Best explanation for 1-way entropy?

AI Thread Summary
The discussion centers on the law of increasing entropy and its foundational role in thermodynamics. Participants explore the concept that while systems can occasionally decrease in entropy, such occurrences are statistically negligible over long time scales. The conversation emphasizes that, given enough time, all equilibrium states will be reached, resulting in a net null entropy variation. The law is viewed as a general rule grounded in probability, with a focus on the overwhelming tendency of systems to evolve towards higher entropy states. Overall, the dialogue highlights the complexity of entropy and its implications in physics.
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What is the best explanation for why entropy must increase BY LAW. I can see it as being a good general rule, but I don't quite see why it's law, especially when you consider a micro-state explanation of entropy. What is the best argument for the law of increasing entropy?
 
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My thermo is a bit rough, but the entropy of a system always increasing actually means the system, with overwhelming probability, tends towards states of increased entropy. You CAN see a system go from higher entropy to lower entry, but the probability is vanishingly small.
 
Statistically, what Peng said is right in a short time scale. When you consider a sufficiently huge amount of time (and this is very, very huge amount of time, many times the age of our universe), every equilibrium state would be accessed and the total entropy variation would be null.
 
Thank you both for the reply! I was thinking along those lines, but I wasn't sure at all. Physics Forums is such a good tool for this kind of thing..
 

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