HASENÖHRL, FRIEDRICH.

Zur Theorie der Strahlung in bewegten Körpern.

Leipzig, Ambrosius, 1904 8vo. In full black cloth with gilt lettering to spine. In "Annalen der Physik", Fourth series, No. 15, 1904. Entire issue offered. Library labels pasted on to front end-papers and stamps to title page, otherwise fine. Pp. 344-70. [Entire volume: VIII, 1064 pp + 4 folded plates].

First printing of Hasenöhrl's important paper in which he showed that electromagnetic energy E, enclosed in an empty box with perfectly reflecting walls, behaves, when the box is set in motion, as if it had a mass proportional to E - also often referred to as inertia of a cavity containing radiation. Since J. J. Thomson in 1881, many physicists like Wilhelm Wien (1900), Max Abraham (1902), and Hendrik Lorentz (1904) used equations for the so-called "electromagnetic mass", which expresses how much electromagnetic energy contributes to the mass of bodies. And Henri Poincaré (1900) implicitly used the expression m=E/c2 for the mass of electromagnetic energy.

"When Hasenöhrl returned to Vienna he wrote the series of papers for which he is best known, on electromagnetic radiation. of these the most important is the prizewinning essay on the effects of radiant energy within a moving cavity.2Using classical theory he showed that the trapped radiation increases the kinetic energy of the motion, the effect being equivalent to an increase in the apparent mass of the cavity.
In his formula h?0 is the total radiant energy in the cavity and c is the velocity of light. Like other similar anticipations, this result was displaced by Einstein's more general theorem on the equivalence of mass and energy." (DSB)

Order-nr.: 50921