My understanding of entropy is that it is a measure of the available states a system can take on. In this context, if the total entropy in the universe always increases, how can it lead to a configuration where everything is at absolute zero? This has an entropy of 0, as there is only 1 possible configuration of the universe where this is the case.
[Physics] If thermodynamics says entropy always increases, how can the universe end in heat death
entropystatistical mechanicsthermodynamics
Best Answer
The total entropy of any isolated system increases until equilibrium is obtained. Then entropy stops increasing. If the system is the entire universe, then entropy will increase until the heat death.
The universe being at maximum entropy does not mean the entire universe is at absolute zero.
Not at all. Maximum entropy means there are a maximal number of configurations.
As a useful analogy, just think of the gas in a box example. The box has a "heat death" when maximum entropy is obtained when there is a uniform gas concentration throughout the box. This doesn't put the box at absolute zero, and it doesn't put the box in a state that only is associated with a single configuration.