3 ms·

The two way speed are the same along the y axis versus the x axis. We have no ways to measure the one way speed. we can’t falsify it. According to some HN-er,

• ben_w 3y ago
  > we can’t falsify it. According to some HN-er, this must be unscientific Apparently more than merely "can't falsify it": the maths is such that if it was different, there would never be any observation that could distinguish between them. That extra step — that it genuinely makes no difference — would, I think, cause it to be unscientific. At least, unscientific within relativity; given relativity can't be the whole picture (singularities popping out of maths that presumes spacetime is differentiable), we may well find another better model that would allow us to make the test, which in turn allows us to ask the question scientifically. That said, after watching the Veritasium video ages ago, I was immediately asking myself: what about the CMB? Surely that would have a stonking big anisotropy if the speed of light wasn't close to the same in all directions? (It does have one which is assumed to be because of our motion relative to it, and I don't know enough to guess what to expect of a different-way-speed-of-light-anisotropy other than its existence, and therefore cannot compare and contrast with the observed one).
  • nyssos 3y ago
    > I was immediately asking myself: what about the CMB? Surely that would have a stonking big anisotropy if the speed of light wasn't close to the same in all directions? No, you can always cancel it out by making the whole rest of physics suitably anisotropic too. Which would, of course, be ridiculous.