Ponderomotive effects of electromagnetic radiation

An additional mechanical friction, which is commensurate with the friction produced by a high-vacuum gas, arises during mechanical vibrations of a body absorbing or reflecting electromagnetic radiation. It is shown that a similar but appreciably larger effect should be observable in an optical Fabry-Perot resonator. The sign of the effect may be reversed at different settings of the resonator mirror. When the optical power fed to the resonator is sufficiently large, vibrational instability of the mirrors may set in. A possible use of the derived relations in astrophysical estimates is indicated.