1. The problem statement, all variables and given/known data This isn't really the problem, but figuring this out will probably help me with the rest of the problem. I want to know what [tex][\gamma^0, L_x][/tex] is. 2. Relevant equations I know the commutation (or rather anticommutation) relations between the gamma matricies, and I know the relations between angular momentum, momentum, and position. Also [tex]\gamma^0=diag(1, 1, -1, -1)[/tex]. 3. The attempt at a solution My guess is that [tex][\gamma^0, L_x]=0[/tex] because that would make my original problem work out. But I don't know how to justify those because [tex]\gamma^0[/tex] doesn't ordinarily commute with any matrix.