Dismiss Notice
Join Physics Forums Today!
The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

Centre of the Universe

  1. Aug 27, 2004 #1
    I just thought of this... I'm sure I'm wrong, somewhere, or there'll be a flaw in my logic, but here we go.

    Assuming the universe is infinite in size, then the edge of the universe is infinitely far away from me in all directions.

    If the edges of the universe are the same distance away from me in all directions - an infinite distance - then all points on the edge of the universe are equidistant from me.

    Surely this means that I (and everyone else) can logically claim to be the centre of the universe?
  2. jcsd
  3. Aug 27, 2004 #2
    The point is that The Big Bang happened everywhere in the universe. It did not expand into something, it just expanded, like inflating a baloon. Thus, the universe has no center, or, if you will, every point in the universe is just as much the center as any other.
  4. Aug 27, 2004 #3
    Isn't that what the questioner already concluded? "Surely this means that I (and everyone else) can logically claim to be the centre of the universe."
  5. Aug 27, 2004 #4


    User Avatar
    Science Advisor
    Gold Member

    It's often explained as trying to define the center or edge of the surface of a sphere. The concepts of edge and center are obviously meaningless. This is, however, merely a visual aid. The universe is not literally a 'sphere'. You cannot 'step outside' of the universe and look at it the way you can a basketball or earth, and perceive it as a geometrical shape surrounded by 'nothing'.
  6. Aug 27, 2004 #5
    Indeed, that is what he concluded, but I do belive he was asking for some help in determining whether or not his conclusion was correct. I tried to provide that help, by showing that my conclusion is the same one.
  7. Aug 27, 2004 #6


    User Avatar
    Staff Emeritus
    Science Advisor
    Gold Member

    Grizzlycomet: "Where did the Big Bang start from? Here!" (points to own heart)
    The Binary Monster: "Actually, it started here!" (points to own heart)
    ;oih?£^fÅioh {denizen of a minor planet, orbiting a minor star, in a minor galaxy, in a nameless small galaxy cluster, ~3,234 Mpc from the Milky Way}: "The Big Bang started here!!!!!!!!" (points tactile sensor #345 to neutrino-sensory lobe #5)

    How can this be? :confused:
  8. Aug 27, 2004 #7
    This is quite an assumption.

    The universe is expanding. I think the question is whether the universe will continue to expand infinitely, not whether or not it already has.

    I think that this is quite a leap, based on my point above.

    Logic has nothing to do with it. You may certainly think this way, but I do not.
  9. Aug 28, 2004 #8
    Thank you all (or most) for helping me with this, and assuring me I've concluded something which isn't completely stupid... as the current ideas and theories stand, at least.

    At the moment, this is indeed the way I think. Saying this, if anyone comes to correct me with any evidence or theories that show the universe is indeed finite and the big bang is a myth then I shall welcome them with open arms. Just because I think this way at the moment does not mean I'm correct, as I'm sure you'd agree. It merely means I don't feel I've been presented with a better alternative yet...
  10. Aug 28, 2004 #9
    You seem to be changing horses in midstream.

    I never suggested that the universe is finite. As well, you now seem to be saying that you suggested that the universe is infinite, which is not what you said at all. You said that the universe if infinite is size. Furthermore, you also maintainted that your source for this contention was an assumption.

    This is the first time that you mentioned that the Big Bang is a myth, is it not?
  11. Aug 29, 2004 #10
    Yes, yes it is. In my mind, the infinite size of the universe (which I had mentioned, infact, check my FIRST post) is part of the consequences of the big bang. So perhaps anything saying the universe was not infinite would show that the big band was not true?

    Please, stop nitpicking. I'm a newbie, and I wish to learn. I welcome people to correct me, and help me learn from my mistakes. I don't welcome people to pick holes in my posts just for arguements sake. If it'll teach me, say something. If you're posting to try and annoy me - don't bother.
  12. Aug 29, 2004 #11
    Why are you getting so upset? Don't blame me. Perhaps it is you who is trying to annoy me. You are changing your statements in a significant manner, perhaps because you equate two concepts that are not at all the same, and you blame me for nitpicking that your changes change everything.

    What are you trying to say? You are assuming that the universe is infinite in size. Why? I have never heard anyone ever make such a statement, so what is your basis for assuming it? Scientists claim that the universe is expanding. If the universe were infinite in size, expanding would have no meaning.

    I recommend that you attempt to develop a more precise way to formulate what you are thinking. If you do not want to dialog with me, then do not respond to me. However, do not complain that you are annoyed with people who respond to your post.
  13. Aug 29, 2004 #12
    I think that if the universe is infinite in size, then it has no center whatsoever. Infinity is a concept, not a numerical value. If there are infinity meters to the left, and infinity meters to the right of any one point, I can't say that the two sides of the universe are "equidistant", because there is no assignable numerical quantity for this distance.

    I cannot know for sure that x = y until I know the actual numerical values for both x and y. I can't assign them both a value of "infinity" to make them equal any more than I can assign them both a value of "love".

    If something is truly an infinite distance away, then technically it doesn't exist based on definition. In fact infinity means "having no boundaries or limits". The universe you describe has no boundary, and therefore you cannot define a center.

    The balloon example is no good. Based on my observations, I am surrounded by three spacial dimensions of universe, but the dots on the surface of the balloon are only reflecting a two dimensional plane. If you scatter the dots inside the balloon at random locations, you can see they aren't all at the three dimensional center. A balloon only has one center, one point that is the radius' distance away from all points on the surface.
  14. Aug 29, 2004 #13


    User Avatar
    Gold Member

    Hi, Prometheus!

    A LOT of scientists believe the universe is expanding and infinite. Here is a link to Ned Wright's page where he explains the concept that the universe can be infinite, and have arisen from a big bang. Actually, there are quite a few models for infinite universes, some incorporating a big bang and some not.


    Hello, TBM, and welcome to the Physics Forum!

    There are in fact lots of models of the universe, in which an infinite universe can arise from a variety of mechanisms, one of which might be the big bang. Here is a link to a heavily cross-referenced on-line encyclopedia that you might enjoy.

    Last edited: Aug 29, 2004
  15. Aug 29, 2004 #14

    The idea of infinite universes is typically that the universe will continue to expand infinitely.

    I do not think that there is much thinking that since the Big Bang the universe has already expanded to the point that it has already reached infinite size. Furthermore, what would that even mean?

    What would it mean to say that since the Big Bang the universe has expanded such that right now at this point in time, if we were to measure the size that it has expanded to since the Big Bang, we would find that it has expanded to infinite size? I claim that such an idea is not compatible with the Big Bang model.

    When scientists conjecture that the universe is infinite in size, they do not mean that it has already achieved infinite size, but that Big Bang expansion will continue infinitely. Therefore, in the future the size will be infinite, not in the present.
  16. Aug 29, 2004 #15


    User Avatar
    Science Advisor
    Gold Member

    It's very possible, perhaps even probable, that the universe is infinite in spatial extent and we can be absolutrely sure it is expanding. Alot of people do have conceptual diffuclties with an infinite expanding universe. One analogy is an infinite piece of graphing paper where the squares are increasing in size.

    What this actually means in the terms of the unievsre is that, in general, galaxies are getting further paart as the unievrse expands, i.e. the unievrse's average density is decreasing.
  17. Aug 29, 2004 #16
    Hi The Binary Monster - Welcome to the forum!

    The big bang does not imply that the universe is infinite in size. There are different possibilities. A closed universe is one in which the size of the universe is finite. An open universe is a universe which is infinitely large. In fact if the universe is an open universe (spatially flat) then the universe was became infinitely large the moment that the big bang occured.

    At the moment the universe appears to be infinite in size and expanding at an accelerating rate. This means that the spatial extent to the universe is infinite and the distance between any two points is increasing at an acclerating rate. Picture an infinitely long ruler for which the distance between the marks on the ruler are increasing at an increasing rate - same idea.
    If you are irritated by certain posters then you can click on "User CP" (i.e. user control panel) above and then scroll down an click on "Buddy / Ignore Lists" and add those persons user names to the ignore list.

    I recommend using it since there are several posters in this forum who are quite irritating and seem to want to bicker alot rather than discuss.

  18. Aug 29, 2004 #17
    this paper postulates the existence of a center of the universe

    "An analysis of the big-bang theory according to classical physics
    Authors: R. Alvargonzalez, L. S. Soto
    Comments: 11 pages, 7 figures
    Subj-class: Classical Physics; General Physics

    This paper collects a consistent body of information on the observable Universe, from which an estimate of the total mass of the Universe is calculated as a function of the angle whose vertex is at the center of the Universe, and whose extremities stand on the Earth and on the limits of the horizon of visibility. This result leads to an analysis of the dynamics of the Big-Bang, taking into account the limitations imposed by the Schwarzschild radius, $R_S$. Where if $R_0$ is the radius of the incipient Universe when the formation of elementary particles has just finished, the value of the quotient $R_0/R_S$ determines its subsequent evolution. An important conclusion from this concerns the expansion of the Universe; all signs point to its being destined to expand indefinitely. "

    Can somebody tell me if the ideas expressed are too much baloney? I'm having difficulties in understanding the ideas in it
  19. Aug 29, 2004 #18


    User Avatar
    Gold Member

    The authors are referring to the center of our visible universe, which is of course centered on us. People who adhere to the Standard Big Bang theory (redshift equates to distance in accordance with the Hubble relationship, etc) generally say that our visible universe has a radius of 13.7 billion light years and is spherical in shape. Most think the universe is infinite, but that due to the limitation of the speed of light, we can only see objects in a sphere of 13.7 billion light year radius (visible universe). The link I gave earlier to Ned Wright's site illustrates how our expanding, finite visible universe can be a subset of an infinite universe.


    According to the standard model, the number of galaxies in our visible universe is actually decreasing because the most distant galaxies we can see are currently receding from as at faster than the speed of light due to cosmological expansion.

    To be fair, there are scientists who do not believe that redshift is caused (wholly or in part) by cosmological expansion, and who say that extrapolating back 13.7 billion light years to a theoretical singularity (at the big bang) is a mistake. They are in the minority, for certain, but the group includes some pretty astute fellows. These include a number of top-notch observational astronomers.
    Last edited: Aug 29, 2004
  20. Aug 29, 2004 #19
    The universe has only one center.
    Assume you consider it consisted of N particles.
    Every particle represents a force pressing at some position.
    Using the rule of lever in equilibrium you can find the center and the central force for the 1st two particles.
    That center is a position in which that central force is pressing and in combination with the third particle you can find the new center and central force and so on...
    In the end, you end up with only one center which, assuming the universe is closed system, is subjected to no force.
  21. Aug 29, 2004 #20
    In this scenario, what do you mean by "infinite in spatial extent"?
Share this great discussion with others via Reddit, Google+, Twitter, or Facebook