Bert and Ernie are two friends of the same age. Bert visits a nearby star system on a spaceship that travels close to the speed of light while Ernie stays at home. Which of the following will be true on Bert's return to Earth?
A) Ernie will be younger than Bert
B) Ernie will be older than Bert
C) Bert and Ernie will still be the same age
D) Ernie will not have been born

Question

Quizplus · Accepted Answer

According to the theory of relativity, time dilates, or slows down, for an object moving at a significant fraction of the speed of light relative to a stationary observer. Therefore, Bert, who is traveling at speeds close to the speed of light, will experience less time passing than Ernie, who remains on Earth. Upon Bert's return, he will find that Ernie has aged more than he has, making Ernie older than Bert.

Bert and Ernie Are Two Friends of the Same Age