Universe - Size . . . something doesn't compute !

If you accept the Big Bang, even if space is infinite, the universe is finite, and the edges can never be reached. This is because, since the speed of light is absolute, nothing can ever catch up to the points that are on a sphere which has been expanding at the speed of light ever since it occurred. Thus, the "universe" is all within this sphere, and outside, even if infinite in dimensions, contains nothing.Of course, there are countless other possibilites, and we don't know enough to speculate reliably on them. One that I'm keen to is the possibility of multiple universes, separated by distant time and/or space. Bubbles of existance from distinct "Big Bang"s. Why should our Big Bang be unique in space/time?------------------
"Illuminant light,
illuminate me."

Hey John !Thanks a lot for your reply - I am learning a great deal here !My main point at the beginning of this thread was to put forward my supremely uneducated view that the universe is infinite. A couple of your replies to my previous post seem to suggest that I was trying to put forward the opposite argument. Just to clarify, I do believe that the universe is everything, and both of my questions were asking for others to give me their thoughts on this. ;-) This point is very fair, although again, the shrapnel has to have somewhere to fly through. My suggestion was in response to the theory that the universe is expanding, and that somehow this was derived by observing that from the center of the "big bang" matter was/is travelling outward. I kind of don't get the relation here between time and the attempts of mankind to comprehend the infinite nature of the universe (or shall we call it space). Just because we aren't travelling anywhere in our pursuit of understanding the universe, again doesn't mean that it doesn't exist, or that it doesn't go on forever. We don't surely need to travel into infinity to grab the notion of it or to try and quantify it. Again, I feel that this argument is pointless.Man, I can see that I'll be doing my head in for another night thinking about this ;-)Thanks again John . . .

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Ok then, has there ever been any successful experiment in forcing space to curve?

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Spacetime is curved wherever matter or energy is present. That has been verified by experiements.

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As I understand it, you could contain space within a curved "container", but there would still be space existing outside that container. This is the crux of my argument. The universe is not a container - it is the space around, and including the container - surely?

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It is not necessarily true that any volume of space must be contained by some larger space outside. The problem is that we've only ever experienced those kinds of spaces. Still, think in terms of logic rather than intuition, and you can see that finite space is possible. For the record, if the unievrse is indeed embedded in a larger space, it must have at least 4 spatial dimensions as opposed to 3. With that, any usefulness of intuition is gone.

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We can try with all our might and limited human knowledge to measure and quantify, but if we go by proven facts, realities which have been scientifically and PHYSICALLY PROVEN, we must conclude, surely that infinity is the only possible "real" explaination.

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Err, why?[This message has been edited by Beercules, 09-09-2003]

I will definitely be looking up some information on space-time. As I have said previously, I am an uneducated thinker, so a bit of a read-up on this wouldn't hurt I think ! In fact if anyone could suggest some good reading material on the subject I would greatly appreciate it ! This is difficult for me to put into words (my meaning) - I don't believe that space is "contained" at all, if fact quite the opposite is what I am trying to put across. That there is no boundary, or "container" - this was in response to the theory that space was curved. Again, I will need to read up on space-time in order to understand your reply fully with regard to the curvature.I have read in other threads that the universe started with a "singularity" or, for want of a better term, a "dot". Again, if indeed this was the case, surely this singularity (or the beginnings of the universe) would have had to reside within something? Otherwise it wouldn't have been a "dot" at all, it would have been an all-encompassing infinite mass. If the "singularity" theory is actually accurate, and this singularity went through a massive expansion creating the universe as we know it (or don't know it;-) this expansion would have had to have somewhere to expand into ??? infinite space perhaps ?Perhaps my understanding of the term "universe" would be better directed if I were to call it "space" or "nothing" . . .I don't know, perhaps I really am a nutcase, but I can't fathom the suggestion that space, or the universe actually has an end - or is finite in nature. If it has an end, I would really appreciate it if someone could explain to me what is on the outside of the boundary. This is the crux of my argument. Because I see no point in conjecture. We can't see the "end" or the "edge" of universe - or should I call it "space" . . . all we know from physical evidence is that space is unlimited - ie. no space probes or telescopes are able to see an end, so why would we speculate that there is one ?

If there's no way that it could affect you or the universe, and no concievable way to test it, Occam's Razor says "throw it out."There's no way that what is outside the universe could be opened to our inquiry. If it could, then it would by definition be inside the universe. So why try to guess what's out there? You'll never be able to be right about it. Um, think about a globe. Start at Africa and trace your finger around the equator, heading west. Eventually you'll come back to Africa from the east. At what point did east become west? At what point did you turn around and head back? The answer is, at no point. You never turned around.In a universe closed in the 4th dimension, all straight lines return to their origins. There's no point where they "turn around". Yes, but we're also talking about non-Euclidian geometry. Straight lines aren't exactly "straight", if you get my meaning. On a globe, the equator (or any other "great circle") is a straight line in two dimensions, but it curves in the third. In a hyperspherical universe, all lines that appear straight to us are still curved in the fourth spacial dimension.I don't know if there's any way that we could determine the volume of the universe, or its potential curvature in any dimension. So we may just be shooting the breeze, here. Glad to hear you're having fun, though.

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Otherwise it wouldn't have been a "dot" at all, it would have been an all-encompassing infinite mass.

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Bingo.

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If the "singularity" theory is actually accurate, and this singularity went through a massive expansion creating the universe as we know it (or don't know it;-) this expansion would have had to have somewhere to expand into ??? infinite space perhaps ?

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Nope. Think about the dot as all-encompassing infinite mass/energy. You seem to understand this as an alternative to having a 'dot' which resides in something. Now, imagine the dot stretched larger, something like a rubber band can be stretched larger. Or imagine yourself small enough to fit inside the dot and look around.

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If it has an end, I would really appreciate it if someone could explain to me what is on the outside of the boundary.

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A sphere is finite in surface area, but where is the boundary? See, you are assuming a great deal about the way things are. As far as what is on the outside, if there is an outside, we have no access to it. We are, for the time at least, stuck inside the dot.

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We can't see the "end" or the "edge" of universe - or should I call it "space" . . . all we know from physical evidence is that space is unlimited - ie. no space probes or telescopes are able to see an end, so why would we speculate that there is one ?

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We know the universe has an end in one direction, the past. We have pretty good evidence of that.One reason people speculate that the universe is finite is that an infinite universe has serious problems. Imagine an infinite universe. Whatever direction you happen to look, you will be looking directly at a star. I don't mean, more or less at a star. That is the situation we have now. I means that the night sky would be brilliant white. There would be no dark spots.------------------
No webpage found at provided URL: www.hells-handmaiden.com

Hey Crash,Yes, you're right, I am having a great deal of fun ! Finally I can get these thoughts down somewhere and out of my head. And it is great to bounce these ideas off people who obviously are a great deal more educated in these matters - I am learning ! I did a bit of research on Occam's Razor, and I came up with this translation of the original theory -"Of two competing theories or explanations, all other things being equal, the simpler one is to be preferred."So that to me would indicate that, as I find the theory of an infinite universe simpler to comprehend than the theories put forward in this discussion, I should simply accept my theory, and be a happy boy . . . ;-)Although I am grateful to hear the perspectives of others at the same time . . . what a predicament I find myself in ! ! ! See, this is where I have a real problem. Because I am of the opinion that the universe is infinite, it couldn't possibly have any shape to it, spherical or otherwise. A spherical universe would indicate to me that the universe was finite, or that it has a boundary. Hence a straight line wouldn't end up at it's starting point - hey, we're talking dead straight here !Perhaps again this is just my lack of knowledge in space-time theory. Note to self: find some material on space-time and read it !Again Crash, thanks for the feedback, I am enjoying it immensely, I just hope that you're not getting too frustrated trying to explain this to a layman I promise to do some research, and then I won't be annoying you with my un-educated ramblings

Thanks John, Forgive me if I am wrong, but this comment seems to be contradictory. You are saying that the dot is an all-encompassing infinite mass/energy, but at the same time you are saying that something that is infinite can be expanded ?? Now I am confused. I really like your analogy here of the brilliant white night sky ! Awesome ! Although, when we look at the night sky, that is one snapshot in time. Could it then be possible that over billions and billions of years with stars forming and dying out, if we were to take snapshots at regular intervals and super-impose them over one another then yeah, sure, that image could very well eventually be a blanket of white. Stars are obviously of varying distances from us. Could it be that we are presently unable to see "all" of them because of the distances involved ? Sure, if we were stuck inside a finite "spherical" universe, then the blanket of white could be true, but in a finite universe, the number of stars would also be finite, and we may not completely cover the sky . . . wow, that has opened up a complete other angle Thanks for your reply John . . . much appreciated

My brain hurts . . .

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You are saying that the dot is an all-encompassing infinite mass/energy, but at the same time you are saying that something that is infinite can be expanded ?? Now I am confused.

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Infinite mass/energy, but zero volume.

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Could it be that we are presently unable to see "all" of them because of the distances involved ?

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Only if the universe has a limited past-- in other words, a beginning. If the universe has an infinite past then light would have had an infinite amount of time to get here from anywhere, so you have a white sky.------------------
No webpage found at provided URL: www.hells-handmaiden.com

Now my brain hurts even more I think though that I am getting close to understanding your point of view. I know that I have some serious research to do in order to understand it completely, but I am starting to understand your argument . . .However, that still doesn't explain to me how the universe, or space can be finite . . . . I know that my theory is going against everything that is "known" to us, but hopefully with a better understanding of the physics etc that are currently taken as being true, I will be able to either change my point of view or strengthen it I'm going for a trip to the chemist for some painkillers, and the library for some books . . .Thanks dude

"brain hurts"Of course it does! This is hard stuff to understand.It is probably too tough to get across in a forum like this. I've had college level courses on some of it and only have a tentative grasp of it.However, there are a few things that you will have to understand to make progress. You have some fundamenatal misconceptions to get rid of.One is, the universe expanding into some preexsiting space. That isn't what is happening. Space itself is expanding. In this view, galaxies are not moving apart. They stay where they are and the space between them expands.The best description that we have right now to describe gravity is general relativity. It holds a view that matter curves space. Since it has proved to be very accurate at describing what actually happens it is convenient to take it's description of space-time as being a good working viewpoint.Since all of space and time may have originated with the big bang at a singularity the universe started out finite and while it has expande a lot it is still finite.You may decide to hold all the "theories" of your own you want. However, the infinite universe idea for one has been considered and found not to be useful. Until you put the effort in to trace the whole history of cosmology you can't expect to make any advances of your own.If you disagree with those who have spent the effort there is a very, very, very good chance you are utterly wrong.All this that we here all struggle with is now old hat and not where the real fun stuff is at anymore.Try grappling with a 10 dimensional something where universes of 4 dimensions move. The whole thing being infinite in time with no beginning. Then a big bang results then one of these moving universes collides with another.Is this wild-eyed speculation? Sort of, maybe, kinda. But it may also produce mathematical constructs that predict measurable things. Then it becomes, like general relativity, something with real meaning. Will it? I dunno. Let's watch as those who can work out the implications.I'll poke around to see if I can find a single book that covers some of this. I haven't read Hawkings latest but I think it may be what you want.

Hi NosyNed,Thanks for your reply, as many perspectives as possible is what I wanted to achieve, and that is certainly coming forward ! !I have noticed that in the forum, people tend to misunderstand points, and so I agree with you that a forum like this is probably not the best place to talk it out. For me however, it is a great starting point. As you may have read throughout this topic, I am not educated in any of this stuff, so yes, I may have some misconceptions. From my current viewpoint, it is very difficult to imagine any other theory. Obviously I'm not going to remain close-minded about it however - I'm totally open to learning ! This point you have misunderstood - I do not believe that the universe is expanding at all - rather, I believe it to be infinite, and therefore not able to expand. If space itself is expanding, what is it expanding into ? This is the theory which I find hard to agree with. How could it be possible that space expands say, between two galaxies, and yet at the same time the galaxies remain the same distance apart? If there is more space between galaxies, surely that means that they are further away from each other ?? This I do understand, of course if something is finite, by expanding it, it is never going to become infinite, just bigger . . . what I believe at this point in time is that the universe was never finite. It has always been infinite, therefore it can't actually get bigger - or smaller for that matter.I am perfectly open to the fact that I could be completely wrong on this, but to my way of thinking, there doens't seem to be an alternative. What would you consider to be useful? Calling the universe finite and then establishing theories and mathematical equations to try to measure it and prove it to be so? I would much rather subscribe to the previously mentioned Occam's Razor and pick the simplest, most obvious theory. No matter how much number crunching and heavy thinking is done, the nature of the universe doesn't change, whether it is finite and expanding, or infinite. Science can have all the fun it wants in pursuit of measuring something, but again, is it possible to measure or try to put boundaries on something that cannot have boundaries?I am going to do some serious reading on the theories which have been introduced to me here. I really appreciate your input, as it helps me to a) understand the views of the scientific community, and b) evaluate my own personal perspective.Thanks Ned

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I do not believe that the universe is expanding at all - rather, I believe it to be infinite, and therefore not able to expand.

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What you believe contradicts the evidence. As the man said, you can't always get what you want. The universe is expanding. Think back to the grenade analogy ( Frell! You replied to that post. Did I respond? ). Everything moves away from us at apparent speeds which increase with distance. This is consistent with a universe that is expanding. For this to work in an infinite universe that is not expanding, you have to assume that EVERYTHING is accelerating away from the Earth. In other words, the Earth would be at the center and some unknown force is pushing the galaxies away from us at ever increasing speed. In an expanding universe, anyone on any planet would see the same effect. No point is special and no unknown force capable of accelerating galaxies is required. Which is easier to swallow? Take a balloon and blow it up just enough to make it firm. Then mark dots on the surface with a marker of some kind. Now inflate the balloon and watch the dots. They all move away from one another at the same speed and, the further away a dot is from another the faster the apparent motion becomes-- measured along the balloon's surface. This also answers your next question...

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How could it be possible that space expands say, between two galaxies, and yet at the same time the galaxies remain the same distance apart?

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Think of the rubber material of the balloon as space. As the balloon gets larger the rubber stretches but the amount of material remains the same. Its just that the material has been stretched. Perhaps if you imagine a rubber ruler it will help. Lay a rubber ruler between two points, then stretch it. If you measure the distance by the marks on the ruler, the distance stays the same. If you measure by some other standard, say, the time it takes to travel from one point to another, then the distance has increased.

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If there is more space between galaxies, surely that means that they are further away from each other ??

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There isn't more space. The space that was there has been stretched.

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I would much rather subscribe to the previously mentioned Occam's Razor and pick the simplest, most obvious theory.

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What you call simple and obvious DOES NOT fit the evidence. You are going to have to come to grips with that.

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Science can have all the fun it wants in pursuit of measuring something, but again, is it possible to measure or try to put boundaries on something that cannot have boundaries?

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This is nothing but your assumption. You don't have any evidence for it.------------------
No webpage found at provided URL: www.hells-handmaiden.com

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I will definitely be looking up some information on space-time. As I have said previously, I am an uneducated thinker, so a bit of a read-up on this wouldn't hurt I think ! In fact if anyone could suggest some good reading material on the subject I would greatly appreciate it!

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There is probably also a lot of good resources on the web. The folks at Physics Forums | Science Articles, Homework Help, Discussion can help you out with some recommendations. For now, try the Ask an Astronomer FAQ, at http://itss.raytheon.com/cafe/qadir/qanda.html.

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This is difficult for me to put into words (my meaning) - I don't believe that space is "contained" at all, if fact quite the opposite is what I am trying to put across. That there is no boundary, or "container" - this was in response to the theory that space was curved. Again, I will need to read up on space-time in order to understand your reply fully with regard to the curvature.

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A universe with hyperbolic curvature can be finite yet have no boundaries. A 2D surface of a balloon has no edge or center, as you would need to go up into the 3rd dimension to find it. Likewise, our universe would have no edge in 3D, and cannot be contained in any 3D space.

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I have read in other threads that the universe started with a "singularity" or, for want of a better term, a "dot". Again, if indeed this was the case, surely this singularity (or the beginnings of the universe) would have had to reside within something?

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A "dot" is a terrible way to put it, and is not correct. The classic singularity is a case where the density of the universe becomes infinite and it's volume shrinks down to a point. IOW, a mathematical point, with no size at all. But before you ask how something so absurd is possible, don't sweat it. I don't think any physicist actually thinks singularities exist in the real world. It is more likely they are just a result of applying general relativity where it is no longer valid. The expectation from a theory of quantum gravity is that singularities of the classic equations will be replaced by something without the infinities or zero volumes of the classic (non quantum) theory. Keep in mind though that even with the classic singularity, only a finite universe shrinks down to a point. In an infinite volume of space, each point reaches infinite density, but the overall size remains infinite even to the moment of the big bang. It is also incorrect to say the big bang implies the universe is finite.Now, if we imagine a finite universe shrinking down to a minium size, then you might ask what that small universe is contained in. And, what is outside, if not more space? Well, think about it for a moment. If the entire universe is finite, then there is no outside at all. No beyond either. As counter intuitive as that is, the idea is logically sound. In geomtetry, spaces are defines by there own continuum of points. IOW, a line is difined by it's own length, not what length lies beyond it. It's quite simple when you think of it that way.

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Because I see no point in conjecture. We can't see the "end" or the "edge" of universe - or should I call it "space" . . . all we know from physical evidence is that space is unlimited - ie. no space probes or telescopes are able to see an end, so why would we speculate that there is one ?

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We can't "see" infinite space either. Nor do we have any physical evidence for an infinite universe that isn't also compatible with a finite cosmos. It is conjecture, because infinite space by it's very nature, could never be proven. However, it may interest you to know that some cosmologists are in fact looking for signatures in the sky that would likely be conclusion evidence that the universe is in fact finite. Nothing through yet though.