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Dark energy and the big bang

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  1. Apr 24, 2012 #1
    Has anyone thought about the big bang and dark energy like this?

    Dark energy is simply empty space which has the opposite affect of gravity. Put simply, stuff is attractive. No stuff is repulsive. Or, gravity is to mass as repulsion is to empty space.

    I think that the bigbang had enough energy to put enough empty space between mass that dark energy takes over. The more empty space between particles the more repulsion. Thats why the universe is expanding.

    What if you had two adjacent big bangs? Eventually large portions of these big bangs would collide with other. I imagine that at these overlap areas, gravity would start to take over agian since in these areas empty space would be getting less and less. Maybe this is how a big bang starts. An entire portion of the universe collapses under its own gravity...bang! Maybe there have been countless big bangs. Maybe thers big bangs going on right now far far away.

    What do you think? Does any of this hold true to actual science?
     
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  3. Apr 24, 2012 #2

    Chronos

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    That is the basic premise of eternal inflation, which is amusing, but, lacks any real observational support. But, then again, these other big bangs are causally disconnected from our universe, so, its no big surprise. Its kind of like the refrigerator light fairy.
     
  4. Apr 25, 2012 #3

    bapowell

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    It seems like you've got some misconceptions about the big bang. It was not an isolated explosion that propelled energy and matter outwards from some central point. It was a uniform process that happened everywhere. Some form of vacuum energy could have taken over at some point (this is called inflation), but expansion happens just fine without it.
     
  5. Apr 25, 2012 #4

    Chalnoth

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    No, not really. Nobody has ever seen any evidence that anything remotely like a refrigerator light fairy might exist, and there is plenty of evidence that nothing like it can exist. We do, however, have evidence of one big bang event. So proposing other big bang events isn't remotely suspicious.

    A more reasonable analogy would be a person who lives his entire life in one small area of the Earth where a single mountain is visible proposing that there might be other mountains that he can't see elsewhere on Earth.
     
  6. Apr 26, 2012 #5

    RUTA

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    I don't know ... we haven't seen the big bang. Maybe modify it to say someone assumes the existence of a mountain over the horizon and out of sight to explain things like river flow or rain patterns in his one small area of Earth. Given its great explanatory power, he might suppose there are many of these unseen mountains on Earth, doing all kinds of explanatory work.
     
  7. Apr 26, 2012 #6

    Chalnoth

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    It really depends upon what you mean by "seen". What we can see, rather directly, is an early hot expanding universe. That's all you need for the analogy I posted to make sense. Many of the other details of the Big Bang theory aren't necessarily relevant to the analogy.
     
  8. Apr 26, 2012 #7

    RUTA

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    Yes, we can see the universe when it was only ~400,000 yrs old (cosmic background radiation from H recombination epoch), but that's nowhere near where all the action took place, i.e., within the first tiny fraction of a second. Thus, my modification to your analogy that the mountain is over the horizon and out of sight.
     
  9. Apr 26, 2012 #8

    Chalnoth

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    Why is the stuff that happened earlier important in this situation?
     
  10. Apr 26, 2012 #9

    RUTA

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    I thought we were talking about "seeing" the big bang, which is the initial singularity proper. Since we can't see that, where would one be satisfied with drawing the line? Well, most of the interesting stuff took place well within the first second (you already have four forces at 10^-12 s). So, it seems to me that if one is talking about "seeing" the big bang, one should at least get to within that first second.
     
  11. Apr 26, 2012 #10
    So the bang wasnt like a firecracker. Was it more like rising dough or something? How big was the thing that went bang?
    your calling the big bang a uniform.event that happened everywhere. Is that because of that background radiation stuff being in everydirection we look?
     
  12. Apr 26, 2012 #11

    Drakkith

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    Nothing went "bang". The entire universe was extremely dense. Imagine the entire observable universe being squished into a pinhead or smaller. (Perhaps infinitely dense, but i cannot explain it well if we say it was infinitely dense) There is still an infinite amount of space everywhere, and it too is full of this super dense beyond all belief material. Now, for some reason, it appears that the universe began to expand VERY VERY rapidly. In the course of a billionth of a billionth of a billionth of a second, the universe expanded by a trillion trillion times. So our pinhead that represented our entire observable universe is now the size of the Earth or so, and any other adjacent areas that used to be the size of a pinhead are also now about the same size as the Earth, along with areas of space adjacent to them, etc. Around this point this expansion, or "inflation" as we call it, stopped and our universe expanded at a much lower rate. This is the "big bang" event.
     
  13. Apr 26, 2012 #12
    I think my idea still might hold water if we assume that the dense early "universe" is not infinately large. Cant prove either way. I just like to think about it in a way I can get my head around. Although in the end I still have to get my head around infinate space. I guess my idea just helps me wrap my head around where the BB came from.
     
  14. Apr 27, 2012 #13

    Drakkith

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    Even in a finite universe it is thought that there are no boundaries. IE you can travel forever and never run into a "wall". Instead you would simply end up back where you started. In such a universe the Big Bang still happened everywhere in the universe at the same time.
     
  15. Apr 27, 2012 #14

    bapowell

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    Yes, to expand on what Drakkith says, you don't need to picture an infinite universe to get a handle on how the big bang really happened. And you are correct, we don't know whether the universe is infinite or not. You can work with a finite universe, say a closed one, in the shape of a sphere. The big bang in this case is best described via the balloon analogy (which is a lower dimensional analogy) in which the inflating balloon simulates the expansion of the universe. In the case of the real universe, everything exists on the surface of a 3-sphere -- there is no outside or inside.
     
  16. Apr 27, 2012 #15

    RUTA

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    The BB didn't come from anywhere. That's like asking what's north of the north pole.
     
  17. Apr 27, 2012 #16
    [there is one thing for sure ...dark matter was here first... the big bang occured in to it ..../SIZE]
     
  18. Apr 27, 2012 #17

    Chalnoth

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    Uh, what?
     
  19. Apr 27, 2012 #18
    I cant help it, Im not going to look up the numbers or do any sourcing here but some of the approximations appear wrong. As I remember the theory goes... In the beginning all 4 forces (gravity, electromagnetism, weak nuclear, strong nuclear) were unified in a primordial atom of infinite heat and infinite density. In the first fraction of a second, on the order of 1/80b, gravity broke free and the universe expanded to about the size of a galaxy before the other forces broke free also some fractions of a second later. Things stayed pretty boring for the next 350,000 years as the universe remained too hot for atoms to form while expanding. Its theorized that hydrogen and helium began to form after this time. Inflation basically describes the period of time when the laws of our "now" were not in effect and allowed the universe to expand faster than the speed of light.(short version) When examining the 4 forces, gravity seems to be allot weaker than it should. For gravity to hold galaxies together, more matter is needed in most(all?) models, and gave rise to the theory of dark matter. My memory isnt perfect but I believe this to be pretty close.
     
  20. Apr 27, 2012 #19

    Drakkith

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    If you are going off of my times and sizes in my earlier post, those are simply approximations to put it in perspective.
     
  21. Apr 27, 2012 #20

    phinds

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    This is a great forum for getting help in understanding actual physics, but posts of utter nonsense (such as your statement) are not very well tolerated.
     
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