Where is the center of the universe?

  1. There must be a center or someplace close to the center of the universe.

    The actual universe can be contained in a physically describable bounding box. This box will have a center. Or, everything emminated from a center, the singularity and the position of that place where the singularity once existed is a fact, even though most will protest that it is unknowable. The point is, there must be some place, maybe known only to God where the center is. If it does exist then there must be some way to extrapolate how and where to find it.

    The proof that it does exist or that people were quite happy to conceed that it exists is found in many television shows like Universe where noted scientists always note that, prior to the discovery that the universe is accelerating faster outward, everyone accepted that the universe would collapse back into a singularity. In other words, the big bang was ballistic in nature and will be so in the reverse when gravity brings it all back to a common center point.

    So......why doesnt anyone try to figure out where that point is or was?

    tex
     
  2. jcsd
  3. No there is no center. You are trying to apply the logic of the everyday physical universe you perceive in a realm where it is not applicable.

    :rofl:
     
  4. Chalnoth

    Chalnoth 5,300
    Science Advisor

    Why would you think that? Take, for instance, a ball. What is the center of the surface of that ball? Which point on the surface is the center of that surface?
     
  5. It's everywhere and nowhere, baby. That's where it's at. Riding down a geometrical distortion in spacetime owing to the presence of a large body of matter... in a Hippy Hat.

    It has a ring.

    If you're serious about understanding the universe as science currently thinks it to be, you need to first understand that no scientist is going to appear on a show like Universe and actually talk to you like he would his colleagues. What you think you have understood, should be treated with caution. Look around a little; at this forum, at the stars. I like stars.
     

  6. I am serious and you havent addressed the question. In a mind experiment, if I could stand off some distance from the universe I could point and say...'there it is' and there would be some central area to that thing. Or, using a different approach....since everything in the universe blasted from the singularity it is obvious that the parts of the universe, including space itself is accelerating outward from that initial start. If it isnt then from what are all the elements of the universe accellerating? IF we could play the tape backward we could easily pinpoint the location of the origination point. Just because we cant, or have difficulty figuring out how to locate the point doesnt mean it doesnt exist. And since it DID once exist...that being the point of the big bang...by what logic do you determine that it immediately is lost and cant be found?

    It seems that everything is accelerating from somewhere common otherwise everything would be accelerating from different origins. Just because everything seems to be accelerating from our vantage point only means we cant tell where the origin is. That does not mean it doesnt exist.

    Unless you are willing to argue that every body is accelerating from different origins then they must be sharing a common origin. Where?

    tex
     
  7. Playing the tape backward, we eventually arrive at a point where the energy of the universe is in a very small region of the space of the universe. Think of it as each point of space having a point of energy. Now shrink and expand the universe at will. Each point of energy moves away from every other point as you swell the universe and rushes toward every other point as you shrink it.

    Your conception relies on a finite universe that has a boundary. This isn't considered an option even in M-theory, which allows for multiple universes beyond our own. No edge: no middle.

    I couldn't tell you why it's not an option, other than an accepted assumption that there is nothing special about our own viewpoint in the universe. Hopefully someone else can provide an unconfusing answer.
     
  8. Well as I see it, the universe started to expand some 14 biliony years ago from singularity. So position of this singularity is the center of the universe. And its position is about 14 bilions years ago from any point in our observable universe.
     
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  10. In balloon analogy your origin of expansion would be in the center of the balloon where once expanded is actually nothig and our present universe would be on surface of that balloon. So you cannot pinpoint center of expansion in 3 dimensions of our universe.
     
  11. If all stars are expanding from a central point, and that point is not us, we would not see the homogeneous universal expansion in all directions.x

    The observed rate of and size of the expansion is the same in every direction. So either WE are at the center of the universe, or there is no center.

    It's a concept that many cannot fathom due to their experience with the limitations of slow, small local space. And the balloon analogy doesn't really help because most people can't deal with analogies without thinking the map is the territory.
     
  12. DaveC426913

    DaveC426913 16,222
    Gold Member

    thetexan, examine the balloon analogy.

    You and all your friends are ants, living shoulder to shoulder on the 2 dimensional surface of a small spherical balloon. Your entire world is 2-dimensional.

    Then the balloon inflates to ten times its size.

    You watch as all your friends recede from you until they are ten times further away, and getting farther every moment. Your entire universe has expanded by ten-fold.

    Which of you can lay claim to being at the centre of your universe? Which one of you did not move as the balloon expanded?

    Answer: everyone and no one. Every ant experiences the same thing: all the other ants receding from it, yet none of them is on a privileged position; none of them can claim to be at the centre (more accurately, all of them can claim to be at the centre, since what was the centre is now everywhere).
     
  13. No one can lay claim to the center, of course.

    This does not address whether THERE IS a center to lay claim to.

    My point is that, at least intuitively (and I see nothing to refute the intuitive inference) that there must be a center from which everything is expanding. Here are my reasons....

    1. At the moment of the explosion (and it certainly was balistic in the sense that everything imminated from that singularity outward) everything began moving outward directly away from it according to all explanations I have heard. This is supported by the fact that everytime I hear an explanation of the expansion I see it defended by showing animations and graphs of an explosion-like event. This is furthur supported by the fact that these same people play the tape backwards to show what would happen if it all fell back inward (this is before acceleration was proven).

    2. Assuming Earth is not the actual center, everything must either be
    a. accelerating away from a common point, or
    b. accelerating way from different points

    even though everything appears to be accelerating from our vantage point, earth.

    3. If the big bang was the cause to the expansion effect we observe then what was its input to that expansion we observe if not the force impetus for that expansion. And if the big bang did not provide that expansive force then what did?

    4. It is argued that space is expanding and that is the cause, not an explosive event. That would not account for the idea of all mass being compacted into a tiny space in the very beginning. There must have been alot of mass stuffed into a small measurable space. This compaction was why in the very beginning of expansion there was a soup of indeterminate particles and forces. This suggest that it was crowded in the beginning and not so crowded later on. The very definition acknowledges that there is a mass/size relationship at the very instant of the bang.

    5. If there is a center from which everything imminated and you could be a far-off onlooker you could point to it and say 'there it is' and everything would, to you, seem to be moving from it.

    6. Anyone on a vantage point inside the system would think they are at the center due to the reasons given already.

    Yes, no ant or any observer can lay claim to being at the center. But, if there IS a center there must be some way we havent thought of yet to point to where it actually is. Simply stating that we cant, YET, lay claim to it doesnt refute it or get us any closer to the idea of discovering it. The question is how. And my simple question was this....

    If there is a definable center (which would be the point from which everything is expanding as seen theoretically from a far off vantage point) is there any way to calculate the various trajectories of the expanding stars that would tend to point to it. In other words, we have run up to a brick wall called the 'dots on the balloon' principle and it SEEMS insurmountable as to using trajectories and velocities to point to any origin other than the individual vantage point. Then it seems we therefore just accept that there MUST NOT BE a real center.

    If the answer is this, 'if there is a center we cant prove it' then I accept that. If the answer is 'there is no center because we cant prove it due to the dots on the balloon principle' then I dont accept that.

    tex
     
  14. No. Everything did not begin moving outward. Stuff did not fly away from someplace. There was an increasing amount of space between everything, everywhere.

    Nothing accelerated away from anywhere. There was more space between everything.

    It was the cause, but the expansion was not stuff being flung, but space being created between everything.

    All energy in the universe (too hot and dense for matter yet) was in a tiny space. The space itself expanded. If this were a ballistic explosion originating at a particular point, there wouldn't be any matter at the 'center' Again, that's not what we see when we look at the universe.

    Yes. But that's not what we see when we look at the universe. We don't see everything moving away from somewhere. We see everything moving away from us. Equally, in all directions. So either WE are the center, (most highly unllikely), or there is no center.
     
  15. You say there are only two alternatives...either...

    1. we are the center...
    2. or there is no center

    There could be a third...

    3. there is a center but because of the 'dots on the balloon' principle we cant determine it. So far there is nothing to refute the possibility of the third alternative.

    Even if it is space that expands, it is expanding from a beginning with a very small space. Take the balloon for example. When you breath in more air it gets bigger. But I can approximate the center of the balloon. And if space is finite and has shape then by definition it should have a geographic center or something close to that definition.

    For there not to be, space would have to in reality infinite. If you subscribe at all to the idea that space is expanding then you define it as finite in your premise and thus it is theorectically able to be contained in a big box and therefore capable of having a center.

    But I go farther than that. Not only do I suspect that there is a 3 deminsional bounding box within which the universe can be contained I suspect that it IS expanding from a center. Just like a raisin which happens to be in the center of a loaf of bread as it expands during baking. The raisin sees its entire universe moving away from it because it is indeed at the center of its universe. However another raisin thinks the same thing since its observation leads it to believe that it is at the center. Only we as outside observers know which raisin is actually in the center. The fact that the second raisin concludes he is at the center does not allow him to deduce that there must be no ACTUAL center. Not based on that alone.

    Any finite object must have a center. Otherwise it is either infinite or we cant deduce which. What we cant do is deduce that there MUST NOT BE a center.

    By the way. Im not trying to come down one way or the other. I just cant buy that we can prove there IS NO center from our observations and explanations with balloons and loaves of bread. While they do explain what we see, they, by themselves do not EXPLAIN AWAY the idea of a center. And if we cant prove it then there is left the possibility that there is, and if so where is the center and how can we figure out how to find it. That's all. Just old fashioned curiosity and determination.

    This is not unlike the sun revolving around the earth theory. Sure they explained quite adaquately what they saw with the sun revolving around the earth theory. But their explanations never DISPROVED the possibility of the earth revolving around the sun. Everyone bought off on the plausible explanation and were satisfied. Right up until they discovered new facts.

    tex
     
  16. Nabeshin

    Nabeshin 2,200
    Science Advisor

    Unfortunately, you have completely missed the point of the balloon analogy, which is leading you to the incorrect conclusions.

    In the balloon analogy (or raisin bread analogy), it is ABSOLUTELY CRUCIAL to remember that you are only taking about THE SURFACE of the object. That is, only THE SURFACE of the balloon is meant to be considered in the balloon analogy. This surface is a 2-dimensional space. Indeed, when we imagine it, we think of it as a 2-dimensional surface of a 3-dimensional object, namely a sphere, which of course has a geometric center in 3-dimensional space. But really, we're talking ONLY about the 2-dimensional surface, precisely because in a mathematical sense, it is not necessary to refer to the full 3-dimensional sphere to talk about its surface -- the surface exists as a geometrical object quite in its own right. The full sphere is merely a convenience introduced by us (3-d human beings) to visualize the situation.

    So, with that said, you have to consider just the surface. Now begin to inflate the balloon, what do you see? The distance between ALL points of the balloon increases. Any particular point sees all the other points receding from himself, and might naively claim to be at the 'center' of the perceived expansion. But any other point would reach the same conclusion. So where is the center of this expansion? Clearly, it is nowhere (or everywhere). (Do not say that it is the center of the balloon in 3-dimensions! Remember, in the balloon analogy, this 3-dimensional object is merely a convenience). THIS is the lesson of the balloon analogy.

    I hope that that clears up the balloon analogy, and you see that in such a toy model, there is no center to the expansion of such a universe. Well then, how about our own universe?

    What we observe is precisely the effect we see in the balloon case: all points (at sufficient cosmological distances to nullify proper motion) are receding from us. Based on this alone we might conclude we are at the center of some grand expansion, or else, it is precisely as in the balloon analogy. But the expansion is even more remarkable than that -- the velocity of recession of any given point is proportional to its distance away from us! This is patently false in any kind of normal ballistic explosion. So a theory that posits that space has always existed and that something merely exploded, sending matter flying away is immediately falsified.

    What are we left with then? Well, we are brought back to the case of the expanding balloon, which has both of the features I just described that we observe in our universe. So, as a model, this kind of scale factor expansion, whereby the distances between adjacent points increases, fits our universe remarkably well. This is why we use the balloon analogy, and why it is a good description of our universe.

    (Note, the same principle applies even if the universe has zero or negative curvature, and we can go through that as well. If you understand the concept of scale factor expansion, it's a straightforward generalization, although a bit harder to visualize, since both spaces are by necessity infinite.)

    If any of this hasn't made sense, what specifically is it?
     
  17. You are equating the thing we are talking about, space, the universe and the stuff in it as a 2 dimensionsl surface of a sphere...which we dont need to consider since two dimensions are quite enough. This seems to be the cart before the horse problem. ie. Let's not consider the three dimensional sphere since we only need two to explain the theory that dismisses the third dimension in the first place!!!

    Are you saying that space can be thought of as the surface of a sphere? I have seen countless examples of the dots on the balloon analogy where the three dimensions are given as layers on an onion. Each dot on each layer getting farther away from each other per layer and the dots getting father away on different layers....every dot in the onion getting farther away. There is no need for a surface analogy for the dots on the onion analogy to work.

    I think because space as a curved 2 dimensional surface is the favorite theory and that dots on a balloon works with that, that a simple 3 dimensional space is thrown out. Remember, these are all theories so no one is known for sure....even the big bang.

    Here is a simple question. Prove, simply, that the universe is something other than what it seems to be...a big 3 dimensional bread loaf. If one cant, then there is the possibility of a center.

    The whole point of this is this....wouldnt it be amazing to figure out that the center of all expansion, the center of the big bang was somewhere in the neighborhood of Beetlegeus or some other place, even our sun.

    tex
     
  18. marcus

    marcus 24,476
    Science Advisor
    Gold Member
    2014 Award

    Tex, the important question here is DO YOU WANT TO UNDERSTAND the picture that astronomers have of the expanding universe? Do you want to learn a bit about the "standard cosmology model"?

    There is a generally accepted model. It does not resemble an explosion (that is what is fed the public on TV but not the real story). It is a pretty nice model that fits the data remarkably well. The model also fits the accepted law of gravity (Einstein equation) which has been tested to very high precision.

    The Forum here provides a kind of common middle ground where some professionals and some general lay public mingle. New people often arrive with this "explosion" picture in their heads and it is very hard for some of them to get it out of their heads.

    The crucial question is do you want to think about the expanding universe in a way that is more like the standard professional model cosmos? Or do you want to cling to the "explosion at some point in space" picture that the general public is fed via popular tv and magazines?

    I hope you will reply. I'm curious to know. Welcome to PF cosmo forum, by the way. Have fun, whichever path you choose.

    Oh, you might like the "charley" link in that block of links at the end of the post.
     
  19. Nabeshin

    Nabeshin 2,200
    Science Advisor

    These are, in my opinion, a dangerous set of analogies to begin to make. It leads to even more misconceptions than the original balloon analogy! What's trying to be done here, is that people are trying to equate the third dimension in the onion example with time. I.e. the two-dimensional spheres (described by two angular coordinates), and then the radial direction is time. As time increases, the radius of the two dimensional spheres too increase. I personally don't find this very helpful in understanding anything, and think it causes more confusion than good. You have to know the limitations of your analogy before you try to push it very far at all.

    Look, if you're going to argue 'you can't prove that X isn't true', then you can leave this forum right now. We're scientists, that's not the way science works. We construct models, which give good predictions, and we have faith in these models because they work. The big bang (complete with no center and all!) is one of these. We can never 'prove' it is true. We do not aim to. But there is an incredible amount of predictive power in the big bang model, and has so far been in accordance with every observation we have made. This is why we put so much stock in the theory, and describe it as if it were 'true'. But you have to understand that it's just a model, like all other physical theories.

    You're welcome to come up with a full mathematical model describing a universe with a center or whatever you like, include unicorns if it pleases you. Show that it matches observational data, and publish in a peer reviewed physical journal. Then maybe we can talk about it. Until that time, we'll stick to the theory which has made countless verified predictions.
     
  20. The simple answer is yes, I want to understand whatever makes sense scientifically without doing violence to common sense. Im not the expert to determine which is which so I rely on you guys. Im sure it must be frustrating for you with people like me. Im sorry.

    I dont mean an explosion in the sense of a violent release of energy sending everything out in all directions. I mean that something, whatever it is, expansion, gunpowder or otherwise sent everything out in all directions. In that sense it resembles an explosion (to my thinking) in that everything, space, objects, whatever, was sent outward from the previous location which was a small point. I understand that space itself expanded and in doing so gives takes everything with it. I dont understand why what ever you call it, doesnt result in the same thing....that is....lots of stuff out there....where....it used to be all bunched up here in this little point. What ever you call all of that you have the beginning condition, that of everything in a little point followed by all of that stuff spread out everywhere. That must mean it went from here to there which implies at least the idea of a trajectory as seen from a far off vantage point.

    I know the idea of a out of system vantage point make seem non-sensical but it helps me to visuallize what happened, if indeed, this is all close to true.

    There are two points that I cant grasp, the idea of space being a surface of something and why the big loaf of bread idea is not correct. Are you saying that the universe is not 'containable' in a big box as a finite object?

    Yes, I want to understand.

    tex
     
  21. marcus

    marcus 24,476
    Science Advisor
    Gold Member
    2014 Award

    I'm trying to think where to begin. Other people may jump in (as some have earlier) and that would be fine. I'll think of something---perhaps not the best.

    You know the problem with the "explosion" image is that it occurs at a point in space. that's the basic reason the image is so bad and causes newcomers such confusion.

    The universe is ALL SPACE so how could it be concentrated in some "location" located in some other space? There is no other space.

    I'm always going to talk about the simplest most standard cosmo model---there are more elaborate fancy models with extra dimensions and crazy extra universes but 9 out of 10 cosmologists never bother with them. The simple standard model is what is used to calculate times/distances with and to compare with observational data.

    So the universe at this moment is 3D and it is all space. There is no surrounding space and no edge or boundary to it. It is all space and all existence. That's how the standard model treats it, and it works. Simplest that way.

    WE DON'T KNOW whether the volume, at this moment, is finite or infinite. We are getting closer to finding out, but it could still go either way. This confessed ignorance is probably another obstacle to communicating at popular level. Probably TV producers don't want to have a scientist come on the program and say we don't know something as simple as that. So the popularizers fudge or gloss over.

    Because it isn't known for sure that the universe is finite, cosmologists of necessity must keep updating both versions. Sometimes showing work in duplicate. They use both the finite version of the standard model and the infinite volume version. More often the infinite version but not so exclusively that it represents a onesided commitment.

    In the finite volume case the full universe would in any case be many times larger than the observable portion--- so effectively, for all practical purposes, it gives the same numbers, looks about the same as the infinite case, and fits the data more or less equally well. Better instruments should eventually decide which version to use.

    In a 2D analogy there would be two cases: an infinite flat plane or else the surface of a very large balloon so large that it seems flat to the 2D creatures living on it. For them it might as well be an infinite flat plane.
    And keep in mind when thinking of any 2D analogy that whichever it is, it is ALL OF SPACE. All existence is concentrated there, there is no above or below the flat plane or inside or outside of the balloon surface.

    It takes some care and concentration to think about those 2D analogies.
    ==========================

    Let me know if there are any urgent questions about this so far. I will get back to it. But I'll take a break now.
     
    Last edited: Jan 18, 2012
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