Elusive vacuum fluctuations may have been measured for the first time

Science : A research team reports the first direct observation of quantum fluctuations in a vacuum, or the temporary appearance of energetic particles in a point in space. Claudius Riek, Alfred Leitenstorfer, and colleagues at the University of Konstanz in Germany studied the phenomenon by looking for the subtle influences that are exerted on a transparent crystal by the fluctuating electric field produced by the birth and death of virtual photons. The researchers shot a “probe” pulse of light through the crystal and then measured the pulse’s polarization as it exited the other side. Over repeated trials, the polarization varied slightly, which, they claim, indicated the influence of vacuum fluctuations. Some scientists have questioned the results, however, saying some other source, such as thermal fluctuations, could be causing the variations in the crystal’s optical properties.