In September 2009 two papers of mine, “Einstein on mass and energy” in the American Journal of Physics1 and “Einstein Never Approved of Relativistic Mass,” in the Physics Teacher,2 appeared in those respective journals. These essays should certainly have been cross-referenced and perhaps even footnoted with an exegetical commentary. Unfortunately, because of the unpredictability of the publishing process, they were not, and for that I claim full responsibility. Although submitted eight months apart, the two papers were coincidentally edited and printed simultaneously, which was a surprise that made proper retroreferencing impossible. In any case, the articles were written to be more-or-less complementary and differ in both intended audience and emphasis.
The Physics Teacher piece (submitted first), while keeping the physics elementary, concentrates exclusively on the fact that Einstein rejected speed-dependent mass in 1906 and shunned relativistic mass after it was conceived by others in 1908. The essay...
