This is the answer to problem 3.2.8.

Return to relativity

For the figure lets say that the velocity of ship B with respect to planet A is (1/2)c after departure in the +x direction and the speed of ship C with respect to planet A is (1/2)c after departure in the -x direction. There are triplets one of which is on planet A, one of which is on ship B and one of which is on ship C. The departure happened on their 30th birthday. After departure they remain in states of constant velocity forever.

a. According to the standard of simultaneity for the one on planet A, show that the ages of the siblings on A's 35th birthday are 34.3 years old.

b. How fast is ship B moving with respect to ship C?

c. According to the standard of simultaneity for the one on ship C how old are the siblings when C is 34.3 years old?

d. According to the standard of simultaneity for the one on ship B how old are the siblings when B is 34.3 years old?

a.

b.

c.

d.