Stars and galaxies can still form. As I mentioned in a previous post, gravity has the reverse entropy configuration of gas. When the parts of a gravity system get closer together, entropy goes up. So the plasma of a star collecting together increases the entropy. The star burning increases the entropy. So there's nothing inconsistent about structures forming and entropy increasing. And that will be true whether the star is run by hydrogen fusion or electricity.junglelord wrote:If plasma exhibits entrophy on the universal scale....how do stars form? How do galaxies form?
Entrophy is a closed system result, the universe is an open system.
As to the question of an open/closed system, I certainly have no authority to declare the universe to be open or closed. I personally prefer to think of it as closed. It's easier for me and a closed system provides a few less hats for one to pull rabbits from. But naturally my personal preference doesn't decide the state of the universe. Unfortunately, the universe rarely seeks my advice before proceeding.
But on large time scales where stars and even galaxies come and go, the "large grain" structure of the universe should look pretty much the same for both plasma and gas. For a closed system, it will tend to diffuse over time unless gravity can stop it. For an open system it will depend greatly on just exactly what is meant by "open". How much "new stuff" enters the system? How much "old stuff" leaves. The answers to those questions will play a big role in what the universe looks like in an open system.
It's probably a good idea to briefly discuss how gas or plasma in an empty box could show all this because as allynh pointed out, there are so many things _not_ happening in that thought experiment. The key to relating an empty box of plasma to the structure of the universe is understanding just how long the universe is expected to live, even in a closed system. The time scale is 10 - 100 _trillion_ years. The lifetime of a star or even a galaxy, is brief in comparison. Their chance to affect the overall structure of the universe with anything other than their their long term entropy configurations is equally brief. Factoring in their gravity will change the long term entropy picture from that in the thought experiment. But whether or not it's gas or plasma doesn't matter that much. They both expand over time unless gravity can stop it.
I will answer the other replies that came after yours in the future because this is a difficult subject for me and I want to take the time to do a good job responding.