Suppose you are a traveling salesman for SSC, the Spacely Sprockets Company. You travel on a spaceship that reaches speeds near the speed of light, and you are paid by the hour.
(a) When you return to Earth after a sales trip, would you prefer to be paid according to the clock at Spacely Sprockets universal headquarters on Earth, according to the clock on the spaceship in which you travel, or would your pay be the same in either case?
(b) Choose the best explanation from among the following:
I. You want to be paid according to the clock on Earth, because the clock on the spaceship runs slow when it approaches the speed of light.
II. Collect your pay according to the clock on the spaceship because according to you the clock on Earth has run slow.
III. Your pay would be the same in either case because motion is relative, and all inertial observers will agree on the amount of time that has elapsed.