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Post by typobrane on Oct 5, 2010 19:48:39 GMT 1
That is a possibility, we would have to look for patterns in the galaxies to prove such a thing but I cannot believe that the universe is finite. Some have difficulty in the concept of infinity I on the other hand have difficulty with the concept of a finite universe as that would imply a concept of a nothing somewhere else.
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Post by Progenitor A on Oct 5, 2010 20:01:38 GMT 1
That is a possibility, we would have to look for patterns in the galaxies to prove such a thing but I cannot believe that the universe is finite. Some have difficulty in the concept of infinity I on the other hand have difficulty with the concept of a finite universe as that would imply a concept of a nothing somewhere else. Why is infinity less difficult than 'nothing somewhere else'? Both seem to me equally difficult
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Post by typobrane on Oct 5, 2010 20:11:30 GMT 1
For nothing to exist nothing can exist, is my take on it.
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Post by abacus9900 on Oct 5, 2010 20:42:24 GMT 1
typobra, I have heard this view expressed before, even by professional physicists, and I am struggling to understand it.
Even though space itself is expanding considerably faster than the speed of light how would it be possible for the universe to be infinite? There must surely be some kind of finite limit to the speed of inflation so that the universe cannot possible be of infinite expanse, or have I missed something here?
Or, do you mean that our universe has infinite 'incarnations' and that the one we are presently aware of is but one of them?
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Post by abacus9900 on Oct 5, 2010 20:49:14 GMT 1
Good point, naymissus, good point.
Are these questions ultimately scientifically meaningless? If so, then is science ultimately meaningless?
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Post by typobrane on Oct 5, 2010 22:52:03 GMT 1
typobra, I have heard this view expressed before, even by professional physicists, and I am struggling to understand it. Even though space itself is expanding considerably faster than the speed of light how would it be possible for the universe to be infinite? There must surely be some kind of finite limit to the speed of inflation so that the universe cannot possible be of infinite expanse, or have I missed something here? Or, do you mean that our universe has infinite 'incarnations' and that the one we are presently aware of is but one of them? I have an understanding of infinity and infinities but have no concept of a nothing As space expands galaxies move apart, this movement is with space rather than through space any movement through space has a separate cause to that of the expansion.
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Post by carnyx on Oct 5, 2010 23:31:55 GMT 1
AFAIK the concept of inflation is an ingenious explanation of increasing red shift with distance, and may be right, or wrong and it is an artefact of some kind.
And so I would be interested to see the results of calculations which would show how much gravity it would take to cause this red shift. And then, taking Abacus's point, how many times round the Universe the light might have to go.
Then this idea of pattern that typobra mentioned; how would that be?
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Post by abacus9900 on Oct 6, 2010 12:46:28 GMT 1
Sorry, but what has this got to do with the idea of an infinite universe?
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Post by Progenitor A on Oct 6, 2010 12:59:34 GMT 1
I have an understanding of infinity and infinities but have no concept of a nothing Well typobra, I am surprised at this inversion of normal 'perceptions' For example most people have direct experience of having nothing in the bank, no-one has any experience of having an infinite number of pounds in the bank; '0' is quite manageable in mathematics, in physics, in economics, in poltics, well, in just about everything really, whereas infinity is not manageable in any field (to my knowledge)
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Post by speakertoanimals on Oct 6, 2010 14:16:04 GMT 1
Yes, you have assumed that the universe had to have expanded from a point, into something infinite. This is wrong. If infinite, it was always infinite, even though any finite piece of it came from a point at the start. There didn't have to be some funny thing we suddenly went from a finite universe to an infinite one.
As regards the finite universe -- this doesn't mean an outside either. The shape of the universe (the curvature), the size of the universe, and the topology of the universe are not necessarily related.
SO, take a sheet of paper, and identify the top edge with the bottom, and the left with the right, like old computer games where going off on edge brought you back in at the other. Such a space is finite, flat, but with the topology of a sphere.
Think of a cylinder (best we can build a model of in 3D), which is FLAT, but with paths that take you all the way round the universe.
To see that a cylinder is flat, think about making one from a sheet of graph paper -- you have to BEND the paper, but not tear or stretch it, hence the surface of a cylinder is intrinsically flat (ie flat from the papers point of view), even though to build a model of it in 3d, you had to bend the paper (ie it looks extrinsically curved).
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Post by abacus9900 on Oct 6, 2010 15:41:00 GMT 1
You have still failed to define what you mean by 'infinite.'
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Post by Progenitor A on Oct 6, 2010 17:12:36 GMT 1
You have still failed to define what you mean by 'infinite.' Indeed, and once more we have a language/conceptual problem, for how can an infinite space expand? And this sentence: If infinite, it was always infinite, even though any finite piece of it came from a point at the start. What, exactly, does it mean?
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Post by mak2 on Oct 6, 2010 18:26:56 GMT 1
Consider the series of numbers 1,2,3,4.....to infinity. Multiply them by two and you get 2, 4 ,6 ,8 ....to infinity. Both series are infinitely large.
If the universe is infinite to start with, the distance between galaxies can still increase and the universe will remain infinite.
P.S. It is not settled that the universe is, in fact, infinite. But it could be.
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Post by Progenitor A on Oct 6, 2010 18:42:58 GMT 1
Consider the series of numbers 1,2,3,4.....to infinity. Multiply them by two and you get 2, 4 ,6 ,8 ....to infinity. Both series are infinitely long. If the universe is infinite to start with, the distance between galaxies can still increase and the universe will remain infinite. P.S. It is not settled that the universe is, in fact, infinite. But it could be. Sorry mak2, do not understand. If we have infinity, in my perception, there is no room for any more.
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Post by speakertoanimals on Oct 6, 2010 19:05:53 GMT 1
It is very easy, as others have already pointed out. Imagine an infinite sheet of graph paper, with little squares on it. Now imagine the same sheet of paper, but now with squares double the size.
So, if the squares are the positions of galaxies, we have the space between them has expanded, every galaxy is now twice as far away as it was before.
But we don't need to have any extra space outside that the expanding paper fills (unlike if we had a finite piece of paper) -- it was infinite and filled the plane when we started, it is infinite and fills the plane when it has expanded. No extra space needed.
Now take a finite chunk of the graph paper, and colour it in red. Now imagine the whole sheet shrinking, so that the squares get smaller and smaller (running the universe backwards). No matter how far you shrink down, you never bring the 'edge' of the paper into view, it is infinite after all! Yet the colored-in region gets smaller and smaller (as small as you like). Hence a finite piece of the universe came from a point at the start, but the universe if infinite now, always was.
What is wrong here? We know that, it is our old friend intuition. For finite objects, if we make it bigger, we need more room. But the same is not true for an infinite universe.
Those who don't know what infinite means should consult a dictionary...........
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