>The speed of light is obviously the same either way It's not obvious that it is :) We don't have any way to prove that it is the same, because every experimen

>The speed of light is obviously the same either way It's not obvious that it is :) We don't have any way to prove that it is the same, because every experiment to measure the speed of light going from A to B requires some light to go from B to A which cancels out any difference. We just assume that it is the same because we don't have any reason to believe it's not. Veritasium video on this topic: https://www.youtube.com/watch?v=pTn6Ewhb27k https://www.youtube.com/watch?v=pTn6Ewhb27k