/sci/ - Science & Math

Let's get this straight, /sci/. The second law of thermodynamics says that the entropy of a closed system never decreases. This is why we can't have nice things, like perpetual motion or perfect engines.

A lot of people like to bring up that this is wrong, and that entropy does decrease. I'll dispel to common myths along those lines.

One of the most common arguments against the second law is life. Life is clearly a decrease in entropy, right? We're well structured and not likely, so we have low entropy. Well, we also generate a ton of heat, and not much has more entropy than heated gas.

The second argument is that entropy decrease is not impossible, just statistically unlikely. If we could somehow weight the probabilities in our favor, we could get our perfect engines. While this is technically true, most people have no feel for exactly how improbable an entropy decrease is. For any reasonably-sized system (for instance, a penny), you could check in on the system ten times every second from the Big Bang until now, and still have only some parts in a million chance of seeing an entropy decrease. That shit is UNLIKELY. So unlikely, it may as well be never.

You can't win. You can't break even.