The Gravity Express

About four hundred years ago– sometime in the latter half of the 17th century– Isaac Newton received a letter from the brilliant British scientist and inventor Robert Hooke. In this letter, Hooke outlined the mathematics governing how objects might fall if dropped through hypothetical tunnels drilled through the Earth at varying angles. Though it seems that Hooke was mostly interested in the physics of the thought experiment, an improbable yet intriguing idea fell out of the data: a dizzyingly fast transportation system.