Electromagnetism

5Propagation: Special Relativity

5.1. Introduction

To look for a quantum formulation of electrodynamics, Feynman (New York, 1918 – Los Angeles, 1988) proposed new physical ideas (see Chapter 4). The first concerns the way electrons interact, eliminating the self-infinite energy – assuming that charges do not act on themselves. With these ideas, he proposed to reformulate classical theory by releasing it from infinite quantities, a theory where force is exerted at a distance.

The difficulty with this theory is that the idea that the electron does not act on itself seems to contradict a fact predicted by conventional electromagnetism: resistance to radiation. According to the laws of electromagnetism, an accelerated (or slowed) electron emits electromagnetic waves and, consequently, loses energy, and so to compensate for the lost energy, it is necessary to dedicate labor to accelerate the electron. This force is called “radiation resistance” or “radiation reaction force”. But where does this resistance come from? The action of the electron on itself seems the most logical explanation of the phenomenon. By eliminating the self-interaction of the electron, Feynman also eliminates the radiation resistance.

To imagine this situation, he thought of two electrons. The first (the source) moves, which induces the movement of the other (the absorber), by remote action.

By generalizing, it is concluded that the advanced and delayed interactions over time give a description of the logically ...