Symmetry "breaking"

drag

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.

rutwig

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.

damgo

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.