2nd law of thermo.

[papernuke]

the second law of thermody states that in an isolated system, the entropy will increase. why is that? isnt an islolated system a system with no external forces? and without external forces acting on it. then for example how can the entropy of an ice cube (isolated) increase? in another sense, how can an ice cube by itself in the middle of nowhere melt? with nothing acting on it.

[Keiji]

Entropy != energy

http://en.wikipedia.org/wiki/Entropy

[papernuke]

what does " Entropy !" mean?

[Keiji]

"!=" means "is not"

So, "Entropy != energy" means "entropy is not energy"

[papernuke]

So, "Entropy != energy" means "entropy is not energy"

ok i knew that . but then how does/can entropy effect an isolated system? how does it do it?

[zero]

One way to describe this is by referring to "the arrow of time." It's easier to take an egg and break it than to take pieces of a broken egg and put them all back together into the original egg again.

If you had some movie projector film of Humpty Dumpty falling off the wall, but couldn't see which end of the tape was the start and which was the finish, you would figure it out easily enough by watching it run. If the pieces all flew back together again, then you would immediately know you were watching the film run in reverse. Why?

You could say that entropy is a measure of the disorder in a system. Even left to themselves with no external forces at work, things can go from an highly ordered to a less highly ordered state easily enough. The reverse, however, is not true. Well, not unless you load the film projector backwards.