A pair of observers moving relative to one another will always agree upon all but which of the following?
A) the speed of light
B) their respective masses
C) whether two events are simultaneous
D) their relative velocity
E) the relativistic factor gamma that links their reference frames

Question

Quizplus · Accepted Answer

According to the theory of relativity, whether two events are simultaneous or not depends on the observer's reference frame. Therefore, two observers moving relative to one another may disagree on whether two events are simultaneous.

A Pair of Observers Moving Relative to One Another Will