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Author Topic:   Problems with an Infinite Universe
Mission for Truth
Inactive Member


Message 1 of 95 (117221)
06-21-2004 5:13 PM


I need some clarification. Present thoughts of the universe say that it is infinite, however, how can this be so? Reading Stephen Hawking's book "The Universe in a Nutshell" he says that if the universe is infinite then it presents certain problems such as how come the night sky isn't totally bright (as there would have been enough time for light to get here from every direction)? So I believe the scientists when they say it's infinite, however, how is this so?
This message has been edited by Mission for Truth, 06-20-2004 08:31 PM
This message has been edited by Mission for Truth, 06-20-2004 08:33 PM
This message has been edited by Mission for Truth, 06-20-2004 08:34 PM

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Melchior
Inactive Member


Message 2 of 95 (117346)
06-21-2004 10:45 PM
Reply to: Message 1 by Mission for Truth
06-21-2004 5:13 PM


I think you are confusing two things.
First, the size of the universe. We don't know how large it is. It could theoretically go on forever, or it could have a certain determinable size, or whatnot. However, we can not presently see all of it, so we can't say for sure. An infinitely large universe poses no direct problem.
Second, the time the universe has been around. It is impossible for the universe to have been around forever before now. If the universe is 13 billion years old, you see all the stars 13 billion light years or closer. However, if the universe would be infinitely old (eternal) you would see all stars from infinitely billion light years or closer. Which we don't.

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Beercules
Inactive Member


Message 3 of 95 (117372)
06-22-2004 12:25 AM


The problem of the night sky being dark was a problem for scientists in the past. Before modern cosmology, 2 assumptions were commonly made about the universe. One, the universe is infinite in extent and second, the universe has existed forever. Olber's paradox demonstrated that at least one of these assumptions must be incorrect. An universe both infinitely old and infinitely large would result in a night sky as bright as the sun.
Modern cosmology solves the paradox in two ways. One, the universe is expanding. This means that even if the universe has been around forever, light will not be able to reach every region, even in an infinite amount of time. As well, modern cosmology suggests the universe has not existed forever, but had a beginning. Either case offers a solution to the paradox, but it just so happens both are in effect.

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Mission for Truth
Inactive Member


Message 4 of 95 (117506)
06-22-2004 11:58 AM
Reply to: Message 3 by Beercules
06-22-2004 12:25 AM


So, in modern cosmology (as in right now), do we know if the universe is infinite or finite? Or is that still a question waiting to be solved? If infinite, how does that correspond with the Big Bang which gave time a starting point?

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Beercules
Inactive Member


Message 5 of 95 (117685)
06-22-2004 10:25 PM


It's not something that has been resolved. The evidence is consistent with both - though cosmologists tend to lean towards an infinite universe for simplicity.
If the universe is infinite, the big bang represents a situation where the density of each point space becomes infinite.

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Mission for Truth
Inactive Member


Message 6 of 95 (117707)
06-22-2004 11:15 PM
Reply to: Message 5 by Beercules
06-22-2004 10:25 PM


Say Again?
quote:
If the universe is infinite, the big bang represents a situation where the density of each point space becomes infinite.

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Melchior
Inactive Member


Message 7 of 95 (117831)
06-23-2004 6:51 AM
Reply to: Message 5 by Beercules
06-22-2004 10:25 PM


Doesn't that occur in any singularity? It certainly didn't seem to present a problem to the area of the universe that we live in.

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Beercules
Inactive Member


Message 8 of 95 (117894)
06-23-2004 12:20 PM


But this singularity is not a single point of infinite density, but infinite density throughout all of space.

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coffee_addict
Member (Idle past 477 days)
Posts: 3645
From: Indianapolis, IN
Joined: 03-29-2004


Message 9 of 95 (117898)
06-23-2004 12:30 PM
Reply to: Message 4 by Mission for Truth
06-22-2004 11:58 AM


MfT writes:
If infinite, how does that correspond with the Big Bang which gave time a starting point?
The big bang event (the original point of expansion) not only gave birth to time but also space itself. It wasn't matter and energy that started to expand from this single point. It's also space itself that expanded.

The Laminator

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Melchior
Inactive Member


Message 10 of 95 (117902)
06-23-2004 1:07 PM
Reply to: Message 8 by Beercules
06-23-2004 12:20 PM


And my argument is that this also happens in a finite universe at the big bang. Why would the size of the universe matter at a point in time where there is no such thing as size?
I understand that you were pointing out that any space can 'fit' into a point during the big bang, but why put emphasis on infinite?
This message has been edited by Melchior, 06-23-2004 12:12 PM

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Mission for Truth
Inactive Member


Message 11 of 95 (117987)
06-23-2004 4:49 PM


Mind Boggler
The universe totally boggles my mind. I find it really hard to comprehend what the Big Bang started from (besides the text book answer -- a singularity). Doesn't there have to be something first that the singularity came from ie: causality? I know that time, space, and matter started with the Big Bang, no problem, but there is always the niggling question of what the hell was there before? and by before I don't mean timewise, I just mean in a logical sequence of events there has to be something before, not necessarily timewise before.
Thinking about these things makes me realize that we can't only be in four dimesions, it seems there has to be a more logical explanation to the natural birth of the universe (or non-birth) because the idea that the universe as a huge smooth bubble with either no boundries or definite boundries and in both cases nothing outside of it seems crazy! I can't picture it, what is outside of time/space/matter, a blank sheet? It's no wonder creationists just do away with the thinking and place 'God' there. I don't blame them!
This message has been edited by Mission for Truth, 06-23-2004 03:50 PM

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sidelined
Member (Idle past 5908 days)
Posts: 3435
From: Edmonton Alberta Canada
Joined: 08-30-2003


Message 12 of 95 (118058)
06-23-2004 9:30 PM
Reply to: Message 11 by Mission for Truth
06-23-2004 4:49 PM


Re: Mind Boggler
Mission fo Truth
, I just mean in a logical sequence of events there has to be something before, not necessarily timewise before.
Is not a sequence of events a good definition of time?

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Buzsaw
Inactive Member


Message 13 of 95 (118065)
06-23-2004 10:07 PM
Reply to: Message 9 by coffee_addict
06-23-2004 12:30 PM


Lam, please define space. If it allegedly expanded what did it expand into and what did it displace?

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jar
Member (Idle past 394 days)
Posts: 34026
From: Texas!!
Joined: 04-20-2004


Message 14 of 95 (118066)
06-23-2004 10:14 PM
Reply to: Message 13 by Buzsaw
06-23-2004 10:07 PM


Does it have to expand into something?
Does it have to displace something?

Aslan is not a Tame Lion

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Mission for Truth
Inactive Member


Message 15 of 95 (118069)
06-23-2004 10:55 PM
Reply to: Message 12 by sidelined
06-23-2004 9:30 PM


Sidelined
quote:
Is not a sequence of events a good definition of time?
...That's not what I'm talking about. Space and time are inextricably connected, as Einstein proved with his general theory of relativity. The Big Bang birthed the universe, and the universe is all the space-time there is (that we know). So, one cannot say "what happened before the Big Bang, because time-wise, there was no before, there was no time... So, what I'm saying is that causality still should hold true. For the Big Bang to happen something had to cause it, didn't it? I would think so.

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