there is no sense of simultaneity that crosses coordinate systems. there are three relationships between events a and b. a is before b, b is before a, and ne

there is no sense of simultaneity that crosses coordinate systems. there are three relationships between events a and b. a is before b, b is before a, and neither. to get the total ordering, you have to arbitrary and non physically pick a or b. in that Newtonian universe, good enough clocks and time stamps could be used to break the tie. good enough clocks will never be enough in our universe, there is no canonical way to say of two events separated in a space like way is first. in a newtonian universe you can.