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The big bang

  1. Apr 27, 2006 #1
    the big bang suggests that there was a huge energy density that exploded to create the universe

    my rather simple(and probably ignorant) questions are these....

    is the energies density consistent throughout?

    what would cause randomness following the explosion if it wasnt

    is it possible that there was energy throughout space before the "bang"

    considering it is believed that the universe is expanding(and speeding up), is it logical to believe that the bigbang is sort of like a waters ripple in space? where the ripples size increases, yet flattens as it expands, hence why we view distant objects as getting further away, when in fact we it is still traveling the same distance, but instead of verticly, horizontally? <--- this was just a wierd thought i had today.

    and could anyone tell me if there is some sort of theory that would relate the origin of the universe to a ripple in a pond, and where i could get more information on that topic. Or rather, whether this is relavent to the bigbang.

    I really just saw a rock drop into a pond, and it reminded me so much of what i read about the big bang, all the scum eventually parks itself around a specific area, there are large areas with nothing in it, and the ripple continues to expand and flatten. I was curious if there was more information about that.

    any book suggestions or articles would be great

    i really have only taken very basic college physics courses and just have a interest in this area. Mathematical models of course are way beyond my comprehension, but i would still be really interested in reading about them
  2. jcsd
  3. Apr 29, 2006 #2


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    For a small initial patch of space the energy density was homogeneous at the beginning because of causal contact. These patch expanded afterwards very fast in a short time (a phase called inflation) and the homogeneity was distributed to spatially separated regions.

    Inhomogeneity that lead to the formation of matter structures was a consequence of quantum fluctuations in the energy density during the initial fast expansion. These fluctuations are a natural phenomenon in the physics at very small scales. Theses are usually unobservable, but in a very fast expanding space there is a transition of some fluctuations to a classical regime, leading to real density perturbations.

    The standard view is that space was created with the big-bang.

    There are such models but these are not the standard view. If you are interested in such models look for example for the work of Joel Smoller and Black Temple, e.g. http://arxiv.org/math-ph/0302036 [Broken].
    Last edited by a moderator: May 2, 2017
  4. Apr 30, 2006 #3

  5. May 1, 2006 #4


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    The question is irrelevant. The Planck wall is invincible.
  6. May 2, 2006 #5
    thank you for the answers. they were very relevant and have given me significant answers that will help me form new questions(heheh)

    thanks again.
  7. May 2, 2006 #6


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    fr0st2k, welcome to PF! It appears you are asserting facts not in evidence . . . i.e., the 'big bang is wrong'. On this forum, you will be viewed as a 'crackpot' right out of the chute. Tone the rheotoric down and up the observational evidence, or expect to be banned.
  8. May 2, 2006 #7
    No, it appears that he just wants to understand the Big Bang.
    Last edited: May 2, 2006
  9. Jun 9, 2006 #8
    The big bang may have created all the matter and energy in the KNOWN universe, but I fail to see how it could have created time and space. Space and time are abstract measurements, they can exsist even in the absence of all matter and energy. Space and time need nothing to come into exsistance. Space is the infinite extension of the three-dimensional field in which all matter and energy exists. (including matter and energy in the big bang) Time is A nonspatial continuum in which events occur in irreversible succession from the past through the present to the future. (including the one second before the bang, supposedly before time exsisted) The big bang has nothing to do with this.
  10. Jun 11, 2006 #9


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    One can indeed model an empty universe with GR (the Milne cosmology), but I don't see why this implies the necessity of an infinite universe. Space can of course be finite if curved and, in GR, this is exactly what matter and energy do (or, rather, can do). The closed, matter-dominated cosmology is one example of a finite universe. Since, as one approaches the moment of the big bang the spatial extent of the universe approaches zero (i.e. nothing), we sometimes think of the big bang as the creation of space and time. This, of course, neglects quantum gravity, which may remove the big bang singularity.
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