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A thought about our universe.

  1. Aug 22, 2003 #1

    Owl

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    I know i'm not a big on mathmatics and physics but i do think about the big bang. Why are we expanding in one big circle?

    Is it a possibility that after the big bang there was one huge blackhole?
    because i read somewhere that when our sun dies out it might turn into a blackhole and that our planets will either get sucked in or keep expanding. Maybe thats why we cannot find the source to our gravity? because the source died out.
    See with zero gravity if a source spins something and then take away the source it will still keep spinning.
     
    Last edited by a moderator: Aug 22, 2003
  2. jcsd
  3. Aug 22, 2003 #2
    It is a moderately accepted claim that some event lies at the "center" of the universe.

    However, it being a black-hole is as likely as any of a billion imaginable events.

    It's actually probably unlikely; a black hole results in a compression, which never occured at the big bang. Also remember that there would be absolutely no matter or waves for the black hole to feed on at all - there's nothing anywhere near the center of the universe.

    It would be like traveling through perhaps 100 trillion trillion lifetimes worth of nothing.......................................

    What do you mean cannot find the source of gravity?

    All strings exact a gravitational force on all other strings.

    The source of gravity is no mystery so I have no clue what you mean!
     
    Last edited by a moderator: Aug 23, 2003
  4. Aug 22, 2003 #3

    mathman

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    There is no "center of the universe".

    When our sun dies, it will not become a black hole. It is too small.
     
  5. Aug 22, 2003 #4
    Sure there is a center to the universe. Where's the outrageous evidence for this claim?
     
  6. Aug 22, 2003 #5

    marcus

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    Mathman just stated that there is no center to the universe

    I can corroborate this by saying that no reputable professional
    cosmologist that I've read over the past 3 or 4 years has suggested that there might be such a thing as a "center of the universe"

    such a thing would be highly unintuitive

    therefore the burden of proof is on you, "Bio...rums" to give
    evidence for YOUR claim that there is a center------your claim is
    the one that runs counter to the informed consensus.

    If there is such a center:wink: then, as I asked you in another thread, in which direction is it?
     
  7. Aug 22, 2003 #6

    marcus

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    Owl, it might be fun for you to read the Cosmology FAQ (frequently asked questions) at John Baez website.
    He is a moderator for the Usenet "sci.physics.research" forum
    and has a large Physics FAQ

    It has a lot of standard answers to some quite interesting questions that have come up again and again.

    One question is whether the "big bang" is similar in any way to a "black hole"--------both are limits to the applicability of General Relativity (barriers where the formulas break down).

    The answer is that the big bang singularity was localized in time but not in space (did not occur at a point)
    while a black hole singularity is just the opposite----localized in space (at some definite spot) but extensive in time (existence normally spread over a considerable interval of time for the big ones)

    Physics FAQ is neat. I will see if I can find a link to the Cosmology part

    edit: for the moment I just find this Cosmology FAQ at a UCLA site of a guy who teaches the graduate course in cosmology there

    http://www.astro.ucla.edu/~wright/cosmology_faq.html

    It is pretty good. He is one of the leaders of the current WMAP
    project, Ned Wright, certainly one of the world's top cosmologists so you can go by his FAQ.

    Hope some of the questions on it correspond to ones youve thought of yourself
     
    Last edited: Aug 22, 2003
  8. Aug 22, 2003 #7
    The very idea that there was a big bang stemed from the very FACT that all matter of the universe is traveling away from a specific location.

    This location is called the center of the universe in cosmology books by the following leading authorities:

    1. Hawking
    2. Kaku
    3. Greene
     
    Last edited by a moderator: Aug 23, 2003
  9. Aug 23, 2003 #8
    There's no real need to go to the Vatican. Just take a college course in elementary cosmology.
     
  10. Aug 23, 2003 #9
    The concept of a Big Bang comes from observations that all matter in the universe is moving away from a specific location - and all matters lies on an even display of the outside of a sphere.

    So explain why the location from which all matter is moving away from is NOT the center of the universe.
     
  11. Aug 23, 2003 #10
  12. Aug 23, 2003 #11
    ...and I can quote just as many experts stating the opposite but with much better explanations:

    "...can be used to find the center of the universe by using the color shifts of the galaxies to see the direction of their movement and map out...the center of the universe."

    Like I stated earlier - the very idea of the Big Bang began because astronomers noted (using said method) that all matter in the universe travels away from the same coordinate in our 3 dimensional space.
     
  13. Aug 24, 2003 #12

    Phobos

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    You misunderstand. None of those folks (AFAIK) state that. It is not a fact that all matter is travelling away from a central point. Cosmologists go to great lengths to explain that this is not the case. Here in our Local Group of galaxies, we see all other galaxies/galaxy clusters moving away from us. But that does not put us at the center. An observer in one of those distant galaxies would see all galaxies (including ours) moving away from him. Space is expanding everywhere in all directions.

    The Big Bang was not an explosion of stuff into empty space but rather the expansion of all Space itself.

    Some light reading here...
    http://itss.raytheon.com/cafe/qadir/acosmexp.html
    http://itss.raytheon.com/cafe/qadir/acosmbb.html
     
  14. Aug 24, 2003 #13

    Phobos

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    Again, such a location has not been found and no one has seen all matter moving away from such a thing. So, there is no reason to explain such a non-observation.
     
  15. Aug 24, 2003 #14

    Phobos

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    Who is that quote from and what is the full context? (provide link if possible)

    The idea of the Big Bang began from Einstein's theories (early 1900s), grew from Hubble's observation of the redshift of galaxies (1929), and became a full-fledged mainstream scientific theory upon the discovery of the Cosmic Microwave Background in all directions (1965). Never has it been observed that all matter is travelling away from the same coordinate in 3D space.
     
  16. Aug 24, 2003 #15

    Phobos

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    Let's see if we can get back to Owl...

    No, all space is expanding in every direction*. Imagine an infinite sheet of graph paper (2D grid to represent 3D space). Now expand the grid. If you imagine yourself at any point/node on the grid, you will see all other points moving away from you. That is true for any point/node (no preferential center). When the universe was younger, the grid was closer and closer together (until time=0 when all points of the grid were merged as one).

    * - The expansion is a very weak force that can easily be overcome by other forces. So, it mainly occurs within the emptiness of intergalactic space. Gravity within a galaxy keeps that galaxy from expanding.

    The Big Bang did probably create some black holes, but there is no indication of "one huge" blackhole that pertains to the beginning of the universe.

    As was mentioned, the sun is too small to become a black hole (not enough mass). The sun will expand to a "red giant", form a "planetary nebula" which may reach the Earth's orbit, and then shrink and cool into a "white dwarf".

    What spin are you referring to? No overall spin of the universe has been identified. (planets, galaxies, etc. spin...but not the whole universe as far as we know)
     
  17. Aug 24, 2003 #16

    Phobos

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    oh, and WELCOME TO PHYSICS FORUMS, OWL! :smile:
     
  18. Aug 24, 2003 #17
    There really is no concrete proof for either arguement.

    A model can be made for both to fit observation. Having a center to the universe would require that the Earth is very close to center. This is distasteful to cosmologist, and is summarily tossed as a possiblity.

    A universe with no center is the accepted view with the expansion of space describing observation. Although there is no proof for expansion other than the observation.

    To blatantly say that one is true verses the other can only be cassified as wishful thinking. A path has been taken however for a universe with no center. Time will tell if the right choice was made.

    I'm sure there are other models that fit observation. We only need but look for the proof that would set it in stone.
     
    Last edited by a moderator: Aug 24, 2003
  19. Aug 24, 2003 #18
    Which is why the universe can't be infinite! No one has yet to show me how an expansion can ever lead to infinite. Besides, infinite has never been shown to actually exist, in any form, in reality - that I've seen...
     
  20. Aug 24, 2003 #19

    Eh

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    I would like to see a single instance where either of those 3 claim there is a center to the universe. Are you sure it's not something else you're thinking of?
     
  21. Aug 24, 2003 #20

    Eh

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    You'd be correct to say that something finite can never become infinite, no matter how much it expands. But that isn't the proposal for the big bang with an infinite volume of space. If the universe is infinite now, it has always been infinite, even at the moment of the big bang itself. In such a case, to distance between all points in flat space begins to increase (the distance between galaxies is one way to think of it) but the overall size of the universe never changes - it is always infinite.

    But that is just a solution for an expanding universe that is infinite in size. Solutions exist for a finite universe as well, and in that case the overall volume of the universe does increase with expansion as expected. At the moment of the big bang, the universe would be very small and highly curved. However, as we run the clock back on an infinite universe, the volume remains infinite but at each location in space the density becomes very high. The classic singularity of course, is an instance of infinite curvature throughout each point in such a universe. But I think we can forget about singularities for now.
     
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