1. The problem statement, all variables and given/known data Here is my problem: DOPPLER EFFECT: Consider a photon traveling in the x direction. Ignoring the y and z components, and setting c=1, the 4-momentum is (p,p). In matrix notation, what are the Lorentz transformations for the frames traveling to the left and to the right at speed v? What is the new 4-momentum of the photon in these new frames? That's all that I have... :( Thank you in advance for any suggestion! Karoliina.