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Big Bang Bubble?

  1. May 8, 2003 #1
    When there is an explosion on earth the void created is quickly filled with earth debris. When we view an exploding star there is no debris (understandable) but there is a large bubble with a void in the middle. Why is the universe NOT shaped like a large bubble with a void since the accepted theory is that it was created with a big bang? Note: Since the expansion is still going on then there should be no debris falling inside the bubble.[?]
     
  2. jcsd
  3. May 9, 2003 #2

    russ_watters

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    Because the Big Bang wasn't an explosion. What was it? It was the Big Bang.
     
  4. May 9, 2003 #3
    Not an explosion?

    If it was not an explosion then why is everything moving away from everything else? Why is there a controversy about it recollapsing on itself? Why is it called a "bang"? What else is a bang?
    You haven't answered a question; you have elicited more.
     
  5. May 9, 2003 #4

    Eh

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    Big bang was an insult made by Fred Hoyle, who was a proponent of the steady state model. For some reason though, the name stuck. And here we are.

    The problem seems to be that the big bang was not an explosion of matter into empty space. Rather, the void itself is expanding, and the BB is the beginning of this expansion. It may help to think of a grid, with galaxies drawn throughout. The galaxies are not flying apart in the background of this fixed, unchanging grid, but the grid itself expands and may eventually contract.
     
  6. May 9, 2003 #5

    russ_watters

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    Re: Not an explosion?

    Yeah, I was lazy and Eh covered it. Good explanation.
     
  7. May 9, 2003 #6
    Colgate University info

    Thanks Radio Wave and also you Infrared Wave for enlightening me.
    In the interim I found a good explanation on the Colgate University site. They compared it to a cookie with raisins; as the cookie expands the raisins move apart. I can understand the analogy but it doesn't explain why some galaxies and other objects wander around in the universe and even sometimes collide.
    My bubble concept seems dead but a rapid expansion to me still describes an explosion. BANG !
     
  8. May 9, 2003 #7

    russ_watters

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    Re: Colgate University info

    There aren't any galaxies that "wander," but there are "local groups" of galaxies that move in relation to each other. We are part of a local group of galaxies that are far closer to each other than the next closest galaxies.
     
  9. May 9, 2003 #8
    Collisions.

    I understand local groups but that just means that they are closer to each other than to other galaxies and groups, and bound by mutual gravity. There are still collisions of galaxies with other galaxies and collisions of other objects with each other so there is movement other than away from each other. All objects do not move on a radii from some central point. We have also recently discovered "planets" that are considered to "wander" rather than being a part of a "solar" system; and of course we have asteroids and comets that get perturbed from orbital paths from time to time.
    So everything is not frozen in an expanding position (how's that for an oxymoron?) with relation to each other.
    I believe that over "astronomical eons" that we would find that there is a lot of lateral movement that is unaccounted for.
    Sidebar: Have two groups ever been known to collide or merge?
     
  10. May 9, 2003 #9
    Hey how's the grid expanding? I thought there were blackholes absorbing things, doesn't this shrink the size? And it's not like I didn't listen to chroot when he said that the blackholes expand after sucking stuff in. But that would make the even bigger right? So that'll cause more things to get sucked in, right? [?]

    Can a black hole contract? Maybe there was once this huge black hole that sucked everything in over a lloonnng period of tim. And then it started collasping because there was nothing more to suck up, however all the previous matter was still within in. So then it was kind of like compaction within the hole and the gravity inside it just kept compacting and building stress, until...BOOM! the Big Bang! hehehe ^_^ do you think that's possible?
     
  11. May 9, 2003 #10

    russ_watters

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    Black holes really aren't much different from any other massive object - they are just massive enough (dense enough) that light can't escape. If you compressed our sun into a little black hole without changing its mass, the orbits of the planets around it wouldn't change at all.

    The expansion of the universe is a separate issue. The universe isn't a "thing" its just empty (more or less) space. And the empty space is getting bigger. How do we know? Because as discussed in wyzowl's other thread, everywhere we look, everything we see is moving away from us at high speed. And if we map those objects, we see that every object is moving away from every other object at high speed. The only possible explanation for this is that space itself is expanding.
    Well thats just it - there is no central point. Like the cookie in the other thread (better yet, a balloon with dots on it that you are blowing up) everything is expanding away from everything else - except when things are already very close together. Also, we don't have the capability to see any planets beyond about 50 light years from us. When talking about the expansion of the universe, its not observable within our own galaxy only between galaxies not within our local group.

    Some scale (distances from earth):

    The Sun: 9 light minutes
    Pluto: 4 light hours
    Center of Galaxy: 25,000 light years
    Nearest local galaxy: 80,000 light years
    Andromeda Galaxy: 2.5 million light years
    Diameter of the Universe: 20 billion light years

    With the Hubble space telescope, we have been able to determine that there are roughly 100 billion galaxies in the universe. In accordance with the description above, if you point the Hubble in ANY direction, you see the same thing: lots of galaxies
     
    Last edited: May 10, 2003
  12. May 10, 2003 #11
    Expansion, yes.

    It is accepted that our solar system is receding from VIRGO so expansion is not limited to just galaxies. It is also assumed that "space" contains a force that is probably causing the expansion. I think of it as negative gravity but that is just my way of understanding it.
    I was corrected when I compared the expansion to the skin of a balloon; and rightly so. However, if you recall I was chastised for calling the big bang an explosion but in my recent research, prompted by chroot, I note that it is commonly referred to as an explosion.
    But let's return to the issue of objects that are not travelling in an "expansion" route but are moving in independent fashions throughout the universe. Have their motions been perturbed by collisions, by massive gravity forces, or by some other force? Maybe their direction is caused because they were thrown off of a developing object that was too loosely composed. (Bad sentence structure.)
    Sidebar question: Galaxies and solar systems are disc shaped due to rotational forces. Is the universe disc shaped; or do we know?
     
  13. May 10, 2003 #12
    I don't even see how can we find out whether it is or not because it's not like it has a boundary. I mean if we reach the edge of the universe somehow, would we even be able to know that that's the edge? Ooo...that's scary..it's almost like infinity, lol
     
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