Warp wrote:
>   This has puzzled me for a while, and I can't find an answer.
> 
>   There was a time during the beginning of the Universe, when all the
> energy in the Universe was compressed into a space smaller than its own
> Schwarzschild radius. This should mean that this energy could not escape
> that radius, and would have quickly collapsed back into a singularity
> (or whatever is happening inside a black hole). However, that didn't
> happen. Why? How did all the energy escape its own event horizon?

Possibly one of these answers:

1) Because gravity wasn't a separate force from the others.

(OK, I see that gravity fell out very early on, but particles had no mass 
anyway. I don't know if they mean rest mass, but...)

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

2) It never did, and that's why the universe is close to flat. (I.e., we're 
still inside the event horizon of the big bang.)

3) Because the big bang didn't start all in the same "place".

(This one apparently has been OBE, but it used to be postulated that

> In the beginning, however, the Universe expanded *a lot* faster.

That too. Look up "inflation".  That's exactly what happened.

http://en.wikipedia.org/wiki/Inflation_%28cosmology%29

>   Gravity, on the other hand, can only propagate at speed c because it's
> also bound by the same law as any particle. Thus because the Universe was
> expanding way faster than c, the gravity wave which all the energy was
> producing was lagging behind. Thus the gravity well necessary for the event
> horizon to form did simply not have time to propagate fast enough to
> "enclose" the energy existing at that point. Thus an event horizon never
> formed, and all the energy got distributed beyond its Schwarzschild radius.

That's what this picture is all about:

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

Basically, the "dots" are how far light would have traveled in the time 
between the time the universe became cool enough to be transparent and now.

>   I wonder if this explanation is even close to correct.

It's not bad, as I understand it. :-)  It certainly has a lot of the pieces 
right. It's probably close enough that someone who actually knows the answer 
could explain it to you without your head exploding.

But I suspect it's the giant FTL "inflation" or some other wonkiness of 
pre-first-microsecond space-time that means the "singularity" wasn't all 
that singular.

-- 
Darren New, San Diego CA, USA (PST)
   Serving Suggestion:
     "Don't serve this any more. It's awful."

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