It's also a useful tool in science. For example, we do not know and cannot prove the one-way speed of light, only a round trip speed of light. That light travel

It's also a useful tool in science. For example, we do not know and cannot prove the one-way speed of light, only a round trip speed of light. That light travels at the same speed in all directions is just a useful application of Occam's Razor; it is effectively unknowable and no experiments have yet been devised that can falsify the alternatives. Having a set one-way speed of light is a convention