Suppose we have a weightless light source that is moving. Its output light will therefore undergo a Doppler shift. Now, if the lightsource had weight but were static, its light would undergo a red shift. If the light source had weight and were moving, would it undergo both a red shift and a Doppler shift, with the end frequency being the linear superposition of both effects? Also, if: The relative velocity of the transmitter and recepient is the same, will the apparent Doppler shift be zero? If the weight of both the transmitter and the recepient is the same, will the apparent red/blue shift be zero?