In reply to subalpine:
> yeah, but how you explain the low entropy of the early universe?
Is this "Whats the difference between the early universe and a black hole?"
Why is the Early universe (all the matter in the universe crammed into a small space) considered a low entropy system when a black hole (shed load of matter crammed into a space so small it warps space time to a asymptotic level) considered a high entropy system?
and the answer is, I don't know. But I hope some one does.
We're taught that gravity is a force that draws all things together based on their energy. And that if we can get the energy close enough this force can override every opposing force (electrical, material, etc). So why does the early universe expand, why does the big bang, bang?
If the early universe is the lowest entropy possible then it must be a homogenous distribution of energy then as it starts to expand fluctuations and variations start to come in and as there are more possibilities then there is a higher entropy (kinda). But why does it expand as without matter or electrical forces surely the gravitational effect of the energy would just cause them to stay in place and never expand.
And I guess that as with a lot of questions the answer comes down to boundary conditions, what we are declaring our closed system. In the case of the black hole our boundary conditions cannot be the event horizon as the black hole would never have formed if it wasn't for the supernova so now this system includes not only a small dense possibly uniform black hole but also the massive cloud of expanding matter that is shooting off around the rest of the universe that could end up being absolutely any where. So it is now a high entropy system.
Logically that would suggest that there is something outside of our universe as well, something that caused the big bang but we are prevented from even knowing what it is because the edge of the universe is an impenetrable barrier where our knowledge ends. Much like the barrier of the event horizon of a black hole.
A lecturer of mine made a throwaway comment that at the event horizon of a black hole the dimensions we know as time and space swap over maybe that's what happens and that inside a black hole is a new universe and we are just inside a black hole in someone elses universe.
Or maybe I'm just talking a load of old twonk as I wait for a machine to slowly compress a piece of plastic (Woohoo for cutting edge research).
Hope that helps.
Pete