A: Mitte, Leipzig, Sachsen, Germany

1905

In 1905, his *Annus Mirabilis,* German born theoretical physicist Albert Einstein published three papers in the periodical, *Annalen der Physik *issued* *in Leipzig from the press of Johann Ambrosius Barth:

(1) Ueber einen die Erzeugung und Verwandlung des Lichtes betreffenden heuristischen Gesichtpunkt.

(2) Ueber die von der molekularkinetischen Theorie der Wärme gefordete Bewegung von in ruhenden Flüssigkeiten suspendierten Teilchen.

(3) Zur Elektrodynamik bewegter Körper.

In the first paper Einstein suggested that light be considered a collection of independent particles of energy, which he called "light quanta." Such a hypothesis, he argued, would provide an answer to the problem of black-body radiation where classical theories had failed, and would also explain several puzzling properties of fluorescence, photoionization and the photoelectric effect Subsequent investigation led Einstein to propose, in 1909, the theory of wave-particle duality in radiation. For this paper, and his paper on the photoelectric effect ("Zur Theorie der Lichterzeugung und Lichtabsorption," 1906), Einstein was awarded the Nobel Prize in Physics in 1921.

In his second paper Einstein used the old and puzzling phenomenon of Brownian motion as a demonstration of the fluctuation phenomena predicted by statistical mechanics, from which he deduced the correctness of the molecular-kinetic theory of heat and determined the basic scale of atomic dimensions. This paper, and the experimental verification of its predictions, helped to convince skeptics of the physical reality of molecules.

The third paper, on the electrodynamics of moving bodies, was Einstein's first paper on special relativity. Two revolutionary conclusions were reached in this paper: first, that all motion was relative to the inertial system in which it was measured; and second, that matter and energy are equivalent. These theories, which were proved some years later, provided a radical reinterpretation of the universe, dethroning the Newtonian view which had ruled for over two centuries.

Concerning the early publishing histories of these papers see Hook & Norman, *The Haskell F. Norman Library of Medicine and Science* (1991) nos. 689-91.