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

Parity violation on macroscopic scale

  1. Nov 26, 2014 #1
    a question which is bugging me....

    Yes, I know that parity is violated only by the Weak Interaction, which is very short range. So I would answer "no, there is no P violation on macroscopic scale"

    However, many macroscopic properties are the results of what happens on the microscopic level. So can P violation somehow "leak" into the macroscopic world? Or, If you insist on the answer "No", is there a solid proof that macroscopic world is P symmetric?
  2. jcsd
  3. Nov 26, 2014 #2


    User Avatar

    Staff: Mentor

    Any experiment that successfully detects parity violation is an example of leakage into the macroscopic world - the experimental apparatus is macroscopic and behaves differently when parity is violated.

    However, you are probably looking for something a bit more exciting than just a few needles reading different values... Like say a big lump of cobalt-60 (google for "Wu experiment parity") blasting gamma radiation and electrons in different directions? There's no reason why such a thing could not in principle be assembled, but the probability of it happening is so low that in practice it will never happen.

    Similar considerations apply to even the more prosaic examples of macroscopic properties emerging from what happens on the microscopic level. A macroscopic dropped brick will pretty reliably fall to to the ground - but in principle all the air molecules underneath it might just randomly happen to be moving up at the same time and then it would float. Generally any time that you want to make a connection between microscopic and macroscopic behavior you have to apply the methods of statistical mechanics.
  4. Nov 27, 2014 #3


    User Avatar
    Science Advisor

    Some theories to explain the fact that we only observe L-Aminoacids and D-sugars (homochirality) in living beings try to trace this back to the parity violating terms in the hamiltonian. I think that even some experiments in the Rosetta comet landing mission where dedicated to explore this.
    http://www.acadeuro.org/fileadmin/user_upload/publications/ER_Symmetry_supplement/Cline.pdf [Broken]
    Last edited by a moderator: May 7, 2017
  5. Nov 27, 2014 #4
    Interesting, thank you
Know someone interested in this topic? Share this thread via Reddit, Google+, Twitter, or Facebook

Similar Discussions: Parity violation on macroscopic scale