scispace - formally typeset
Search or ask a question

Showing papers in "Physics Today in 1988"


Journal ArticleDOI
TL;DR: In this paper, a detailed and self-contained presentation of the replica theory of infinite range spin glasses is presented, paying particular attention to new applications in the study of optimization theory and neural networks.
Abstract: This book contains a detailed and self-contained presentation of the replica theory of infinite range spin glasses. The authors also explain recent theoretical developments, paying particular attention to new applications in the study of optimization theory and neural networks. About two-thirds of the book are a collection of the most interesting and pedagogical articles on the subject.

3,846 citations


Journal ArticleDOI
TL;DR: Koestler's book The Sleepwalkers as discussed by the authors is an account of the Copernican revolution, with Copernicus, Kepler, and Galilei as heroes, and he concluded that they were not really aware of what they were doing.
Abstract: ‘… the history of cosmic theories may without exaggeration be called a history of collective obsessions and controlled schizophrenias; and the manner in which some of the most important individual discoveries were arrived at reminds one of a sleepwalker's performance …’ This is a quotation from A. Koestler's book The Sleepwalkers . It is an account of the Copernican revolution, with Copernicus, Kepler, and Galilei as heroes. Koestler was of course impressed by the magnitude of the step made by these men. He was also fascinated by the manner in which they made it. He saw them as motivated by irrational prejudice, obstinately adhered to, making mistakes which they did not discover, which somehow cancelled at the important points, and unable to recognize what was important in their results, among the mass of details. He concluded that they were not really aware of what they were doing … sleepwalkers. I thought it would be interesting to keep Koestler's thesis in mind as we hear at this meeting about contemporary theories from contemporary theorists. For many decades now our fundamental theories have rested on the two great pillars to which this meeting is dedicated: quantum theory and relativity. We will see that the lines of research opened up by these theories remain splendidly vital. We will see that order is brought into a vast and expanding array of experimental data. We will see even a continuing ability to get ahead of the experimental data … as with the existence and masses of the W and Z mesons.

3,750 citations


Journal ArticleDOI
TL;DR: In this paper, a detailed description of the statistics, dynamics and statics of Josephson junctions is given, with particular emphasis on the dynamics of new circuits and analog and digital devices using single quanta of magnetic flux.
Abstract: This monograph offers a detailed description of the statistics, dynamics and statics of Josephson junctions. Particular emphasis is placed on the dynamics of new circuits and analog and digital devices using single quanta of magnetic flux.

1,261 citations


Journal ArticleDOI
TL;DR: One of the most interesting features of the book is that it makes a start at explaining "dynamical diseases" that are not the result of infection by pathogens but that stem from abnormalities in the timing of essential functions.
Abstract: In an important new contribution to the literature of chaos, two distinguished researchers in the field of physiology probe central theoretical questions about physiological rhythms. Topics discussed include: How are rhythms generated? How do they start and stop? What are the effects of perturbation of the rhythms? How are oscillations organized in space? Leon Glass and Michael Mackey address an audience of biological scientists, physicians, physical scientists, and mathematicians, but the work assumes no knowledge of advanced mathematics. Variation of rhythms outside normal limits, or appearance of new rhythms where none existed previously, are associated with disease. One of the most interesting features of the book is that it makes a start at explaining "dynamical diseases" that are not the result of infection by pathogens but that stem from abnormalities in the timing of essential functions. From Clocks to Chaos provides a firm foundation for understanding dynamic processes in physiology.

1,244 citations


Journal ArticleDOI
TL;DR: In this paper, the static defects that disrupt the translational symmetry of the periodic crystal lattice are the source of the disorder considered in this article, and a residual resistivity ρ 0 caused by the scattering of the electrons at the Fermi energy by lattice imperfections such as impurities and vacancies.
Abstract: The electrical conductivity of an ordinary metal such as gold is usually thought to be well understood. The electrons form a Fermi sea made up of plane waves modulated by the periodic crystal lattice. Because electrons obey Fermi statistics, only a narrow band of them, with an energy within kBT of the Fermi energy, contributes to the conductivity. At room temperature these electrons are scattered by lattice vibrations, resulting in a loss of momentum and a nonzero resistivity ρ(T). At low temperatures electron‐electron scattering is the dominant scattering mechanism. In the limiting case of zero temperature there is a residual resistivity ρ0 caused by the scattering of the electrons at the Fermi energy by lattice imperfections such as impurities and vacancies. The static defects that disrupt the translational symmetry of the crystalline lattice are the source of the disorder considered in this article.

441 citations


Journal ArticleDOI
TL;DR: In this article, a phase detected output control signal is filtered and utilized to provide greater stability in a phase-locked loop, where an adder adds the phase detected control signal to a signal corresponding to the preceding filtered control signal multiplied by a constant factor which is less than unity (<1).
Abstract: The invention relates to a novel filtering circuit whereby a phase detected output control signal is filtered and utilized to provide greater stability in a phase-locked loop. The filtering circuit is placed in the connecting path between a phase detector and an oscillator; the oscillator supplies output signals, having a repetition rate which depends on the instantaneous values of the filtered control signal. The filtering circuit comprises an adder which adds the phase detected control signal to a signal corresponding to the preceding filtered control signal multiplied by a constant factor which is less than unity (<1).

388 citations


Journal ArticleDOI
TL;DR: The Description for this book, When Time Breaks Down: The Three-Dimensional Dynamics of Electrochemical Waves and Cardiac Arrhythmias, will be forthcoming.
Abstract: The Description for this book, When Time Breaks Down: The Three-Dimensional Dynamics of Electrochemical Waves and Cardiac Arrhythmias, will be forthcoming.

283 citations


Journal ArticleDOI
TL;DR: In this new edition, Fine looks at Einstein's philosophy of science and develops his own views on realism as mentioned in this paper, and a new Afterword discusses the reaction to Fine's own theory.
Abstract: In this new edition, Arthur Fine looks at Einstein's philosophy of science and develops his own views on realism. A new Afterword discusses the reaction to Fine's own theory. "What really led Einstein . . . to renounce the new quantum order? For those interested in this question, this book is compulsory reading."-Harvey R. Brown, "American Journal of Physics" "Fine has successfully combined a historical account of Einstein's philosophical views on quantum mechanics and a discussion of some of the philosophical problems associated with the interpretation of quantum theory with a discussion of some of the contemporary questions concerning realism and antirealism. . . . Clear, thoughtful, [and] well-written."-Allan Franklin, "Annals of Science" "Attempts, from Einstein's published works and unpublished correspondence, to piece together a coherent picture of 'Einstein realism.' Especially illuminating are the letters between Einstein and fellow realist Schrodinger, as the latter was composing his famous 'Schrodinger-Cat' paper."-Nick Herbert, "New Scientist" "Beautifully clear. . . . Fine's analysis is penetrating, his own results original and important. . . . The book is a splendid combination of new ways to think about quantum mechanics, about realism, and about Einstein's views of both."-Nancy Cartwright, "Isis" "

262 citations


Journal ArticleDOI
TL;DR: A neural network is a large, highly interconnected assembly of simple elements that resemble biological neurons, which fire when the sum of the inputs from their synapses exceeds a “firing” threshold.
Abstract: A neural network is a large, highly interconnected assembly of simple elements. The elements, called neurons, are usually two‐state devices that switch from one state to the other when their input exceeds a specific threshold value. In this respect the elements resemble biological neurons, which fire—that is, send a voltage pulse down their axons—when the sum of the inputs from their synapses exceeds a “firing” threshold. Neural networks therefore serve as models for studies of cooperative behavior and computational properties of the sort exhibited by the nervous system.

166 citations


Journal ArticleDOI
TL;DR: In this article, the experimental techniques and instrumentation most often used in nuclear and particle physics experiments as well as in various other experimental sciences are described and discussed in a laboratory course in nuclear physics given to advanced students.
Abstract: The book is based on a laboratory course in nuclear physics given to advanced students. It treats the experimental techniques and instrumentationmost often used in nuclear and particle physics experiments as well as in various other experimental sciences. It provides most useful results and formulae, technical know-how and informative details on -interactionof radiation in matter; - radion protection and radioactive sources; - statistics for the interpretation and analysis of data; - principles and operation of the main types of detectors (ionization, scintillation and semiconductor detectors); - nuclear electronics instrumentation (NIM, CAMAC); - various systems and techniques for experiments. Thanks to the author's long teaching experience the material is presented in a verypractical, hands-on way making the book a useful text and lab companion for students and experienced scientists.

110 citations


Journal ArticleDOI
TL;DR: Classical equilibrium statistical mechanics magnetic systems the Ising model the lowtemperature and high-temperature expansions the Landau-Ginsberg model near the transition the renormalization group perturbative evaluation of the critical exponents near four dimensions on spontaneous symmetry breaking other models as discussed by the authors.
Abstract: Classical equilibrium statistical mechanics magnetic systems the Ising model the low-temperature and high-temperature expansions the Landau-Ginsberg model near the transition the renormalization group perturbative evaluation of the critical exponents near four dimensions on spontaneous symmetry breaking other models the transfer matrix path integrals for quantum mechanics semiclassical methods relativistic quantum field theory particle-field duality time dependent correlations the approach to equilibrium the stochastic approach to equilibrium the stochastic approach computer simulation.


Journal ArticleDOI
TL;DR: For example, this article pointed out that when faced with a piece of rock, not only do we not know where to begin, but we also may question whether it is even possible to find interesting physics in such a dirty and uncontrolled system.
Abstract: Sedimentary rock makes up much of the Earth's surface and contains two of the most vital fluids for our lives—water and hydrocarbons. Yet physicists have paid little attention to rock, mainly because we are discouraged by its apparent complexity. We are well trained in working with idealized models, but when faced with a piece of rock, not only do we not know where to begin, but we also may question whether it is even possible to find interesting physics in such a “dirty” and uncontrolled system. With further thought, however, we should realize that these are but the usual mental barriers that we have to overcome every time we study something new.

Journal ArticleDOI
TL;DR: In this article, a helium-neon laser is used to illuminate a barium titanate crystal, and after a few seconds, the incident beam begins to scatter into a broad fan of light.
Abstract: Shine a helium‐neon laser at a crystal of barium titanate, and at first the beam merely passes through the crystal. After a few seconds, however, the incident beam begins to scatter into a broad fan of light. After a few more seconds, a weak beam of light emerges from the crystal, traveling back exactly along the direction of the incident beam. As the laser continues to illuminate the crystal, the fan of scattered light disappears and the backscattered beam grows in strength, until it has stolen over half the power of the incident beam.


Journal ArticleDOI
TL;DR: In this paper, a simple model of magnetism is proposed to capture the essential physics of the phases and ordering transitions in more complicated systems, which is due in part to the availability of a host of experimentally accessible magnetic systems.
Abstract: Much of the enormous increase in our understanding of collective phenomena during the past few decades has arisen from the study of magnetic systems. The formulation of concepts such as universality, broken symmetry, and scaling near continuous phase transitions, as well as the development of the powerful ideas of the renormalization group, have been strongly influenced by research in magnetism. This is due in part to the availability of a host of experimentally accessible magnetic systems, and in part to the remarkable fact that simple models of magnetism capture the essential physics of the phases and ordering transitions in more complicated systems.



Journal ArticleDOI
Richard A. Webb1, Sean Washburn
TL;DR: In this paper, the authors describe quantum coherence properties in an intermediate "mesoscopic" regime that lies between the microscopic world of atomic and molecular orbitals and the thoroughly macroscopic world where averages tell all.
Abstract: In statistical physics one is trained to think about the properties of large ensembles of particles, and to calculate bulk properties by averaging over many microscopic configurations. Although the quantum mechanical properties of the individual constituents of a macroscopic object are important over some length scale (typically a few lattice spacings), they are usually not correlated across the whole object. We are, however, becoming acquainted with more and more disordered systems for which this effective length scale, at low temperatures, can be 100–10 000 times the characteristic microscopic scale; the correlation can involve more than 1011 particles. Such phenomena occur in an intermediate “mesoscopic” regime that lies between the microscopic world of atomic and molecular orbitals and the thoroughly macroscopic world where averages tell all. The wealth of novel quantum coherence phenomena recently observed in this intermediate size regime is the subject of this article.

Journal ArticleDOI
TL;DR: The science and technology of thin films have advanced so rapidly in recent years that investigators are now specializing, responding to the growing need to understand the properties of films of various compositions and thicknesses as discussed by the authors.
Abstract: The science and technology of thin films have advanced so rapidly in recent years that investigators are now specializing, responding to the growing need to understand the properties of films of various compositions and thicknesses. Of particular scientific and technological promise are organic thin films grown by the classical dipping technique developed during the period 1917–35 by Irving Langmuir and Katharine Blodgett. By building multiplayer films on solid surfaces from monolayer films on water, investigators are now developing and studying innovative materials with a wide range of potential technological applications, including molecular electronics, microelectronics, integrated optics and microlithography. Inorganic thin films of materials such as silicon dioxide have made possible the very‐large‐scale integration of electronic circuits. If the device geometries in these circuits shrink to nanometer dimensions over the next several decades, as some expect, Langmuir‐Blodgett films with nanometer dim...

Journal ArticleDOI
TL;DR: In the course of diagnosing the technical causes of the Challenger space shuttle disaster, the author also formed some impressions of NASA and became acquainted with some of the pitfalls of participation in an official investigation.
Abstract: A few days after the Challenger accident, on a Friday, I got a call from William Graham, who was the acting director of NASA. Mr. Graham had been a student of mine—at Caltech, and also at the Hughes Aircraft Company, where I gave a series of lectures—and thought maybe I would be of some use to the investigation. When I heard it would be in Washington, my immediate reaction was not to do it. I have a principle of not going anywhere near Washington or having anything to do with government. In the course of diagnosing the technical causes of the Challenger space shuttle disaster, the author also formed some impressions of NASA and became acquainted with some of the pitfalls of participation in an official investigation.

Journal ArticleDOI
TL;DR: The answer to why the sky is dark at night seems relatively simple: the sun has set and is now shining on the other side of the earth as discussed by the authors. But suppose we were space travelers and far from any star, the sky would be even darker than the sky seen from the earth on cloudless and moonless nights.
Abstract: Why is the sky dark at night?The answer to this ancient and celebrated riddle, says Edward Harrison, seems relatively simple: the sun has set and is now shining on the other side of the earth. But suppose we were space travelers and far from any star. Out in the depths of space the heavens would be dark, even darker than the sky seen from the earth on cloudless and moonless nights. For more than four centuries, astronomers and other investigators have pondered the enigma of a dark sky and proposed many provocative but incorrect answers. "Darkness at Night" eloquently describes the misleading trails of inquiry and strange ideas that have abounded in the quest for a solution.In tracing this story of discovery--one of the most intriguing in the history of science--the astronomer and physicist Edward Harrison explores the concept of infinite space, the structure and age of the universe, the nature of light, and other subjects that once were so perplexing. He introduces a range of stellar intellects, from Democritus in the ancient world to Digges in the reign of Queen Elizabeth, followed by Kepler, Newton, Halley, Cheseaux, Olbers, Poe, Kelvin, and Bondi. Harrison's style is engaging, incisive yet poetic, and his strong grasp of history--from the Greeks to the twentieth century--adds perspective, depth, and scope to the narrative. Richly illustrated and annotated, this book will delight and enlighten both the casual reader and the serious inquirer.

Journal ArticleDOI
TL;DR: The physical conditions required for primordial element-building also provide useful insights into neutrinos, the number and properties of weakly interacting particles, the mean density of luminous matter, and the entropy per baryon, or photon-to-baryon ratio as mentioned in this paper.
Abstract: Primordial nucleosynthesis of the lightest elements in the early universe and stellar nucleosynthesis of the heavier elements are by now both reasonably well understood. The classic paper on stellar nucleosynthesis of elements heavier than helium was published in 1957 by Margaret Burbidge, Geoffrey Burbidge, William Fowler and Fred Hoyle, and that on light‐element primordial nucleosynthesis in 1967 by Robert V. Wagoner, Fowler and Hoyle. The physical conditions required for primordial element‐building also provide useful insights into—and constraints on—the allowable number, type and degeneracy of neutrinos, the number and properties of weakly interacting particles, the mean density of luminous matter, and the entropy per baryon, or photon‐to‐baryon ratio. For many years that ratio was the one “free” parameter in the canonical Big Bang model, although we, with George Gamow, and others had long since suggested that it should not be considered free, but should be explained as a natural consequence of the ph...

Journal ArticleDOI
TL;DR: The New Alliance as mentioned in this paper provides an in-depth look at this significant phenomenon, analyzing the successes and failures of R&D consortia in the areas of leadership, research management, and technology transfer.
Abstract: The 1980s may be remembered as America's R&D consortia years. Since the beginning of this decade, industry, universities, and government have been working together as never before, developing new business ideas, researching new technologies, and tapping new markets. These are America's new R&D consortia, say the authors of THE NEW ALLIANCE, and they represent a phenomenon important enough to be termed a "movement." These alliances involve a wide and varied array of industries, educational institutions, political actors, and economic conditions. Founded by industry executives, academics, and government leaders who share a common recognition of the importance of high technology to our economy, as well as education's vital role in maintaining our competitive strength, the R&D consortia may be the newest examples of America's traditional resourcefulness, creativity, and resilience. THE NEW ALLIANCE provides the first in-depth look at this significant phenomenon, analyzing the successes and failures of R&D consortia in the areas of leadership, research management, and technology transfer. Based on extensive interviews at fourteen consortia nationwide, this book looks into the possible future of the consortia experiment, focusing on electronics, manufacturing, robotics, and new materials consortia.

Journal ArticleDOI
TL;DR: In this article, the authors present the highlights of modern solid state chemistry, an emerging area of chemical science, and take the reader to the very frontiers of the subject, which is concerned primarily with new methods of synthesis, identification and characterization of solids, and above all with new strategies for tailor-making materials with desirable and controllable properties.
Abstract: This book presents the highlights of modern solid state chemistry, an emerging area of chemical science. In adopting a unified and up-to-date approach the authors take the reader to the very frontiers of the subject, which is concerned primarily with new methods of synthesis, identification and characterization of solids, and above all with new strategies for tailor-making materials with desirable and controllable properties. The eight chapters are devoted to structure, methods of characterization, preparative strategies, phase transitions, defects and non-stoichiometry, structure-property relations, materials design, and reactivity of solids. Each of these reflects the way solid state chemistry is growing today and brings out the flavour of the subject to show how it works. In addition, every chapter ends with a list of important references.

Journal ArticleDOI
TL;DR: An overview of the various types of laser‐tissue interactions and some examples of how these interactions are exploited in medicine are given.
Abstract: The use of lasers in medicine began soon after the first ruby laser was invented in 1960. In recent years the number and variety of applications of lasers to biology and medicine has been increasing rapidly. I will review some of these applications, with emphasis on the physical mechanisms and the technology. After an overview of the various types of laser‐tissue interactions, I give some examples of how these interactions are exploited in medicine.

Journal ArticleDOI
TL;DR: In this paper, a more direct analogy with classical mechanics that would consider deterministic processes free from probabilistic uncertainty was proposed, based on the line of "God does not play dice".
Abstract: Forty years ago Albert Einstein wrote to Max Born, “God does not play dice.” Their correspondence dealt with the probabilistic interpretation of quantum theory, which Einstein opposed. He searched for a more direct analogy with classical mechanics that would consider deterministic processes free from probabilistic uncertainty.

Journal ArticleDOI
TL;DR: In this article, a quantitative measure of the cost-effectiveness of the journals is presented. But this measure does not consider the impact of the articles in the journal on the overall cost of the journal.
Abstract: The rapid increase in the prices of physics journals has forced many physics libraries, in the face of static budgets, to cancel some of their subscriptions. Decisions on cancellations are usually based on the research interests of the users of the library, but the decision‐making process can be improved if a quantitative measure of the cost‐effectiveness of the journals is available. An often‐used measure is the cost per printed character; another is the frequency with which articles in the journal are cited, often referred to as the “impact.” The ratio of these two measures is perhaps the best indicator of a journal's cost‐effectiveness.


Journal ArticleDOI
TL;DR: In 1932, Cockcroft and Walton as mentioned in this paper developed an electrostatic accelerator at the Cavendish Laboratory, thus starting the modern age of particle accelerators, and their capabilities have increased tremendously, as may be seen in figure 1.
Abstract: In 1932 John Cockcroft and Ernest Walton developed an electrostatic accelerator at the Cavendish Laboratory, thus starting the modern age of particle accelerators. Since then, our capabilities have increased tremendously, as may be seen in figure 1, which shows the energy of acceleratorsthrough the years. There has been an exponential increase in energy (the “Livingston curve”)—but it is the envelope that displays this exponential behavior, not any particular technique. One can conclude that if we are to stay anywhere near the Livingston curve, new techniques need to be developed.