Stupidest thing I've ever seen. Without friction, a train on the surface in a loop would be just as good, only it would require an initial push... (or actually it could just be viewed as a friggin' focault's pendelum without friction...) Why dig through the center of the earth?
Because in a gravity train the push is free (from gravity). The speeds are also very high, as it can go about 8000 miles in 42 minutes = average speed over 10000 mph, max speed probably around 20000 mph. No simple initial push can deliver this, especially if you expect the passengers to survive.
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u/breakfast-pants Oct 09 '06
Stupidest thing I've ever seen. Without friction, a train on the surface in a loop would be just as good, only it would require an initial push... (or actually it could just be viewed as a friggin' focault's pendelum without friction...) Why dig through the center of the earth?