alt Hacker NewsThat will be the case when Alice stands close to where C happens, and Bob stands close to where D happens.
It's a little trickier to imagine introducing cause-and-effect though. (Alice sees that C caused D to happen, Bob sees that D caused C to happen).
I think a "light cone" is the thought-experiment to look up here.
Replies
hinkley • last Saturday at 8:00 PM
If Bob and Alice are moving at half the speed of light in opposite directions.
There is distinction between seeing when events happened, and when they really happened. The latter can be reconstructed by an observer.
In special relativity, time is relative and when things actually happened can be different in different frames. Casually linked events are always really in the same order. But disconnected events can be seen in different orders depending on speed of observer.