lalbatros

Thanks robphy!
I am not sure if members of the conformal group should have det(M)=1.
But I would guess yes because rescaling is not incompatible with the laws of physics.
Weinberg says that physics excludes the proper members of the conformal group as a symmetry of physics.
Weinberg also says that these tranformations are nonlinear.
One example of these would make my day.

Thanks,

Michel