JesseM
Science Advisor
- 8,519
- 17
I guess I don't understand what you mean by "two answers for one velocity". Do you mean "speed" rather than "velocity"? In the classical version, two objects which have equal speeds along the axis from the viewer to the object but opposite velocities (i.e. opposite directions, one object coming towards the viewer and one moving away) yield different doppler shifts, and exactly the same thing is true in the relativistic version. I don't understand why you think they're different, except for the magnitude of the shift for a particular velocity.Antenna Guy said:It's seems we agree (in an awkward sort of way) that the relativistic form is uni-directional; but the question of "why?" remains. The classical version yields two answers for one velocity (bi-directional result) - the relativistic form yields one answer for one velocity (uni-directional result).