>>719122993
time dilation, the order in which you perceive events depends on your velocity compared to them. someone going in one direction can see A happen and then B happen. someone going in the other direction can see the order reversed.

now this only applies to two events that have a 'spacelike interval' meaning light doesnt have enough time to travel from one event and arrive before the other one happens (think two lightbulbs that turn on 1 hour apart but are 1 lightyear away from eachother, no light from one can reach the other before it turns on). any events happen on a 'timelike interval' (the distance between events is such that light has time to reach from one to the other before it occurs. like two lightbulbs turning on 1 year apart but 1 lighthour away) will always happen in the same order regardless of time dilation.

timelike = there's a hypothetical observer that sees the two events happen in the same place but on different times,order of events is constant
spacelike = there's a hypothetical observer that sees the two events happen in the same time but in different places. order can be reversed

the speed of light is the exact border between the two. if you move slower than light you move along 'timelike curves' if you move faster than light you move along 'spacelike curves'. for example if you have a spaceship flying from star A to star B in constant-speed FTL then depending on your speed relative to the ship you will see it:
>arrive at B before you see it leave A
>leave A and then arrive at B
>the exact border between the two, where you see the ship leave A, flying at every point between A and B and arriving at B at the same time