THE FIRST EXPLICIT STATEMENT OF THE ENERGY-MASS EQUATION

EINSTEIN, ALBERT.

Über die vom Relativitätsprincip geforderte Trägheit der Energie.

Leibzig, Johann Ambrosius Barth, 1907.

8vo. In contemporary full cloth with gilt lettering to spine. In "Annalen der Physik", Vierte Folge, Band 23. Entire volume offered. Ex-libris pasted on to top right corner of pasted down front free end-paper. Light rubbing to extremities, a very fine and clean copy (not an ex-library copy). Pp.371-384. [Entire volume: VIII, 1000 pp. + 4 plates].

First edition of the first explicit statement of Einstein's landmark energy-mass equation E=mc2.

Nearly all descriptions of Einstein's scientific work state that the mass-energy equivalence E=mc2 was first formulated in Einstein's 1907 review paper 'Über das Relativitätsprinzip und die aus demselben gezogenen.' published in 'Jahrbuch der Radioaktivität und Elektronik' (see Weil no. 21 and Dictionary of Scientific Biography, vol. 4 pp.323 for examples). However, in his paper 'Über die von Relativitätsprincip geforderte Trägheit der Energie' [the offered paper] which predates the former mentioned by six months, Einstein gave a clear statement of the mass-energy equivalence E=mc2. See Lanczos: The Einstein Decade, pp.149-150 and 153 as well as Volume 2 of 'The Collected Papers of Albert Einstein' pp. 428.

Einstein's first paper regarding the relation E=mc2 is his fourth 1905 paper, 'Ist die Trägheit eines Körpers von seinem Energieinhalt abhängig?'. In this short paper Einstein showed that a body releasing the energy E in the form of radiation will have its mass decreased by E/c2, and concluded that the mass of a body is a measure of its energy content, e.g., that all energy has mass.

The next time Einstein returns to the subject is in his 1906 paper 'Das Prinzip von der Erhaltung der Schwerpunkts Bewegung und die Trägheit der Energie.'. Here Einstein concluded that one must either ascribe the inertial mass E/c2 to any form of energy E or else give up the fundamental law mechanics regarding conservation of the motion of the center of gravity.

Then finally in the 1907 paper 'Über die von Relativitätsprincip geforderte Trägheit der Energie.' [the offered paper] Einstein makes the decisive step of assuming that all mass has energy. On page 382 Einstein considers the total energy of a moving mass point as the sum of its kinetic energy and its rest energy. In classical mechanics it is most convenient to set the second term to zero but in relativistic mechanics one obtains the simplest expression by setting the rest energy equal to mc2. Einstein then continues to show that this stipulation cannot lead to a contradiction in any relativistic argument. In a footnote on page 382 Einstein states for the first time the equation E=mc2 and mentions that this equation is the expression of the principle of the equivalence of mass and energy - see Volume 2 of 'The Collected Papers of Albert Einstein' pp. 428.

The volume contains another paper by Einstein "Bemerkungen zu der Notiz von Hrn. Paul Ehrenfest: "Die Translation deformierbarer Elektronen und der Flächensatz"", pp.206-208. - Weil No. 18.

Collected Works, Doc. 45. Weil 19. Boni 19.

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