In thermodynamics only there are 3 distinct ones. Meta-stable equilibria can be order while the one that is used in the second law is the global minimum.Ī comment on entropy in general: there isn't just one, there is a lot of them. So I think your problem is the two uses of the word equilibrium. In the universe as a whole there is energy exchange between such subsystems and the second law of thermodynamics states that the overall order decreases by these processes. This brings your closer to the global equilibrium. Intuitively: if you smack the crystal with a hammer it breaks to pieces. But you can get certain systems that are in a meta-stable "local" equilibrium (here meaning that you need some energy to move it from there), for example a crystal. But microscopically - in the movements of the particles - that is the state in which there is the least order: no structure whatsoever, just a big soup of whizzing particles.įirst of all as stated by Madan Ivan: equilibrium is not order. In that sense, the universe is homogeneous and thus ordered. In the projected "heat death" of the universe, everywhere there is constant temperature and density. Indeed, there is a precise formula linking the macroscopic state variable $S$, entropy, and the microscopic conception of disorder I described.Ĭonclusion: the two ideas are reconcilable You know from thermodynamics that the gas has higher entropy than the solid. Which of the two - the still, regular lattice of the solid or the whizzing commotion of the particles that forms a gas - seems to you more disordered? Definitely the second. In particular, temperature of a gas is the disorganised jiggling of the atoms making it up.Īs you increase the temperature, the atoms will move more and more erratically, and will have diverse speeds at any given time.Īs you cool it, the particles will move slower and slower, until perhaps they freeze in place, forming a solid. In Physics, we know that the properties of macroscopic objects are determined by the motions of the particles that compose them. Well, let's keep that in mind for the next bit.
What transpires is that less information needed corresponds to a higher degree of order. In our out of equilibrium, my body, my laptop, the room, outer space, all have different temperatures, and I need more information to know the state of everything, and I feel this is less "ordered" than the thermal equilibrium case.
Indeed, if everything is in thermal equilibrium, you just need to measure the temperature somewhere, and then you will know the temperature of everything. What you are missing is the microscopic definition of entropy, once you know that, you will understand why people say that entropy is disorder.įirst, let's address your valid intuition that equilibrium as a form of order.
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