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

Symmetry breaking

  1. Mar 22, 2003 #1


    User Avatar
    Science Advisor

    Symmetry "breaking"

    Greetings !

    I'd like to ask and possibly discuss questions
    about symmetry :
    1. I heard that there is a 2% lacking symmetry in
    weak nuclear force reactions. Does this
    mean energy-conservation (and other physical laws)
    are violated ?!
    2. Does the HUP possibly represent the
    general principle of sponteneous symmetry
    "breaking" in the Universe ?
    3. I've heard many scientists in the past
    say things that eventually mean the following :
    "The Universe had no choice but have the present
    laws." However, wouldn't sponteneous symmetry
    "breaking", if it takes place, violate that hypothesys ?

    "Does dice play God ?"

    Live long and prosper.
  2. jcsd
  3. Mar 22, 2003 #2
    No, the symmetry breaking is the tool that says that the actual models which describe the states (e.g. the eightfold way) are good approximations, but that some quantities are not preserved. Thus the model does not exactly correspond to the symmetry of the system, since some restrictions to some substructure are not conserved. This is not very surprising, since the models are chosen to be manipulable. The symmetry breaking is then analyzed by the use of the branching rules, which allows you to see what actually happens. The fact that a lagrangian is not invariant by some subgroup is not telling you that convervation laws are violated.
  4. Mar 22, 2003 #3
    1) No... they were probably talking about CP-violation, which is a different symmetry altogether.
    2) I don't think so, but I'm not sure what the question means exactly.
    3) Not really... the fundamental laws wouldn't be affected by the symmetry breaking, but things like the proportions of various particles existant would be. You should note that that statement is more like a religious belief, a faith that things aren't random, than a scientific position.
Share this great discussion with others via Reddit, Google+, Twitter, or Facebook