Einstein and Planck on mass–energy equivalence in 1905–1906: a modern perspective
Einsteinʼs theoretical analysis of mass–energy equivalence, already at the time, experimentally evident in radioactive decays, in two papers published in 1905, as well as Planckʼs introduction, in 1906, of the concepts of relativistic momentum, and, by invoking Hamiltonʼs principle, relativistic energy, are reviewed and discussed. Claims in the literature that Einsteinʼs analysis was flawed, lacked generality, or was not rigorous, are rebutted.