Physical nature and magnitude of optically induced forces derived from laws of mechanics

Abstract

We derive the true magnitude of the optically induced force (OIF) in a linear transparent optical medium where ε≥1 and μ≥1 from unambiguous but contradictory results of two known thought experiments where no preliminary assumption about phenomena connected with electrical and magnetic fields are used. The analysis is based on laws of mechanics only. By means of comparing these forces with known types of forces we conclude that there are four kinds of force. First, this is the Coulomb force known in electrostatics. Second, this is the magnetic force known in magneto statics. Third, this is Ampere-like force arising at an interaction between the alternate polarization current and the alternate magnetic field of the light wave. Fourth, this is the force arising at an interaction between alternate magnetization current and the alternate electrical field of the light wave studied by Einstein and Laub in 1908. A sum of the third and fourth kinds of force in a field of an electromagnetic wave averaged over time is equal to zero at a steady state. We show that the existing formulas for third and fourth kinds need to be corrected for the medium where ε>1 and μ>1.