ALMA sees old galaxies before they merged. two ways to look back into the past?

Discussion in 'Alternative Theories' started by nebel, Dec 8, 2017.

  1. Seattle Valued Senior Member

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    3,483
    Time goes on even in an infinite universe. Where do you get any evidence that there is no time nor space?
     
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  3. Write4U Valued Senior Member

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    But that would alter our definition of the universe as we know it, wouldn't it? How could we speak of an expanding universe if it were already infinite in size?

    A Hilbert Hotel model?
     
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  5. Seattle Valued Senior Member

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    That has nothing to do with your comment about their being no time or space.

    I don't know anything about a Hilbert Hotel and I have no comments about infinity. The evidence that we have is limited to the Big Bang and red shifting being explained by expansion.
     
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  7. Write4U Valued Senior Member

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    I understand that.

    But it is the conflict between the estimated time of the BB and the estimated size of our universe (spacetime) which confuses me.

    Trying to think this through, I recalled the Hilbert paradox also known as the Hilbert Hotel.
    https://en.wikipedia.org/wiki/Hilbert's_paradox_of_the_Grand_Hotel

    Perhaps this may not have any bearing on our discussion, but somehow it seemed to present a similar paradox. I am really interested in any comment.
     
  8. Xelasnave.1947 Valued Senior Member

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    Should I interpret that to mean our universe is finite?
    Alex
     
  9. Xelasnave.1947 Valued Senior Member

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    5,013
    You can add or subtract from infinite yet it will remain infinite.
    A finite Universe expanding would seem difficult as well I mean the first thing someone asks here is what is it expanding into.
    There is only one way to sort it out.
    Can you hold this end of my tape measure while I check?
    Alex
     
  10. Seattle Valued Senior Member

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    We don't even know if the concept of infinity has any bearing on reality so it's a little hard to discuss. I don't really (without any evidence) buy that concept.

    I don't know why you have any problems with the time since the Big Bang (approx. 14 billion years) and the estimated size of our visible universe. No one is estimating the size of the entire universe so you can't have any problem with that.
     
  11. Write4U Valued Senior Member

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    In context of age it would seem so.
     
  12. Seattle Valued Senior Member

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    I don't particularly have a problem with the concept of a finite expanding Universe. I don't know that asking what it is expanding into is necessarily a question with any meaning.

    That "might" be similar to asking what happens when you get to the end of the Earth.
     
  13. Write4U Valued Senior Member

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    8,186
    I don't, but then how can we tell the age of our universe as a separate object created by the BB ?

    Perhaps the universe has always been an infinite timeless condition (nothingness), and the BB was the release of pure energy from a singularity which became responsible for an expanding volume of matter which we named "the (our) universe" and given it the properties of "spacetime"?
     
  14. Xelasnave.1947 Valued Senior Member

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    5,013
    I don't ask it but I have seen it asked on many occasions.
    We all know the answer ... There be monsters and past them you fall off the edge of course.
    Back to the first part.
    A student asks you " Sir, what does the universe expand into?"
    Can you give an answer without involving a flat Earth.
    Alec
     
  15. Seattle Valued Senior Member

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    3,483
    My answer would be the same as my response here. I don't know, and it might be a question without meaning. There might not be anything outside of the Universe so that question might not have meaning.

    There may be no meaning to the question, "What came before the beginning of our Universe" (if there was a beginning).

    Sometimes you just have to deal with what we have evidence for and say "I don't know" for the rest.
     
  16. Seattle Valued Senior Member

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    3,483
    Again, you seem to be conflating two things.

    Your second paragraph is conjecture as to what was before the BB. Great. No one knows the answer to that at the moment. That's why we start with the BB.

    Your first question really has little to do with the second question. You ask how do we know how old our Universe is (since the BB). My understanding is that it is just the physics involved and predictions that we now have evidence for.

    The short answer is the CMB (Cosmic Microwave Background). The BB made certain predictions and those were born out. Starting out with how hot the Universe was and how cool it should be today and how that initial radiation would be distributed results in the current age of our Universe.
     
  17. NotEinstein Valued Senior Member

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    1,582
    So you agree that when you wrote "The illustration is looking at the universe from a side view" (post #7) and "from an observation point outside the universe" (post #9), that was non-sense. OK, we agree there.

    That is not a response to my statement.

    Of the visible universe, yes. But that only sets a minimum bound on the size of the total universe. If I am standing in a closed room inside a building, I have no way (in general) to determine how large the building is; I can only set a minimum size for it (namely, the size of the room).

    (You had a quote in your post that wasn't mine, seemingly attributing it to me.)

    Wrong; the OP doesn't mention any center at all; that was you in post #3.

    A white hole is not "another dimension"; please learn what a dimension (in physics) is.

    Again, it was you bringing up the "center of a 3D sphere", not anybody else.

    Yes, the ekpyrotic theory of brane cosmology is interesting, but at the moment, it's merely a hypothesis. Unless branes were explicitly the topic at hand, I would stick with standard cosmology.

    Ah, OK, understood. Note that this is not possible in practice, due to the finite speed of light. In reality, the further out we look, the further into the past we observe.

    Nobody in this thread is making that assumption but you.

    The visible universe is (roughly) spherical, and has an obvious center (us!), but the universe itself doesn't. Please stop confusing the two!
    No, that's not an assumption; please look up what an assumption is. Saying "we don't know if X" (truthfully) is not an assumption of any kind.

    It certainly is! But it's quite speculative at the moment, and it seems weird to introduce such a speculative idea in response to the OP. In fact, it's quite irrelevant to answering the OP, so I'm not sure why you even brought it up.

    That's irrelevant to what we were discussing. Seattle explained it to you in post #30: do you understand what (s)he said there resolves your issue, yes or no?
     
  18. Xelasnave.1947 Valued Senior Member

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    5,013
    You have the correct answer.
    So few, actually just you and me, can provide such an honest answer.
    Alex
     
  19. Write4U Valued Senior Member

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    I agree we need to work with what we know, but IMO, it is never too late to ask questions or offer another approach that may shed new knowledge from a different perspective.

    If Galileo had not questioned Aristotle about his theory that heavier objects tend to fall faster then lighter objects, which is true on earth but with false proof, but was corrected (expanded) by Newton's Law of falling bodies, which is a universal phenomena. Even so it took about 2000 years for this "correction" to be made..
     
  20. Write4U Valued Senior Member

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    8,186
    The theory that spacetime (our universe) is limited in age and size.
     
  21. nebel Valued Senior Member

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    Thank you for all your replies, While I did not directly mention a center, it was implied, since in an expanding universe, there would not be two path in opposing directions to any event, or would there? We are all still in the center, it looks that way! and so is everybody else, from their viewpoint!?
    Is my misunderstanding really about the expansion rate versus the speed of light?
    What is the universe expanding into? how about into time, if that is a fundamental 4st
    dimension?
    ranting: if there was a point in time at the BB, there was a small center, that has now expanded to the confines {perimeter}of the universe. so we were both at the former center and are all now the extreme reach?
     
    Last edited: Dec 11, 2017
  22. Write4U Valued Senior Member

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    8,186
    Or a timeless pemittive condition? A nothingness which creates it's own Imperative, such as a vacuum that demands to be filled, even as that demand creates a dynamic singularity.
    Good and logical questions, IMO. In a multiverse, where each separate universe is created by a similar event as the BB, each universe would have it's own center from which that universe expanded, would it not?

    Can you have a multiverse inside our universe ? If not, then how could other universes begin? Don't we call those smaller universes inside our universe Galaxies?

    Simultaneous creation of a multiverse is a possible answer, however those universes would still be in apart from our universe, no?
     
    Last edited: Dec 12, 2017
  23. Xelasnave.1947 Valued Senior Member

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    No we call them galaxies. However before galaxies were understood they did refer to them as " island universes".
    Alex
     

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