Consider the setup in Problem 11.28 (and feel free to use the results from that problem in this exercise). Let the spaceship travel to a planet a distance L from the earth.
(a) By working in the frame of the earth, find the time of the journey, as measured by the earth. Check the large and small L (compared with c2/a) limits.
(b) By working in the (changing) frame of the spaceship, find the time of the journey, as measured by the spaceship (an implicit equation is fine). Check the small L limit. How does the time behave for large L?