1. The problem statement, all variables and given/known data Observer O at the origin of a coordinate system is at rest relative to two equidistant space stations located at x=+3.00×10^6km (station A) and x=−3.00×10^6km (station B) on the x axis. In reference frame O, station A sends out a light pulse at t = 0 (event 1) and station B also sends out a light pulse at t = 0 (event 2). Observer C moves relative to O with velocity 0.650 c0 in the positive x direction. What is the displacement from event 1 to event 2 according to observer C? 2. Relevant equations L = Lproper / gamma 3. The attempt at a solution If event 1 and event 2 occur at two locations that are at rest relative to observer O, can I say that the measured distance from 1 to 2 in O's reference frame is the proper length? Because that's how I approached the problem. Lproper = 2*(3.00*10^6 km)*(1000m/1km) = 6*10^9 m gamma = 1/sqrt(1 - ((0.65c)^2/c^2)) = 1.316 L observer C = L observer O / gamma = (6*10^9 m)/(1.316) = 4.56*10^9 m Is the assumption I made incorrect?