In school, I was taught that the speed of light is constant, in the sense that if you shoot a laser off of a train going 200 km/h, it still just goes at a speed of c=299,792,458 m/s, not at c + 200 km/h.
What confuses me about this, is that we’re constantly on a metaphorical train:
The Earth is spinning and going around the sun. The solar system is going around the Milky Way. And the Milky Way is flying through the universe, too.
Let’s call the sum of those speeds v_train.
So, presumably if you shoot a laser into the direction that we’re traveling, it would arrive at the destination as if it was going at 299,792,458 m/s - v_train.
The light is traveling at a fixed speed of c, but its target moves away at a speed of v_train.
This seems like it would have absolutely wild implications.
Do I misunderstand something? Or is v_train so small compared to c that we generally ignore it?
Not only that, but the speed of light might not be the same in all directions, we just assume that because we measured it by reflecting it, but for all we know it could be way more going out that coming in or viceversa.
See this and this nifty video.
That video seems excellent, thanks. Going to have to watch it ten more times, maybe I’ll understand it. 🙃
I do massively prefer it, though, when all the complexity is presented and I have to work it out, rather than a half-accurate, simplified explanation.