Last class:

 Physics and Group Theory

 (1) "symmetry" and "transformations" is a _big_ part of modern physics.
    example : conservation laws
                  - if theory is "invariant" => something is conserved
                    space       -> momentum
                    time        -> energy
                    rotations   -> angular momentum
                    QM phase    -> electric charge
                    space/time/charge parity , "handedness" of physics

    

 (2) Each particule must be mathematically a "representation" of all 
     the transformation groups

     example:  spin      -1/2  1/2    (discuss history of that) -   SU(2) is group, not O(3)
               2 particles:   [-1, 0, 1]  + [0] 

     example2: quarks, eightfold way
               pattern of found particles => underlying SU(3) quarks  (discuss history)