Why worry? Each one of us is carrying an unlicensed nuclear accelerator on his - Wrist?

From ScienceDaily:

The world's most precise clock - on which all time-keeping and navigation systems are based - might be made as small as a wristwatch with a new design proposed by an international team of physicists.

A new class of atomic clocks of at least equivalent accuracy could be made much smaller and simpler by trapping aluminium, gallium, cesium or rubidium atoms in a lattice of laser light operated at a specific "magic" wavelength, according to a new theory put forward by physicists at the University of Nevada, in the US, and the University of New South Wales.