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Centre of the universe

  1. Jan 31, 2014 #1
    If the Big Bang was really a big expansion and if the universe is still expanding, then surely that implies a central point from which it expanded from, right? I've read that there is no centre, how is that possible if the universe came from a single expansion?
     
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  3. Jan 31, 2014 #2

    DrClaude

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    There is a FAQ on the subject: https://www.physicsforums.com/showthread.php?t=506991 [Broken]
     
    Last edited by a moderator: May 6, 2017
  4. Feb 9, 2014 #3
    First post! Anyways, how I understand it goes like this: if the Universe is infinite in all directions then any point in the Universe would be the center. If it's not infinite, then I suppose there is a defined 'center'.
     
  5. Feb 9, 2014 #4

    bapowell

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    Not necessarily. Imagine the surface of a sphere: where's the center? If the universe is finite and closed, then it can be considered the 3-dimensional surface of a 3-sphere and therefore has no center.
     
  6. Feb 9, 2014 #5
    Yeah that's true. And if space is expanding unevenly then that would be true. If it was finite, it probably would have to be a perfect sphere or whatever you want to call it. (to have a center)
     
  7. Feb 9, 2014 #6

    phinds

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    As has been pointed out, this is a very serious misunderstanding of cosmology. I would add that it is a very COMMON misunderstanding, abetted by pop-science TV shows.

    I recommend the link in my signature.
     
  8. Feb 9, 2014 #7
    how i understand it is that everywhere was in the "center" all at the same time
     
  9. Feb 9, 2014 #8

    Drakkith

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    As far as we know, there is no center and there never was.
     
  10. Feb 10, 2014 #9
  11. Feb 10, 2014 #10
    Phinds, unfortunately for the profession of cosmology and to the surprise and disappoint of many layman, like me, it appears that cosmologists themselves are responsible for the "misunderstanding' by misdescribing cosmological events such as the Big Bang and the Singularity.

    For example, just several weeks ago, a television special was aired on PBS concerning the life of Stephen Hawking. There, Hawking himself described the origin of the Universe as the result of an "explosion."!!!!!!

    He earlier described the Singularity as a tiny black hole that exploded to become the Universe.

    Both descriptions are wrong, misleading, confusing and insulting as the cosmologists (including physics professors) assume that the layman-listener does not have the mental capacity to understand, in layman, non-mathematical terms, the emerging cosmological principles that were unknown to science until just recently.

    Albert Einstein once said that "physics can be taught to a barmaid." In saying this, he was merely pointing out that his theories of relativity and other physical laws and theories, while complex subjects, are and should be capable of being taught to the layman if the person doing the teaching knows how to teach.

    It is too bad that many cosmologists are not teachers.
     
  12. Feb 10, 2014 #11

    phinds

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    Sadly, even some of those who ARE teachers are known to have made insultingly dumbed-down (and blatantly incorrect) statements on pop-science TV shows. It seems to be part of their contract that in order to get paid they have to say at least one thing that they know to be incredibly stupid.
     
  13. Feb 10, 2014 #12
    It could be a case of them just reading what's in the script.
     
  14. Feb 11, 2014 #13
    Very sorry to report that it is still happening, today, even in unscripted presentations.
    I watched the youtube of the big evolution debate the other night between Bill Nye and Ken Ham. This was 2 hours and 45 minutes; plenty of time to get things right and not gloss over a point or two with misconceptions, and yet...

    Bill Nye ("the science guy") argued that since the universe is moving apart, it can be traced back to a single point (rather than the expansion occuring at all places and there being to single point). 1:21:25 in video
    He also presented the expansion as the observasion that stars are moving apart (rather than distant galaxies, clusters, super clusters, etc.) 1:20:55 in video

    This was very disturbing to me, as he should know better; he even mentioned that his teacher was Carl Sagan.

    video is at youtube -
     
    Last edited by a moderator: Sep 25, 2014
  15. Feb 11, 2014 #14
     
  16. Feb 11, 2014 #15
    I have watched a lot of videos of Feynman and he always tried very carefully to not mislead his audiences or leave out critical details... and when he had to do so for the sake of the audience or students, he always said so and "drew the line" for them explicitly identifying the "slightly incorrect or incomplete" parts so they would not be misled, so they would know just what part of the explanation or demonstration had been "simplified" or "adapted" to their level of understanding.
     
  17. Feb 11, 2014 #16
    In many cases, when one tries to describe this or that aspect in cosmology. One either has to describe it using the math's involved or resort to use of an analogy. The maths would lose an audience rather quick, so the analogy method is usually used. Unfortunately every analogy is subject to misinterpretation. Unfortunately most programs do not take the time to point out those perils in their analogy usage. For one pointing them out could quickly get boring for viewers, one could spend a full hour covering the misconceptions involved with the balloon analogy as one example. lol

    In media, most viewers are more interested in the quick and dirty explanations, as opposed to the nitty gritty details. That juggling act between ratings and accuracy is one major factor in why media cosmologists say what they do.

    but take heart, the media method gains interest in the field of cosmology. This encourages more students to take up the field. Not to mention coming here for better clarity
     
  18. Feb 11, 2014 #17
    The big bang was indeed an explosion - an explosion of spacetime. This concept isn't something that most lay people are going to understand. In fact, I suspect most of us can't visualize it either, and can only use the balloon analogy to sort of get it. Getting some of the public to at least know that at one time everything was compressed and then expanded dramatically - that's progress. Let's not knock people who simplify things a bit but get at least some of the idea across rather than make it totally incomprehensible by insisting that they have a full understanding or bust.
     
  19. Feb 11, 2014 #18

    bapowell

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    Define "explosion"
     
  20. Feb 11, 2014 #19

    Drakkith

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    I believe the general consensus, at least according to the guys here on PF who know much more than I do, is that we don't know what happened at the point in time that our math says a singularity occurred. We only know that the universe was once very dense and expanded from there.
     
  21. Feb 11, 2014 #20
    One definition of explosion is a violent expansion. It's true that we can't know what happened exactly at the ?singularity but "explosion" seems appropriate if you're trying to get the concept across to non-scientists, and during and after inflation it was pretty rapid. Let's not be so literal. Just be happy that the lay public knows that the universe is expanding.
     
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