Entropy. What is it?

jim hardy

to me it's just navigation markers through the steam tables.

Though it is curious - if as my old thermo book said, entropy of universe is increasing ; what then is decreasing in exchange? The amount of stuff remaining unknown?

old jim

Khashishi

In Penrose's book the Road to Reality, he sort of asserted without proof that when gravity pulls things together, this increases the entropy. It seems that if this is to be the case, gravity must somehow increase the degrees of freedom of the system, but this wasn't explained.

Studiot

Page reference please?

I think this claim will not stand up to detailed examination.

There is not complete overlap between the domains of applicability of thermodynamics and statistical mechanics. They both deal with areas not covered by the other.

justsomeguy

My understanding is that as gravity pulls disorganized masses together into objects like stars and planets, the entropy of that particular system decreases, but that this is offset by the rise in entropy over a wider scale / bigger system. As with most of these things, I suppose it depends on how wide you want to cast your net when defining the boundaries of the system.

A house of cards on its own is a low entropy arrangement, but the entropy of the system has increased overall if you include the energy used by the person building it.

akhtarphysic

I think the famous article by Eric Verlinde " on the origin of gravity and the laws of newton "