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not the first BIG BANG





spinout
I heard at the coffetable that scientists have discovered traces of "big bang"s before the latest...

Anyone heard of this???

So with revision is this of the universe?
ocalhoun
What kind of traces?
Indi
It's hard to guess at exactly what you mean, but several theoretical physicists have suggested models that include multiple big bangs. One of the coolest is Lee Smolin's evolutionary model, where every singularity (for example, black hole) in our universe is actually the creation of another baby universe... and our universe is the baby of a greater universe - our entire universe may be "inside" a black hole in another universe.

But discovering traces? No, this is all theoretical physics. Nothing has been observed. Everything before a few picoseconds after the Big Bang is all fuzzy in current physics.
DoctorBeaver
There was talk last year of the cosmic microwave background radiation (CMBR) maybe containing the signatures of events from before the big bang. Dr Adrienne Erickcek, of Caltech (the California Institute of Technology), believes our universe may have formed as a bubble within another universe and that traces of this can be found in the CMBR.

Here's a link to a BBC article from June 2008:

http://news.bbc.co.uk/1/hi/sci/tech/7440217.stm

The article also says that this may give a clue to the nature of time. That could be interesting.
snowboardalliance
Indi wrote:
It's hard to guess at exactly what you mean, but several theoretical physicists have suggested models that include multiple big bangs. One of the coolest is Lee Smolin's evolutionary model, where every singularity (for example, black hole) in our universe is actually the creation of another baby universe... and our universe is the baby of a greater universe - our entire universe may be "inside" a black hole in another universe.

But discovering traces? No, this is all theoretical physics. Nothing has been observed. Everything before a few picoseconds after the Big Bang is all fuzzy in current physics.


Multiverse theory is a part of String Theory and from what I understand, they say there are multiple universes in other dimensions beyond the 3+time we can see existing as M-Branes. And these branes can hit each other, creating a "big bang" effect. Another thing I've heard about what you are saying is that the universes go through an evolutionary process where the constants in physics that define how the universe works can be different. Universes are then more "fit" (natural selection) if they have more blackholes. I forget exactly and it's all very theoretical, but interesting.
ocalhoun
snowboardalliance wrote:
Universes are then more "fit" (natural selection) if they have more blackholes. I forget exactly and it's all very theoretical, but interesting.

But why would more black holes make a universe more 'fit'? Would the 'fittest' one be one that had nothing but black holes?
_AVG_
Nobody can actually prove whether this was the only Big Bang ever.

One of the many theories in circulation is that of the Big Bang and Big Rip being an infinite and periodic cycle. According to this theory, a Big Bang creates space-time and the universe which expands and then contracts until the Big Rip after which there is another Big Bang and then another universe and then another Big Rip and so on. This process has been occurring forever and will continue to occur forever.

Even if this theory is true, nobody can tell or prove. At least not with today's technology and brain power.
Bikerman
ocalhoun wrote:
snowboardalliance wrote:
Universes are then more "fit" (natural selection) if they have more blackholes. I forget exactly and it's all very theoretical, but interesting.

But why would more black holes make a universe more 'fit'? Would the 'fittest' one be one that had nothing but black holes?

Not necessarily. For black holes to form in the first place the physical constants have to be in a certain range (no stable atom, no black hole), so only a sub-set of possible universes can support black holes. I haven't read Lee Smolin's theory in depth (just abstracts and commentary) but I don't think a universe with nothing but BHs is possible physically. Therefore those that allow BH formation will spawn other universes, and those which don't, won't. As has been pointed out, it apprently brings together evolutionary theory and cosmology. It is a nice hypothesis (elegant) and Smolin has proposed some tests, so it isn't purely speculation.
You can read Smolin debating the idea HERE
ocalhoun
Bikerman wrote:
Therefore those that allow BH formation will spawn other universes, and those which don't, won't.

Ah, so the theory is that each black hole created makes another universe?
That would make sense, then, to call a black-hole-having universe 'fitter' than another, as it is better able to 'reproduce'.

What makes them think that black holes create universes though?
Bikerman
ocalhoun wrote:
Bikerman wrote:
Therefore those that allow BH formation will spawn other universes, and those which don't, won't.

Ah, so the theory is that each black hole created makes another universe?
That would make sense, then, to call a black-hole-having universe 'fitter' than another, as it is better able to 'reproduce'.

What makes them think that black holes create universes though?

Well, there has always been speculation about what happens at the 'singularity'. All we know for sure is that the laws of physics that we have don't work at that level. This is actually one of the few absolutely 'sure' indicators that Einstein's Relativity is missing something important. GR simply breaks down when we look at BH, and Quantum physics doesn't seem to help much. When we have a theory which can tell us much more about singularities, then we will have some much more 'complete' physics (though I really don't like the phrase 'Grand Unified Theory' - it smacks of hubris to me).
We need to know if spacetime 'quantises' (whether it can be reduced to fundamental 'bits' or not) before we can say anything much about the singularity...
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