


Description: The main part of this volume is a new publication of Einstein's valuable book Relativity: The Special and the General Theory, written for a wider audience. Four other articles, which nicely complement the issues discussed in the book, are also included in the volume. The selected works contain not only Einstein's own explanations of his revolutionary contributions to fundamental physics, but also give the readers, particularly his popular book, the unique chance to be exposed to Einstein's original thinking in action. The five works by Einstein included in this volume are: 1. Relativity: The Special and the General Theory. A Popular Exposition (Methuen And Co. Limited 1920) 2. "What is the Theory Of Relativity," written at the request of The London Times and published on November 28, 1919 3. "Ether and the Theory of Relativity," An Address delivered on May 5th, 1920, in the University of Leyden 4. "Geometry and Experience," An expanded form of an Address to the Prussian Academy of Sciences in Berlin on January 27th, 1921 5. "A Brief Outline of the Development of the Theory of Relativity," Nature volume 106, pages 782784 (17 February 1921)
Einstein's assertion that the circumference of the rotating disk will be larger for a stationary observer is incorrect. He erroneously assumed that the measuringrod along the circumference contracts but the space (along the circumference) does not and therefore more measuringrods will fit in the space along the circumference and the circumference will be longer (it will contain more measuringrods) than when at rest. Unfortunately, this erroneous Lorentzian view (that bodies contract but space itself does not) is a common misconception. This misconception can be immediately overcome when it is taken into account that the Lorentz transformations predict that the distance between two points, as measured by a moving observer, will be shorter than the distance between the same points measured by an observer at rest with respect to the points, no matter whether these points are the end points of a rod or just two points in space. The physical meaning of length contraction was made exceedingly clear by Minkowski in his groundbreaking lecture "Space and Time" delivered in 1908 (in: Hermann Minkowski, Space and Time: Minkowski's papers on relativity, edited by V. Petkov (Minkowski Institute Press, Montreal 2012), p. 116)  Minkowski showed that not only two observers in relative motion have different times but they also have different spaces (forming an angle) and these spaces intersect two parallel worldliness (representing either the end points of a rod or just two points in the space of one of the observers) under different angles; as a result the distance between the points will be different for the two observers. In 1909 Ehrenfest gave the original formulation of the rotating disc problem (Ehrenfest considered a cylinder  see P. Ehrenfest, Gleichförmige Rotation starrer Körper und Relativitätstheorie, Physikalische Zeitschrift, 1909, 10: 918) "on the basis of Minkowski's ideas" and correctly concluded that "the periphery of the cylinder has to show a contraction compared to its state of rest: 2πR' < 2πR."

