In this day & age of real-time photorealistic graphics engines on every laptop computer, it amazes me that there is still no relativistic animation program available to every high school student, so that _every_ student can relatively (!) quickly develop intuition re _special_ relativity, at the very least. I realize that animating _general_ relativity may require more horsepower than most laptops possess, but I hope I'm wrong about this. I don't know how the U.S. Dept of Education or the Dept of Energy decide to spend their money, but a simple program of this sort would seem to be a slam dunk in terms of "bang for the buck". I had hoped that someone would have come up with a "first person shooter" game in general relativistic space by now, but it doesn't seem to have happened. Perhaps Grand Theft Auto VI will allow for cars having relativistic speeds, so students can learn about relativity relatively (!) painlessly. At 06:23 AM 10/28/2013, Cordwell, William R wrote:

Another interesting special rel. "paradox" is a spaceship of rest-length L, travelling at a significant fraction of c, approaches a berth, or dock, of rest-length L. When the nose of the spaceship touches the far end of the berth, the spaceship stops. Just before that instant, a person standing on the ship sees the berth as shorter than the ship (the ship is sticking out); a person on the dock sees the ship as shorter than the dock (the ship is well inside the dock). What is going on?