4 ms·

> then drive with constant velocity for 1 hour 1 hour according to who's clock? The point is that if the 1 way speed of light is different, the clocks travelin

> then drive with constant velocity for 1 hour 1 hour according to who's clock? The point is that if the 1 way speed of light is different, the clocks traveling in opposite directs will measure the 1 hour passing at different speeds.

AnimalMuppet 3y ago
The (non-GR) time dilation rate difference will be proportional to v^2/c^2 (neglecting 4th order terms and higher). The total time dilation difference will be that times the time in transit, which is d/v (with d being the distance traveled). So the total time dilation difference will be proportional to vd/c^2. By making the velocity small, I can make that term as small as I want. But what if I don't know what c is? Doesn't matter. I know it's much, much larger than the velocity I'm moving at. So I don't buy the "according to who's clock" argument. I can make it so that it doesn't matter, just by going slow enough.
- adgjlsfhk1 3y ago
  the part you're missing is that during the acceleration phase, if the 1 way speed of light is different, the velocities achieved relative to a stationary observer by accelerating for t seconds relative to the clock that is doing the acceleration will be different depending on the direction of acceleration.
  - AnimalMuppet 3y ago
    To what order in v? I'd like to see your math, but I'm pretty sure I can still minimize that by going slow (relative to the speed of light in any direction).
    - adgjlsfhk1 3y ago
      Wikipedia does the math for us here. https://en.wikipedia.org/wiki/One-way_speed_of_light#Slow_clock-transport https://en.wikipedia.org/wiki/One-way_speed_of_light#Slow_cl.... The TLDR is that the standard lorentz transform assumes the 1 way speed of light doesn't vary, so to do the math correctly you need generalized lorentz transformations https://en.wikipedia.org/wiki/One-way_speed_of_light#Generalizations_of_Lorentz_transformations_with_anisotropic_one-way_speeds https://en.wikipedia.org/wiki/One-way_speed_of_light#General...

AnimalMuppet 3y ago

The (non-GR) time dilation rate difference will be proportional to v^2/c^2 (neglecting 4th order terms and higher). The total time dilation difference will be that times the time in transit, which is d/v (with d being the distance traveled). So the total time dilation difference will be proportional to vd/c^2. By making the velocity small, I can make that term as small as I want. But what if I don't know what c is? Doesn't matter. I know it's much, much larger than the velocity I'm moving at. So I don't buy the "according to who's clock" argument. I can make it so that it doesn't matter, just by going slow enough.

adgjlsfhk1 3y ago
the part you're missing is that during the acceleration phase, if the 1 way speed of light is different, the velocities achieved relative to a stationary observer by accelerating for t seconds relative to the clock that is doing the acceleration will be different depending on the direction of acceleration.
- AnimalMuppet 3y ago
  To what order in v? I'd like to see your math, but I'm pretty sure I can still minimize that by going slow (relative to the speed of light in any direction).
  - adgjlsfhk1 3y ago
    Wikipedia does the math for us here. https://en.wikipedia.org/wiki/One-way_speed_of_light#Slow_clock-transport https://en.wikipedia.org/wiki/One-way_speed_of_light#Slow_cl.... The TLDR is that the standard lorentz transform assumes the 1 way speed of light doesn't vary, so to do the math correctly you need generalized lorentz transformations https://en.wikipedia.org/wiki/One-way_speed_of_light#Generalizations_of_Lorentz_transformations_with_anisotropic_one-way_speeds https://en.wikipedia.org/wiki/One-way_speed_of_light#General...