Anti-Matter Concerns

[Seeker]

"relatively small."

what the heck does this mean with regard to the universe? It was "small" relative to what?

"This meant that the multiplicity of any configuration of the system at the time would be smaller than the multiplicity of the current configuration."

How is this possible wrt to a universe which presumably contains and has always contained the same amount of matter/energy and space?

Unless the universe is gaining or losing net energy, I don't see why the early universe should have a lower number of 'possible configurations' as you say than now.

[KrazyHorse]

Relative to its current size.

[KrazyHorse]

End of inflation happened some time prior to z = 1000 (scale factor 0.001)

[Vince278]

Re: Anti-Matter Concerns

Originally posted by Sn00py
If CERN produces enough of it, and suddenly it all explodes, they could blow half of Europe off the map.

They can only make extremely tiny amounts at best. (Besides, we can do without half of Europe. )

There's a greater danger in creating artificial black holes, but not by much.

[DaShi]

I more worried if people figure out ways to split an atom. The consequences would be extremely dire.

[Seeker]

OK I think this is where you lost me...what I mean and what you mean by 'started out' seem to be different.

You are talking Big Bang, while I am talking about the speculative 'quantum fluctuation' which is supposed to have provided the energy for the Big Bang.

"When the universe started out, while it was energetic (meaning a greater entropy)"

If it was energetic, where did that energy come from, and isn't that a violation of entropy if there is no outside contribution.

[Ramo]

How is this possible wrt to a universe which presumably contains and has always contained the same amount of matter/energy and space?

Unless the universe is gaining or losing net energy, I don't see why the early universe should have a lower number of 'possible configurations' as you say than now.

A bigger universe means more variables to worry about. Suppose that the universe can be represented by coins. After a Planck second after the Big Bang, suppose that the universe was represented by two coins. The degeneracy of its most entropic configuration was 2 (HT and TH). After a short time, the number of coins doubles, and the degeneracy of its most entropic macrostate becomes 6. And so forth. This degeneracy continues to increase, therefore the system continues to generally gain entropy (of course, the system may not necessarily be in its most probable state, therefore this is not absolutely true).

[KrazyHorse]

You are talking Big Bang

I don't know what people mean by "the Big Bang". I call the moment inflation stopped "the end of inflation". I call the time during inflation "the inflationary epoch". I don't know what to call the time prior to the inflationary epoch.

I don't profess to understand the physics of what happened prior to the inflationary epoch well enough to make any statement about its entropy, and anybody who does is a quack. We don't really understand the inflationary epoch very well either. We're working on it as hard as possible, though. I promise you. I went in to work on the weekend just so you could get an answer quicker.

[Seeker]

"I don't profess to understand the physics of what happened prior to the inflationary epoch well enough to make any statement about its entropy"

Speculate damn you!! I DEMAND YOU ENGAGE IN SPECIOUS SPECULATION SO I CAN READ YOU IN SCIENTFIC AMERICAN!!

[Ramo]

You are talking Big Bang, while I am talking about the speculative 'quantum fluctuation' which is supposed to have provided the energy for the Big Bang.

If it was energetic, where did that energy come from, and isn't that a violation of entropy if there is no outside contribution

1. We don't understand what happens at singularities. Period.
2. I was talking about a short time after the Big Bang.
3. It stared out with energy.

[KrazyHorse]

1. We don't understand what happens at singularities.

We also don't understand anything about the inflaton field(s). Right now people just propose interaction models that they pull out of their asses.

[Vince278]

Originally posted by DaShi
I more worried if people figure out ways to split an atom. The consequences would be extremely dire.

I have some news for you.

[Ramo]

True

[Seeker]

"1. We don't understand what happens at singularities. Period.
2. I was talking about a short time after the Big Bang.
3. It stared out with energy."

Can I then add:
4. Therefore, we can't make confident predictions about the 'end of the universe' given our lack of understanding of what could be possible in 'empty' space given an indefinite period of time.

If we can't undertand why we strated out with initial energy than why the heck are we allowed to make speculations about an 'inevitable' "entropy death" of the universe? I'd say that if we can't make certain statements about the origin of the universe then by the same token it's ridiculous to make these predictions about 'inevitable' this and that since we can't be certain.

[KrazyHorse]

4. Therefore, we can't make confident predictions about the 'end of the universe' given our lack of understanding of what could be possible in 'empty' space given an indefinite period of time.

No. There are reasons why high energy densities correspond to unknown physics. Those reasons do not apply for the energy density of today's universe.