Hrvoje Dodig
In 19th century Maxwell derived Maxwell equations from the knowledge of three experimental physical laws: the Coulomb's law, the Ampere's force law and Faraday's law of induction. However, theoretical basis for Ampere's force law and Faraday's law remains unknown to this day. Furthermore, the Lorentz force is considered as experimental phenomena, the theoretical foundation of this force is still unknown.
To answer these fundamental theoretical questions, we derive Lienard Wiechert potentials, Maxwell's equations and Lorentz force from two simple postulates: (a) when all charges are at rest the Coulomb's force acts between the charges, and (b) that disturbances caused by charge in motion propagate away from the source with finite velocity. The special relativity was not used in our derivations nor the Lorentz transformation. In effect, it was shown all the electrodynamic laws, including the Lorentz force, can be derived from Coulomb's law and time retardation.
This was accomplished by analysis of hypothetical experiment where test charge is at rest and where previously moving source charge stops at some time in the past. Then the generalized Helmholtz decomposition theorem, also derived in this paper, was applied to reformulate Coulomb's force acting at present time as the function of positions of source charge at previous time when the source charge was moving. From this reformulation of Coulomb's law the Lienard Wiechert potentials and Maxwell's equations were derived.
In the second part of this paper, the energy conservation principle valid for moving charges is derived from the knowledge of electrostatic energy conservation principle valid for stationary charges. This again was accomplished by using generalized Helmholtz decomposition theorem. From this dynamic energy conservation principle the Lorentz force is derived.