If the universe is much more bigger

Discussion in 'Astronomy, Exobiology, & Cosmology' started by Saint, Sep 14, 2019.

  1. Saint Valued Senior Member

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    If the universe is much more bigger than the size we estimated by big bang theory, will it nullify big bang?
     
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  3. geordief Valued Senior Member

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    How do you suggest we measure the size of the Universe?

    And what ,according to you is the size of the Universe as "estimated by the Big Bang Theory"?
     
    Last edited: Sep 15, 2019
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  5. Michael 345 New year. PRESENT is 72 years oldl Valued Senior Member

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    Well with all such questions of this nature I would say something along the lines :-

    The Big Bang explains the Universe as we know it taking into consideration the observations and evidence we currently have

    If we have new observations and evidence well the question becomes - do the new observations and evidence
    • modify Big Bang theory? OR
    • overturn Big Bang theory? for new theory with new name?

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  7. Seattle Valued Senior Member

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    No, the BB doesn't estimate the size of the Universe. It applies to the observable Universe.
     
  8. Jeeves Valued Senior Member

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    Plus, it keeps growing. Unless it's already started shrinking again.
     
  9. geordief Valued Senior Member

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    Suppose,for the sake of argument that U did in fact shrink eventually and come to a single point....could we say (as another way of looking at it) that it had continued growing , except "backwards" in its "part 2"?

    So ,space time ( and matter-time if such a concept exists or is valid) would always increase.
     
  10. Seattle Valued Senior Member

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    If by increase you mean decrease, sure. Next year I'll be another year younger, except "backwards".
     
  11. geordief Valued Senior Member

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    Is there such a thing as a 4D spacetime volume that would apply to an evolving universe ?

    Would it be static ?Would it evolve with "time"?
     
  12. Jeeves Valued Senior Member

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    So much left for you to find out!
     
  13. geordief Valued Senior Member

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    Yes I am not quite sure what a 4D spacetime volume would actually represent outside the mathematics.

    I doubt it would represent anything "real" as we don't know whether the Universe is bounded or not (and a volume would have to be bounded by definition,I imagine)
     
  14. Saint Valued Senior Member

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    astronomy says the universe is expanding faster than light, how do they know?
    what we see is light, if the space is expanding faster than light, then its real size must be bigger than what we can see.
     
  15. geordief Valued Senior Member

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    They would know** if they observed a Galaxy receding from us at almost the speed of light and then they observed that it had disappeared (because its light could no longer reach us)

    What I have bolded in your question is true.We only see the observable Universe and do not know what lies outside it.

    **the scientific method is verified prediction
     
  16. Michael 345 New year. PRESENT is 72 years oldl Valued Senior Member

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    My understanding is that that is not the case

    If we consider, the light heading out in the direction of travel by the Galaxy, this only results in the Galaxy moving into the light it has emitted. The light emitted out the back of the Galaxy still travels at light speed to us

    The Galaxy does not drag light ,emitted in the opposite direction from its direction of travel, behind itself as it recedes away from us

    The only light not reaching us would be light from any Galaxies already out front from the furthest we can see

    Also suspect that Galaxies are not traveling faster than light, the anomaly a defect in observation data

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  17. geordief Valued Senior Member

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    I suspect you are wrong but it would be foolish for me to argue the point from my sketchy understanding of the situation as a whole.

    But ,just to clarify what I was trying to say ,an observer might observe (via redshift ,I think) a Galaxy receding at just under the speed of light.

    Some (=very many years) later another observer might notice that that Galaxy was no longer to be seen and so conclude that that same Galaxy had slipped from view as a result of its speed of recession having increased beyond the speed of light.

    I think that is the current mainstream understanding as I have heard it,anyway.
     
  18. Michael 345 New year. PRESENT is 72 years oldl Valued Senior Member

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    Agree and would be foolish of me to argue my view from my sketchy understanding (dueling cosmologists?)

    Stay tuned

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  19. Saint Valued Senior Member

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    in this case we would not know the exact size of the universe, then why scientist says the universe is 13.8 billions years old?
     
  20. geordief Valued Senior Member

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    There is no connection between the estimated age of the Universe and the estimated size of the Universe that I know of .
     
  21. Michael 345 New year. PRESENT is 72 years oldl Valued Senior Member

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    I understand that they can calculate the distance of the most distance Galaxies from Red Shift and Hubble Constant

    https://www.cfa.harvard.edu/~dfabricant/huchra/hubble/

    Then from know of the speed of light calculate how long it has taken for the most distant Galaxies to reach us = Universe age

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  22. geordief Valued Senior Member

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    Confusing if we do not specify if we are talking about the observable Universe or if we are also including the Universe that we cannot see because it's light can no longer reach us.

    But I think you may think that is a false distinction,Michael... (Saint seems to have accepted it)

    Yes,I think we can probably calculate the age of U from observations of its observable part but (self evidentially ) not from its non observable part.
     
  23. Michael 345 New year. PRESENT is 72 years oldl Valued Senior Member

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    Sorry I don't follow how "light can no longer reach us"

    Can you explain how that works?

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