Who is measuring proper time and proper length?
Channel: Stefan Bracher
Date: 2021-01-29

If two observers are travelling at a high relative speed to each other, they will measure different times and lengths. The effect is described in special relativity as time dilation and length contraction. But who is measuring the dilated, longer, time, and who is measuring the proper time? Similarly, who is measuring the contracted, the shorter length, and who is measuring the proper length? The goal of this video is to help you figure it out.