1. The problem statement, all variables and given/known data Given Space Time Coordinate of object <t, x, y, z> = <0, 0, 0, 0> Velocity of object as Vector <betaX, betaY, betaZ> = <.866, 0 ,0> Velocity of target reference frame as Vector <betaX, betaY, betaZ> = <-.866, 0 ,0> Transform velocity of object to the target reference frame using the 4-vector technique. 2. Relevant equations 3. The attempt at a solution Following directions from a source on the internet........ Velocity as a 4-vector (tau, vx, vy, vz) = <1, betaX, betaY, betaZ> = <1, 0.866, 0.0, 0.0> magnitude of 4-vector = Sqrt( 1 + betaX * betaX + betaY * betaY + betaZ * betaZ ) = 1.3228590249909473 Velocity as a 4-vector normalized (tau, x, y, z) = <1/magnitude, betaX/magnitude, betaY/magnitude, betaZ/magnitude> = <0.7559384493044097, 0.6546426970976188, 0.0, 0.0> Transform the 4-vector where L is the Lorentz Transform populated for the target velocity: v' = Lv resulting in v'(tau, x, y, z) = <2.6454852575216505, 2.6183403845739543, 0.0, 0.0> ??? I should be getting a vx value somewhere around .98c. Totally lost.