# What is the direction of angular momentum vector of a photon?

by jartsa
Tags: spin
 P: 411 Let's say momentum vector of a photon points to direction D. What are the possible directions that this photon's angular momentum vector can point to? The spin angular momentum is the angular momentum that I'm interested of.
 Mentor P: 11,036 A photon's intrinsic angular momentum ("spin") is either parallel or antiparallel to its momentum. This is a consequence of its mass being zero.
P: 1,583
 Quote by jtbell A photon's intrinsic angular momentum ("spin") is either parallel or antiparallel to its momentum. This is a consequence of its mass being zero.
How do you reconcile this with the fact that angular momentum operators along perpendicular directions do not commute, and thus satisfy an uncertainty relation?