Originally Posted by KrisZ
Entropy like you said is decay. Breaking down. If you have a cell, thats order. Elements were bound together to form it. When that cell dies it breaks down back to the elements that formed it, that's chaos. It's pretty much that simple.
And while our laws of physics work in our little closed system, I'm not sure we can apply the same thing to the whole universe.
I fully understand that on earth if it weren't for the external source of energy provided by our sun, the entropy would ensure our planet is a dead rock. But if the same applies to the whole universe, where does it get its energy from?
Look up cosmic inflation. That state existed for a while way way back.
Also a few misconceptions, even without the sun, you'd still have some heat because the earth is also made up of some radioactive materials and you have the energy from the core of the earth. Of course it wouldn't be as hot without the sun. That's true of other planets out there too, they're hotter than the energy they get from the sun.
There's also some strange things out there in quantum mechanics, there's vacuum energy where energy appears and disappears, it's the basis for Hawking radiation. Then there's also dark energy which causes the acceleration of the universe and is pushing us toward the heat death of the universe. At the heat death, even time will stop because there's not enough energy left in the universe to measure time.