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Steely Dan
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If the universe is finite, what would its total volume have been at [itex]t = 1[/itex] s?
Some Slacker said:I would posit that the universe is not finite, though our view of it is limited by the speed of light and of course time. Though we can look back through time to see what things looked like 12 billion years ago, we cannot see what a current galaxy looks like at 12 billion light years distant. (or beyond).
at T=1 second? Who knows? I would posit that the universe was infinite at any time after inflation which is a factor of billions sooner that 1 second. The reason I would posit this is that simply expansion happened at faster than light making everything infinitely far apart...
phinds said:I also tend to the belief (and I recognize that it is ONLY a belief with no basis in fact) that the universe is likely infinite, but your post doesn't make any sense. If the universe was finite at ANY time after the singularity, as you seem to believe, then it is of necessity finite now.
Inflation most certainly did NOT make everything infinitely far apart; that's just ridiculous.
Some Slacker said:Yes I should have perhaps said, infinite to any possible observer in the inflationary universe.
And yes I would also posit that if the universe came from a singularity that too would be infinite! HAH! (to any possible observer from inside the singularity)
Some Slacker said:Yes I should have perhaps said, infinite to any possible observer in the inflationary universe.
And yes I would also posit that if the universe came from a singularity that too would be infinite! HAH! (to any possible observer from inside the singularity)
Drakkith said:I don't understand this post, nor your previous one. They don't seem to make any sense. Are you sure you adequately got your thoughts down correctly?
Cosmo Novice said:I am with phinds and previous posters in my OPINION that the Universe is, will continue to be and always has been infinite in its nature.
Steely Dan said:So I want to get a better intuitive feel for what that universe would have looked like in early times.
Steely Dan said:I understand the basic concepts of the early universe. What I am looking for is a discussion on what the subtle differences would be, if any, between the infinite and finite universes when it comes to the very early universe. Does Weinberg address this?
manojr said:After the Big Bang, volume of universe increased by factor of at least 10^78 within 10^-32 seconds. This is described as Inflation (http://en.wikipedia.org/wiki/Cosmic_inflation). After inflation, the universe continued its expansion at lower rate.
This Wikipedia article gives timelines of the Big Bang (http://en.wikipedia.org/wiki/Timeline_of_the_Big_Bang), but there is no mention of sizes at various stages. In my opinion, since Big Bang did not happen at a particular point, it happened everywhere, it probably makes no sense of talking of sizes.
But I think there is a valid question. Since universe is expanding, it must have been smaller back in time, and therefore, what was the size of our current observable universe say 1 billion years back, 10 billions years back and just 1 second after the Big Bang?
Some Slacker said:Okay, we are at t=0 and the universe is a singularity?
Yes? (if no, then I have no answer)
Not to plunge back into darkness but... how long was the singularity around?
Since t=0 must not have been there for long?
Yes? No? Doesn't really matter, my point here is that time (in our universe?) begins with a singularity, there is nothing else. To any observer from within the singularity the universe to me would still appear infinite (though very boring) as the singularity has no space, (or light, or matter or anything else) so if there were some way for you sense anything from within the singularity it would appear the same in all directions and go on forever, since nothing can escape the singularity anyway and there is nothing out there to see.
So from the start I see the universe as infinite and then during inflation I would also see the universe as infinite since expansion is happening at faster than light speed after that the universe ends up as infinite because I want it to be (yes back to flippancy so shoot me). Infinity +/- 1 makes no sense so I'm stickin with infinite.
...there would NOT be any way to sense anything from within any said singularity.
...the theory is a quantum gravity proposal concerning the state of the universe prior to the Planck epoch... that there was no time before the Big Bang because time did not exist before the formation of spacetime associated with the Big Bang...that if we could travel backward in time ... time gives way to space such that at first there is only space and no time...
Naty1 said:possible if you mean 'observe'...but Hawking-Hartle might disagree:
Hartle–Hawking state
http://en.wikipedia.org/wiki/Hartle%...3Hawking_state
The size of the universe just after the Big Bang is estimated to be incredibly small, about the size of a marble or even smaller. This is known as the singularity, the point of infinite density and temperature from which the Big Bang originated.
After the Big Bang, the universe underwent a period of rapid expansion known as inflation. This expansion caused the universe to grow at an incredibly fast rate, expanding from the size of a marble to the size of a grapefruit in less than a trillionth of a second.
Yes, the universe is still expanding. The expansion is happening at a slower rate now, but it is still occurring. This expansion is supported by observations such as the redshift of distant galaxies and the cosmic microwave background radiation.
The size of the universe is measured in terms of its observable universe, which is the portion of the universe that we can see. This is estimated to be about 93 billion light years in diameter. However, the actual size of the entire universe is unknown and may be infinite.
It is currently believed that the universe will continue to expand forever. However, there is a possibility that the expansion may slow down or even reverse if the gravitational pull of matter and dark energy becomes stronger than the expansion rate. This is still a topic of ongoing research and debate in the scientific community.