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B What is "space"?

  1. Jun 5, 2016 #1
    Hi. This may seem a straightforward question, but I'm not sure given some of the threads about expansion, infinite universes, and multiverses. How about I make a statement, and you folks shoot it down? Space is nothing. It is the absence of all particles and energy. It is infinite and timeless. The Big Bang occurred within this Space. Multiple Big Bangs have and are happening beyond our observation sphere.
     
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  3. Jun 5, 2016 #2

    PeterDonis

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    You haven't asked a question in your post. You've made statements, at least some of which look incorrect.

    If your actual question is the one in the title of this thread, it's much too vague. In what context are you looking for some meaning of the term "space"?

    Again, your statements, while they look incorrect, are too vague to be "shot down" in any productive sense. You need to be more specific about the context in which you are looking for a meaning of the term "space".
     
  4. Jun 5, 2016 #3

    PeterDonis

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    Also, btw, labeling a thread as "A" for advanced indicates that you have a graduate level understanding of the subject matter. That does not seem to be the case. I have re-labeled the thread as "B".
     
  5. Jun 5, 2016 #4
    Hi Peter. I have a PhD. While you say my statements are incorrect, you don't say why. Just that they are vague. Let me try again. I often hear that the Big Bang created Space. Did it create it or occur in it? If there could be multiple big bangs creating multiverses, what is between them?
     
  6. Jun 5, 2016 #5

    russ_watters

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    In what? Not physics, astronomy or any other field related to this topic, I would assume...?
    Some don't really lend themselves to much of a "why". If you point at something that is blue and I say it is red, is there a "why"?

    For example, space is not believed to be infinite.
    ....the big bang created space. What you "often hear" was correct....

    It would really be better if you just tried to learn correctly reading about this instead of learning by guessing things that may be wrong. Try starting here:
    https://en.wikipedia.org/wiki/Space
     
  7. Jun 5, 2016 #6

    PeterDonis

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    Yes, vague as in too vague to even be able to say why they are wrong. In Wolfgang Pauli's phrase, they are "not even wrong".

    Please give an acceptable reference--a textbook or a peer-reviewed paper--that says this. Just saying "I often hear" or giving a pop science reference like a book or TV special for lay people is not enough.

    Same comment.
     
  8. Jun 5, 2016 #7
    How would one answer a question like that? We currently cannot witness a big bang, and although theories say that there is a multiverse, (in order for some theories to work) we cannot definitively prove something like that unless we can venture "outside" our own universe take measurements (assuming the universe is not infinite, assuming we can actually even get far enough in a plausible amount of time and assuming our spacecraft travels faster than the current expansion of the universe).
     
  9. Jun 5, 2016 #8
    If each universe has it's own space, there is no space between them. They have their own space. That means that no matter how far you travel in space, you will never reach another universe if that universe is in a different space from ours.
     
  10. Jun 5, 2016 #9

    Drakkith

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    Well, here's the opening paragraph from wiki's article on space:

    Space is the boundless three-dimensional extent in which objects and events have relative position and direction.[1] Physical space is often conceived in three linear dimensions, although modern physicists usually consider it, with time, to be part of a boundless four-dimensional continuum known as spacetime. The concept of space is considered to be of fundamental importance to an understanding of the physical universe. However, disagreement continues between philosophers over whether it is itself an entity, a relationship between entities, or part of a conceptual framework.

    There's no real way to know for sure at this point, but it is a possibility.
     
  11. Jun 5, 2016 #10

    Fervent Freyja

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    And? Your declaration is reminiscent of when my nephew was 9 years old and got a few big bangs upside his head...

    The term space is inappropriate to use for any condition outside of the Big Bang, it couldn't be considered spatial or ever be observed and should remain unnamed. The term space implies there is a distance to begin with, which must also have a position and direction. So, using the word "nothing" to define space is incorrect.

    Your starting line of thinking is common when children try to understand the Universe. It doesn't mean anything. You need to go further than that. Starting out with speculation about other Universes without getting deeper into more confirmed facts first isn't going to help either, it doesn't matter if there are others. Let's try to understand more about our own first.

    Which Big Bang Model are you looking at? Look at that.
     
  12. Jun 6, 2016 #11
    here's a monkey wrench. if space-time itself is "expanding", doesnt by that definition alone mean that space-time boundaries are finite. something that is already infinite cannot be observed to be expanding. an infinitely large balloon and you add some more air is still infinite, thus no reference to observe an expansion.

    i no scholar in this area, but some things on basic terms dont add up for me.

    we could in fact be observing "stuff" within the ~13.7 billion light year distance limits, but perhaps space-time is finite but magnitudes bigger than 13.7 billion light years, this would skew our conclusions and space-time would appear to be infinite ??

    how abut this, since some of our observations of deep space is from light sources that are now dead, maybe some of these deep space observations are of light that has been reflected from some bizarre cosmic mirror?

    my personal philosophy is this. we dont really know too much about our own solar system, we constantly make corrections to what we know in this small distance. in doing deep space observations and making conclusions likely means magnitudes bigger corrections to come. as much as we "know" about deep space its all just a big guessing game at this point. is there life elsewhere? math says yes, observations thus far have not proven that math to be correct. Hubble can see almost to the edge of 13.7 billion light years, but if we turn Hubble to stuff much closer we cannot find "life" beyond this planet.
     
  13. Jun 6, 2016 #12

    jbriggs444

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    It is enough that every "stationary" point gets farther from every other "stationary" point. One need not have an edge-of-the-universe to have expansion in this sense.

    The remainder of the previous post seems to go off into speculation and philosophizing.
     
  14. Jun 6, 2016 #13

    Drakkith

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    There's too much hostility in this thread to keep it open. PeterPendragon, in the future I recommend asking questions instead of making statements to be shot down.

    Thread locked.
     
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