Is the universe infinite?

[Buffy]

Originally Posted by C1ay

So you are saying that conclusions from WMAP suggesting the universe to be 156 billion light-years wide are incorrect? Do you also disagree with claims that the universe has a finite quantity of matter?

Its the issue of the definition of "boundary": current cosmological models say its isomorphic which colloquially means "same everywhere" which translates into "everyone anywhere in the universe perceives they are at the center". No one is "near the edge." Paradoxically to we 4-dimensional beings--who oft times have a hard time even with 3 dimensions--this still means there is no "boundary" but it *is* finite and it *does* have a "measurable" diameter!

Go figure!

Cheers,
Buffy

[EWright]

Originally Posted by C1ay

So you are saying that conclusions from WMAP suggesting the universe to be 156 billion light-years wide are incorrect? Do you also disagree with claims that the universe has a finite quantity of matter?

I'm saying what the concensus among most cosmologists seems to be. I did read the 156Gy diameter article in SciAm a year ago and found it very interesting. But cosmologists need to then decide if they want to use this figure or the 13.7Gy figure that is most often quoted.

In either case, it doesn't matter. If you are going to say that the universe is finite, then you must be able to say what it is expanding into. But by definition, the universe is all that there is. It may be that what is beyond the observable universe is very different than what we see (though unlikely if you use the bb model). But in both cases it is believed, as I understand it, that the universe is still believed to be infinite in size in the sense that it wraps back around on itself and if you travel in a straight direction you will end up back where you began (after a very long voyage). If you do so, you may aquire 156Gy (plus added expansion) on your odometer, but according to bb theory you will not encounter an 'edge' of the universe as you do. And because the universe is expanding, and given the time it will take you to make the hypothetically plausible trip, you will not be able to return to the same "point" and that section of the universe will have likely changed so much in the given time that you will not recognize it. (We can say the Earth is xx,xxx miles around, but you will not find an 'edge' in your travels around the world.)

Let me stress that I am expressing the ideas of bb theorists as I understand them to be. This does not mean that my own theory agrees with them. It does, however, support the evidence they site and explains many of the events that the bb theory does not.

[C1ay]

Originally Posted by EWright

I'm saying what the concensus among most cosmologists seems to be. I did read the 156Gy diameter article in SciAm a year ago and found it very interesting. But cosmologists need to then decide if they want to use this figure or the 13.7Gy figure that is most often quoted.

In either case, it doesn't matter. If you are going to say that the universe is finite, then you must be able to say what it is expanding into. But by definition, the universe is all that there is. It may be that what is beyond the observable universe is very different than what we see (though unlikely if you use the bb model). But in both cases it is believed, as I understand it, that the universe is still believed to be infinite in size in the sense that it wraps back around on itself and if you travel in a straight direction you will end up back where you began (after a very long voyage).

Because you can go around something and end up where you started, it cannot be infinite. If it were infinite you would never get around it.

[EWright]

Originally Posted by C1ay

Because you can go around something and end up where you started, it cannot be infinite. If it were infinite you would never get around it.

Your preaching to the choir, my friend. I didn't say I buy into the infinite universe idea per se. But the big bang model does not call for a finite universe. Take that up with bb theorists as well as the rest of the things they can't explain. I take issue with the theory too. It is your perception or interpretation that defines it as infinite (not the bb model itself), and in the context you describe, I would agree with you.

[tatwood106]

If there was no time or space before the Big Bang and the entire universe was a singularity then What did the singularity exist in? It had to be somewhere didn't it? If not space then what? If there was no space and time till after the big bang does place or when even apply?

[arkain101]

Well, just by reading your title it noticed some issues.

Infinite can imply a number of meanings. Infinite is size, infinite it time, infinite in speed.


My thoughts on this;

I find it difficult to comprehend anything existing, even existence itself, if it was not infinite. To suggest it is not infinite, leaves two unknowns before and after its existence. In fact, unknowns is not even a strong enough word.

However, you are referring to the universe. And I am going to assume you are referring to the current state that we observe the universe.

The universe will go through many changes, it always goes through changes. There may be possible states of the universe that you and I would not consider a universe, such as a singularity, or somthing to this kind of effect.

What I can propose is that the source of the universe as we see it today, the deepest, and most fundamental source, is infinite in the sense that it always was, always is, and always will be.

This most pure, deep, fundamental source, I consider should be unchanging. That is because if it, itself goes through changes, then it itself can not -as far as I can determine- be considered as the most fundamental ever lasting region of existence. If the essence of the most fundamental were able to transform, then I suppose we would be left with no fundamental identity, which would cause us to look deeper or conclude nothing lasts forever, and what does exist, is entirely random and chaotic needing no source.

However, it is difficult to imagine anything existing without a source, and respectfully difficult to think of a source requiring no preceeding source.

Because it is difficult to provide proof, I can for the most part only provide my own view. And my own view prefers a fundamental source, and that it be infinite, in how long it lasts, in how far it can reach, expand, or shrink. Infact, one of the only ways to warp our minds around this concept is to exclude these limitation types of ideas like time, and size and scale. Then, replace them with a conceptions of being, now, am, is, and are.

[arkain101]

Originally Posted by tatwood106

If there was no time or space before the Big Bang and the entire universe was a singularity then What did the singularity exist in? It had to be somewhere didn't it? If not space then what? If there was no space and time till after the big bang does place or when even apply?

Oh I had just realized that this topic is actually a revival from 2005.

In response to you Tatwood, I suggest the following.


Imagine mankind never developed the ability to see, yet still managed to become quite intelligent socialists. I suppose we would require a low preditor environment to survive, , hah, but that is besides the point.

If we never conceived the idea of visual space, where would we consider anything exists, not to mention the universe.

This is actually a very useful though experiment to 'see' things in a different 'vision'.

We would very unlikely have formulated the idea of a universe, since we would never see any stars or horizons, or anything for that matter. However, given that we had the minds we do now minus our visual perception, it is expected we would still formulate the idea of something existing, what do you think that would be?

Ask yourself, Would it be any less true than the world we have come to "SEE" and "KNOW" as we are now, as visually able humans?

Ask yourself ,How true is visual perception? and does it have any more superiority over a definition of existence?

And furthermore, how true are any of our conceptions that define the universe and existence?

It is likely that things, otherwise known as reality can exist in all places, at all times, and it is our perception that has confined us to assume that it does not, therefore providing us with the very issue your provide here for us in your post.

Reality has truth on more than one level and those truths are not always true for each individual level. Reality has unique 'truths' to each respectful level.

This tells us that reality is both unified and separated at the same time, the choices of which are defined by the observer. It also tells us that reality is extended beyond our perceptions in many ways, and has truths entirely unknown to us.

This means the universe both exists, and does not, depending on the limits and restrictions that an observer places on the potential the universe contains.

In this respect, the universe is over, and beginning, and right now, all at the same time, but the only truth of which is more or less true is held in the observer itself.

[tatwood106]

Ok, here is the definition of infinite I mean. I am located on earth, I leave earth and travel in any direction in the universe and I am traveling far faster than the universe is expanding. No matter how fast I travel or how far I would never reach an edge or boundary of the universe; I would keep traveling forever there would be no end to the universe, it would be infinite. I would however still be in space and there would still be time.
Now if the universe if finite and I make the same trip I would eventually reach the edge of the universe's expansion. If I keep traveling out past that boundary, what would I pass into? Or without the construct of space/time is there no way either physically or mathematically to predict what I would encounter?

[arkain101]

Originally Posted by tatwood106

Ok, here is the definition of infinite I mean. I am located on earth, I leave earth and travel in any direction in the universe and I am traveling far faster than the universe is expanding. No matter how fast I travel or how far I would never reach an edge or boundary of the universe; I would keep traveling forever there would be no end to the universe, it would be infinite. I would however still be in space and there would still be time.
Now if the universe if finite and I make the same trip I would eventually reach the edge of the universe's expansion. If I keep traveling out past that boundary, what would I pass into? Or without the construct of space/time is there no way either physically or mathematically to predict what I would encounter?

I tried to communicate that you idea of what the universe is like is based on your senses. This is the trouble.

I am gathering You expect that the universe is like a sphere, because you are using your world view acquired by your senses..

How do you know you are not on the edge of the universe already?

Do you think you are at the center?

Where is your location?

Accroding to scientific theory, special relativity would describe that if you were to travel in a real ship, trying to "reach the edge of the universe", as you speed up more and more and more getting ever closer to the speed of light, the universe would become shorter and shorter in the direction that you are traveling. So as you travel, very fast it would take barely any time relative to your observation to travel this earlier percieved vast distance.



Muon Experiment: Relativistic, Muon-Frame Observer



However, what you see before you start your journey is a very very old representation, and it is not what you are going to observe when you reach those destinations.

I actually need to brush up on all of this myself...


I don't expect you would ever reach any sort of end to a universe, in the sense that stars and suddenly started dissapearing and you headed off into the void.

I really dont expect that nature works like we imagine it 3 dimensionally.

[tatwood106]

I didn't mean to get into a discussion on the physics of space travel, just presenting a simplified example to illustrate the definitions of infinite and finite. If analyzed the major flaw with the example as that as the speed increases so does the mass and if you could actually obtain light speed your mass would be infinite and would require all the energy in the known universe just to keep moving.

And no I don't think the universe is a sphere, current theory says it is either flat or saddle shaped. Both of which would make it finite. Unimaginably LARGE but still finite and expanding.

As there are galaxies moving away from us in all directions It is unlikely that we are at the edge of the universe. At the edge if space/time is being created then there would likely be fluctuations and deformations of both, can't say that I have noticed either.

So again, is there any theory for what is beyond the universe's boundaries?