Harry takes a space voyage and returns to find his twin sister has aged more than he has. This is evidence that
A)she has changed frames of reference.
B)he has changed frames of reference.
C)both have changed frames of reference.
D)neither has changed frames of reference

Question

Quizplus · Accepted Answer

This scenario can only occur if Harry has traveled at near-light speeds, which causes time dilation, while his sister has remained on Earth. Therefore, Harry has changed frames of reference while his sister has not. Choice A and C are incorrect because they suggest that both twins have changed frames of reference. Choice D is incorrect because the scenario explicitly involves a change in frame of reference for at least one individual.

Harry Takes a Space Voyage and Returns to Find His