PPPL COLLOQUIUM: A Slightly Longer History of E=mc2, Or How I Came to Hate 4/3

Wed, May 2, 2012, 4:00 pm to 6:00 pm
PPPL: Lyman Spitzer Building
According to popular mythology, the equivalence of mass and energy was suddenly conceived of and proven by Einstein in 1905. In fact, serious attempts to connect mass and energy went back at least to J.J. Thomson in 1881 and over the next two decades became the subject of numerous investigations by Maxwellians such as Heaviside, Abraham and Poincaré. The talk focuses on a 1904 thought experiment of Fritz Hasenöhrl, who first announced that blackbody radiation had an equivalent mass such that E = (3/8)mc2, which he subsequently corrected to E = (3/4)mc2. Why did Hasenöhrl get the wrong answer and Einstein get the right one? What does it mean to prove a law of nature? Stephen Boughn and myself have recently carried out an complete relativistic analysis of Hasenöhrl’s thought experiment and, for the first time in the century since it was proposed, have correctly solved the problem. I will try to keep the mathematics at a reasonable level but it will require familiarity with electrodynamics and special relativity.