On 29-Jul-08 1:26, Warp wrote:
> andrel <a_l### [at] hotmailcom> wrote:
>> And what exactly does this all prove? I haven't seen anything in those 
>> links that I did not know (but I admit I did not read everything) and 
>> nothing that even remotely supports your 'The real size of the universe 
>> is completely impossible to know. It could be just slightly larger than 
>> the observable universe, or it could be staggeringly larger. There's 
>> just no way of knowing.' but I might have missed it.
> 
>   Uh? I said that the current widely agreed consensus is that the universe
> not only can expand faster than c (which you don't seem to disagree with),

Oh, but I do. Two points may move from one another faster than c, making 
it impossible for one point ever to see the other one. That does not 
imply, however, that the universe itself expands faster that c. I think 
that is also the point that 
http://en.wikipedia.org/wiki/Metric_expansion_of_space is trying to make.

> but most probably has done so (because that would explain many observed
> phenomena). I gave links to wikipedia pages where you could find references
> to more material.

No you gave a website that discusses the 'observable universe' which is 
a totally different beast than the size of the universe at some moment 
in time.

>   Of course there's no absolute *proof* of this. By the very definition
> of cosmological horizon it's *impossible* to have an absolute proof of
> this (ie. that the universe is larger than the observable universe).
> However, currently science most agrees that this is very likely.

What is in the page you referred to seems to me to be a standard 
relativistic approach of the concept of what the observable universe is. 
'Currently' would then seem to mean 50+ years or so.

>   Your way of writing seems to imply something like "you have not given
> me any proof about this, and thus I don't believe you". In other words,
> you still state that the size of the universe is at most the size of
> a sphere with a radius of the age of the universe itmes the speed of
> light (although you don't seem to deny that the universe *can* expand
> faster than c).

I think that the size of the universe (at least from some time, say, a 
million years, after the big bang) is expanding with at most c. I have 
not followed cosmology really closely over the last 20 years or so, so I 
am not really familiar with any recent theories on the early years of 
the universe. Yet, the couple of hundred thousand years that span that 
era are dwarfed by the nearly 14 billion years when normal physics 
applies. What I do know is that I studied special and general relativity 
and some cosmology when I was at the university and that your claim that 
the real size of the universe may be 'staggering larger' than the 
observable universe does not seem to fit what I remember. Although I 
moved to applied physics for my masters, I have still some links with 
the physics and astrophysics community and I tend to think that I would 
have noticed a theory that would imply that.

Please also note that even if someone comes up with a new cosmological 
theory that does not mean that from now on that is the accepted theory. 
Not even when it is reported on discovery channel. Science journalists 
have a habit of suggesting that (and not only for cosmology), but 
science does not work that way.

>   Well, where's your proof? Or any serious references, for that matter.
> At least I gave you *something*.

Yes, a page that was about something else and if anything was 
contradicting your claim. ;)

BTW the concept of the universe having a size at one point in time is 
rather useless, indeed because of relativistic reasons. Observable 
universe is a more useful concept, I grant you that one.

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