It keeps me awake at night #2 – the speed of light.

Yeah it does, when the darkness comes without sleep the idea that I can understand or get my head around the statement that light has a finite speed. That’s it. Nothing faster.

I get that I observe light, I see it at the speed of light. And then I imagine that I’m a spaceship of some kind. And then it gets interesting. To me that is.

If I’m banging along at a fair lick of speed, say 1/2 the speed of light and I look at a star, I observe the light at, guess what? the constant that is the speed of light. I don’t see it at say one and a 1/2 the speed of light. If I’m advancing to the light source at 1/2 the speed of light the speed of light is still the same. Which is weird. Unless I got it all wrong.

And if I’m observing two objects, one on my right and one on my left, and each of the objects  is approaching the other in straight line (imagine a triangle ABC, I’m at A, and they are at B and C and heading towards each other). If they are both going 1/2 the speed of light I think I should see them converging at the speed of light. If they are both going the speed of light (ok so it’s a big triangle) then I imagine that I should see them converge at twice the speed of light, which isn’t possible, is it?

Now if there are observers on B and C looking at each other how fast do they think they are converging. It’s worse if I imagine that one of them is going the speed of light and one is going 1/2 the speed of light.

Like I said it keeps me awake, for all of about 7 minutes.