下面是在网上与英文读者就本文英文版的对话 (https://www.academia.edu/s/49453d40aa#comment_770918)： Eduardo D Dib23 hrs ago Doesn't have the velocity of spaceship B to be modified in order to change the shift? That requires energy, possibly compensating the loss due to the shift... rongqing Dai23 hrs ago The energy changes is irrelevant to the change of the wave length of the photon....actually you might even say the total of the red shifts and blue shifts in the universe might cancel each other to keep the total energy the same...but that would no longer be the same sense of the energy conservation as we have been assumed, because that would be the energy conservation in a statistical sense....Thanks rongqing Dai22 hrs ago Put it this way: When the mass of spaceship B changes, the energy that used to change its speed would change, but the loss of the energy of the laser beam would not change, which is only related to the amount of the speed change...so that energy cost for changing the speed of spaceship B does not come into the equation of energy conservation (or nonconservation) of the laser beam at all... Eduardo D Dib12 hrs ago However, the amount of the speed change itself is related to the amount of energy used to produce it. So, there is not a covariant relation linking the energy loss of the beam with the specific amount of energy used to produce that specific speed change? The more energy used in decelerate B, the more energy lost in the shift. Nothing random there... rongqing Dai12 hrs ago the deceleration is the illusion in my layout of the scenario for the sake of comparing "no change" and "loss"....we don't need the deceleration...the whole point is the relative departure of two spaceships...look at it this way: we have three spaceships: A, B, C...and John in A shoots a blue laser beam to B which is received by Jack on B without any energy loss because those two spaceships moving at the same speed, but then he shoots another blue beam laser to C, and received by Joe on C which is so much slower than A, and what Joe received is red laser beam.....the energy loss goes to nowhere, but just completely lost...The weirdest thing here is that when John shoots out the laser beam, nobody knows whether the energy would be conserved or changed until it hits the retina of Joe... |
