Physicist solves century old problem of radiation reaction

A Lancaster physicist has proposed a solution to the question of how an electron responds to its own field.

The question has been posed to physicists for over 100 years.

It is well known that if a point charge is accelerated it will produce radiation. This radiation has both strength and weakness. It is assumed that they come from the charged particle.

The history of attempts to calculate the radiation reaction goes back to 1892. Major contributions were made by many physicists including Plank, Abraham, von Laue, Born, Schott, Pauli, Dirac and Landau. There are many articles published every year.

The electric field at the point where the particle is is infinite according to the equations. The force on that point particle should be infinite.

Various methods have been used to normalise the situation. This leads to the well established equation.

This equation has known pathological solutions. A particle obeying this equation can accelerate forever without external force or before force is applied. There is a quantum version of radiation. One of the few phenomena where the quantum version occurs at lower energies than the classical one.

Physicists are looking for this effect. This requirescolliding very high energy electrons and powerful laser beams, a challenge as the biggest particle accelerators are not located near the most powerful lasers. The high energy electron produced by the lasers will interact with the laser beam. This requires a powerful laser. The current results show that there is a quantum radiation reaction.

The approach is to consider many charged particles, where each particle responds to the fields of all the other charged particles, but not itself. This approach was dismissed because it was assumed that it wouldn't conserve energy.

Dr. Gratus shows that the assumption is false, with the energy and momentum of one particle being used to accelerate it.

The controversial implications of this result is that there isn't a need for classical radiation reaction at all. The discovery of quantum radiation reaction is similar to the discovery of Pluto, which was found following predictions based on discrepancies in the motion of Neptune. Corrected calculations showed there were no discrepancies. The radiation reaction was predicted and found not to be needed.

More information: Jonathan Gratus, Maxwell–Lorentz without self-interactions: conservation of energy and momentum, Journal of Physics A: Mathematical and Theoretical (2022). DOI: 10.1088/1751-8121/ac48ee Citation: Physicist solves century old problem of radiation reaction (2022, January 25) retrieved 26 January 2022 from https://phys.org/news/2022-01-physicist-century-problem-reaction.html This document is subject to copyright. Apart from any fair dealing for the purpose of private study or research, no part may be reproduced without the written permission. The content is provided for information purposes only.