>>14363741With a caveat. You have to be careful about frames. If you're in frame A traveling at speed v1, and observe a second object (in frame 2) traveling at speed v2, then you must use the Lorentz addition of velocities.
If, however, you're in frame A, traveling at velocity v1, and observe an object in frame B traveling at v2, and observe an object in frame C traveling at v3, then you measure the relative velocity between v2 and v3 via Galilean velocity addition.
This is something not even graduate students in physics frequently get right.
