The Big Bang: Where Did It Happen?

Discussion in 'Astronomy, Exobiology, & Cosmology' started by Aladdin, Dec 15, 2011.

  1. AlexG Like nailing Jello to a tree Valued Senior Member

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    We pretty much do.

    That is, matter within the universe move in all directions, towards us, away from us, at various angles with respect to us.

    This is superimposed upon the general expansion of space, which tends to move every point away from every other point, but only manifests itself outside of the local galactic supergoup, at about 200 million lys. Closer that that we don't see expansion because gravity is stronger on that scale.

    There is no center of the universe. On the large scale, every point appears to be the center, because everything is moving away from it.
     
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  3. AlexG Like nailing Jello to a tree Valued Senior Member

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    Your astronomy dates to the middle ages.
     
    Last edited: Dec 16, 2011
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  5. AlexG Like nailing Jello to a tree Valued Senior Member

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    To refresh your memory implies you knew it once. That is obviously not the case.

    Nothing with mass can move through space at c or greater.

    However, the creation of more space between two objects does not impart any velocity to the objects. If enough space is created between them quickly enough, a photon from one object will never be able to reach the other object. Space is created faster than the photon, which is limited in it's velocity, can cover the distance. But the objects themselves are not moving through space at c.

    So, wl, how many times will this be explained to you before you get it? Or have you simply decided to deny it and claim that your ignorance is 'out of the box'.
     
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  7. CptBork Valued Senior Member

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    Yes, your picture doesn't correspond to the way it works in General Relativity. Here are the essential details: http://en.wikipedia.org/wiki/Friedmann%E2%80%93Lema%C3%AEtre%E2%80%93Robertson%E2%80%93Walker_metric

    So picture two arbitrary points on the lattice I mentioned, with coordinates \(x_1,y_1,z_1\) and \(x_2,y_2,z_2\) respectively. In the simplest Big Bang models, the physical distance between these points at time \(t\) is \(a(t)\sqrt{\left(x_2-x_1\right)^2+\left(y_2-y_1\right)^2+\left(z_2-z_1\right)^2}\). At time \(t=0\), we have \(a(0)=0\), so no matter how far apart the points might be on the lattice, at the initial moment of the Big Bang they are separated by zero physical distance, so one may say the entire universe was initially contained in a single point.

    Most Big Bang models assume that we're living in an infinitely large universe with an infinite number of stars, planets and galaxies. Naturally, we're only affected by those stars and planets whose light has had time to reach us since the initial Bang.
     
  8. Robittybob1 Banned Banned

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    I was trying to understand what I had read earlier which said a zero energy university means that the Universe is "flat" and they gave some geometric shapes that have a flatness about then. Obviously I have not yet got the concept right.
    http://en.wikipedia.org/wiki/Zero-energy_universe
    "Quantum fluctuation

    Due to quantum uncertainty energy fluctuations such as electron and its anti-particle a positron can arise spontaneously out of vacuum space but must disappear rapidly. The lower the energy of the bubble, the longer it can exist. A gravitational field has negative energy. Matter has positive energy. The two values cancel out provided the universe is completely flat.[not in citation given] In that case the universe has zero energy and can theoretically last forever.[6]"

    See how it says the "Universe is completely flat".
    when i open the link through Wiki
    http://en.wikipedia.org/wiki/Flat_universe#Flat_universe

    Flat universe

    "In a flat universe, all of the local curvature and local geometry is flat. It is generally assumed that it is described by a Euclidean space, although there are some spatial geometries that are flat and bounded in one or more directions (like the surface of a cylinder, for example).

    The alternative two-dimensional spaces with a Euclidean metric are the cylinder and the Möbius strip, which are bounded in one direction but not the other, and the torus and Klein bottle, which are compact.

    In three dimensions, there are 10 finite closed flat 3-manifolds, of which 6 are orientable and 4 are non-orientable. The most familiar is the 3-Torus. See the doughnut theory of the universe

    In the absence of dark energy, a flat universe expands forever but at a continually decelerating rate, with expansion asymptotically approaching some fixed rate. With dark energy, the expansion rate of the universe initially slows down, due to the effect of gravity, but eventually increases. The ultimate fate of the universe is the same as that of an open universe.

    A flat universe can have zero total energy and thus can come from nothing.[10][11]"

    So even though it is flat it can still be 3D. Have you got a simple way of explaining this?

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  9. CptBork Valued Senior Member

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    Yep. The simple explanation is that analogies with curved surfaces in 3-dimensional Euclidean space can only get you so far when describing the properties of a 4-dimensional curved/flat spacetime manifold. General Relativity is about the math, and not all of it matches with our limited, naive human intuition (as physicists say when it comes to interpreting the consequences of a theory, "shut up and calculate"). The definition of "flat" in General Relativity doesn't mean the same thing it does with a 2D surface.
     
  10. Robittybob1 Banned Banned

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    Thanks I'll try and see flat in 3D from now on. For it sure had me confused how we can see in every direction yet possibly living within a "flat universe"!
    I always read your replies with a high degree of certainty that what you say is fairly right. It can be very confusing on the forums for there are unlimited views and ideas.
    Cheers

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  11. Boris2 Valued Senior Member

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    http://arxiv.org/pdf/0709.4024v1

    I like max.
     
  12. Aqueous Id flat Earth skeptic Valued Senior Member

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    Empedocles would answer that the universe is a volume whose center is everywhere and whose surface is nowhere.

    First encounters with Big Bang theory are simplified by describing a spherical explosion in a space that already existed. The explosion has a starting point, at the center of the sphere. Physicists call this the naïve point of view, because it reduces the model to a level of simplification that is useless.

    The next level of detail is that space and time are created in the event itself. This changes the idea of an explosion to one of expansion. Furthermore, it limits the meaning of expansion to the interior of the putative sphere, which remains, on the “outside”, a dimensionless point.

    One could turn from this to the question of how the universe expands, in order to look for where it expands, but will immediately be confronted by the breakdown of standard tools like classical mechanics and Euclidean geometry.

    In other words, even if there were a singular where, its location would be arbitrary at best.
     
  13. origin Heading towards oblivion Valued Senior Member

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    Damn, I really like that!

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  14. Gravage Registered Senior Member

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    I'm sorry, but I really can't accept this, I truly can't. Let's take balloon analogy. Balloon represents big bang. But the problem begins when the balloon is expanding, sure the matter pushed inside the balloon is expanding space inside the balloon, but the balloon itself cannot expand itself if there is no space outside the balloon, the same goes with the big bang.
     
  15. Gravage Registered Senior Member

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    Yes, sure but when you look at the model there is still a limit, infinte means infinite, itdoesn't matter is it a size or a mass, which I truly don't believe this is the case with this universe, multiverse or omniverse, you name it. There is no infinite energy to create infinite number of universes/multiverses/omniverses.
     
  16. CptBork Valued Senior Member

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    Says who? Last I heard, the "total energy of the universe" isn't even a well-defined General Relativity concept. And it's not really about multiverses, although there are some vague possibilities for that involving black holes. The standard cosmological picture is literally of an infinitely big universe; if you could keep flying off further in your spaceship or wait long enough for distant starlight to reach us (since it's only had a finite time to do so since the Big Bang), you'll just keep seeing more and more stars and galaxies ad infinitum. Of course, in the most modern picture, the universe is actually tearing itself apart and we'll be trapped in an increasingly isolated pocket until all matter in the universe is ripped apart atom by atom.
     
  17. Gravage Registered Senior Member

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    You need infinite amount of energy for infinitely expanded universe? Again from where?
     
  18. Boris2 Valued Senior Member

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    the balloon analogy is a godaweful analogy, same as rubber sheets et al. But if we must use it then you must realise that only the surface of the balloon is considered. There is no inside and no outside. so the balloon is not expanding into anything.

    You have shown by your misunderstanding why the balloon analogy is bad.
     
  19. RealityCheck Banned Banned

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    .

    Hi CptBork. Pleased to meet ya.

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    Mate, I'm intrigued about this 'expansion tearing atoms apart' business. I was led to understand that within a certain distance, any galactic groups gravity would 'locally' negate any space-time' expansion effects, Hence Andromeda and Milky way etc 'closing' rather than 'separating'.

    I'm not sure if it was AlexG (here at SciForums or elsewhere) that pointed out that the effects of expansion only starts to overcome local galaxy/group gravity at approximately 200 million (or more?) light years distance from galaxy/group.

    If so, then any aggregation of matter at the scale of galaxy/group will remain aggregated and subject to local gravity/electromagnetic etc etc forces/effects.

    In which case, while expansion may 'isolate' galaxies/groups, it cannot actually 'tear apart' atoms within such aggregations. Can it?

    Cheers. Back tomorrow.

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    .
     
  20. Gravage Registered Senior Member

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    Wrong, there is space outside the balloon, if there was no space outside the balloon, the balloon would never be able to expand.
     
  21. Dywyddyr Penguinaciously duckalicious. Valued Senior Member

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    Repeating a misunderstanding doesn't make your misunderstanding any more valid.
    Try to read what Boris2 actually wrote.
     
  22. Gravage Registered Senior Member

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    I'm sorry, but you and the rest of the team is not understandable, how can expand balloon, if there is no space outside the balloon, in which balloon would expand?
     
  23. NietzscheHimself Banned Banned

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    Nice to meet you Reality.

    Depends... If the expansion happening on a large scale also happens at the atomic level we could see the same mechanism expanding the universe as decaying its foundations.

    How they would be connected I have no idea.
     

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