A fun little program I decided to write up in my free time. Basically, the idea stems from whether or not gravity travels at the speed of light. Image that the sun vanished. Would Earth be flung out into the depth of space instantly, or would it take about 8 and a half minutes? (Time it takes the sun's light to reach Earth) I am of the opinion that it takes 8 and a half minutes, because information can't travel faster than light speed. Imagine that gravity could be felt instantly. Then, someone on another planet could swing around a heavy object, and theoretically and very precise gravity measuring device light years away could pick up on it, effectively carrying a message faster than light speed. Everything else in science goes against this.
Anyway, my program has little asteroids flying around which are attracted to where the other asteroids were rather than where they are. At every tick, where asteroids are are registered, and it creates a sort of ripple in space-time, propagating outwards. Any asteroid on the ripple will see the asteroid as being where that ripple was first triggered. Hence, a time lag. Adjusting the speed of light adjusts the lag, and accelerating towards an asteroid will decrease the lag, etc.
As always, code is here.