http://arxiv.org/abs/1001.2485 --- The above paper is about a possible two-time formulation of physics. It is by serious people. To understand it I'm trying to generalized the Dirac eqn. to 3+2 dimensions with signature (++---) I found the following (now closed post) useful: https://www.physicsforums.com/threa...f-dirac-spinor-in-arbitrary-dimensions.244296 Apparently the Dirac matrices would still be 4x4 in 5 dimensions. Is this the case? I also guess that there's not another linear combination that could be used to distinguish the two times, so you don't get cross terms when the you square up the Dirac eqn. to find the space-timel part of the plane wave solution. With 4x4 matrices obeying Dirac orthogonality condition (g_a*g_b+g_b*g-a=g_ab*delta_b=0) Are there more than 4 independent matrices? I don't think I can use gamma_5, it already got a role.