Experiments currently being undertaken at Stanford, and also by John Price, a physicist at the University of Colorado, will measure the force of gravity over a distance of less than a millimetre (the size of loop expected if there are only two extra gravity-swallowing dimensions).

ECONOMIST: A matter of gravity

An even stranger suggestion, made in 2002 by Mikhail Gershteyn, then at the Massachusetts Institute of Technology, is that the force of gravity is different in different directions.

ECONOMIST: Gravitational anomalies

On a lark, Mr. Minsky spent some time "inventing useless things, " he says, such as a "gravity machine, " a device that would ring a bell if the force of gravity changed.

WSJ: Looking for Something Useful to Do With Your Time? Don't Try This