Pressure Exerted on a Semi-Infinite Lossles Dispersionless Dielectric by a Plane Electromagnetic Wave

Abstract

We show that a correct answer to the simplest question about the pressure exerted on semiinfinite transparent lossles dispersionless dielectric at normal incidence of a continuous plane electromagnetic wave is absent at present. It is believed since 1904 that the pressure is negative and is given by -2W 0(n-1)/(n+1) where W 0 is the momentum flux in free space, n is the refractive index of the medium. It is shown in 2002 that the pressure should be positive in accordance with the approach based on the Lorentz density force that is believed at present as a principal theoretical tool that is directly related to the various observable quantities in a transparent way. We use results of two unambiguous but contradictory experiments as a ground of our consideration and conclude that the Lorentz density force approach is incorrect and Abraham density force should be used rather than the Lorentz one. The pressure produced by a continuous wave is negative and coincides with the pressure derived in 1904. The pressure produced by a pulse of the wave when the leading edge of the pulse is entering the dielectric is positive and is equal by value to the pressure produced by the continuous wave.