Thread: The Universe, Finite or Infinite?

There is no such thing as "relative infinity". Infinite is that which has no bounds. If space has no bounds, it is infinite. I used the modifier "physically infinite" to make myself more clear but since it's bothering you so and since space is obviously physical, it really is unnecessary. Therefore, I'll state that, "If the density of massenergy in the universe is equal to or below the critical density, space is infinite." No epithet. No modifier. No caveat. It is simply infinite. If you want to work out a new terminology, then make up some new words. Do not call that which is infinite “indefinite”. It's not indefinite, for the reasons I've repeated far too many times and which you say you understand but choose to ignore.

It doesn't matter if you think that the words' definitions have changed over time. Since we are writing in modern English, we should be using the accepted modern definition of the words. If you wish to use a Medieval definition, then write your entire post in Old English so the context will inform the definition. In order to communicate we must use a common language. That common language on this forum is modern English, so if you wish to be understood, the word definitions found in modern English are those you must use. Modern English defines infinite to be “that which is without bounds,” and by that definition, space (if the density of massenergy is below the critical density) is infinite, not indefinite. Perhaps you would be better served, if you insist on using the term “indefinite” contrary to its accepted meaning, to say, “indefinite (and by indefinite I mean what modern English defines as ‘infinite’).” That would certainly clarify the situation.

This is similar to the question "Is everything is pre-determined or doi we make decisions?" in the sense that both choices are correct. I don't like being asked to pick betweent the two since any object is infinite and it has boundries at the same time.

Originally posted by Peregrinus
There is no such thing as "relative infinity". *Infinite is that which has no bounds.

Yes, that is exactly my point.

Originally posted by Peregrinus
If space has no bounds, it is infinite. *

Let's look a little closer at this. "If space has no bounds, it is infinite." So this would mean that space includes everything; that it is bound by nothing at all. But let me use my original example: ordinary thought. Where in space does thought exist? Does thought take up physical space? If not, then space would not include thought, and therefore would be limited by thought because thought cannot be defined by physical space. In other words: that which cannot be located in physical space is something other than physical space, and therefore limits physical space. Now, because of this, when we speak of "physical" infinity, we are obviously not talking about that which includes all without boundry since it does not include thought. So the word "infinity" in this respect is only related to the "physical", and not to the "all", therefore making it "relative" infinity. But since the word "infinity" is defined as that which has absolutely no limits, and space is limited by thought, it is not actually "infinite" in the truest sense of the word. If it is not so, if it extends without bounds in relation to the physical but not to the all, then it bound by all that is not physical, yes? And therefore it has a boundry, although we cannot define it because it is beyond our understanding as human beings. It makes perfect sense then to call it indefinite because it is bound by that which is not physical, yet we cannot define that boundry. So space is "infinite" in relation to the physical (or the symbolic "horizontal") but definitely not if you consider it in relation to all that is not physical (the symbolic "vertical"). Do you see my point? I cannot explain this any more clearly, and I hope this can be understood. Please show me where this doesn't make sense to you. Which parts make sense and which part do not?

I understand your contestation that spacetime may not be all that is, that it is definitionally bound by that which it is not (as is everything else, btw), but that is irrelevant to the determination of whether spacetime itself is infinite. (It is also a philosophical discussion into which I do not want to delve at the moment because if it turns out that, minus all of the jargon and specific formulations and cultural influences, our philosophical positions are not completely and foundationally utterly dissimilar, it might foster a buddying sense of well-being and understanding, and we can’t have that in a heated debate, now can we?)

I stated that according to our most recent and thorough examination, spacetime is infinite in extent. It extends on and on and on ad infinitum without boundary - without spatial boundary, because space is spatial and spatial is physical. So when I dropped the word “physically” from “infinite” when describing the extent of spacetime, the word continues to be implied by the very fact that “infinite” is describing spacetime and spacetime is by definition physical. You saying that spacetime does not deserve to be called infinite because it does not contain some nonphysical realm is like saying a number line which is numerically infinite does not deserve to be called infinite because it does not contain colors. Colors are not part of the definition of a number line just as the nonphysical is not part of the definition of (physical) spacetime. The fact that number lines do not contain colors does not in any way negate the fact that numerically, it has no boundary, no edge, no end. Numerically, it is infinite, not indefinite. Spacetime and number lines are each infinite within their own contexts, and neither is “more infinite” or “relatively more infinite” than the other (assuming, of course, that spacetime has a flat or open geometry as is currently understood).

If there is something beyond spacetime, some meta-reality of which the physical universe is only a manifestation, it does not make spacetime less infinite in its extent. Spacetime would still be considered infinite in extent because one could continue traveling through it and never return to one’s point of origin, never reach an “edge,” never reach a boundary. And that is the definition of infinite. The existence of anything else is immaterial to the determination of spacetime’s infinitude. It is infinite unto itself, infinite by those qualities contained within its definition and existence. It is spatially, physically infinite - the modifiers "spatially" and "physically" simply restate what is inherent in the phrase "spacetime is infinite in extent". Of course the extent under consideration is physical. Spacetime is physical, so how could its extent be anything else? Those modifiers are not necessary, but they are helpful in discussion. Also, there is no ambiguity in the "boundaries" of spacetime of which you speak. You mean definitional boundaries while I mean physical boundaries. You say that space is not infinite because it does not include the nonphysical and that by not including the nonphysical, it is somehow indefinite. It's not indefinite. Its definition is quite clear and quite specific. Since spacetime is by definition physical, the only infinitude which we could sensibly speak of regarding spacetime is a physical infinity - namely that it physically goes on without end. There is no other word for "goes on without end" besides "infinity." "Indefinite" simply does not describe the situation.

What if there is something “beyond” spacetime? What is infinity plus one?

Edit: Who needs to learn to use spell check before posting?

I have one simple question.
If space is infinite (aka, has no boundries) then how can ''it itself'' be expanding?
Expanding means that it becomes bigger, if something becomes bigger it means it must have boundries in SOME sense.

Thus, I would reckon it impossible for something to be infinite if it's changing in SIZE.
(Because size means boundries in my eyes).

Now unless someone shows me otherwise (either that scientists are wrong and space does not expand) OR that ''infinity'' can expand (Which sounds like a paradox to me). I will keep my statement of space = finite.

OR, if you are referring to ''space / universe'' as ''the big black room'' then I might agree about infinity.. (Considering that ''before the big-bang'' we had the big black room)

But I won't agree when it comes to ''the area that has ever been expanding since the big bang''. Because of what I stated above.

Note: Replace space with universe.

Originally posted by [Alpha
-0mega-]I have one simple question.
If space is infinite (aka, has no boundries) then how can ''it itself'' be expanding?
Expanding means that it becomes bigger, if something becomes bigger it means it must have boundries in SOME sense.

Spacetime isn't "growing," it's expanding. Think of a rubber sheet marked out in a grid like:

Now imagine stretching that sheet. The grid lines get further apart - that's the expansion of spacetime - but no new space is created. If spacetime is infinite now, it was infinite at the moment of the Big Bang as well. The only difference between then and now (besides the decoupling of matter and radiation, the breaking of supersymmetry, etc - you know, small stuff) is the distance between the grid lines. See The Shape of the Universe and WMAP for more information.

Originally posted by Peregrinus

Spacetime isn't "growing," it's expanding. *Think of a rubber sheet marked out in a grid like:

Now imagine stretching that sheet. * The grid lines get further apart - that's the expansion of spacetime - but no new space is created. *If spacetime is infinite now, it was infinite at the moment of the Big Bang as well. *The only difference between then and now (besides the decoupling of matter and radiation, the breaking of supersymmetry, etc - you know, small stuff) is the distance between the grid lines. *See The Shape of the Universe and WMAP for more information.

One will ask what is beyond those grid lines? More grid lines, more space, etc etc.
But infinite can be looked at as --- infinitely growing no?
like an infinite number. It is a set of numbers. It consists of something.
It is possible to find the end but yet it is expanding, therefore infinite.

I thought this was a good image too.

it is my understanding that, at least in mathematics, there are different sizes of infinity.

Originally posted by ignatz
it is my understanding that, at least in mathematics, there are different sizes of infinity.

yeah , depending on how much u payed for ur calculator .

I believe that most calculators will define Infinity as: "Error" (aka, too much numbers )

Ok, other question: If space is infinite (it has no boundries), then how can it have a SHAPE at all?.

If it is infinite in the sense of, it has boundries, but it's INFINITELY "expanding", then technically it is not infinite, but it will ''expand'' infinitely.

In my eyes, Infinite ''size'' is not the same as ''infinitely expanding''
After all: If I would be infinitely expanding, from now on, at a slow rate, you'd still be able to walk from my head to my legs.
And about the ''stretching rubber''. Then still it would need to have an ''edge'' from which it is expanding right? Because infinite in my eyes would mean ''there is no end'', so how can it ''stretch'' if there is no end? (Unless the INSIDES of the universe stretch, but that would cause other problems)
The only thing that link made me any wiser is the shape of the universe =_=
If you don't really understand what i'm asking here i'll re-write my post xD

[

Ok, other question: If space is infinite (it has no boundries), then how can it have a SHAPE at all?.[/b]

It doesn't have a "shape" in the sense that you're thinking. Those 2D representations of sphere, plane, and saddle are simply illustrations. If it helps to distinguish between a geometry and a shape, don't think of the universe as having a "shape." It's not actually a flat plane, you know. (Well, obviously, since a plane is 2D and the universe has three and possibly 9 spatial dimensions.) The geometry of the universe describes the behavior of two parallel beams of light. In a closed universe, they cross. In a flat universe, they remain parallel. In an open universe, they diverge.

If it is infinite in the sense of, it has boundries, but it's INFINITELY "expanding", then technically it is not infinite, but it will ''expand'' infinitely.[/b]

The universe may indeed expand forever, but that is not why it is infinite. It is infinite in extent because (according to our most recent, most accurate measurements and theories yadda yadda disclaimer about the finitude of current knowledge) spacetime has no boundaries, regardless of the behavior of its expansion. If it has an open or flat geometry, it is spatially infinite - no boundaries. Please read the previous posts in this thread.

And about the ''stretching rubber''. Then still it would need to have an ''edge'' from which it is expanding right?[/b]

Not right. It is not expanding from an "edge" - there is no edge. It is expanding everywhere at once. If you have access to a copy machine, do this: Draw a bunch of little spiral galaxies on an 8.5"x11" sheet of paper. Then copy that image at 125-150% of the original (i.e. "blow the image up") and print it on very thin paper that you can see through. Now place the thin "expanded" sheet of paper atop the original and line up one of the galaxies. It doesn't matter which. When you superimpose these to images you'll also understand what cosmologists term the "redshift" where large structures in the universe appear to be moving away from each other (I say appear because this motion is not due to proper velocity of the structures involved, but rather the expansion of spacetime itself), thereby redshifting any emitted radiation. Notice that all of the space on the paper has expanded, not just near the edge of the sheet. Do it yourself so you understand how it works, but here's one I've done for you. The black galaxies are what my flatland universe looks like at t=0, the red ones are some time thereafter at t=1. The expansion is everywhere, and from any one perspective, the galaxies farther away appear to be "moving" away more quickly.

Of course, unlike that sheet of paper, the universe as we now understand it, has no edge.

The universe, as defined by cosmology, is a spacetime continuum in which all matter and energy exist. The rubber sheet simply provides a convenient illustration and two dimensional metaphor of universal expansion. The universe is where spacetime exists. It currently appears that spacetime is infinite in extent. There can be no "edge" to an infinite expanse, nor can there be anything "beyond" it. The universe is not expanding "into" anything. If WMAP's measurements are accurate, then the universe was infinite in extent the instant of the Big Bang and it has been and will continue to be for all time thereafter.

The problem here is that I am trying to explain in visual, 2D terms what is essentially a mathematical formulation in multiple dimensions. In its true form, it's not something that any human being I've yet met can visualize. So when I use the rubber sheet metaphor, it's to illustrate a principle. The universe is not actually a rubber sheet. If you want a closer mental approximation of what the universe is actually like, think simply that if you fire two superluminal beams (yes, I am perfectly aware that no such thing exists, but I use superluminal to avoid the inevitable argument of the horizon) in parallel across empty space, their beams will never converge, never diverge, and never return to their point of origin.

When i first read all your questions and replys, i thought that they were facinating! But as i was reading them, i thought to myself that there was something missing. I thought that you are all talking and disscussing something that you cannot be sure even exists. Can we really know what amount of universe is actually out there? Most of you have agreed that the universe is infinate, but can we define 'infinity'? What does it actually mean? Is there a concept that lays behind it, that we as dreamers have yet to discover?

When i think of the universe, i think of spiritual forces guarding our sacred barrier. But it is what is beyond that barrier? What does that barrier contain within it, that makes us want to search harder for answers, and what drives our research? What is the barrier protecting?

If the universe is finite, then maybe it does loop back on itself, (as one of you said), but then could you not say that we could all be stuck in a time loop, and that whatever we are doing, there could be someone somewhere in our universe, that looks the same as you, and is leading a duplicate of your life. But then the question is this, who out of the two is the real you, or are you both results of our infinate universe?

An eye for an eye, and soon the whole world will be blind!

Originally posted by spirit
When i first read all your questions and replys, i thought that they were facinating! But as i was reading them, i thought to myself that there was something missing. I thought that you are all talking and disscussing something that you cannot be sure even exists. Can we really know what amount of universe is actually out there? Most of you have agreed that the universe is infinate, but can we define 'infinity'? What does it actually mean? Is there a concept that lays behind it, that we as dreamers have yet to discover?

When i think of the universe, i think of spiritual forces guarding our sacred barrier. But it is what is beyond that barrier? What does that barrier contain within it, that makes us want to search harder for answers, and what drives our research? What is the barrier protecting?

If the universe is finite, then maybe it does loop back on itself, (as one of you said), but then could you not say that we could all be stuck in a time loop, and that whatever we are doing, there could be someone somewhere in our universe, that looks the same as you, and is leading a duplicate of your life. But then the question is this, who out of the two is the real you, or are you both results of our infinate universe?

Hello Spirit and welcome to the Forum.

I am glad to see the mention of dreams interpreted withing this discussion, as well as a more metaphysical approach to the entire idea.
I realize the normal outlook on science, space and what it intails ismostly based around fundementals.
I think that entire concepts can be missed without the more unearthly and intangible ways of thought to be part of the entire philosophical discussion.
It is almost abstruse. And just because you can talk theoretical, it by no means should be considered as unsubstantial.
Any real subtantial new findings may include an approach that would require a more abstract process of thinking.

v.true Howetzer. our uniververse is very fragile and we should look after it. But i suppose in all fairness we can discuss something even if we dont understand
it, as that was why we were discussing it in the first place.
But i think that this sort of discussion is like trying to prove religion. i suppose we are all individuals, and we believe what we want to believe,and then share our thoghts with everyone else.

I'm not answering the poll, I have no idea.

If the universe really is infinite that would mean that there also are infinite different earths where erverything is the same and for example all the cars drive on the wrong side of the road and one where I'm gonna die in 5 minutes and one where I die in 6 minutes and one where I am filthy rich another earth for everything you can think of. Because a planet that is totally Identical to ours except for one of these details is possible it's just very very very very very very very unlikely but if the universe was infinite it would eventually appear no matter how unlikely it is...............well maybe I'm just writing crap and no one's here to stop me

And what if it's finite what the hell comes after the end????ß *head explodes*

Originally posted by nightshade

If the universe really is infinite that would mean that there also are infinite different earths where erverything is the same and for example all the cars drive on the wrong side of the road and one where I'm gonna die in 5 minutes and one where I die in 6 minutes and one where I am filthy rich another earth for everything you can think of. Because a planet that is totally Identical to ours except for one of these details is possible it's just very very very very very very very unlikely but if the universe was infinite it would eventually appear no matter how unlikely it is...............well maybe I'm just writing crap and no one's here to stop me

I don't think this is true. The Infinite includes Being (which includes all possibilities of manifestation) and Non-Being (which includes all possibilities of nonmanifestation and manifestation in its unmanifested state). Even if it is possible, it doesn't mean it will come into manifestation.

And on a side note:
If these other worlds do exist, what connection is there between the "you" in this world and the "you" in the other world other than physical form (and could your form be the same if the events leading up to your birth were different)? If you have no memory of these other "you"s, then isn't the same as saying that "you" are everyone in this world too? What is the connection between these different "you"s that is distinct from everyone else?

Originally posted by nightshade
I'm not answering the poll, I have no idea.

If the universe really is infinite that would mean that there also are infinite different earths where erverything is the same and for example all the cars drive on the wrong side of the road and one where I'm gonna die in 5 minutes and one where I die in 6 minutes and one where I am filthy rich another earth for everything you can think of. Because a planet that is totally Identical to ours except for one of these details is possible it's just very very very very very very very unlikely but if the universe was infinite it would eventually appear no matter how unlikely it is...............well maybe I'm just writing crap and no one's here to stop me

And what if it's finite what the hell comes after the end????ß *head explodes*

Do any of us have the truth
Although it is in a fitting manner that we equate ourselves in the entire scope of things I find it humorous that most cannot see out side ourselves and our existence. As if the Universe is revolving around us.

OK I know some of you would like to for taking this in a different direction. But the redundancy and the pragmatic approach to the same word and how they are used were driving me insane.
I know it is important to distinguish the terminolgy and how it is used.It just seems to be going to and for. <----o---->

the universe has to be finite. its still expanding. it has an end, exept the univcerse is just so damn huge that u would never reach the end. ever.

Originally posted by Tavasion
the universe has to be finite. its still expanding. it has an end, exept the univcerse is just so damn huge that u would never reach the end. ever.

Did you even read this thread before posting?