An observer moving with a light clock in a spaceship sees a light flash bouncing up and down between parallel mirrors in 1 nanosecond. An observer at rest outside the spaceship sees the same up-and-down flash in
A)1 nanosecond also.
B)less than 1 nanosecond.
C)more than 1 nanosecond.

Question

Quizplus · Accepted Answer

According to the theory of relativity, time dilates (or slows down) from the perspective of a stationary observer watching a moving clock. Therefore, the observer at rest outside the spaceship would see the light flash taking more time to bounce between the mirrors compared to the observer moving with the light clock.

An Observer Moving with a Light Clock in a Spaceship