Computers that run on chips made from tiny magnets with no moving parts may be as energy-efficient as physics permits.

According to new calculations by electrical engineer Brian Lambson of the University of California at Berkeley, if nanomagnetic computers used any less energy, they’d break the second law of thermodynamics. Such computers are still semi-theoretical, but they could someday be used in the deep oceans or even deep space, where energy is at a premium.

Ref.: “Exploring the Thermodynamic Limits of Computation in Integrated Systems: Magnetic Memory, Nanomagnetic Logic and the Landauer Limit.” Brian Lambson, David Carlton and Jeffrey Bokor. Physical Review Letters, in press.