Dismiss Notice
Join Physics Forums Today!
The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

Big Bang temperature

  1. May 3, 2015 #1
    Dear forum,

    Can someone tell me what WAS the temperature of the Big Bang in time zero?
    Before Planck epoch I think.
    Or the question is not relevant because there were no four forces then, like asking what is the "north" of the North Pole.

    Thanks for your attention.
  2. jcsd
  3. May 3, 2015 #2


    User Avatar
    Gold Member

    We have no idea. The Big Bang Theory does not include any statements about t=0, only about one Plank Time after T=0, and thereafter.
  4. May 3, 2015 #3
    The temperature rises as the one Plank Time is approached from thereafter, so two questions that can be asked:

    What was the temperature at one Plank time?

    Plank Temperature was 1.41 x 10^32 Kelvin,
    it happened at one Plank Time 10^-43 seconds,
    when the radiation wavelength was the Plank Length 1.616 x 10^−26 nanometers

    Is there a highest theoretical temperature?

    Issac Asimov wrote for a popular audience that although c limits the velocity of particles, their increased energy (what used to be called mass increase) would appear in the equation terms subject to a raised positive power, so he concluded mathematically that temperature was without upper limit.
    The current thinking looks at the temperature in a similar way accounting for relativistic and quantum effects, which makes the consideration of higher temperatures than the Plank temperature problematic and calculations undefined as yet... strength of gravitation becomes comparable to the other forces and there is not yet a theory for quantum gravity.
  5. May 3, 2015 #4


    User Avatar
    Science Advisor

    I'm sorry, but this is unfounded speculation. We really don't have good information as to precisely how hot our universe became. The hottest point that is relevant to our universe today was probably attained at the end of inflation. That temperature was set by the energy density of the inflaton field at the end of inflation. We don't yet know what that energy density was, though if we manage to detect primordial B-mode polarization in the CMB, that could tell us.
  6. May 4, 2015 #5
    What part is unfounded speculation (as opposed to the whole subject)? Or are you saying the whole subject?
  7. May 4, 2015 #6


    User Avatar
    Science Advisor

    From the first sentence on. We can't talk with certainty about anything before a few seconds after the end of inflation (inflation itself isn't certain).
  8. May 4, 2015 #7


    User Avatar
    Science Advisor
    Gold Member

    Just to put things into perspective, inflation was probably over by around t=10^-32 seconds.
Share this great discussion with others via Reddit, Google+, Twitter, or Facebook