Captain Kirk reports to headquarters that he left the planet Senesca 1.88 *104 seconds earlier. Headquarters sends back the message: 'Was that spaceship proper time?' It will be spaceship proper time if it was:
A)measured by one clock fixed at one spot on Senesca.
B)measured by one clock fixed at one spot on the spaceship.
C)measured by a clock on Senesca at departure and by a clock on the spaceship when reporting.
D)measured by a clock on the spaceship when departing and by a clock on Senesca when reporting.
E)calculated by dividing the distance from Senesca according to Senesca by the speed of the spaceship.

Question

Quizplus · Accepted Answer

Proper time is the time interval between two events that occur at the same point in space. In this case, the event is the spaceship leaving Senesca and arriving at its destination. Therefore, the proper time can only be measured by one clock fixed at one spot on the spaceship (option B), since the spaceship is the only object that is present at both events. The other options involve measuring time at two different locations and are not proper time measurements.

Captain Kirk Reports to Headquarters That He Left the Planet