3 ms·
Events can't occur in a "reverse" order. At sufficient distances, the evolution of two regions is entirely causally independent, so there is no sense of simulta
by mjburgess 4y ago
Events can't occur in a "reverse" order. At sufficient distances, the evolution of two regions is entirely causally independent, so there is no sense of simultaneity.
Otherwise, the causal order of events is always defined. Different observers may have "more information" about some events over others, but over ordinary (even multi-galactic) distances, events are well-ordered and sequential.
- planede 4y agoEvents are partially-ordered. Two events that can't have causal relationship between them are incomparable causality-wise.
- moring 4y ago> Events can't occur in a "reverse" order. At sufficient distances, the evolution of two regions is entirely causally independent, so there is no sense of simultaneity. This discussion is essentially about whether "events can occur in reverse order for different observers" is the right way to say "the order of time coordinates of two spacelike-separated events is reversed for different observers". This was in reply to: > the overall outcome is a reasonably coherent notion of what the current time is The notion of an observer-independent "current time" implies simultaneity which doesn't exist in SR, and if you mistakenly assume an observer-independent "current time" which you'd likely assume to be the time axis of your own frame of reference, then two spacelike-separated events would be reversed for some observer who did the same but moves with almost speed-of-light relative to you. Please keep in mind that I wanted to point out the irony in using GPS for a universal reference time without giving an intro into special relativity.