- Jun 12, 2005
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I miss Second Law arguments so I am going to create one. I should point out my biases at first; I believe the universe is not deterministic at a fundamental level and this indeterminism produces quasi-deterministic laws. One of these is the Second Law of Thermodynamics. I do not believe that the argument I am about to present is correct, however I cannot for the life of me find that it is wrong. So I am just typing this so hopefully another can find its flaws.
At its core the Second Law states that in a closed system that the microstates of the system will evolve so that the size of the partition of the microstate's phase state into marcostates will always increase until an equilibrium point is reached. Basically heat flows from a hot body to a cold body. The justifications for this are experimental of course, but the theoretical justifications all depend on indeterminancy. The evolution of microstates are random and due to the laws of probability they will tend to the larger partitioned macrostates.
If we assume a deterministic universe the second law cannot really hold. We could imagine the case of a scientist taking a gas, and through the use of some yet to be invented technology, reversing all the particle's velocities. This would mean that the systems mircostates would evolve deterministically into smaller and smaller marcostate partitions. In reverse following the phase path that it took to get to the higher entropy state. Basically he/she would have invented a sort of perpetual motion machine.
I should point out that it does not matter the entropy of the scientist increases (possibly
) to reverse the particle velocities. Since once he/she has reversed them he/she closes the system. So now it is a closed system that is reducing its entropy.
Now if a scientist can do this, so can nature. So we would more than likely see violations of the second law. We don't. How can the universe be deterministic?
Edit: It is funny how the brain works, once I externalised the argument I realised the problem with it. The mircostate of the particles with reversed velocity is not the same as the microstate with the initial velocities. Therefore the entropies have changed and the system may be evolving into higher entropy states. I think. Maybe my argument against my argument is wrong. What do you think?
At its core the Second Law states that in a closed system that the microstates of the system will evolve so that the size of the partition of the microstate's phase state into marcostates will always increase until an equilibrium point is reached. Basically heat flows from a hot body to a cold body. The justifications for this are experimental of course, but the theoretical justifications all depend on indeterminancy. The evolution of microstates are random and due to the laws of probability they will tend to the larger partitioned macrostates.
If we assume a deterministic universe the second law cannot really hold. We could imagine the case of a scientist taking a gas, and through the use of some yet to be invented technology, reversing all the particle's velocities. This would mean that the systems mircostates would evolve deterministically into smaller and smaller marcostate partitions. In reverse following the phase path that it took to get to the higher entropy state. Basically he/she would have invented a sort of perpetual motion machine.
I should point out that it does not matter the entropy of the scientist increases (possibly
) to reverse the particle velocities. Since once he/she has reversed them he/she closes the system. So now it is a closed system that is reducing its entropy. Now if a scientist can do this, so can nature. So we would more than likely see violations of the second law. We don't. How can the universe be deterministic?
Edit: It is funny how the brain works, once I externalised the argument I realised the problem with it. The mircostate of the particles with reversed velocity is not the same as the microstate with the initial velocities. Therefore the entropies have changed and the system may be evolving into higher entropy states. I think. Maybe my argument against my argument is wrong. What do you think?
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