Jagdish Mehra

Temperature correction to the casimir effect

Abstract The temperature correction to the Casimir effect is calculated by applying statistical mechanics to a resonant cavity at finite temperature. Comparison is made with the macroscopic theory of Lifshitz based on a fluctuating electromagnetic field. It is found that the effect of temperature on the interaction between the plates is negligible for separations of 0.1–2 μ, but it becomes considerable for separations greater than 3 μ.

Einstein, Hilbert, and the Theory of Gravitation

From 1907 to 1925, Albert Einstein dominated the development of the general relativity theory of gravitation. His own work on the theory of gravitation from 1912 to 1916 had the drama of high adventure. David Hilbert, fascinated by Einstein’s work on relativity and Gustav Mie’s work on electrodynamics, decided to construct a unified field theory of matter. In two communications to the Gottingen Academy (on 20 November 1915 and 23 December 1916), Hilbert developed his theory of the foundations of physics. In the first of these communications, he derived the field equations of gravitation and the conditions governing them. Hilbert’s work, although inspired by Einstein, was independent of and simultaneous with Einstein’s derivation of the field equations and, in certain essential respects, went beyond Einstein’s. Einstein, at that time, was very critical of the efforts of Mie, Hilbert and Weyl to construct a unified field theory of gravitation and electromagnetism. After 1925, such a programme became his primary mission.

Climbing the Mountain

APPENDIX A: JULIAN SCHWINGER - LIST OF PUBLICATIONS APPENDIX B: PH.D. STUDENTS OF JULIAN SCHWINGER INDEX

Planck's Half-Quanta: A History of the Concept of Zero-Point Energy

Max Planck introduced the concept of zero-point energy in spring 1911. In the early struggles to establish the concept of the energy-quantum, it provided a helpful heuristic principle, to guide as well as supplement the efforts of some leading physicists in understanding the laws that applied in the atomic domain. The history and growth of this concept, and its application in the general development of quantum theory during the past many decades are studied under three principal headings: (1) The Birth of the Concept of zero-Point Energy; (2) Does Zero-Point Energy Really Exist? and (3) The Ground State of Quantum Systems.

Niels Bohr's discussions with Albert Einstein, Werner Heisenberg, and Erwin Schrödinger: the origins of the principles of uncertainty and complementarity

In this paper, the main outlines of the discussions between Niels Bohr with Albert Einstein, Werner Heisenberg, and Erwin Schrödinger during 1920–1927 are treated. From the formulation of quantum mechanics in 1925–1926 and wave mechanics in 1926, there emerged Borns statistical interpretation of the wave function in summer 1926, and on the basis of the quantum mechanical transformation theory—formulated in fall 1926 by Dirac, London, and Jordan—Heisenberg formulated the uncertainty principle in early 1927. At the Volta Conference in Como in September 1927 and at the fifth Solvay Conference in Brussels the following month, Bohr publicly enunciated his complementarity principle, which had been developing in his mind for several years. The Bohr-Einstein discussions about the consistency and completeness of qnautum mechanics and of physical theory as such—formally begun in October 1927 at the fifth Solvay Conference and carried on at the sixth Solvay Conference in October 1930—were continued during the next decades. All these aspects are briefly summarized.

Einstein and the foundation of statistical mechanics

In three papers (1902–1904), Albert Einstein developed the essential principles of the statistical mechanical approach to thermodynamics before he was twenty-five years old. Einsteins work was inspired by Ludwig Boltzmanns Vorlesungen uber Gastheorie, but it was completely independent of J. Williard Gibbs (whose monograph on statistical mechanics was published in 1902). In certain respects, especially in the search for the existence of atoms of matter and quanta of radiation by a study of fluctuations, Einsteins work went beyond Boltzmanns and Gibbs. For Einstein, his study of the principles of statistical thermodynamics was merely a prelude to his achievements in quantum theory and brownian motion.

Erwin Schrödinger and the rise of wave mechanics. II. The creation of wave mechanics

This article (Part II) deals with the creation of the theory of wave mechanics by Erwin Schrödinger in Zurich during the early months of 1926; he laid the foundations of this theory in his first two communications toAnnalen der Physik. The background of Schrödingers work on, and his actual creation of, wave mechanics are analyzed.

The Probability Interpretation and the Statistical Transformation Theory, the Physical Interpretation, and the Empirical and Mathematical Foundations of Quantum Mechanics 1926–1932

Contents-Part 1.- 1 The Probability Interpretation and the Statistical Transformation Theorythe Physical Interpretationand the Empirical and Mathematical Foundations of Quantum Mechanics (1926-1932).- I The Probability Interpretation and the Statistical Transformation Theory.- II Uncertainty, Complementarity, and Quantum Fields.- III The Empirical and Mathematical Foundations of Quantum Mechanics.

The Conceptual Completion and the Extensions of Quantum Mechanics (1932–1941)

The invention of quantum and wave mechanics and the great, if not complete, progress achieved by these theories in describing atomic, molecular, solid-state and—to some extent—nuclear phenomena, established a domain of microphysics in addition to the previously existing macrophysics. To the latter domain of classical theories created since the 17th century applied—principally, the mechanics of Newton and his successors, and the electrodynamics of Maxwell, Hertz, Lorentz, and Einstein. The statistical mechanics of Maxwell, Boltzmann, Gibbs, Einstein, and others indicated a transition to microphysics; when applied to explain the behaviour of atomic and molecular ensembles, it exhibited serious limitations of the classical approach. Classical theories were closely connected with a continuous description of matter and the local causality of physical processes. The microscopic phenomena exhibited discontinuities, ‘quantum’ features, which demanded changes from the classical description.

The Young Julian Schwinger. I. A New York City Childhood

In this series of articles the early life and work of the young Julian Schwinger are explored. In this first article, Schwingers childhood, growing-up, and early education are discussed.