Maxwell Demon

>>7682012
>can be a law if it can be violated?
ask criminals

Several physicists have presented calculations that show that the second law of thermodynamics will not actually be violated, if a more complete analysis is made of the whole system including the demon. The essence of the physical argument is to show, by calculation, that any demon must "generate" more entropy segregating the molecules than it could ever eliminate by the method described. That is, it would take more thermodynamic work to gauge the speed of the molecules and selectively allow them to pass through the opening between A and B than the amount of energy gained by the difference of temperature caused by this.

>>7682018
And it may not even be possible to do

>>7682012
This is a thought experiment. You've yet to prove that it's a) possible and b) actually violating the second law.

>>7682012
>when you realize the principle of conservation of energy is possibly being violated continuously in an accelerating universe generating dark energy.

>>7682017
>send black people to space
>reverse entropy

wow its genius

>>7682012
It obviously cannot be violated, that's why it's a paradox. You have to find out where you made the error. In this case you forgot to take into account the energy it takes for the devil to perform is mechanism.

I have a question:
Isn't surface evaporation basically what the second law says cannot happen? Faster molecules escape the fluid and lower the average speed of the fluid molecules and thus the temperature of the fluid and increase the temperature of the gas over the fluid.

>>7683612
Anyone?

>>7683691
The molecules that escape end up creating more entropy than the cooling liquid loses. It can be shown quantitatively too.

>>7683698
Okay, but in the end what we have is heat transfer from a water at say 25 degrees to air at 25 degrees which technically shouldn't happen, or is that OK since the temperature difference between air and water is very very small?

>>7683703
The molecules that escape do so because they have on average a higher kinetic energy (higher temp) than the majority. If the liquid was in equilibrium with its environment, this phenomenon would still occur, and the escaping particles still add entropy to the environment due to their higher "temp". Does that make sense?

>>7683723
I guess so.
Is evaporation an irreversible process? Do we have entropy generation here?

>>7683703
Also think of it this way:
A liquid has a LOT less entropy than a gas in general. The particles that escape the liquid can be thought of as a gas. The creation of this "gas" adds more entropy to the environment than what is lost by the liquid becoming cooler.

>>7683727
It's reversible if all the evaporated particles condense back into the liquid. But nothing is truly reversible, there will be some sort of loss to the environment, thus adding to the total entropy.

Another form of the 2nd law of thermo: Entropy tends to increase.

>>7683740
Alright, thank you.