Railgun recoil and relativity

Abstract

In relativistic electromagnetism the recoil force of a railgun should act on the magnetic field and absorb field energy-momentum. The Ampere-Neumann electrodynamics, on the other hand, requires the recoil forces to reside in the railheads and push the rails back toward the gun breach. Experiment confirms the latter mechanism.

Railgun recoil and relativity

“…Turning to Graneau's own experiments (Graneau 1987), I observed a similar effect during some early experiments with high currents (Allen and Craggs 1954). When a current of the order of 200 kA flowed through a thin copper strip (by mistake!)…”

“…In a recent paper with the above title Graneau (1987) calculates the energy associated with certain railgun experiments, using relativity theory. In these calculations, however, the author displays a misconception concerning electromagnetism and relativity.…”

On Newton's Third Law

“…(3) This means that the force between two current elements depended not only on their distance, as in the inverse square law, but also on their angular position (in particular, implicating the existence of a longitudinal force, confirmed experimentally by Saumont [19] and Graneau [20], and discussed by Costa de Beauregard [21]). The other force generally considered is given by the Biot-Savart law, also known as the Grassmann's equation in its integral form:…”

On Newton's third law and its symmetry-breaking effects

“…This means that the force between two current elements depends not only on their distance, as in the inverse square law, but also on their angular position (in particular, implicating the existence of a longitudinal force, experimentally confirmed by Saumont (Saumont, 1968) and Graneau (Graneau, 1987), and discussed by Costa de Beauregard (?) and Ref.…”