The problem of radiation-reaction may be stated as follows: if an accelerating charge loses energy by emitting radiation, how does this energy loss affect the charge itself?
This problem initiated the development of more than a dozen of alternative theories to the Maxwell-Lorentz theory of electromagnetism. It was also the precursor of Bohr's model of the atom and eventually quantum mechanics. After all, if the electron is accelerating while traveling around the nucleus and an accelerating charge emits radiation, then the electron itself must emit radiation, lose energy and eventually collapse into the nucleus, right? This theoretical prediction of classical electrodynamics contradicts one of our most elementary observations - the existence of stable atoms!
So there was clearly something wrong.
With the invention of quantum mechanics, the majority of physicists forsaken this issue completely, arguing that it was no longer a problem in quantum theory. Nevertheless, there was (and still is) a number of striking theorists who claim that the problem was never really solved, including Paul Dirac himself.
The goal of this codex is to explain the origin of the problem of radiation-reaction, our most important attempts to solve it and whether or not we can experimentally test for it with current technology. I will argue that the problem is still unsolved, and that it is one of the reasons many of our current theories have so many divergences.
In my opinion, the problem of radiation-reaction holds the key to precious new physics.