Any vibrating object should be slowed by quantum “virtual”
particles that permeate empty space, according to theory. This
weak “friction” should spew photons like sparks from a dangling
bumper. In the 26 May PRL researchers propose detecting this
effect by vibrating one end of a small reflective cavity in
which the photons would rebound and be amplified by ultracold
atoms. The experiment, which lies at the limit of technical
feasibility, would expose a direct effect of virtual particles
on moving objects. Quantum field theory demands that seemingly
empty space be filled with virtual photons, particles of light
that constantly flit into and out of existence. One measurable
effect of these particles is the so-called Casimir force between
two objects placed nanometers apart [see Focus story from 1998].
The weaker “dynamical” Casimir effect occurs when a small object
vibrates rapidly: An ideal conducting surface, for example, has
no electric field parallel to itself and no perpendicular
magnetic field. Around it