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

Implications of the divisibility of time for the study of the big bang

  1. Jun 20, 2014 #1
    Does the fact that time is infinitely divisible have implications for studying the big bang?

    As with all studies of historic events, we are looking at the big bang from a backwards perspective. So, if we look at the first second of the start of our universe in the big bang model, we try to chip away backwards from 1 second in order to get to the beginning, eg half a second from the big bang, 0.1 seconds from the big bang, 1 millionth of a second from the big bang, etc. However, if time is infinitely divisible, can we ever get to 0 (the start) or are we destined to chip away without getting to the beginning?

    Does this attribute of time (its infinite divisibility) mean that there is a paradox - there can be a start but that the start is infinitely far away (in time) that we can never actually study the moment itself?
  2. jcsd
  3. Jun 20, 2014 #2


    User Avatar
    Science Advisor
    Gold Member

    Yes. If time were quantized, the quantization of time would definitely show up in the study of the big bang. Because the big bang is a singularity, any quantization of space time or quantization of gravity would show up there, where there is classically an infinite energy density.

    Without a unified theory of quantum gravity (perhaps a theory of everything), we are not allowed to go any closer to the big bang than the Planck time (~10^-44 s). There are several other epochs after that that we don't currently know much about (e.g. the grand unified epoch, the electoweak separation epoch). Right now we are only able to know about as far back as maybe the inflationary epoch (~10^-32 s) or so, and even then the physics is a little shaky.

    Less speculative would be way later, after inflation has ended, perhaps during the quark epoch or the hadron epoch (~10^-12s or ~10^-6s) respectively.
Share this great discussion with others via Reddit, Google+, Twitter, or Facebook