scispace - formally typeset
Search or ask a question

Showing papers in "Physics Today in 1989"


Journal ArticleDOI
TL;DR: The history of physics envy can be found in this paper, where the authors discuss the history of the energy concept and its relationship with the field theory of value in political economy, and the corruption of the field theories of value and the retrogression to substance theories of values.
Abstract: List of figures List of tables Epigraph Acknowledgments Dedication 1. The fearful spheres of Pascal and Parmenides 2. Everything an economist needs to know about physics but was probably afraid to ask: the history of the energy concept 3. Body, motions and value 4. Science and substance theories of value in political economy to 1870 5. Neoclassical economics: an irresistible field of force meets an immovable object 6. The corruption of the field theory of value, and the retrogression to substance theories of value: neoclassical production theory 7. The ironies of physics envy 8. Universal history is the story of different intonations given to a handful of metaphors.

796 citations


Journal ArticleDOI
TL;DR: The pion has emerged as the main feature of nuclear structure beyond the traditional description in terms of neutrons and protons and it manifests itself in a number of areas which are normally only loosely interlinked, but intimately related to the pion-nucleon and pion nuclear interactions.
Abstract: The pion has emerges as the main feature of nuclear structure beyond the traditional description in terms of neutrons and protons. It manifests itself in a number of areas which are normally only loosely interlinked, but intimately related to the pion-nucleon and pion-nuclear interactions: the nucleon-nucleon force; the nuclear many-body problem; nuclear electromagnetic and weak interactions; nuclear spinisospin interactions; pion-nucleus scattering and reactions; etc. This book is a systematic introduction to and survey of nuclear pion physics, a major sub-field of nuclear pion physics. The theoretical foundations are padagogically developed and the physical picture is illustrated with supporting experimental examples.

606 citations


Journal ArticleDOI
TL;DR: In this paper, it was shown that spontaneous emission is not a property of an isolated atom but of an atom-vacuum system and can be inhibited or enhanced by placing the excited atom between mirrors or in a cavity.
Abstract: Ever since Einstein demonstrated that spontaneous emission must occur if matter and radiation are to achieve thermal equilibrium, physicists have generally believed that excited atoms inevitably radiate. Spontaneous emission is so fundamental that it is usually regarded as an inherent property of matter. This view, however, overlooks the fact that spontaneous emission is not a property of an isolated atom but of an atom‐vacuum system. The most distinctive feature of such emission, irreversibility, comes about because an infinity of vacuum states is available to the radiated photon. If these states are modified—for instance, by placing the excited atom between mirrors or in a cavity—spontaneous emission can be greatly inhibited or enhanced.

500 citations


Journal ArticleDOI
TL;DR: In this article, a unified picture of the physics of neutrinos as it is now understood from studies of nuclear physics, particle physics, astrophysics, and cosmology is presented.
Abstract: The study of the neutrino has emerged as important in the elucidation of weak interactions, and possibly, for future theoretical descriptions of the physics of elementary particles. The authors aim to offer a unified picture of the physics of neutrinos as it is now understood from studies of nuclear physics, particle physics, astrophysics, and cosmology. Focus is on the neutrino's mass and particle-anti-particle symmetry. Because neutrinos interact so weakly with matter, their basic properties are not well known, and the authors offer a framework for discussion. Physical aspects are stressed with an interlacing of theoretical and experimental considerations.

290 citations


Journal ArticleDOI

289 citations


Journal ArticleDOI
TL;DR: The mass of the elementary particles is the central problem of modern physics, and is intimately connected with other fundamental problems such as the origin of CP violation, the mystery of the energy scales that determine the properties of the weak and gravitational interactions, the compositeness of particles, supersymmetry theory, and properties of not yet discovered Higgs bosons as mentioned in this paper.
Abstract: Mass is one of the most fundamental concepts of physics. Understanding and calculating the masses of the elementary particles is the central problem of modern physics, and is intimately connected with other fundamental problems such as the origin of CP violation, the mystery of the energy scales that determine the properties of the weak and gravitational interactions, the compositeness of particles, supersymmetry theory and the properties of the not‐yet‐discovered Higgs bosons.

241 citations


Journal ArticleDOI
TL;DR: Science and technology as hegemony Marx - science as social relations - the scientific theory of society Engels and the return to epistemology The Frankfurt School - science and technologies as ideology Habermas - the retreat from the critique Marxism as a positive science as mentioned in this paper.
Abstract: Science and technology as hegemony Marx - science as social relations - the scientific theory of society Engels and the return to epistemology The Frankfurt School - science and technology as ideology Habermas - the retreat from the critique Marxism as a positive science Soviet science - the scientific and technological revolution the breakup of certainty - the discourse of the history and philosophy of modern physics the science of sociology and the sociology of science scientism or critical science - the debates in biology science as power - toward a new social theory of science.

239 citations


Journal ArticleDOI
TL;DR: The concept of singular perturbation theory was introduced in this paper and the concept of layer-type problems was introduced as a generalization of regular differential equations and partial differential equations.
Abstract: I. Introduction: General Concepts of Singular Perturbation Theory.- II. Layer-type Problems. Ordinary Differential Equations.- III. Layer-type Problems. Partial Differential Equations.- List of References.

172 citations


Journal ArticleDOI
TL;DR: The role played by clouds in the global radiation energy balance is investigated in this paper, with a view to the role of clouds in reducing the global radii absorbed by the atmospheric column.
Abstract: Data from NASA's Earth Radiation Budget (ERB) Experiment instruments carried by the ERB Satellite and by NOAA-9 and -10 are presently evaluated, with a view to the role played by clouds in the global radiation energy balance. While an individual water droplet scatters 85 percent of incident energy in the forward direction, a cloud of such drops can scatter 75 percent or more of the energy backward. The resulting enhancement of surface-atmosphere albedo reduces the solar radiation absorbed by the atmospheric column. Clouds also significantly enhance the long-wave opacity of the atmosphere; like gaseous absorption, this reduces the radiation emitted to space.

169 citations







Journal ArticleDOI
TL;DR: In this paper, the authors explain how light causes clusters of silver atoms to form on silver halide microcrystals in a photographic emulsion, and how these clusters, which may contain as few as three or four silver atoms, catalyze the reduction of all the silver ions in the micro-crystals to which they are attached.
Abstract: How does photographic film give such good images with so little exposure to light? The answer, in a word, is amplification. Light causes clusters of silver atoms to form on silver halide microcrystals in a photographic emulsion. These clusters, which may contain as few as three or four silver atoms, catalyze the reduction of all the silver ions in the microcrystals to which they are attached, giving a “gain” of over a billion. This is the basis for the high sensitivity and image quality of silver halide photographic film. As I will explain in this article, much is known about the physical mechanisms involved, and by using this knowledge one can improve the sensitivity and efficiency of film.

Journal ArticleDOI
TL;DR: The goniometer made possible the discovery of the fundamental laws of descriptive crystallography: that the angles between the facial planes are determined by the chemical composition of the crystal and that the relative orientations of facial planes follow a simple rule, the law of rational positions as mentioned in this paper.
Abstract: With the invention some 200 years ago of the goniometer, an instrument for measuring the angles between the faces of a crystal, the science of crystallography was born. The goniometer made possible the discovery of the fundamental laws of descriptive crystallography: that the angles between the facial planes are determined by the chemical composition of the crystal and that the relative orientations of the facial planes follow a simple rule, the law of rational positions.

Journal ArticleDOI
TL;DR: In this article, the authors consider two extremes of condensed matter states: crystalline solids, in which atoms form a perfectly periodic array that extends to infinity in three directions, and fluid or glasses, in where the atoms or molecules are completely disordered and the system is both orientationally and positionally isotropic.
Abstract: In thinking about the states of condensed matter, we usually consider two extremes. At one extreme are crystalline solids, in which atoms form a perfectly periodic array that extends to infinity in three directions. At the other extreme are fluids or glasses, in which the atoms or molecules are completely disordered and the system is both orientationally and positionally isotropic—that is, the materials look the same when viewed from any direction.

Journal ArticleDOI
TL;DR: A major impediment to writing physics gracefully comes from the need to embed in the prose many large pieces of raw mathematics as mentioned in this paper, which is a major obstacle to physics writing.
Abstract: A major impediment to writing physics gracefully comes from the need to embed in the prose many large pieces of raw mathematics. Nothing in freshman composition courses prepares us for the literary problems raised by the use of displayed equations. Our knowledge is acquired implicitly by reading textbooks and articles, most of whose authors have also given the problem no thought. When I was a graduate teaching assistant in a physics course for nonscientists, I was struck by the exceptional clumsiness with which extremely literate students who lacked the exposure even to such dubious examples treated mathematics in their term papers. The equations stood out like droppings on a wellmanicured lawn. They were invariably introduced by the word "equation," as in "Pondering the problem of motion, Newton came to the realization that the key lay in the equation

Journal ArticleDOI
TL;DR: The second volume, "Observation, Experiment, and Hypothesis in Modern Physical Science," edited by Peter Achinstein and Owen Hannaway, was published by The MIT Press for the Center for the History and Philosophy of Science at the Johns Hopkins University as discussed by the authors.
Abstract: In 1884 Sir William Thomson (later Lord Kelvin) delivered a significant series of lectures on physics at the Johns Hopkins University in Baltimore. The lectures remain important because, through their explicit presentation of the theories and metaphysical assumptions of the Newtonian mechanistic tradition, they illuminate the roots of the revolution in physics that began around 1900.This book presents the twenty lectures in their original form for the first time. (A greatly revised version of the lectures appeared in 1904.) In addition, it contains ten original essays in which well-known historians and philosophers of science discuss the physical issues raised in the Baltimore Lectures and developments in theoretical physics since they were delivered.Several of the accompanying essays deal with differences between Kelvin's views of molecular dynamics and the wave theory of light and the ultimately more successful electromagnetic concepts of James Clerk Maxwell. Others consider G. F. FitzGerald's approach to the question of mechanical models and Ernest Rutherford's attitudes toward theoretical matters.The philosophical context of the Baltimore Lectures is taken up, along with the subsequent development of theoretical physics. Several essays reflect upon issues important in the era of relativity and quantum theory - among them the quantum-measurement problem, space-time and action at a distance, parts and wholes, locality and nonlocality, and the transition from natural philosophy to the metaphilosophy of science.Following an introduction by Robert W Kargon, the essayists who address theoretical physics in Kelvin's time and after are P. M. Harmon, Bruce J. Hunt, M. Norton Wise, Crosbie Smith, Howard Stein, Lawrence Badash, Abner Shimony, Paul Teller, John Earman, Arthur Fine, and Thomas Nickles.The editors are affiliated with the Center for the History and Philosophy of Science at the Johns Hopkins University. This volume is the second in a series published by The MIT Press for the Center. The first volume, "Observation, Experiment, and Hypothesis in Modern Physical Science," edited by Peter Achinstein and Owen Hannaway, was published in 1985. A Bradford Book.

Journal ArticleDOI
TL;DR: In this paper, the authors describe how experimenters are using the radiation pressure of laser light to manipulate neutral atoms and how this pressure can be used to control beams of photons or massive particles.
Abstract: In ordinary optics one exploits the interaction of radiation with matter to manipulate beams of light. One can also turn the tables and control beams of charged or neutral material particles through their interaction with light. There are deep analogies and similarities between these two sorts of optics, even though they involve very different kinds of interactions between matter and radiation. Perhaps one can exploit every such interaction for some kind of “optics”—controlling beams of photons or massive particles. In this article we will describe recent developments in the laser optics of atomic beams—how experimenters are using the radiation pressure of laser light to manipulate neutral atoms.

Journal ArticleDOI
TL;DR: The only human activities that routinely cause doses approaching those from natural radiation are medical uses of radiation for diagnosis or therapy as mentioned in this paper, which is the case of nuclear power plants and medical uses.
Abstract: Our use of nuclear technology for medicine, energy and weapons during this century has led to growing awareness of the potentially harmful effects of radiation. Many people are even aware that exposures from weapons testing and from normally operating nuclear power plants have been far below those from the Earth's natural radioactivity and cosmic rays. The only human activities that routinely cause doses approaching those from natural radiation are medical uses of radiation for diagnosis or therapy.



Journal ArticleDOI
TL;DR: In physics research, change comes quickly, disseminates rapidly and is widely appreciated In physics teaching, change evolves gradually, spreads slowly and frequently meets with resistance On 6 June 1988 The Wall Street Journal published a story with the headline “Computers Failing as Teaching Aids” The reasons cited for this failure at the general pre-college education level apply equally well to physics teaching at the introductory college level: lack of access to computers, poor software and faculty members who are inadequately prepared to use computers effectively as mentioned in this paper.
Abstract: The computer has revolutionized the way we do physics, but surprisingly, it has not significantly altered the way we teach physics Talks and papers on teaching with computers fill the meetings and journals of the American Association of Physics Teachers, and workshops on the topic abound, yet the real impact of computers in the classroom is slight In physics research, change comes quickly, disseminates rapidly and is widely appreciated In physics teaching, change evolves gradually, spreads slowly and frequently meets with resistance On 6 June 1988 The Wall Street Journal published a story with the headline “Computers Failing as Teaching Aids” The reasons the Journal cited for this failure at the general pre‐college education level apply equally well to physics teaching at the introductory college level: lack of access to computers, poor software and faculty members who are inadequately prepared to use computers effectively

Journal ArticleDOI
TL;DR: To attain such perfection, these evolutionary processes had to recognize the quantum nature of light—a remarkable accomplishment.
Abstract: Our visual system provides our principal contact with the world around us. This system, thanks to millions of years of natural development, achieved a high degree of perfection long before humans arrived on the scene. To attain such perfection, these evolutionary processes had to recognize the quantum nature of light—a remarkable accomplishment.

Journal ArticleDOI
TL;DR: Insight is promised into such topics as the mechanisms of enzyme action, the implications of protein structure for evolutionary development, the relation of amino acid sequences to three‐dimensional structure and the relation between structure and function in complicated systems such as viruses, muscle, ribosomes and chromatin.
Abstract: Knowledge of the structures of macromolecules is of major importance both to basic science and to new, burgeoning industries. The determination of these structures is improving our understanding of fundamental biological processes, and so it sets the stage for the broad explanation of diseases on the molecular level and for the rational design of drugs. It promises to give insight into such topics as the mechanisms of enzyme action, the implications of protein structure for evolutionary development, the relation of amino acid sequences to three‐dimensional structure and the relation between structure and function in complicated systems such as viruses, muscle, ribosomes and chromatin.

Journal ArticleDOI
TL;DR: Nuclear astrophysics is a science that attempts to understand and explain the physical universe beyond the Earth by studying its smallest particles as discussed by the authors, and "Cauldrons in the Cosmos", by Claus E. Rolfs and William S. Rodney, provides a basic introduction to these endeavors.
Abstract: Nuclear astrophysics is, in essence, a science that attempts to understand and explain the physical universe beyond the Earth by studying its smallest particles. "Cauldrons in the Cosmos", by Claus E. Rolfs and William S. Rodney, serves as a basic introduction to these endeavors. From the major discoveries in the field to a discussion of the makeup of stars to an explanation of standard lab techniques, this text provides students and scientists alike a thorough and fascinating survey of the accomplishments, goals, and methods of nuclear astrophysics. A classic in its field, "Cauldrons in the Cosmos" will surely remain an important reference in nuclear astrophysics for years to come.


Journal ArticleDOI
TL;DR: The first time this term that we are going over there for it was in the first term of the first year of the present term as discussed by the authors, and it was a beautiful day.
Abstract: Just a brief letter before we go off to Rochester. We have every Wednesday a seminar at which somebody talks about some item of research, and from time to time this is made a joint seminar with Rochester University. Today is the first time this term that we are going over there for it. It is a magnificent day, and it should be a lovely trip; Rochester is due north of here, and we go through some wild country. I am being taken in Feynman's car, which will be great fun if we survive. Feynman is a man for whom I am developing a considerable admiration; he is the brightest of the young theoreticians here, and is the first example I have met of that rare species, the native American scientist. He has developed a private version of the quantum theory, which is generally agreed to be a good piece of work and may be more helpful than the orthodox version for some problems; in general he is always sizzling with new ideas, most of which are more spectacular than helpful, and hardly any of which get very far before ...