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Thread: Grand Unification Epoch

  1. #1 Grand Unification Epoch 
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    I'm trying to understand this passage from the Wikipedia article on the Grand Unification Epoch:
    In physical cosmology, assuming that nature is described by a Grand unification theory, the grand unification epoch was the period in the evolution of the early universe following the Planck epoch, starting at about 10^-43 seconds after the Big Bang, in which the temperature of the universe was comparable to the characteristic temperatures of grand unified theories. If the grand unification energy is taken to be 10^15 GeV, this corresponds to temperatures higher than 10^27 K. During this period, three of the four fundamental interactionsóelectromagnetism, the strong interaction, and the weak interactionówere unified as the electronuclear force. Gravity had separated from the electronuclear force at the end of the Planck era. During the grand unification epoch, physical characteristics such as mass, charge, flavour and colour charge were meaningless.
    (bold added by me for emphasis)
    (ref. http://en.wikipedia.org/wiki/Grand_unification_epoch )

    The last sentence seems to be saying that quarks, as such, didn't exist and that, moreover, mass and charge didn't exist. Was everything just high energy photons?

    Chris


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  3. #2 Re: Grand Unification Epoch 
    . DrRocket's Avatar
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    Quote Originally Posted by CSMYTH3025
    I'm trying to understand this passage from the Wikipedia article on the Grand Unification Epoch:
    In physical cosmology, assuming that nature is described by a Grand unification theory, the grand unification epoch was the period in the evolution of the early universe following the Planck epoch, starting at about 10^-43 seconds after the Big Bang, in which the temperature of the universe was comparable to the characteristic temperatures of grand unified theories. If the grand unification energy is taken to be 10^15 GeV, this corresponds to temperatures higher than 10^27 K. During this period, three of the four fundamental interactionsóelectromagnetism, the strong interaction, and the weak interactionówere unified as the electronuclear force. Gravity had separated from the electronuclear force at the end of the Planck era. During the grand unification epoch, physical characteristics such as mass, charge, flavour and colour charge were meaningless.
    (bold added by me for emphasis)
    (ref. http://en.wikipedia.org/wiki/Grand_unification_epoch )

    The last sentence seems to be saying that quarks, as such, didn't exist and that, moreover, mass and charge didn't exist. Was everything just high energy photons?

    Chris
    Assume whatever you like until someone can actually produce a grand unification theory. Statements about the implications of a hypothetical theory that does not exist should be taken as speculative. That statement is really a definition of what one would expect a grand unification theory to be.


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  4. #3 Re: Grand Unification Epoch 
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    Quote Originally Posted by DrRocket
    Assume whatever you like until someone can actually produce a grand unification theory. Statements about the implications of a hypothetical theory that does not exist should be taken as speculative. That statement is really a definition of what one would expect a grand unification theory to be.
    Thanks DrR.

    A related Wikipedia article on Baryon number includes this passage:

    In particle physics, the baryon number is an approximate conserved quantum number of a system. It is defined as



    where is the number of quarks, and is the number of antiquarks. Baryons (three quarks) have a baryon number of +1, mesons (one quark, one antiquark) a baryon number of 0, and antibaryons (three antiquarks) have a baryon number of -1.
    (ref. http://en.wikipedia.org/wiki/Baryon_number )

    From this I gather that the number of baryons (quarks/antiquarks, if you will) is believed to remain aproximately the same throughout the evolution of the universe.

    Also,

    The anomalies that break baryon number conservation and lepton number conservation individually cancel in such a way that B − L is always conserved...
    (ref. http://en.wikipedia.org/wiki/B_%E2%88%92_L )

    If I understand these passages, then would it be correct to say that the various nuclear processes that produce energy in stars involves a change in the binding energy of the nucleons rather than a conversion of any of the fundamental constituent "matter" particles of the star into energy?

    Chris
    It is difficult to say what is impossible, for the dream of yesterday is the hope of today and the reality of tomorrow.
    Robert H. Goddard - 1904
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