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

Why Planck scale?

  1. Dec 1, 2011 #1
    What are the reasons for scientists believing the planck scale is the smallest unit of length? I have been hearing a lot of this length scale recently and i know we cant even do expiremental research at these small of levels. I'm wondering where they got the idea that strings [from string theory] exist at this level.

    thanks guys!
    Amanda
     
  2. jcsd
  3. Dec 1, 2011 #2

    Bill_K

    User Avatar
    Science Advisor

    It's the scale at which the effects of gravity and quantum mechanics become comparable. Crudely, one might suppose that fluctuations in the metric become comparable to the metric itself, and so the concept of distance needs modification. People do talk about a "trans-Planckian" regime, even smaller than the Planck length, but as you say, what happens at such distances is highly speculative, at this point well out of reach of both theory and experiment.
     
  4. Dec 1, 2011 #3

    mathman

    User Avatar
    Science Advisor
    Gold Member

    http://en.wikipedia.org/wiki/Planck_length

    Above describes subject. In particular note that the question you are raising is related to particular theories uniting Gen. Rel. and quantum theory.
     
Know someone interested in this topic? Share this thread via Reddit, Google+, Twitter, or Facebook