You need to go from point A to point B, and then back to point A. Points A and B are 20 miles apart. You go to point B at a constant speed of 15 miles per hour. If you want your overall speed to be 30 miles per hour, how fast would you have to go from point B back to point A?

Unfortunately an infinite speed cannot be achieved as nothing can appear to go faster than light, therefore this problem has no solution in the real world. The only way is could be achieved is in the frame of me, the  traveller in which case I would need to become a massless particle and move exactly at the speed of light so the distance was Lorentz contracted to zero and I got there at the same time as I left (like photons do).

Posted by Jils on 2004-03-10 16:14:35