EINSTEIN, Albert. Autograph manuscript, unsigned, comprising diagrams and calculations ILLUSTRATING THE SPECIAL THEORY OF RELATIVITY for Einstein's non-scientific friend, David Rothman, n.d. [September 1939]. 1 page, 4to, in pencil, with two later dockets by Rothman authenticating the document.
AN UNPUBLISHED EINSTEIN MANUSCRIPT ILLUSTRATING THE SPECIAL THEORY OF RELATIVITY FOR A LAYMAN
A great rarity, Einstein created this visual explanation of his special theory of relativity for his Long Island friend and neighbor, David Rothman, during the same summer that the Nobel physicist explained to President Roosevelt the urgency of creating an atomic bomb before the Nazis. Rothman, a department store owner with only a high school education, nevertheless had a strong interest in physics as well as music (he and Einstein comprised one-half of a local chamber music quartet). During one of their pleasant, summer afternoon conversations on the porch of Einstein's house in Peconic, Rothman asked his friend to explain the special theory of relativity as best he could without resort to mathematics. Einstein chose to explain (in Rothman's words), "the reason for the contraction of a rod in the direction of its motion and why a clock changes its rhythm."
A scientist from the Einstein Papers Project, Dr. Daniel Kennefick, authenticated the manuscript, and provides a summary of Einstein's visual explanations. The paper is divided by Einstein into four horizontal sections, with each diagram or theme marked off by a bold line across the page. In the first diagram Einstein shows how the movement of a rod will be perceived differently by two observers, one who is moving parallel to the rod and the other of whom is stationary. The movement of light rays along the rod, and the relative motion of the two observers, will cause each of them to measure the length of the rod differently.
The second diagram again shows how two observers in different states of motion relative to each other would perceive time differently. In the third diagram, in which Einstein cannot resist resorting to some mathematical formulae, he depicts time dilation for moving particles. He shows (in Dr. Kennefick's words), "two coordinate systems, one for each observer...Off to the right Einstein begins to calculate the transformation of relation between the two frames, primed and unprimed." In the fourth and final diagram, Einstein illustrates the idea of length contraction for moving particles, finishing with more mathematical calculations.
A very rare and significant Einstein scientific manuscript, written in the historically momentous month of September 1939 (Ironically, Rothman was with Einstein at Peconic when fellow physicists Eugene Wigner and Leo Szilard arrived from New York City that summer, to urge Einstein to write his famous letter to FDR). There are only three other known Einsetin manuscripts relating to the special theory of relativity. A 1912 manuscript is in The Israel Museum in Jerusalem. A 1916 manuscript is in the Hebrew University in Jerusalem. A 1913 manuscript is currently believed to be in private hands. This is the only other manuscript known to be in private hands.