Kevin's Watch

Gravity has a secret side. As well as the brute force that holds us to the ground, large masses should also exert a subtle swirling influence when they rotate, a force called gravitomagnetism. It's so faint that a NASA spacecraft called Gravity Probe B has been orbiting the Earth for over two years to accrue enough evidence to have a chance of confirming this force.

Yet in a lab in Austria, Martin Tajmar and his team have already succeeded in detecting a faint signal that seems to be due to this elusive component of gravity. A reason for celebration? Not quite. Puzzlingly, the force they seem to have generated is vastly more powerful than anyone else expected.

The results could be out in a year or so. If they are positive, it puts the technology of science fiction on the horizon. Levitating cars, zero-g playgrounds, tractor beams to pull objects towards you, glassless windows that use repulsive fields to prevent things passing through. Let your imagination run riot: a gravitomagnetic device that works by changing the acceleration and orientation of a superconductor would be the basis for a general-purpose force field.