A spaceship is headed toward Alpha Centauri at 0.999c.According to us,the distance to Alpha Centauri is about 4 light-years.How far away is Alpha Centauri according to the travelers in the ship?
A)also about 4 light-years
B)very slightly more than 4 light-years
C)very slightly less than 4 light-years
D)quite a bit less than 4 light-years
E)quite a bit more than 4 light-years

Question

Quizplus · Accepted Answer

Due to the effects of length contraction in special relativity, when moving at a significant fraction of the speed of light (in this case, 0.999c), distances in the direction of motion appear shorter for the travelers compared to the stationary observer. Therefore, Alpha Centauri would appear "quite a bit less than 4 light-years" away to the travelers on the spaceship.

A Spaceship Is Headed Toward Alpha Centauri at 0