Two spaceships approaching each other move at very close to the speed of light, each sending a beam of light to the other. Each measures the speed of light from the other spaceship as
A)slightly less than c.
B)c.
C)slightly greater than c.
D)much greater than c.

Question

Quizplus · Accepted Answer

According to Einstein's theory of relativity, the speed of light in a vacuum is always constant and equal to $c$, regardless of the relative motion of the source and the observer. This means that each spaceship will measure the speed of light from the other as $c$, not affected by their high speeds towards each other.

Two Spaceships Approaching Each Other Move at Very Close to the Speed