Hi,(adsbygoogle = window.adsbygoogle || []).push({});

I'm a bit befuddled about something my lecturer wrote:

[tex]

S^{\dagger}\sigma_{\alpha}R_{{\alpha}\beta}B_{\beta}S=R_{{\alpha}\beta}B_{\beta}S^{\dagger}\sigma_{\alpha}S

[/tex]

R is a 3x3 rotation matrix which transforms the magnetic field B between frames, sigma_alpha are the pauli matricies. S is a rotation matrix that acts on spin wave vectors

I don't understand wh one can simply move the RB term to the left. It seems to make sense since RB is a vector rotation and S sigma S is a spin rotation operator and so they should be written in this way but I just don't know why mathematically one can do that.

thanks

**Physics Forums | Science Articles, Homework Help, Discussion**

Join Physics Forums Today!

The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

# Relativistic QM though maybe more of a math question

**Physics Forums | Science Articles, Homework Help, Discussion**