The space elevator

The August 5 issue of IEEE Spectrum has a feature article on space elevators.

Springing out from an anchor point on the equator, the space elevator cable would rise straight up, passing through geostationary orbit at 36 000 km and continuing for another 64 000 km until it terminates in a 600-ton counterweight. The cable would be held up in a manner similar to that which holds a string taut as a weight tied to it is swung in a circle. The key detail that would make the elevator work would be the fact that its center of gravity would be at the geostationary orbit mark, forcing the entire structure to move in lockstep with Earth's rotation.