Showing papers in "Physics Today in 1985"
441 citations
TL;DR: The EPR paper and the theoretical and experimental work it inspired remain remarkable for the vivid illustration they provide of one of the most bizarre aspects of the world revealed to us by the quantum theory.
Abstract: In May 1935, Albert Einstein, Boris Podolsky and Nathan Rosen published an argument that quantum mechanics fails to provide a complete description of physical reality. Today, 50 years later, the EPR paper and the theoretical and experimental work it inspired remain remarkable for the vivid illustration they provide of one of the most bizarre aspects of the world revealed to us by the quantum theory.
438 citations
412 citations
TL;DR: In this article, an introduction to plasma physics and controlled fusion volume 1 plasma physics by is just one of the most effective vendor publications on the planet? Have you had it? Never? Silly of you.
Abstract: introduction to plasma physics and controlled fusion volume 1 plasma physics by is just one of the most effective vendor publications on the planet? Have you had it? Never? Silly of you. Currently, you can get this outstanding publication merely right here. Discover them is format of ppt, kindle, pdf, word, txt, rar, and zip. How? Just download or even review online in this site. Currently, never late to read this introduction to plasma physics and controlled fusion volume 1 plasma physics. This is really going to save you time and your money in something should think about. If you're seeking then search around for online. Without a doubt there are several these available and a lot of them have the freedom. However no doubt you receive what you spend on. An alternate way to get ideas would be to check another introduction to plasma physics and controlled fusion volume 1 plasma physics. Our goal is always to offer you an assortment of cost-free ebooks too as aid resolve your troubles. We have got a considerable collection of totally free of expense Book for people from every single stroll of life. We have got tried our finest to gather a sizable library of preferred cost-free as well as paid files. GO TO THE TECHNICAL WRITING FOR AN EXPANDED TYPE OF THIS INTRODUCTION TO PLASMA PHYSICS AND CONTROLLED FUSION VOLUME 1 PLASMA PHYSICS, ALONG WITH A CORRECTLY FORMATTED VERSION OF THE INSTANCE MANUAL PAGE ABOVE.
157 citations
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TL;DR: The X-Ray Universe as discussed by the authors is a first-hand account of the X-ray universe and its evolution from the early days of the Naval Research Laboratory through the era of V-2 rocketry, Sputnik, and the birth of NASA.
Abstract: Beyond the range of optical perception--and of ordinary imaginings--a new and violent universe lay undetected until the advent of space exploration. Supernovae, black holes, quasars and pulsars--these were the secrets of the highenergy world revealed when, for the first time, astronomers attached their instruments to rockets and lofted them beyond the earth's x-ray-absorbing atmosphere. The X-Ray Universe is the story of these explorations and the fantastic new science they brought into being. It is a first-hand account: Riccardo Giacconi is one of the principal pioneers of the field, and Wallace Tucker is a theorist who worked closely with him at many critical periods. The book carries the reader from the early days of the Naval Research Laboratory through the era of V-2 rocketry, Sputnik, and the birth of NASA, to the launching of the Einstein X-Ray Observatory. But this is by no means just a history. Behind the suspenseful, sometimes humorous details of human personality grappling with high technology lies a sophisticated exposition of current cosmology and astrophysics, from the rise and fall of the steady-state theory to the search for the missing mass of the universe.
149 citations
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TL;DR: In this article, Hartree and Hartree-Fock proposed the Hartree potential, which is an extension of the Schrodinger Equation of the Green's Function, and showed that it can be used to approximate a wave.
Abstract: 1. The Interacting System.- 1.1. The Basic Problem.- 1.2. The Jellium Solid.- 1.3. Hartree Theory-The Sommerfeld Model.- 1.4. Hartree-Fock.- 1.5. Exchange and Correlation Holes.- 1.6. Correlation Effects and the Thomas-Fermi Model.- Problems.- 2. Green's Functions of the Single-Particle Schrodinger Equation.- 2.1. Green's Functions of the Schrodinger Equation.- 2.2. Green's Functions and Perturbation Theory.- 2.3. Time-Dependent Green's Functions.- 2.4. Green's Function Diagrams.- 2.5. Green's Functions or Wave Functions?.- Problems.- 3. Quantization of Waves (Second Quantization).- 3.1. Waves and Particles.- 3.2. The Linear Chain of Atoms.- 3.3. The General Quantization of a Wave System.- 3.4. Quantization of the Electromagnetic Field.- 3.5. Elementary Excitations and "Particles".- 3.6. Perturbations and the Elementary Excitations.- 3.7. Summary.- Problems.- 4. Representations of Quantum Mechanics.- 4.1. Schrodinger Representation.- 4.2. Heisenberg Representation.- 4.3. Interaction Representation.- 4.4. Occupation Number Representation.- 4.5. Interaction between Waves and Particles.- 4.6. Field Operators.- Problems.- 5. Interacting Systems and Quasiparticles.- 5.1. Single-Particle States.- 5.2. Absorbing Media.- 5.3. Exact and Approximate Eigenstates.- 5.4. Landau Quasiparticles.- Problems.- 6. Many-Body Green's Functions.- 6.1. Definition of the Many-Body Green's Function.- 6.2. Relationship to Single-Particle Green's Function.- 6.3. Energy Structure and the Green's Function.- 6.4. The Lehman Representation and Quasiparticles.- 6.5. Expectation Values.- 6.6. Equation of Motion for the Green's Function.- 6.7. Hartree and Hartree-Fock Approximations.- 6.8. The Self-Energy.- Problems.- 7. The Self-Energy and Perturbation Series.- 7.1. Functional Derivatives and the Calculation of G and ?.- 7.2. Iterative Solution for the Green's Function and Self-Energy.- 7.3. Screening and the Perturbation Series.- 7.4. The Screened Interaction and Selective Summations.- 7.5. The Uniform System.- Problems.- 8. Diagrammatic Interpretation of the Green's Function Series.- 8.1. Diagrammatic Interpretation of the Perturbation Series.- 8.2. Diagrammatic Expansion.- 8.3. Infinite Series and Irreducible Diagrams.- 8.4. The Hartree Potential.- 8.5. The Uniform System.- 8.6. Rules for Evaluating Diagrams.- 8.7. Selective Summations.- 8.8. Practical Aspects of Diagrammatics.- Problems.- 9. The Normal System.- 9.1. The Jellium Solid Response Function.- 9.2. The Self-Energy (Physical Considerations).- 9.3. Evaluation of the Self-Energy and Quasiparticle Properties.- 9.4. Landau Quasiparticles.- 9.5. Insulating Systems.- 9.6. Surfaces.- Problems.- 10. Thermal Effects on the Green's Function.- 10.1. The Density Matrix.- 10.2. Statistical Mechanics.- 10.3. The "Thermal" Heisenberg Representation.- 10.4. Evaluation of the Perturbation Expansion.- 10.5. Periodicity of G and the Extension to Energy Dependency.- 10.6. Real-Time Thermal Green's Functions.- Problems.- 11. Boson Particles.- 11.1. Collective Excitations in Solids.- 11.2. Electron-Phonon System.- 11.3. Plasmons and the Total Interaction.- 11.4. Boson Systems with a Condensate.- Problems.- 12. Special Methods.- 12.1. The Density Functional Method (Nearly Uniform Electron Gases).- 12.2. Highly Localized Systems (Anderson-Hubbard Models).- 12.3. Canonical Transformations.- 12.4. Mean-Field Theory.- Problems.- 13. Superconductivity.- 13.1. Cooper Pairs.- 13.2. Canonical Transformations.- 13.3. Propagator Approach.- Problems.- Appendix: List of Symbols.
57 citations
43 citations
TL;DR: The role of the neutron in nuclear fission has been extensively discussed in the literature as mentioned in this paper, and it has been used in fields as diverse as logging oil wells, detecting art forgeries and doping electronic semiconductor materials.
Abstract: Since its discovery 50 years ago, the neutron has commanded public attention and respect. As an intermediary in nuclear fission, it is woven into the political fabric of modern life and seems destined to remain so. But the neutron plays many other, less prominent and controversial roles as well. It has, for example, technological applications in fields as diverse as logging oil wells, detecting art forgeries and doping electronic semiconductor materials, as D. Allan Bromley has reviewed in these pages.
TL;DR: In this paper, the authors discuss the application of small-angle neutron scattering to the study of polymers and the possibility of fulfilling a mentor's desire to understand the conformation and dynamics of polymer molecules.
Abstract: Some years ago, one of our mentors expressed the desire to “color polymer molecules red” so that one could follow them in a solid and see how they arrange themselves and how they move among similar or different molecules. As we will see in this article, the excitement today over the application of small‐angle neutron scattering to the study of polymers lies in the possibility of fulfilling his wish to understand the conformation and dynamics of polymer molecules.
TL;DR: In the past decade, the semiconductor laser has become a key device in optical electronics because of its pure output spectrum and high quantum efficiency as mentioned in this paper, and this property and its compact size make it useful in a vast range of applications, from fiber-optic communications to optical radar.
Abstract: In the past decade the semiconductor laser—also known as the diode or junction laser—has become a key device in optical electronics because of its pure output spectrum and high quantum efficiency. Not coincidentally, its output can be modulated at very high speeds; this property and its compact size make it useful in a vast range of applications, from fiber‐optic communications to optical radar.
TL;DR: The cavity magnetron was developed by two British physicists, Henry A. Boot and John T. Randall, and was built at the British General Electric Laboratory at Wembley as mentioned in this paper, but the British at first hesitated to divulge the design of the magnetron to Americans for fear that it would fall into the hands of German intelligence, but the subsequent developments completely justified the Tizard commission's actions.
Abstract: In the autumn of 1940, a British technical and scientific mission, headed by Sir Henry Tizard, brought to the United States a famous black tin trunk containing, among other things, an electronic device that exerted a profound influence on the outcome of the war. This device, the cavity magnetron, was developed by two British physicists, Henry A. Boot and John T. Randall, and was built at the British General Electric Laboratory at Wembley. The British at first hesitated to divulge the design of the magnetron to Americans for fear that it would fall into the hands of German intelligence, but the subsequent developments completely justified the Tizard commission's actions. The disclosure of this device led to the formation later that year of the Radiation Laboratory at Massachusetts Institute of Technology. An elite group of scientists and engineers recruited from universities and industry developed there a variety of magnetrons during the war years and incorporated them into more than 100 radar systems, giv...
TL;DR: The linear accelerator at Stanford University (SLAC) produces electron beams with energies as high as 32 GeV and peak currents of about 120 milliamps as discussed by the authors, which has proven extremely successful in high-energy physics experiments.
Abstract: To probe deeper into the subnuclear structure of matter, physicists over the last 50 years have developed a remarkably sophisticated technology of high‐energy accelerators. By design, these accelerators have operated at relatively low currents, primarily to avoid complications due to electric fields generated by the charged‐particle beams themselves. Machines such as the linear accelerator at Stanford University (SLAC) produce electron beams with energies as high as 32 GeV and peak currents of about 120 milliamps. Although of fairly low current, these devices have proven extremely successful in high‐energy physics experiments, where one can irradiate a target over an extended period of time to get a statistically significant number of collisional events.
TL;DR: In this article, the first images of a living cell at a near-molecular resolution of 75 A were obtained by using a soft x-ray photon as a probe in a synchrotron.
Abstract: Biologists have long dreamed of a microscope capable of imaging specimens in their natural state, at molecular or near‐molecular resolution. Physicists have for some years known that the soft‐x‐ray photon has properties that suit it for use as a probe in such microscopy. With the advent of synchrotron radiation sources, and with other technical advances, the difficulties that impeded the development of soft‐x‐ray microscopy have begun to give way, and in 1983 the technique produced the first images ever obtained of a living cell at a near‐molecular resolution of 75 A.
TL;DR: One of the most glamorous aspects of monolayer films is their thinness, and another is their two dimensionality as mentioned in this paper, although it might seem that each implies the other.
Abstract: One of the most glamorous aspects of monolayer films is their thinness, and another is their two dimensionality. These properties are not the same, of course, although it might seem that each implies the other. We know some monolayers that are not two dimensional, and some much thicker films that are nearly so. Even more confusing is that a film can be two dimensional and three dimensional—and some‐where in between—at the same time. A simple change of temperature can change a film's dimensionality.
TL;DR: In this article, the authors reconstruct the circumstances that converged to the discovery of nuclear fission in America, by examining private correspondence and other unpublished documents, in conjunction with the published literature.
Abstract: In January 1939 the news of the discovery of nuclear fission burst in America, sending physicists into their laboratories to try to confirm the startling new discovery. Some aspects of the story of how this news reached America are well known. Others, however, are not; they have remained hidden in private correspondence and other unpublished documents. By examining these materials in conjunction with the published literature, one can reconstruct the circumstances that converged to produce this historic event.
TL;DR: The physics of systems with many degrees of freedom often differs in crucial ways from what we understand for simple systems as mentioned in this paper, which is a challenge common to all areas of physics is to understand the properties of systems having large or infinite numbers of degrees offreedom in terms of known underlying interactions.
Abstract: One of the fundamental challenges common to all areas of physics is to understand the properties of systems having large or infinite numbers of degrees of freedom in terms of known underlying interactions. Simply knowing the Schrodinger equation and Coulomb's law, for example, is not sufficient to let us understand the chain through which atoms form molecules, which, in turn, beget macromolcules, which eventually aggregate into a biological object with a life of its own. Nor has knowledge of the Lagrangian for quantum chromodynamics yet yielded an understanding of hadrons. The physics of systems with many degrees of freedom often differs in crucial ways from what we understand for simple systems.
TL;DR: The authors recognize that historical narrative without investigation of conceptual transformation is just chronology, and that great advances in science alter our view of the world, including the theory of motion, Albert Einstein's theory of special relativity and Werner Heisenberg's invention of quantum mechanics.
Abstract: Great advances in science alter our view of the world. Galileo Galilei's theory of motion, Albert Einstein's theory of special relativity and Werner Heisenberg's invention of quantum mechanics, with its subsequent interpretation by Niels Bohr and Heisenberg himself, spring immediately to mind (figure 1). In exploring these episodes we must recognize that historical narrative without investigation of conceptual transformation is just chronology.
TL;DR: The 184-inch cyclotron was used to construct the world's greatest atom smasher, a hill overlooking the Berkeley campus of the University of California in the early 1970s as discussed by the authors.
Abstract: Long ago, shortly before World War II, when I was but 13 years of age, I was excited by an article in Popular Mechanics magazine that described Ernest O. Lawrence's project to construct the world's greatest atom smasher, a 184‐inch cyclotron, on a hill overlooking the Berkeley campus of the University of California. From that point on, my career goal was to become a physicist. While the 184‐inch‐cyclotron project has always symbolized to me the beauty and excitement of unlocking the mysteries of nature, I never suspected, even for many years into my career as a high‐energy and cosmic‐ray physicist, that I would have a rendezvous with destiny involving the 184‐inch cyclotron: using it in its waning years to make my most significant contribution to the progress of science.
TL;DR: In this article, the difference between doing experiments at steadystate and at pulsed sources is discussed, and the authors illustrate what has been done with the modest sources now available, and speculate on some future experimental efforts.
Abstract: The other articles in this issue are concerned with the variety of science that goes on at reactor‐based neutron sources. Such sources, based on nuclear fission, have been available since 1942. It has been known since the 1930s that neutrons could be produced through spallation by sending a charged beam of accelerated protons or electrons into a target. However, it has only been in the last few years that the intensity of these spallation sources has been sufficient for the range of sophisticated experiments required to study the properties of condensed matter. Today there are a number of operating spallation neutron sources, and more with higher intensity are planned (see the table). In this article we want to explain the difference between doing experiments at steady‐state and at pulsed sources, illustrate what has been done with the modest sources now available, and speculate on some future experimental efforts. We do not have space to describe how a spallation source works: this information is present...
TL;DR: The study of science in secondary schools can be compared to a pyramid with physics at the apex as discussed by the authors, and it is nice to be on top. Unfortunately, there are not many there to keep each other company.
Abstract: Science is regarded as a difficult subject by students, and most graduate from high school with only a very limited knowledge about it. The study of science in secondary schools can be compared to a pyramid with physics at the apex. It is nice to be on top. Unfortunately, though, there are not many there to keep each other company.
TL;DR: The crystalline and electronic structures of semiconductors reflect a delicate balance of very large electromagnetic forces, and consequently minute compositional variations or small perturbations can induce large changes in the properties of these materials.
Abstract: The crystalline and electronic structures of semiconductors reflect a delicate balance of very large electromagnetic forces, and consequently minute compositional variations or small perturbations can induce large changes in the properties of these materials. for several decades now, research scientists and device designers have exploited his exceptional flexibility to tailor the electronic and optical properties of semiconductors for a variety of fundamental studies and applications. Semiconductor technology has made its most apparent impact, of course, in solid‐state electronics.
TL;DR: The Superconducting Super Collider (SSC) was proposed by the High Energy Physics Advisory Panel of the United States Department of Energy as mentioned in this paper, which recommended that the highest priority be given to construction of a very large accelerator.
Abstract: In July of 1983, the High Energy Physics Advisory Panel of the Department of Energy recommended that the highest priority be given to construction of a very large accelerator, the Superconducting Super Collider. The recommended energy per beam of this accelerator is 20 TeV, or 20 000 GeV—this is a macroscopic energy of about 32 ergs for each proton in the beam. Head‐on collisions of protons against protons will thus make 40 TeV available in the center of mass, more than 60 times the energy available at the present CERN collider and 20 times that to become available at the Fermi National Accelerator Laboratory in the near future. The committee urged, moreover, that this facility be completed and available for physics research within about a decade. The solemnity of the advice was underscored by the simultaneous recommendations that all other proposals for high‐energy accelerators not be approved. This included both the Colliding Beam Accelerator, in which the Brookhaven National Laboratory had invested con...
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TL;DR: Asteroids that orbit the Sun in a belt between the orbits of Mars and Jupiter are well known as discussed by the authors, and from time to time, one collides with our planet, as figure 1 so clearly indicates.
Abstract: Asteroids that orbit the Sun in a belt between the orbits of Mars and Jupiter are well known. A few other asteroids cross Earth's orbit, and, from time to time, one collides with our planet, as figure 1 so clearly indicates. What are they made of? How did they originate? We suspect that material much like the asteroids played a part in the origin of the solar system—can we see similar forces at work elsewhere?