[ianburrell]

Causality moves at the speed of light. Events that are farther apart are called spacelike and aren't causally connected.

I think you might be confusing events that have some history between them, and those are influence each other. Like say right now, Martian rover sends message to Earth and Earth sends message to them, those aren't causally connected cause don't know about the other message until light speed delay has passed.

[hinkley]

We still haven’t proven whether some quantum effects do or don’t follow this. So there may be a loophole where information can move faster than light but the carrier for that information can not. Which might make ansibles possible some day, with the caveat that you can only have so many conversations per ansible before you need a refill with new entangled matter. In which case you have to divide the information by the travel time to determine your aggregate data rate. And the travel time will be at a fraction of the speed of light.

So you might be able to consult on which planet to terraform but you’re not going to video call the wife and kids unless you’re the richest person in the galaxy.