Front Cover
An artist's impression of an ‘atomic fountain’, one
of the devices made possible by the work of this year's physics
Nobel Prize winners. The atoms are cooled by laser beams (see article
pp.16-27 in this issue) which can also be used to give them a controlled
vertical velocity. They traverse the radio frequency cavity (dark
box) twice. There is resonance between the microwaves in the cavity
and the atoms, and the electrical oscillations act as the atomic
clock.
