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Did the big bang create space or time?

  1. May 13, 2010 #1
    Forgive me if this question is very basic but I have trouble finding a clear answer on it. In the big bang theory did space and time exist before? or was it created during?

    thanks
     
  2. jcsd
  3. May 13, 2010 #2

    mathman

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    In the simplest version of the big bang theory space and time originated with the big bang. However there are many ideas out there (multiverse, brane, etc.) where there was something before the big bang.
     
  4. May 14, 2010 #3

    Chalnoth

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    One way of saying it is that our space-time originated with the big bang, but there's no reason to believe that there wasn't quite a lot of stuff that came before.
     
  5. May 14, 2010 #4
    I always took it to mean that space and time were not necessarily created in the big bang, but they were so distorted and wrought out of shape by the initial singularity that they were not meaningful concepts 'before' the big bang occured.

    Of course, we'll probably need a theory of everything before we can do more than speculate in this area.
     
  6. May 14, 2010 #5

    Chronos

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    In the quantum fluctuation model, time and space were emergent properties of the universe in BBT. Matter was the late arrival, crashing the party.
     
  7. May 14, 2010 #6
    The way I understand is this: in order to explore the moment of the big bang we need a quantum theory of gravity. We dotn have an accepted theory yet. We have candidate theories, eg LqG and strings , all of these suggest a pre big bang universe as does eternal inflation
     
    Last edited: May 14, 2010
  8. May 14, 2010 #7
    I have kind of a secondary question along the lines of this topic: If the BBT did in fact create space and time, then what happened one second before the Big Bang and what exists one inch outside our universe?
     
  9. May 14, 2010 #8
    As i understand n LQG the there wss a previous univers that ours bounced from, in strings theory the universe exists in a larger structure called the bulk and our universe was created by two membrames colliding within the bulk In eternal inflation there are lots of bings bangs creating lots of universes, Penrose now has a theorom that also has a cyclical universe. Perhaps with new gravitational wave measurement we might be bale to desitnugih between these ideas but at the moment we cant. But inflation does have good observaitonal support,so thats where my moment is on at the moment.
     
  10. May 14, 2010 #9

    Fredrik

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    Since the big bang theory is a part of general relativity, I assume that you would like to know how general relativity answers your questions, but "outside" and "before" are both undefined concepts in the theory, so there's not even a meaningful way to ask the question.

    I would disagree with the claim that the big bang created space and time. GR doesn't say anything about "creation". It just describes a relationship between how things are distributed in the universe and how things will move.

    These are two of my posts about this that might clarify a few things: 1, 2.
     
  11. May 14, 2010 #10

    phyzguy

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    The simple answer is, nobody knows the answers to these questions, and nobody even knows if these are meaningful questions to ask.
     
  12. May 14, 2010 #11

    Chalnoth

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    Basically, these questions are completely meaningless in that situation. If time started with the big bang, then asking, "What happened before the big bang?" is equivalent to asking, "What lies north of the North Pole?" The same goes for asking about the space outside of our universe.

    Note, by the way, that neither statement precludes the possibility that there are other things out there, it's merely a statement that if they are, they are disconnected from our universe.

    With what little we know of how quantum gravity works, this can be made sense of in the following manner: consider, first of all, our observable universe. Now, what is the Schwarzschild Radius of a black hole with the mass of our observable universe? If you do the calculations, you find that the Schwarzschild Radius of the stuff within a Hubble radius is actually the Hubble radius itself. However, our observable universe is larger than a Hubble radius, and the way that these things scale makes it so that the Schwarzschild Radius must then be larger still. Put this together, and it's a statement that if our universe could possibly be observed from the "outside", it would look like a black hole.

    In fact, this simple statement must have been true from very early times, because it's a statement about the geometry of the universe: a universe with a Hubble radius equal to the Schwarzschild Radius of what it contains is a flat universe. And if our universe is flat today, it had to be flat at very early times as well. But back then, our universe was vastly, vastly smaller than it is today.

    From the outside, then, if our universe was born from some other space-time, it would have looked like a tiny black hole. From the inside, we know this led to a growing, expanding universe that got more and more massive as time went on. But from the outside, from what we know of quantum gravity, we know that black holes don't act like this: black holes decay. So if our universe was born from some other space-time, it would have started as a black hole, but very rapidly decayed away into nothing.

    This doesn't mean that our universe disappeared, but rather that it must have sort of "split off" of its parent space-time. You might think of the parent universe as being a large rubber sheet that is sort of randomly wiggling and waving around. Every once in a great while, one of these wiggles gets tight enough that it sort of twists and pinches off a part of the sheet, and that new part grows to make its own universe, but necessarily is disconnected from its parent: you can't get there from here (or vice versa).
     
  13. May 14, 2010 #12
    This "other stuff" that is not part of our universe, what does it mean to say it came before or after or east or west. Your statement presupposes a "container" space and time which preexisted our spacetime. As long as there are no possible measurements between the two supposed spacetimes these statements are meaningless. And if there is a causal connection between a universe which crunched and then banged into our universe isn't it all just different "phases" of the same universe?

    Skippy

    PS I am not disputing that there might be "other stuff", just any statement about its being "before".
     
  14. May 14, 2010 #13

    Chalnoth

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    Well, fair enough, but in this case we'd have to use time as seen from the "outside" if our universe was indeed born from a parent universe. That timeline would be disconnected from our timeline, but in it we could rather sensibly talk about what came before.
     
  15. May 14, 2010 #14
    For what it is worth, I dont believe in the big bang theory as being the beginning of the universe or time. Certainly there was a very large event and as for time, it is a measurement of motion I think. If time stood still as it is said, that was when the universe and time began in regards to the big bang, the big bang could not have occurred as time standing still is still time, therefore time existed. It seems to me to be a paradox. This is a great subject!!
     
  16. May 15, 2010 #15
    Just because a closed system or structure cannot answer this question does not make it meaningless. It just means that the system must be developed and/or enhanced to better address these questions... not hinder them entirely. The phrase 'What's north of the North Pole?' may be quite catchy, but it has no relation (aside from the presenter's influence) to the fundamental dynamics of space and time themselves. The majestic expanse of physical reality need not conform to man's theories and philosophies...
    The big bang was an effect and we all know that every effect has a cause for a source. Just like the hippies used to say; Everything happens for a reason! Now a certain frame of time MUST elapse for the cause to occur to initiate the effect and not only that, but time must also pass from the cause to the effect or the effect cannot come to pass.
    Just like to be able to assume that our universe is expanding, we must admit that there is something beyond or outside of it... something for it to expand into.
    To suggest that time (or any dimension) has a beginning, you must accept that there must be an end. But to avoid your 'north pole' trick by setting time in motion already (throughout all of existence, universe and beyond) Now let's ask the question, "What happens one second after the end of time? Or even better yet, how could time even possibly end?" Will everything just freeze-frame and be paused for the rest of eternity?

    Im sorry, but it seems to me that the mere implications of (a) finite measure of dimension(s) surfaces just too many paradoxes and conundrums to be able to logically exist in our physical reality. It may make for some wild and exotic notions for theoretical physics, but ultimately- it doesn't make much sense in the real world. (beyond the chalkboard)
     
    Last edited: May 15, 2010
  17. May 15, 2010 #16

    Chalnoth

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    The difficulty here is that the question is in the first place asked in the context of terms which we talk about within our own universe. It is exactly like asking, "what is north of the north pole," because the terms which we use to describe the space-time of our own universe just can't get us out of our universe, no matter what hypothetical thought problem you might think of to do so. This is because, from what we understand, it appears that anything that lies beyond our universe, that is anything that didn't come from the event that precipitated our universe, is actually physically disconnected from us. Disconnected in the same sense that you can't walk to the Moon from the Earth.

    In order to talk about the location of other such regions in relation to our own universe, you'd first have to consider something outside of our own four dimensions of space-time. And even then it might not actually be possible due to the nature of gravity.

    Nope. There is no such rule. Quantum mechanics appears to routinely violate it, in particular.
     
  18. May 15, 2010 #17
    Please correct me if I am wrong. We can only see light today that is approximately 18 billion years old or so. I do not believe that our universe is finite. Time, gravity are laws we know of today(quantum mechanics I believe will have laws someday). The big bang was in my opinion two massive galaxies in a pre-existing universe colliding, fracturing their massive black holes. These Fractures (cracks or slits) are to me similar to diffraction (which fits nicely into the universal wave theory and what we know about photons) in the sense which the contained conserved momentum stored in these giant black holes blasted out of creating waves and changing that existing portion of the universe and who knows what else we can identify today. I don not believe this can be proven wrong, but that does not prove it is right either. I would argue that the two giant galaxy theory is provable and is supported by all the existing evidence we have today. (please note that there may have been other galaxies as well that did or did not collide) As for time, this event may have also changed time as well.
     
  19. May 15, 2010 #18

    Chalnoth

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    13.7 billion, but it doesn't make a difference here.

    Well, I think it's likely that our universe was started from some other space-time, but that doesn't mean that our universe isn't finite. Our universe certainly had a beginning, about 13.7 billion years ago.

    Er, why don't you think we know about quantum mechanics today? And by the way, I'd like to point out that in science, there isn't a clear distinction between "law" and "theory". One is not more certain than the other. It's just that "law" usually refers to a simple relationship, while "theory" usually refers to a more encompassing explanation. If we find a theory of everything, and find convincing evidence that it actually is accurate, then if the current terminology holds, we'll call it a theory, not a law.

    There's no reason to believe any such thing. This is pure speculation.
     
  20. May 15, 2010 #19
    Chalnoth, Thank you very much for your great input. I will try to find the NASA info regarding how old the time we can see is, I remember it was updated a year or so ago from the 13.7 billion years, however as you stated, it really does not matter. Every single thing I have found on the single big bang can be applied to this theory as well, everything! I agree with you on theory as opposed to laws whereas I was over simplifying things. Virtually everything know about the big bang is also speculation or a stretch including what specifically caused the gamma rays and certain particles that are theorized to have come from the big bang. Black holes are thought of as giant galaxy eating lawless tyrants. I speculate the opposite, whereas black holes are trapped and caused by the galaxies cyntrifical forces and gravity that surround them, somewhat like a tornado, where as the eye is trapped by the tornado itself. One fact that is important, in fractal geometry, is how small a fraction can be is infinite. Therefor logically how big the universe is, can be and is most likely infinite as well. Can anyone show where the universe ends or an edge of the end anywhere? I have not found that in any published document ever. Why cant the universe be star and gas storms just like tornados and clouds forever changing, that which we call galaxies with a storm eye (black hole) that is calm? That seems to me that is a much better fit and more logical than the big bang and a single beginning of time and space. But I appreciate input/facts/theories and have an entirely open mind to any facts and input.
     
  21. May 15, 2010 #20

    apeiron

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    Agreed that this is one possibility. But another way of looking at it is as a phase transition. So before the big bang, dimensionality itself was in a vague state of orientation. Dimensionality had maximum symmetry because it pointed in all directions, so to speak. Then that symmetry broke and the "whole" of what previously "existed" became organised into a 3+1D cooling and expanding spacetime.

    So if we could head north of our big bang origins, we would see not a global rubber sheet spawning many local universes as events, but just a vagueness of spatiotemporal dimensionality, more like an infinite dimensional quantum foam.

    @ Fredrik: The big bang may seem like an extrapolation of GR, but QM is what many use to speculate about the origins of things. And I see no reason not to throw thermodynamics at the problem too. My view of how a foam of possibility actually could form itself up into a highly constrained broken symmetry of 3+1D is in fact based on thermodynamics (dissipative structure theory). So no need to limit ourselves to just GR.
     
  22. May 15, 2010 #21
    Anything bigger than an singularity consists of a infinite number of points on which a metric can be defined. Each point of which looks like flat spacetime in its immediate vacintiy. Without the effects of matter and radiation, there is no way to distinguish how big this universe is; it would just be a question of how close you are looking at it. So the question becomes why is a temperature associated with the velocity and energy of particles differ with the size of the universe. Somehow the size of the universe can be measured by the temperature of the fields within. How does a particle or field know how big the universe is? How do wavefunctions know what wavelength to vibrate at with respect to the size of the universe?
     
  23. May 15, 2010 #22

    Chalnoth

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    It's all about history. They don't "know" how big the universe is, but the change in the size of the universe affects local physics. Specifically, radiation is redshifted in proportion to the expansion. So what happened is some event in the past set up our universe as being extremely uniform, and from that everything you have written here immediately follows. What set up our universe as being extremely uniform was cosmic inflation.
     
  24. May 15, 2010 #23

    Fredrik

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    I'm aware that GR isn't the complete answer (and I mentioned that in one of the two posts I linked to), but I think it's appropriate to focus on what GR says about the big bang in answers here, because it's hard enough to explain that, and because most people who ask about it here clearly don't even understand what a theory is.
     
  25. May 15, 2010 #24

    apeiron

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    Good point but the planck scale determines that. The universe would have been born planck scale already. Infinitely small points would also have to represent infinitely high temperatures and energies.

    Why the planck scale was set at a certain size is another issue of course.
     
  26. May 16, 2010 #25
    The planck scale depends on "constants" of nature such as the speed of light, graviational constant, and h-bar. There is no reason to even suspect that these constants had the same value in the very early universe.
     
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