1. The distance to the farthest star in our galaxy is of the order of 10 5 light years. Explain why it is possible, in principle, for a human being to travel to this star within his lifetime, and estimate the required velocity.
2. Two spaceships, each of proper length 100 m, pass near each other heading in opposite directions. If an astronaut at the front of one ship measures a time interval of 2.50 x 10 -6 sec for the second ship to pass him, then
(a) what is the relative velocity of the spaceships?
(b) What time interval is measured on the first ship for the front of the second ship to pass from the front to the back of the first ship?