Is this universe infinite?
- Thread starter Deepak
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Cartoon Corpse
Veteran
the universe is infinite (as i 'see' it). the stuff contained in the blast area of the big bang is not the universe, but a part of it. what contains it...even if nothing is part of the universe and MUST be infinite.
EasyRaider
Regular
By definition, there cannot exist anything outside the universe. I suppose there could be multiple universes though, in which case the whole cosmos might better be termed the multiverse.
Bouncing Zabaglione Bros.
Legend
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OpenGL guy
Veteran
Except the universe is expanding. In fact, the expansion seems to be accelerating.Humus said:
My gut feeling used to be that the universe went through perpetual big bangs and collapses, but recent evidence seems to rule out that idea.
If the universe was to be continuously accelerating expansion after the initial "bang" (or whatever we want to call it), what in the name of heck caused the bang to begin with? There had to be some kind of trigger mechanism, some source, origin, root cause etc. I hesitate to say "creator", because that'd be dumb, but the possibility cannot be ruled out if a scenario like that is the correct one.
With a cyclic universe, the only thing we need to worry about was what caused the FIRST bang (and that would not really be possible to determine after perhaps the n:th bang that we might be living in). With an open-ended universe, the reason for our existence is a lot more immediate and pressing.
With a cyclic universe, the only thing we need to worry about was what caused the FIRST bang (and that would not really be possible to determine after perhaps the n:th bang that we might be living in). With an open-ended universe, the reason for our existence is a lot more immediate and pressing.
OpenGL guy said:
Well, the universe in the sense "where there's physical matter available" is expanding since big bang. The question is if big bang was the first and only such event. There has been theories that the universe would ultimately collapse again by gravity forces pulling it all together again, which however has been shown will not happen since it's expanding too quick for it to ever be able to pull back again, it will just expand slower and slower. That's assuming the universe is infinite. If my theory would be correct, then the most pheripheral stars may ultimately wrap around and thus make cyclic big bangs possible anyway, but it could of course take 10^100 years until the first star wraps around and gets closer to its original position again if the size if large enough, or it could also be possible that it will expand slower and slower, and never really get far away to wrap around, even in infinite time.
Edit: I missed this. Accelerating? What would cause that, where's the energi coming from? Not that I follow this science much these days, but last time I heard the theory of the day was that it will keep expanding forever, but slower and slower, but gravity would never be able to stop the expansion entirely. If it's indeed accelerating, then I'd rather see that as a sign that objects are beginning to wrap around and are feeling the pull from other objects on the other side.
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OpenGL guy
Veteran
That's the big question. There are theories that on very large scales, gravity may actually be repulsive. This is one reason why people are looking for a quantum theory of gravity as the current theories are lacking.Humus said:
One problem with your idea about things on the far sides of the universe attracting each other is that it's impossible
Imagine our universe was the surface of a balloon. Draw two points on the balloon and inflate it. The points only get further apart, never closer. Also notice that the center of the "universe" is not on the balloon, but inside it. Our universe may be similar, but a 3 (or n) dimensional sphere as opposed to the balloon's 2 dimensions (we neglect the thickness of the balloon). Hopefully our universe never "pops" like a balloon does if you over-inflate it! Up to the late 90s cosmologists were indeed debating whether the universe would be expanding forever or whether its gravity would be enough to halt the expansion. Then it was discovered that the expansion was actually accelerating.Humus said:
http://en.wikipedia.org/wiki/Dark_energy
pocketmoon66
Newcomer
Guden Oden said:
No there doesn't
As soon as you have a trigger you have to ask what created the trigger, or the source of the source or the origin of the origin.Bouncing Zabaglione Bros.
Legend
Yes, it's the next iteration of string theory (strings in higher dimensions). Potentially explains things like gravity being strong yet weak, big bang, etc.silence said:
Bouncing Zabaglione Bros.
Legend
silence said:
The problem is that we have four dimensional brains, and we're trying to come up with explanations of a 11 dimensional (or more) universe. I wonder if it will all stay as arcane mathematical proofs or if we'll ever find some kind of practical application for all this outside of science fiction novels.
No, but it's so bloody big to make arguing the point silly.
I have a lot of trouble taking some of the crap that cosmologists come up with very seriously. There was a superb paper on astro-ph a few years ago by Mike Disney (not related to Walt) which gave cosmology a good, hard slagging. It was very entertaining reading. It's very hard to test theories if your experimental evidence is gathered from a sample of one, so by extension all cosmological theories should be treated with suspicion, even if they are apparently supported by observational evidence.
I don't think we as a species are in a position to get enough observational evidence to support ANY of the current theories of the universe.
We're looking thru a straw at the ocean and trying to figure out how big it is, and we just can't yet.
We're looking thru a straw at the ocean and trying to figure out how big it is, and we just can't yet.
Bolloxoid said:
This result really should be treated with scepticism. It relies heavily on standard candles, which is always an assumption at best. It's not clear to me that our understanding of the mechanisms underlying Type 1a supernovae is yet sufficiently robust that we need to overturn our entire understanding of physics on the basis on the apparent evidence.
Put simply... our models of Type 1A supernovae are incomplete at best. So when observational evidence comes along which suggests that either a) our models are incorrect at high redshift, or b) that we need to invent some fancy new type of energy which gives mathematicians a hard-on, which should we choose? Dodgy incomplete model, or overturn a century of physics?
But, no, negative energy is much more "stimulating". It seems that Occam has moved into disposables these days.
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