04 Oct 17
Originally posted by @eladarIf a cosmologist says 'volume of the *whole* universe' that person is saying ALL of the universe, which is definitely more volume than the *Observable* universe. The observable universe is that which we can see with telescopes, a radius of about 14 billion light years. So that would imply a diameter of 28 billion LY. But the volume of the rest of it is unknown, maybe infinte but my guess is not but the BB event shot out trillions of times faster than matter can go, the speed of light and it is still expanding faster than c so there are parts of the universe that expanded past the limit we can visualize with telescopes which is why they separate the two distances. One more or less known and the other maybe forever unknowable. News at 11.
So you have a problem with calculating the volume of entire universe?
Originally posted by @fabianfnasIf space was infinitely small in the primordial universe (before the expansion) then an infinite amount of space could be said to make up an infinitely small universe.
"crazy small ... but still infinite in size"
You really have to explain this to me.
It's often said that the primordial universe was the size of an atom, but, really, what do statements about size mean in a universe where the expansion of space hadn't taken place yet?
Just thinking out loud here.
04 Oct 17
Originally posted by @sonhouseI think you are mistaken here.
If a cosmologist says 'volume of the *whole* universe' that person is saying ALL of the universe, which is definitely more volume than the *Observable* universe. The observable universe is that which we can see with telescopes, a radius of about 14 billion light years. So that would imply a diameter of 28 billion LY. But the volume of the rest of it is unk ...[text shortened]... te the two distances. One more or less known and the other maybe forever unknowable. News at 11.
I believe it is said the diameter of the observable universe is around 96 billion light years. Give or take 2 or 3 kilometers.
Originally posted by @great-king-ratI don't doubt that the estimate isn't completely way off but somehow I still think the error bar should represent somewhat more than 3 kilometers 🙂
I believe it is said the diameter of the observable universe is around 96 billion light years. Give or take 2 or 3 kilometers.
Originally posted by @humyI was talking about the observable universe. Doesn't it stand to reason if we can look in all directions and come up with what looks to us like we are in the center (I know all observers would THINK they are the center) but sticking a yardstick out in all directions 14 billion light years, wouldn't it stand to reason we could be correct saying the observable universe has a diameter of 28 billion light years? Even though we might be in some kind of 4th dimensional bubble?
I don't doubt that the estimate isn't completely way off but somehow I still think the error bar should represent somewhat more than 3 kilometers 🙂
04 Oct 17
Originally posted by @humyAn error margin larger than 3,3^-22???
I don't doubt that the estimate isn't completely way off but somehow I still think the error bar should represent somewhat more than 3 kilometers 🙂
Pfff... pseudoscience is what that is.
😉
04 Oct 17
Originally posted by @sonhouseBasically, because of the expansion of space, the light that we can still observe is a maximum of 96 billion LY away. Not 14.
I was talking about the observable universe. Doesn't it stand to reason if we can look in all directions and come up with what looks to us like we are in the center (I know all observers would THINK they are the center) but sticking a yardstick out in all directions 14 billion light years, wouldn't it stand to reason we could be correct saying the observa ...[text shortened]... eter of 28 billion light years? Even though we might be in some kind of 4th dimensional bubble?
https://en.m.wikipedia.org/wiki/Observable_universe
04 Oct 17
Originally posted by @great-king-ratThere is a difference between infinitely small and infinite in size. A size of an atom isn't infinite in size but rather finite. No, I don't buy that.
If space was infinitely small in the primordial universe (before the expansion) then an infinite amount of space could be said to make up an infinitely small universe.
It's often said that the primordial universe was the size of an atom, but, really, what do statements about size mean in a universe where the expansion of space hadn't taken place yet?
Just thinking out loud here.
The question is still there: If something in one time is finite in size and infinite in size another time - then it should change from finite to infinite at one point of time. How did this happen? And when? It's a drastic change, not to be taken lightly.
Sometime I hear people use the world infinitely large synonymously with unthinkably large. That's of course a mistake because they are not the same. This is not what you meant, is it?
04 Oct 17
1 edit
Originally posted by @great-king-ratThomas Pilgaard says:
The maximum distance from which light can reach us would be the radius, at 45 B LY. Not 96.
"Thus, the 46 billion light years figure is the current radius of the observable universe (giving it a diameter of ~93 billion light years). 46 billion light years in either direction are objects that are currently at that distance of 46 billion light years away, but whose light has just reached us after being emitted 13.8 billion years ago."
Do you agree to this or do you think it is nonsense?
04 Oct 17
1 edit
Originally posted by @fabianfnasNo, that is of course not what I meant.
There is a difference between infinitely small and infinite in size. A size of an atom isn't infinite in size but rather finite. No, I don't buy that.
The question is still there: If something in one time is finite in size and infinite in size another time - then it should change from finite to infinite at one point of time. How did this happen? And w ...[text shortened]... ge. That's of course a mistake because they are not the same. This is not what you meant, is it?
I have briefly googled your question, but found very little information. This maybe, but it wasn't all that interesting: https://www.thenakedscientists.com/forum/index.php?topic=51175.0
Edit: this is more or less what I meant with the early universe being "small", but still infinite:
"If the Universe is spatially infinite, it always had to be spatially infinite, even though the distances were shortened by an arbitrary factor right after the Big Bang.
In the case of a spatially infinite Universe, one has to be careful that the singularity doesn't necessarily mean a single point in space. It is a place - the whole Universe - where quantities such as the density of matter diverge.
In general relativity, people use the so-called Penrose (causal) diagrams of spacetime in which the light rays always propagate along diagonal lines tilted by 45 degrees. If you draw the Penrose diagram for an old-fashioned Big Bang cosmology, the Big Bang itself is a horizontal line - suggesting that the Big Bang was a "whole space worth of points" and not just a point. This is true whether or not the space is spatially infinite.
At the popular level - and slightly beyond - these issues are nicely explained in Brian Greene's new book, The Hidden Reality."
From https://physics.stackexchange.com/questions/9419/how-can-something-finite-become-infinite
04 Oct 17
Originally posted by @fabianfnasYes, I believe that is the scientific consensus.
Thomas Pilgaard says:
"Thus, the 46 billion light years figure is the current radius of the observable universe (giving it a diameter of ~93 billion light years). 46 billion light years in either direction are objects that are currently at that distance of 46 billion light years away, but whose light has just reached us after being emitted 13.8 billion years ago."
Do you agree to this or do you think it is nonsense?
04 Oct 17
Originally posted by @great-king-ratI don't see how. Light takes 14 billion years to reach us and it goes in a straight line or at least follows the curve of space that long. They would have to be saying there are 45 billion light years curled up in a 14 billion light year radius space. I think the thinking goes, if you had a spacecraft going exactly at the speed of light you could see a spot in the universe and you would go and go and then come back to the same spot and that should be 28 billion light years because it would be like an upper dimensional nature of riding on the surface, inside surface, of a balloon, you go in a straight line on the balloon but you are really curving over and will eventually come back to the same point in space but you would be 28 billlion years into the future.
Yes, I believe that is the scientific consensus.
04 Oct 17
Originally posted by @sonhouseI assume you read the wiki page I posted?
I don't see how. Light takes 14 billion years to reach us and it goes in a straight line or at least follows the curve of space that long. They would have to be saying there are 45 billion light years curled up in a 14 billion light year radius space. I think the thinking goes, if you had a spacecraft going exactly at the speed of light you could see a sp ...[text shortened]... ntually come back to the same point in space but you would be 28 billlion years into the future.
"... space itself is expanding, so we can actually detect light from objects that were once close, but are now up to around 45.7 billion light years away (rather than up to 13.799 billion light years away as might be expected)"
05 Oct 17
1 edit
Originally posted by @great-king-ratHer question was more or less the same that I pose. But I cannot find an answer of 'how' and 'when' the transition from finite to infinite happened.
No, that is of course not what I meant.
I have briefly googled your question, but found very little information. This maybe, but it wasn't all that interesting: https://www.thenakedscientists.com/forum/index.php?topic=51175.0
Edit: this is more or less what I meant with the early universe being "small", but still infinite:
"If the Universe ...[text shortened]...
From https://physics.stackexchange.com/questions/9419/how-can-something-finite-become-infinite
If the universe at a time near to t=0 was finite, then the universe is finite today too.
If the universe at the beginning was infinite yet small, then there is some explaining needed.
It seem that many people think that the universe has a center (the position of the BigBang) and it expands out into something. I see it often in popular articles in picture depicting an explosion from outside. This is not the case. BigBang happened in all the universe at the same time, there is no center, not then, not now. And there is nothing 'outside' the universe that the universe can grow into. Universe is everything there is, nothing more.
Not even the second link provided, gave the answer how the transformation took place. But introduced other properties of the universe as I see speculative. Worth another thread...
But the question still hangs there: "When and how did the transition from finite to infinite take place?"
I have the answer: It didn't. The universe started as finite in size, and is still finite in size.