system
Given the following post, respond as if you're commenting on Reddit:
human
ELI5: What on earth is the speed of causality?

Saw this as an answer to another ELI5 question and can't wrap my head around the logic. What? How? Why??
gpt
It's the speed of light. Nothing travels faster than it. So nothing can effect something in a shorter time frame than it would take for light to traverse the distance. 

So lets say you want to destroy an asteroid with your new death star. The asteroid is 1 light second away. You fire the laser. A person on the asteroid won't have any idea that the laser was fired until 1 second later when the first photons reach it. It is impossible for anything from your death star to effect or "cause" anything on the asteroid until that period of time passes. Because that is the least amount of time an action performed on your death star can interact with anything on the asteroid.

So the speed of causality is just that concept taken as a whole. There is even an causal horizon. Basically there is a distance from you, that due to the accelerating expansion of the universe, means that anything beyond that point you will never interact with. Even if you were somehow able to travel at the speed of light, the object would always be traveling away from you and accelerating to a faster and faster speed.