DISSIPATIVE FORCE ON A SPHERE MOVING IN VACUUM

We derive the spectrum of fluctuations of the vacuum radiation pressure on a spherical perfectly reflecting mirror. From the fluctuation-dissipation theorem, we obtain the dissipative force exerted upon the mirror when it moves in vacuum. As,in the classical problem of scattering by a plane wave, the spectrum presents a resonant behavior at wavelengths of the order of the sphere's radius. The high-frequency limit agrees with Barton's general result for a large body of arbitrary shape.