Comment Re:11,000 years ago, not 300 (Score 1) 56
Simultaneity as you said is a better term, and "according to the special theory of relativity, it is impossible to say in an absolute sense that two distinct events occur at the same time if those events are separated in space." So if, say, I see my alarm clock go off at say 10pm and just then see a star exploding, then the explosion and the alarm activation are happening simultaneously -- as far as I'm concerned.
The trouble with that definition of simultaneity is that it's asymmetrical. By that definition, someone sitting at the point of the explosion would disagree that the explosion and your alarm clock going off happened at the same time - he'd have to wait 11,000 years for the light from the alarm clock going off to reach him.
Two observers in the same frame of reference (assuming Earth and the exploding star are not moving very much relative to each other) should agree on the order and simultaneity of events - otherwise it's not much use as a frame of reference.