Re:Entropy as Disorder: History of a Misconception
by bonoboTP on Saturday September 21, 2019 @08:40PM
(#21038864)
That's why I tried to shift focus to density based layering rather than the more complicated oil water interaction.
And the reason it happens is because it doesn't magically get the corresponding external energy. However if we artificially, like gods, arranged everything to be non layered but the same temperature, the entropy would be higher than if layered and same temperature.
Re:Entropy as Disorder: History of a Misconception
by kgwgk on Saturday September 21, 2019 @08:46PM
(#21038884)
No, the entropy would be lower and the phases would separate spontaneously because that would increase the entropy. The only reason you get layers in the first place is that oil and water don’t mix! Water and alcohol also have different densities.
But it doesn’t, which is the reason why it happens. Because that intuition of “oh, there are two phases, this means order and entropy is disorder so the entropy is lower” doesn’t correspond to the reality of the physical concept of entropy (the thing that is maximized for a thermodynamic system In equilibrium). That’s the point of the article.
Note that the discussion about potential energy is a red herring, phase separation does also happen in absence of gravity (you get droplets which don’t coalesce as easily, but it happens nevertheless).