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The Einstein-Podolsky-Rosen Argument and the Bell Inequalities
Full text linkIn 1935 Einstein, Podolsky, and Rosen (EPR) published an important paper in which they claimed that the whole formalism of quantum mechanics together with what they called ``Reality Criterion'' imply that quantum mechanics cannot be complete. That is, there must exist some elements of reality that are not described by quantum mechanics. There must be, they concluded, a more complete description of physical reality behind quantum mechanics. There must be a state, a hidden variable, characterizing the state of affairs in the world in more details than the quantum mechanical state, something that also reflects the missing elements of reality. Under some further but quite plausible assumptions, this conclusion implies that in some spin-correlation experiments the measured quantum mechanical probabilities should satisfy particular inequalities (Bell-type inequalities). The paradox consists in the fact that quantum probabilities do not satisfy these inequalities. And this paradoxical fact has been confirmed by several laboratory experiments in the last three decades. The problem is still open and hotly debated among both physicists and philosophers. It has motivated a wide range of research from the most fundamental quantum mechanical experiments through foundations of probability theory to the theory of stochastic causality as well as the metaphysics of free will
Einstein’s Investigations of Galilean Covariant Electrodynamics prior to 1905
Full text linkEinstein learned from the magnet and conductor thought experiments how to use field transformation laws to extend the covariance to Maxwell’s electrodynamics. If he persisted in his use of this device, he would have found that the theory cleaves into two Galilean covariant parts, each with different field transformation laws. The tension between the two parts reflects a failure not mentioned by Einstein: that the relativity of motion manifested by observables in the magnet and conductor thought experiment does not extend to all observables in electrodynamics. An examination of Ritz’s work shows that Einstein’s early view could not have coincided with Ritz’s on an emission theory of light, but only with that of a conveniently reconstructed Ritz. One Ritz-like emission theory, attributed by Pauli to Ritz, proves to be a natural extension of the Galilean covariant part of Maxwell’s theory that happens also to accommodate the magnet and conductor thought experiment. Einstein's famous chasing a light beam thought experiment fails as an objection to an ether-based, electrodynamical theory of light. However it would allow Einstein to formulate his general objections to all emission theories of light in a very sharp form. Einstein found two well known experimental results of 18th and19th century optics compelling (Fizeau’s experiment, stellar aberration), while the accomplished Michelson-Morley experiment played no memorable role. I suggest they owe their importance to their providing a direct experimental grounding for Lorentz’ local time, the precursor of Einstein’s relativity of simultaneity, and do it essentially independently of electrodynamical theory. I attribute Einstein’s success to his determination to implement a principle of relativity in electrodynamics, but I urge that we not invest this stubbornness with any mystical prescience
Albert Einstein with Helen Dukas, Peter Bucky, Frida Sarsen-Bucky, Gustav Bucky and dog in garden.
No full textDigital ImageDigital ImageDigital ImageGustav bucky was a German physicist and radiologist, best known for his work with scattered x-rays which was improved upon by Hollis E. Potter and later came to be known as the Bucky-Potter grid. He also worked with Albert Einstein to patent a “light intensity self-adjusting camera.”Frida Sarson-Buckywrote musical scores, poems, and stories for children. She married Gustav Bucky in 1910. The Bucky family emigrated to the United States of America in 1923, settling in New York City. They returned to Germany for a brief time in 1930 before escaping persecution and moving back to the USA in 1933.Peter Bucky was a radiologist and author. He wrote "The Private Albert Einstein" based on his conversations and interactions with Einstein himself and his father's friendship with him.Helen Dukas was Albert Einstein's personal secretary
Albert Einstein with his son-in-law Rudolf Kayser in Saranac Lake, NY.
No full textDigital ImageDigital ImageRudolf Kayser was a German literary historian and author. He was married to Albert Einstein's stepdaughter, Ilse Lowenthal Einstein, until her death in 1934. In 1935, he emigrated to the United States, teaching German and European literature at Brandeis University.Record added to DigiTool. Aleph record suppressed. J. Palmisano 09/15/2010
Albert Einstein with his son-in-law Rudolf Kayser at Einstein's summer home in Saranac Lake, New York.
No full textRudolf Kayser was a German literary historian and author. He was married to Albert Einstein's stepdaughter, Ilse Lowenthal Einstein, until her death in 1934. In 1935, he emigrated to the United States, teaching German and European literature at Brandeis University.Digital Imag
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Null Geometry and the Einstein Equations
No full textThis paper is based on a series of lectures given by the author at the Cargèse Summer School on Mathematical General Relativity and Global Properties of Solutions of Einstein’s Equations, held in Corsica, July 29—august 10, 2002. The general aim of those lectures was to illustrate with some current examples how the methods of global Lorentzian geometry and causal theory may be used to obtain results about the global behavior of solutions to the Einstein equations. This, of course, is a long standing program, dating back to the singularity theorems of Hawking and Penrose [24]. Here we consider some properties of asymptotically de Sitter solutions to the Einstein equations with (by our sign conventions) positive cosmological constant, ⋀> 0. We obtain, for example, some rather strong topological obstructions to the existence of such solutions, and, in another direction, present a uniqueness result for de Sitter space, associated with the occurrence of eternal observer horizons. As described later, these results have rather strong connections with Friedrich’s results [11, 13] on the nonlinear stability of asymptotically simple solutions to the Einstein equations with ⋀ > 0; see also Friedrich’s article elsewhere in this volume. The main theoretical tool from global Lorentzian geometry used to prove these results is the so-called null splitting theorem [16]. This theorem is discussed here, along with relevant background material
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