The education of Walter Kohn and the creation of density functional theory

The theoretical solid-state physicist Walter Kohn was awarded one-half of the 1998 Nobel Prize in Chemistry for his mid-1960's creation of an approach to the many-particle problem in quantum mechanics called density functional theory (DFT). In its exact form, DFT establishes that the total charge density of any system of electrons and nuclei provides all the information needed for a complete description of that system. This was a breakthrough for the study of atoms, molecules, gases, liquids, and solids. Before DFT, it was thought that only the vastly more complicated many-electron wave function was needed for a complete description of such systems. Today, fifty years after its introduction, DFT (in one of its approximate forms) is the method of choice used by most scientists to calculate the physical properties of materials of all kinds. In this paper, I present a biographical essay of Kohn's educational experiences and professional career up to and including the creation of DFT

History of Spin and Statistics

These lectures were given in the framework of the ``Dixi\`eme s\'eminaire rhodanien de physique'' entitled ``Le spin en physique'', given at Villa Gualino, Turin, March 2002. We have shown how the difficulties of interpretation of atomic spectra led to the Pauli exclusion principle and to the notion of spin, and then described the following steps: the Pauli spin with 2$\times$2 matrices after the birth of "new" quantum mechanics, the Dirac equation and the magnetic moment of the electron, the spins and magnetic moments of other particles, proton, neutron and hyperons. Finally, we show the crucial role of statistics in the stability of the world.Comment: latex file, 7 figures, 3 table

Autumn 2001

https://surface.syr.edu/arc_news/1006/thumbnail.jp

‘One must eliminate the effects of … diffuse circulation [and] their unstable and dangerous coagulation’: Foucault and beyond the stopping of mobilities

Foucault spent time investigating the stopping of mobilities, notably when studying carceral spaces such as asylums and prisons which effectively immobilise their inmates at a societal scale. In Discipline and Punish, he speculates on how such spaces are designed to put a stop to casual ‘nomadisms’. The purpose here is to inspect this aspect of Foucault’s thinking, particularly to recover what he also said about the regulation and cultivation of mobilities within the depths of immobility. Attention is also drawn to an engagement with mobility-immobility appearing in Foucault’s little-discussed Psychiatric Power lectures, prompted by the ideas and practices of Edouard Seguin, an educator of ‘idiot’ children, whose own words provide additional ‘empirical’ weight to an emerging argument. Reading the unabridged English translation of Madness and Civilization, a final claim is that Foucault’s phenomenology of ‘madness’ depends upon unruly mobilities within the asylum, the very stuff of ‘unstable and dangerous coagulation’. The overall ambition is to furnish an alternative account of Foucault and mobilities, concentrating on those Foucauldian texts initially seeming the least promising for scholars of mobilities

Misleading signposts along the de Broglie-Bohm road to quantum mechanics

Eighty years after de Broglie's, and a little more than half a century after Bohm's seminal papers, the de Broglie--Bohm theory (a.k.a. Bohmian mechanics), which is presumably the simplest theory which explains the orthodox quantum mechanics formalism, has reached an exemplary state of conceptual clarity and mathematical integrity. No other theory of quantum mechanics comes even close. Yet anyone curious enough to walk this road to quantum mechanics is soon being confused by many misleading signposts that have been put up, and not just by its detractors, but unfortunately enough also by some of its proponents. This paper outlines a road map to help navigate ones way.Comment: Dedicated to Jeffrey Bub on occasion of his 65th birthday. Accepted for publication in Foundations of Physics. A "slip of pen" in the bibliography has been corrected -- thanks go to Oliver Passon for catching it

Bowdoin College Catalogue (1988-1989)

https://digitalcommons.bowdoin.edu/course-catalogues/1269/thumbnail.jp

Problem of Time in Quantum Gravity

The Problem of Time occurs because the `time' of GR and of ordinary Quantum Theory are mutually incompatible notions. This is problematic in trying to replace these two branches of physics with a single framework in situations in which the conditions of both apply, e.g. in black holes or in the very early universe. Emphasis in this Review is on the Problem of Time being multi-faceted and on the nature of each of the eight principal facets. Namely, the Frozen Formalism Problem, Configurational Relationalism Problem (formerly Sandwich Problem), Foliation Dependence Problem, Constraint Closure Problem (formerly Functional Evolution Problem), Multiple Choice Problem, Global Problem of Time, Problem of Beables (alias Problem of Observables) and Spacetime Reconstruction/Replacement Problem. Strategizing in this Review is not just centred about the Frozen Formalism Problem facet, but rather about each of the eight facets. Particular emphasis is placed upon A) relationalism as an underpinning of the facets and as a selector of particular strategies (especially a modification of Barbour relationalism, though also with some consideration of Rovelli relationalism). B) Classifying approaches by the full ordering in which they embrace constrain, quantize, find time/history and find observables, rather than only by partial orderings such as "Dirac-quantize". C) Foliation (in)dependence and Spacetime Reconstruction for a wide range of physical theories, strategizing centred about the Problem of Beables, the Patching Approach to the Global Problem of Time, and the role of the question-types considered in physics. D) The Halliwell- and Gambini-Porto-Pullin-type combined Strategies in the context of semiclassical quantum cosmology.Comment: Invited Review: 26 pages including 2 Figures. This v2 has a number of minor improvements and correction

Address: job insecurity and technology

Technology ; Employment (Economic theory)