I am back again, I might as well answer this one, even if it won't help 
explain my point. ;)

On 22-7-2010 1:48, Darren New wrote:
> andrel wrote:
>> yikes, my mind boggles again as it does everytime when someone uses 
>> the phrase "before the big bang".
> 
> I know that *our* time started with the big bang. But you're giving no 
> indication that there wasn't something out there for the "big bang" to 
> have come from.

Even if the 'energy' of the Big Bang came from 'somewhere' the time in 
that 'somewhere' has no relation to our time, it is neither before or 
after, it does not necessarily run in the same direction as ours.

>> There is no before, because there was neither space nor time for 
>> anything to happen.
> 
> How do you know, if your physics doesn't cover or explain the event?
> 
> *That* is what we're asking.  You have a singularity. You're assuming 
> there's nothing on the other side of the singularity. Why is that?

Because of the nature of this singularity.

> In other words, why are you so convinced that
> http://en.wikipedia.org/wiki/Big_Bounce
> is actually necessarily incorrect?

That is not a true Big Bang theory with a singularity. In such models 
you might indeed have a time before the moment of greatest density as 
long as the universe keeps a finite size.

> I'm sure this guy publishing letters in Nature's Physics journal is 
> simply confused by the counter-intuitive nature of physics, right?
> 
> http://www.nature.com/nphys/journal/v3/n8/abs/nphys654.html

No, it is just that he is apparently (can not read the full paper) using 
the term Big Bang for something it didn't mean when I was studying. IMHO 
he is using it in a way that is still considered incorrect. Yet, I can 
understand why he does so if he wants to get a paper in Nature.

> I'm quite comfortable with the concept that time started with the big 
> bang. I just don't know that there's actually *evidence* for that beyond 
> the fact that the math we use *breaks down* at the big bang. In order 
> for you to definitely assert that there was no time or space before 
> then, you actually have to explain how you know, instead of just 
> handwaving that because you're right, I'm mistaken to ask how you know 
> you're right.

I have all the time been aware that there are other theories than the 
Big Bang. All I have tried to say is that in a true Big Bang theory you 
have a moment in time and space where time and space are created. That 
is what a.o. causes the mathematical problems. In any such theory there 
is by definition no time or space before, or it wouldn't have been created.

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