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Ending point for initial condition theories

  1. Feb 4, 2016 #1
    I am not a scientist, but as a hobby I am summarizing different initial condition theories, specifically, eternal inflation, LGC, cyclic, and bounce theories. I need a completion time ATB where all theories produce an identical plasma. The plasma then enters the big bang process of expansion. I’m considering three possibilities for the starting time ATB: 10-12 sec (1016 K); 10-10 sec (1015 K); and, 10-4 sec (1012 K).

    Selecting 10-12 sec (1016 K) implies that electroweak unification (spontaneous symmetry breaking) has not occurred - it is predicted at a later time (≈10-11 sec) and lower temperature (10-15.5 K). Thus, this time seems too early since all initial condition theories do not predict the electroweak force breaking into the weak and electromagnetic force, for example, the cyclic theory assumes four forces.

    At 10-10 sec (1015 K), the issue of electroweak unification is avoided and only elementary particles (quarks, electrons, neutrinos) and bosons (force carriers: gluon, photon, and W) exist in the plasma. Also, the density is extremely high to accommodate the bounce and cyclic theories. Thus, a plasma at this time/temperature may be reasonable for all initial theories.

    At 10-4 sec, quarks were forming neutrons and protons. The universe’s diameter was a macro value of approximately one thousand meters. Since quarks were not free and since the density may not have been adequate for the cyclic and bounce theories, this may be too much elapsed time.

    Is my logic sound, are there other considerations? Thanks
  2. jcsd
  3. Feb 4, 2016 #2


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    Typically people producing theories of the early universe make use of observational constraints to limit their theories. So there's not really a specific time where all the theories converge: it depends upon how the various theories impact observables.

    Perhaps the observation which is sensitive to physics at the earliest times that's used to constrain early-universe theories is big bang nucleosynthesis (BBN), which lays down the abundance of light elements. Different theories about the early universe will have a different impact upon BBN, so that there are theories which don't change BBN at all, but may have an impact on observables that show up a bit later, such as the pattern of hot and cold spots on the CMB.
  4. Feb 4, 2016 #3
    Thanks, that sounds logical. My sources show nucleosynthesis: at 100 seconds ATB; a temperature of 109 K; a diameter of observable universe about 1010 meters; and a combination of helium, deuterium, and lithium nuclei plus elementary particles. Not knowing the technical details of bounce and cyclic theories, I assumed smaller time scales based on inflation ending prior to 10-12 sec.
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