath, for example, the energy of the microstates compatible with those constraints is not fixed and their probability depends on the energy. The energy and the pressure fluctuate. > I wonder, though, does this actually matter to anyone but a physicist? The people most concerned with the question of entropy on a conceptual level tend to be physicists - and philosophers. https://deepblue.lib.umich.edu/bitstream/handle/2027.42/43415/11098_2004_Article_207174.pdf https://deepblue.lib.umich.edu/bitstream/handle/2027.42/4341...