LORENTZ, Hendrik Anton, Das Relativitätsprinzip (B.G. Teubner, Leipzig and Berlin), 1914

169 x 253mm; pp. 52

Good condition: spine neatly repaired; library stamps and markings

The true first appearance of the most famous equation in the history of science.

Einstein’s ‘annus mirabilis’ papers on the equivalence of mass and energy were published in the Annalen der Physik in 1905. However, Einstein did not write E=mc2 in 1905, stating only the mass-energy relation in terms of changes in each.

Of all the many physicists who discussed and analyzed Einstein’s work in the years after 1905, Hendrik Lorentz was perhaps the most imaginative, and certainly the best qualified. It was Lorentz who first stated ‘E=mc2’ in the present volume (on p. 24; see photograph). Since the early years of the 20th century Lorentz had been seeking equations for ‘electromagnetic mass’.

Einstein himself first used E=mc2 in 1946, in the title of an article in Science Illustrated.