(1) Theorie der lichterzeugung und lichtabsorption; (2) Prinzip von der erhaltung der schwerpunktsbewegung und die tragheit der energiein. In Annalen der Physik 20 (1906)-- Two landmark papers

(1) First Edition, journal issue. The brilliant follow-up to Einstein’s landmark 1905 paper on the photoelectric effect. In the 1905 paper Einstein had explained the photoelectric effect—the emission of electrons from a metal when irradiated by light—by making the revolutionary proposal that light, rather than consisting of continuous waves, was instead made up of discrete particles of energy (“light quanta”), which transferred their entire payload of energy to an electron on impact. In the 1905 paper Einstein made use of Planck’s mathematical formula for blackbody radiation, which had introduced the concept of energy quanta, but he was only able to derive (truncated) part of the formula. In his 1906 paper Einstein “used his statistical mechanics to demonstrate that when light interacts with matter, Planck’s entire formula can arise only from the existence of light quanta—not from waves” (Cassidy; emphasis ours). Einstein had realized, as he stated in the present paper, that “’Planck’s theory makes implicit use of the . . . light-quantum hypothesis’ . . . his acceptance of Planck’s [formula], albeit as a hypothesis, led to a major advance in his own work” (Pais, Subtle is the Lord, p. 378). In 1921 Einstein was awarded the Nobel Prize in physics for his work on the photoelectric effect. Cassidy, David, “Einstein on the Photoelectric Effect.” Einstein: Image and Impact. American Institute of Physics, n.d. Web. Accessed 09 July 2014. Shields, “Writings of Albert Einstein” (in Albert Einstein: Philosopher-Scientist [1948], pp. 689-758), no. 13; also included in Shields’ “Chronological list of principal works” on p. 757. Weil, Albert Einstein: A Bibliography, no. *12. (2) First Edition, journal issue of Einstein’s second paper on the inertia of energy, following his 1905 paper “Ist die Trägheit eines Körpers von seinem Energieinhalt abhängig?” [Is the inertia of a body dependent on its energy content?]. In the present paper Einstein presented another argument in support of the proposition that a body’s energy depends on its energy content. “About a year after he first introduced the inertia of energy, Einstein published a paper, entitled “The Principle of the Conservation of the Center of Gravity and the Inertia of Energy,” in which he showed that E = mc2 is necessary and sufficient to ensure that the center-of-mass theorem holds for systems in which ‘not only mechanical, but also electromagnetic processes take place’ . . . As Einstein acknowledges, his paper is similar to Poincaré’s contribution to the Lorentz Festschrift [1900]. Einstein showed that in order to avoid the kind of violations of the center-of-mass theorem discussed by Poincaré, one has to assume that energy has inertia” (Janssen, pp. 39-40). Janssen, “The Trouton experiment, E = mc2, and a slice of Minkowski space-time,” in Revisiting the Foundations of Relativistic Physics: Festschrift in Honor of John Stachel (2003), pp. 27-54. Weil, Albert Einstein Bibliography, 13. . (Inventory #: 50414)