Say I put a bunch of powerful square magnets on a nearly frictionless table in a disordered fashion. The second law of thermodynamics states that the system shall spontaneously get more disordered, yet the magnets will attract each other and form a chain (typically), thereby increasing the order of the system-and, seemingly, decreasing its entropy.
It would seem to me that the system is closed and the lattice is indeed the equilibrium state. Therefore, I suspect that by attracting each other, the magnets increase their own entropy by a larger amount than the decrease in entropy caused by the lattice formation. Is it true? If yes, what are the thermodynamics of magnets responsible for this? Is there a microscopic explanation?
Thanks!
Answer
The magnets will indeed attract each other. This attraction will put them in motion, and they will head towards each other, converting electromagnetic energy into kinetic energy. Then they will collide, and loose their kinetic energies in the collision, finally coming to rest in a more ordered, low-energy state.
In terms of energy, the outcome of the experiment is that you have converted electromagnetic energy into heat: the heat released in the collisions. This conversion creates far more entropy than the entropy lost by arranging the magnets in a more ordered fashion.
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