Here's another physics type question:
So... we look at galaxies like this. We estimate the "original distance" of one of them to be -- let's pick a number -- 50 million light years away. So the light left that place 50 million years ago and got here yesterday.
However the distance of the galaxy today is something very different (potentially), right? It could be the same distance, but only if traveling the same direction and at speed as our galaxy. Or it could be much further (if traveling the opposite direction or otherwise divergent path). It could also be closer if on the same path and traveling at a higher speed. Headscratcher: is the only way galaxies collide by one overtaking the other, as opposed to crossing one another's paths?
Anyway, during the intervening 50 million years, that galaxy has been zooming (towards, away from, etc) our viewpoint, at whatever speed it has, right? Let's say the galaxy moves 1000 miles per second and assume it's not accelerated appreciably in that time frame (even though the universe is both expanding in all directions and accelerating now).
So now the actual position of that galaxy could be 1000 miles * (50,000,000 years * 31536000 seconds per year not counting leap years) farther away from us if traveling in the opposite direction... or some lesser distance closer, right (based on closing speed)?
...into the light of a dark black night.
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