First Shape Found That Can’t Pass Through Itself
A geometry problem that originated with a royal bet has been solved after more than three centuries.
Imagine holding two equal-size dice, is it possible to bore a tunnel through one die that’s big enough for the other to slide through? Many would say "no".
In the late 1600s, Prince Rupert of the Rhine was involved in a bet regarding this problem. The mathematician John Wallis proved mathematically that a straight tunnel in the direction of one of the cube’s inner diagonals can be made wide enough to allow another cube through.
A tunnel can be made wide enough to allow another cube through if drilled in the direction of one of the cube’s inner diagonals.
Author's summary: Geometry problem solved.