Thanks. It's decent, actually, but there's still some barrier. Increasing that barrier is changes to physics notation since then (no vectors!).
Fortunately my university library appears to have a copy of an older edition of Rohrlich's Classical Charged Particles, which may help piece things together.
Petkov wrote:
Feynman [wrote], ”It is therefore impossible to get all the mass to be electromagnetic in the way we hoped. It is not a legal theory if we have nothing but electrodynamics” [13, p. 28-4]; but he was unaware that the factor of 4/3 had already been accounted for [10]).
It's worth noting that Feynman's statements are actually correct. According to Wikipedia, the problem is solved by postulating a non-electromagnetic attractive force holding the charged particle together, which subtracts 1/3 of the 4/3 factor, leaving unity. Petkov doesn't explicitly say that Feynman is wrong, but his phrasing might leave that impression.
We've had these for a year, I'm sure we all know what to do by now.
This thread is for the discussion of Less Wrong topics that have not appeared in recent posts. If a discussion gets unwieldy, celebrate by turning it into a top-level post.