1. The problem statement, all variables and given/known data events A(ct,x)=(1m, 2m) and B(ct,x)=(3m,4m) are separated in a lightlike interval. I need to find the velocity of a seperate reference frame in which they BOTH occur at the same time. Next I need to find the velocity of the frame where they will occur at the same LOCATION. 2. Relevant equations t=(gamme)t' 3. The attempt at a solution To solve for this, I need to find where the t' for both events is equal. But when i set tb'=ta', everything cancels out and I end up getting 1=3. Is there any other way of doing this that I am missing? I am getting the same problem with the location part as well. Thanks in advance!