  This is a review of recent work on quantum fluctuations of the electric field
and of stress tensor operators and their physical effects. The probability
distribution for vacuum fluctuations of the electric field is Gaussian, but
that for quadratic operators, such as the energy density, can have a more
slowly decreasing tail, leading to an enhanced probability of large
fluctuations. This effect is very sensitive to the details of how the
measurement is performed. Some possible physical effects of these large
fluctuations will be discussed.
