Question

In order to cross the galaxy quickly, a spaceship leaves Earth traveling at 0.9999993 c. After 19 minutes a radio message is sent from Earth to the spacecraft.

1. In the Earth-galaxy frame of reference, how far from Earth is the spaceship when the message is sent?

2. How much time elapses on spaceship clocks between when the ship leaves Earth and when the message is sent?

3. How much time elapses on Earth clocks between when the message is sent and when it is received?

4. If the spaceship replies instantly with another radio message, what total time elapses on Earth clocks between when the message is sent and when the reply is received?

Answer 1