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I Find the Age of the Universe when Matter and Radiation densities were equal

  1. Feb 28, 2017 #1
    The universe is believed to be 13.8 billion years old and at least 45 billion light-years in radius. Now there is also a black hole at the center of our galaxy, with my basic understanding of black holes I understand that this would warp time and space, is it possible that it's warped so much that we are living in a small pocket of the universe that is 13.8 billion years old and the rest of the universe at least the parts not affected by any influence of black holes are older?
     
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  3. Feb 28, 2017 #2

    phinds

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    No, you misunderstand the effects. BH "time warping" is a purely local phenomenon and is only meaningful when considered relative to an observer far away from the BH and do not affect that observer, just his observations of what he "sees" in the vicinity of the BH.
     
  4. Feb 28, 2017 #3
    I'm sorry to ask but could you explain more? I fear I still misunderstand why it wouldn't be true. I believe you because you would know more than me but in my mind it still seems as if a local phenomenon could still act the way I said. Unless the "time warping" is at the closest points of a black hole and doesn't extend as far as it's other gravitational effects?
     
  5. Feb 28, 2017 #4

    phinds

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    That's correct. The "time warping" is local to the region of the BH. The gravitational effect extends, in theory at least, to infinity, but both the power of the gravity and the affect of the "time warping" drop off precipitously as you move away from the BH.
     
  6. Feb 28, 2017 #5
    Not only a black hole but any massive object changes the curvature of space, (locally).
    This results in gravity as described by general relativity.
    However the amount of gravity is only significant close to the massive object, it becomes nearly zero at any appreciable distance.
    The Milky way's SMBH does have a number of very nearby stars orbiting it, but it has no effect on more distant stars.
     
    Last edited: Feb 28, 2017
  7. Feb 28, 2017 #6
    Is there a formula that can be used to find the area of affect of the "time warping"? Or is it just assumed the limit is the edge of the BH?

    So is the Milky Way not really orbiting a black hole but just moving in tandem with it?
     
  8. Feb 28, 2017 #7

    phinds

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    https://en.wikipedia.org/wiki/Gravitational_time_dilation

    The objects in the Milky way, NOT the milky way itself, are orbiting the center of the galaxy. The BH is at the center of the galaxy but only accounts for something like 1% of the total mass of the galaxy so contributes little to the orbital dynamics other than to that of the stars VERY close in to it.
     
  9. Feb 28, 2017 #8
    That makes a lot of sense to be honest. But i have to ask. Are we assuming a 4 dimensional universe or a 10 dimensional universe?
     
  10. Feb 28, 2017 #9
    The currently accepted theory of gravity is general relativity which models spacetime in terms of 3 spatial dimensions and 1 time dimension.
    10 dimensional models and others belong to string theories, where the additional dimensions are very small in scale.
    They apply mostly (if they are correct), to consideration of subatomic scale entities, not to very large objects like galaxies.
     
  11. Feb 28, 2017 #10

    phinds

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    10 dimensional universes are PURE speculation and there is zero empirical evidence for them.
     
  12. Feb 28, 2017 #11
    Would the "little" that it contributes to the orbital dynamics of further-out-stars be the fact that they orbit around the SMBH at all?
     
  13. Feb 28, 2017 #12
    I think the accepted idea is that galaxies form from collapsing gas and dust clouds that have some angular momentum to begin with.
    A black hole in the center is not a prerequisite, but most galaxies end up that way
     
  14. Feb 28, 2017 #13

    phinds

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    They orbit around the center of the galaxy based on the total mass of the galaxy. The BH contributes to that total.
     
  15. Mar 1, 2017 #14
    I researched the 10 dimensional universe and wow I didn't know it was just speculation. I always thought that since the galaxy had a black hole in the center that we were affected by it. I heard of a theory on spacetime being a liquid state, a quantum gravity theory to be exact, but again just personal speculation, if spacetime were in a liquid state would gravitational forces send force waves out?
     
  16. Mar 1, 2017 #15

    phinds

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    Gravitational forces ALREADY send out waves. Google LIGO
     
  17. Mar 1, 2017 #16
    I need to say more when I say things lol. I didn't mean waves as in gravitational forces like the usual but as in waves that influence spacetime. I can't put it into words but rather pictures.....
     
  18. Mar 1, 2017 #17

    phinds

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    Gravitational wave DO influence spacetime.

    EDIT: and by the way, I'd suggest you drop the "spacetime as a liquid" concept.
     
    Last edited: Mar 1, 2017
  19. Mar 1, 2017 #18
    is it not a liquid? Or is that just another theory that can't be proven? Does it just exist?
     
  20. Mar 1, 2017 #19

    phinds

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    Google MichelsonMorley experiment
     
  21. Mar 1, 2017 #20
    Alright I'll google that. Do you have any clue about why the name of this thread was changed?
     
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