Showing papers in "Physics Today in 1971"
TL;DR: In this article, the authors present a theory intermediate in position between operator field theory and S-matrix theory, which rejects the dogmas of each and gains thereby a calculational ease and intuitiveness that make it a worthy contender to displace the earlier formulations.
Abstract: This classic, the first of three volumes, presents techniques that emphasize the unity of high-energy particle physics with electrodynamics, gravitational theory, and many-particle cooperative phenomena. What emerges is a theory intermediate in position between operator field theory and S-matrix theory, which rejects the dogmas of each and gains thereby a calculational ease and intuitiveness that make it a worthy contender to displace the earlier formulations.
644 citations
TL;DR: According to present cosmology, certain stars end their careers in a total gravitational collapse that transcends the ordinary laws of physics as mentioned in this paper, which is known as a total geyser collapse.
Abstract: According to present cosmology, certain stars end their careers in a total gravitational collapse that transcends the ordinary laws of physics.
467 citations
257 citations
TL;DR: Cosmic rays origin, discussing nuclear, electron and electromagnetic components, supernovae, pulsars, white dwarfs and gas motions in the Galactic Center are discussed in detail in this article.
Abstract: Cosmic rays origin, discussing nuclear, electron and electromagnetic components, supernovae, pulsars, white dwarfs and gas motions in Galactic Center
205 citations
203 citations
166 citations
TL;DR: In this article, the authors describe the absorption of Finite-Amplitude waves and the acceleration of Cavitation Voids, and the Cavitation Zone, the area around which the cavitation zone is defined.
Abstract: I - Absorption of Finite-Amplitude Waves.- II - Acoustic Radiation Pressure.- III - Acoustic Streaming.- IV - Pulsations of Cavitation Voids.- V - Experimental Investigations of Ultrasonic Cavitation.- VI - The Cavitation Zone.
160 citations
95 citations
TL;DR: In this paper, the authors present a method for computing the Mossbauer effect from a set of measurements of the magnetic field of a single-point charge in order to detect the presence of nuclear neutrally charged particles.
Abstract: 1 Introduction to the Mossbauer Effect.- 1. Pictorial Description.- 2. Background Concepts.- 2. 1. Natural Line Width.- 2. 2. Recoil Energy Loss.- 2. 3. Resonance and Resonance Fluorescence.- 2. 4. Doppler Broadening.- 2. 5. Einstein Solids.- 2. 6. Recoil-Free Emission of Gamma Rays.- 3. The Mossbauer Effect.- 3. 1. Pictorial Approach.- 3. 2. Observation of the Mossbauer Effect.- 4. Theory.- 2 Instrumentation.- 1. Instrumentation.- 1. 1. Gamma-Ray Detection.- 1. 2. Doppler Velocity Drive.- 2. Accuracy and Precision.- 2. 1. Calibration Methods.- 2. 2. Time of Counting.- 3. Experimental Techniques.- 3. 1. Sources.- 3. 2. Mossbauer Absorbers.- 3. 3. f-Factor Measurements.- 3. 4. Variable Temperature.- 3. 5. Scattering Methods.- 4. Applications of Computers to Mossbauer Spectra.- 4. 1. Computation of Mossbauer Spectra from a Theoretical Model.- 4. 2. Curve Fitting of Mossbauer Data by Least-Square Analysis.- 4. 3. Curve Fitting of Mossbauer Data by Constrained Least-Square Analysis.- 3 Nuclear Properties Determined from Mossbauer Measurements.- 1. A Phenomenological View of the Hyperfine Interactions.- 2. Differences in the Nuclear Charge Radius?R/R.- 2. 1. ?|?(0)|2 from "Pure Ionic" Valence States.- 2. 2. ?|?(0)|2 from Band Theory.- 2. 3. ?|?(0)|2 Caused by Overlap.- 2. 4. ?|?(0)|2 from the Shielding of p Holes.- 2. 5. ?R Ratios Method.- 2. 6. Nuclear Information from?R.- 3. Nuclear Quadrupole Moments Q and Spins I.- 3. 1. Quadrupole Moment Ratios Q*/Q.- 3. 2. Direct Determination of Quadrupole Moment Values.- 3. 3. Direct Determination of Nuclear Spins.- 4. Nuclear Magnetic Dipole Moments.- 5. Nuclear Lifetimes.- 6. Internal Conversion.- 7. Parity, Multipole Mixing, and Time Reversal.- 7. 1. Mossbauer Observation of Parity Nonconservation.- 7. 2. Multipole Mixing and Time Reversal.- 8. Nuclear Reactions and Devices.- 4 The Electric Field Gradient Tensor.- 1. The "Standard Form" EFG Tensor Due to a Single-Point Charge.- 2. The Ligand Contribution.- 3. The Valence Electron Contribution.- 4. Quadrupole Splittings.- 4. 1. The Nuclear Quadrupole Interaction.- 4. 2. Ligand-Only Splittings.- 4. 3. Valence-Only Splittings.- 4. 4. Ligand-Valence Combined Splittings.- 5. Potpourri.- 5. 1. Compounds with Internal Magnetic Fields.- 5. 2. Applied Magnetic Fields.- 5. 3. The Gol'danskii-Karyagin Effect.- 5. 4. Single Crystal Samples.- 6. The Utility of EFG Information.- Appendix I.- Appendix II.- 5 Application to Solid-State Physics.- 1. Isomer Shift.- 2. Magnetic Hyperfine Structure.- 3. Electric Quadrupole Interaction.- 4. Lattice Dynamics.- 6 Application to Coordination Chemistry.- 1. Crystalline Structure.- 2. Complex Isomerism.- 2. 1. Cis-Trans Isomerism.- 2. 2. Ligand Linkage Isomerism.- 2. 3. Spin-State Equilibria.- 3. Structure of Complicated Complex Compounds.- 4. Electronic Structure of Molecules.- 4. 1. Using Ligand Field Theory.- 4. 2. Using Molecular Orbital Theory.- 4. 3. Using the Spin Hamiltonian.- 7 Application to Organometallic Compounds.- 1. Isomer Shifts.- 1. 1. Organoiron Compounds.- 1. 2. Organotin Compounds.- 2. Quadrupole Splitting.- 2. 1. Organoiron Compounds.- 2. 2. Organotin Compounds.- 3. Conformational Studies.- 3. 1. Cyclooctatetraene Iron Tricarbonyl [COTFe(CO)3].- 3. 2. [?-C5H5Fe(CO)2]2 SnCl2 and Related Molecules.- 4. Conclusion.- 8 Mossbauer Spectroscopy and Physical Metallurgy.- 1. Mossbauer Application to Physical Metallurgy.- 1. 1. Precipitation in the Cu-Fe System.- 1. 2. Phase Transition in Stainless Steel.- 1. 3. Internal Oxidation Studies.- 1. 4. Magnetic Properties in Au-Fe Alloys.- 1. 5. Near-Neighbor Interaction in ?-Fe-Mo Alloys.- 1. 6. Near-Neighbor Interaction in Fe-C Alloys.- 1. 7. Order-Disorder in FeAl and Fc3Al.- 1. 8. Thin Films and Superparamagnetism.- 1. 9. Mossbauer Effect as a Nondestructive Analytical Tool.- 2. Physical Metallurgy Considerations Concerning the Mossbauer Effect.- 3. Summary.- 9 Application to Biochemical Systems.- 1. Hemoproteins.- 2. Experimental Conditions.- 2. 1. Enrichment.- 2. 2. Effect of Thickness.- 2. 3. State of the Absorber.- 3. Effect of Experimental Variables.- 3. 1. Effect of Temperature.- 3. 2. Effect of Magnetic Field.- 4. Spin-Spin Equilibrium.- Appendix A Nomenclature of Mossbauer Spectroscopy.- Appendix B Bibliographic Sources.- Appendix C Selected References on Mossbauer Spectroscopy.
TL;DR: In this article, a book on celestial mechanics covering perturbation methods, two body problems, astronomical coordinates, orbital mechanics, satellite rotation, gravitational effects, etc., is presented, which is a reference for this work.
Abstract: Book on celestial mechanics covering perturbation methods, two body problems, astronomical coordinates, orbital mechanics, satellite rotation, gravitational effects, etc
TL;DR: The boundary between these two dream worlds has become totally blurred during the last decade as discussed by the authors, and today, today, superconductivity at room temperature together with controlled thermonuclear fusion are the two most important and crucial problems in physics relevant to the needs of society.
Abstract: Since 1911 superconductivity at room temperature has been the dream of scientists and science‐fiction writers alike. Unfortunately for superconductivity, the boundary between these two dream worlds has become totally blurred during the last decade. Still, today, superconductivity at room temperature together with controlled thermonuclear fusion are often mentioned as the two most important and crucial problems in physics relevant to the needs of society. Controlled fusion has now become a distinct possibility, and its progress over the last twenty years has covered many orders of magnitude. During this same time, superconducting transition temperatures have expanded from a range of 0.4 K to 16 K to a range stretching from 0.0002 K to 21 K. If this upper limit could be further increased, not by another order of magnitude, but by a factor of as little as 1.2, or as large as 1.5, superconductivity, while still far from room temperature, would revolutionize our technology. This revolution would encompass elec...
TL;DR: In this article, a unified theory of the relations observed between load and deformation for elastic solids of various shapes, sizes, and compostions is presented, where the elastic character of the materials to which the theory is applicable may be loosely described as follows: if a body of elastic material is subjected to a load, it will be deformed and on the removal of the load will regain its initial dimensions and shape.
Abstract: In a previous chapter, the foundations of the classical theory of elasticity have been presented. It is concerned with the description and explanation in terms of a unified theory of the relations which are observed between load and deformation for elastic solids of various shapes, sizes, and compostions. The elastic character of the materials to which the theory is applicable may be loosely described as follows: If a body of elastic material is subjected to a load, it will be deformed and on the removal of the load will regain its initial dimensions and shape. In the concept of the elastic solid is also contained the assumption that the mechanical system constituted by an elastic solid and a system of forces applied to it is a system in which energy is conserved. The work done by the applied forces during the iso thermal deformation of the body is balanced by potential energy stored in the elastically deformed body and the kinetic energy of the various parts of the body and the members through which the deforming forces are applied.
TL;DR: DeWitt as discussed by the authors pointed out that despite its enormous practical success, quantum theory is so contrary to intuition that experts themselves still do not agree what to make of it, and his attempt to resolve the indeterminism question has resulted in a series of letters that appear to prove his opening statement right.
Abstract: “Despite its enormous practical success, quantum theory is so contrary to intuition that, even after 45 years, the experts themselves still do not agree what to make of it…” noted Bryce DeWitt at the start of his September 1970 physics today article, “Quantum mechanics and reality.” His attempt to resolve the indeterminism question has resulted in a series of letters that appear to prove his opening statement right.
TL;DR: The potential of amorphous semiconductors has been discussed in this article, where the authors focus on the challenge of theoretical understanding in the field of AMOS and their potential applications.
Abstract: “Potential” is the word that first comes to my mind in thinking about the field of amorphous semiconductors. The field is potentially very large because of the wide range of phenomena and materials it encompasses. The phenomena lend themselves to a multitude of potential technological applications (see box). What I am concerned with here, however, is the challenge offered by amorphous semiconductors to our theoretical understanding.
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TL;DR: Men and women physicists are a rare breed, but most of us agree that we need more of them as mentioned in this paper. But women physicists have many problems in common with other professional women, but some are peculiar to physics.
Abstract: Women physicists are a rare breed, but most of us agree that we need more of them. They have many problems in common with other professional women, but some are peculiar to physics. Many would like to work part time while raising families. Some feel that the system should have a bias built in to help women get into science and stay there. Others caution against lowering our standards. How do we provide models for young girls to identify with? Is the situation different abroad? Can the federal government help? Can genuine discrimination be observed?
TL;DR: In the realm of plasma physics, there appears to be no reason why known basic laws, formulated in the laboratory, should not hold just as well at the astrophysical and cosmological scale as mentioned in this paper.
Abstract: The study of astrophysics in modern times should essentially involve the application of laboratory results to cosmical problems, with help from theoretical physics. In the realm of plasma physics, there appears to be no reason why known basic laws, formulated in the laboratory, should not hold just as well at the astrophysical and cosmological scale.
TL;DR: For example, if two identical stationary clocks in the same inertial frame of reference are synchronized, and if one of them is accelerated away into different inertial frames and then returned to the original one, would the time readings of the clocks still be synchronized at this later rendezvous?
Abstract: Ever since the initial successes of the theory of relativity, physicists and philosophers of science have written a great deal about a paradox that seems to arise when theory tries to answer the question: If two identical stationary clocks in the same inertial frame of reference are synchronized, and if one of them is accelerated away into different inertial frames and then returned to the original inertial frame, would the time readings of the clocks still be synchronized at this later rendezvous?
TL;DR: The Gum Nebula was first recognized as a single emission complex by Colin S. Gum during the 1950's as discussed by the authors, and it was assumed that it was a Stromgren sphere, excited by ultraviolet light from the hot stars gamma Velorum and zeta Puppis within it.
Abstract: The Gum Nebula is seen on photographs of the southern skies as an extensive region of ionized hydrogen that surrounds the well known Vela X supernova remnant. One of the largest objects in our galaxy, the Nebula was first recognized as a single emission complex by Colin S. Gum during the 1950's. Until recently, astronomers assumed that it was a “Stromgren sphere,” excited by ultraviolet light from the hot stars gamma Velorum and zeta Puppis within it. This excitation process accounts for the Orion Nebula and other H‐II regions. The synchrotron and thermal bremsstrahlung mechanisms account for the radiation from supernova remnants, such as the Crab Nebula and Vela X; these objects consist of rapidly expanding matter ejected by the supernova explosions.
TL;DR: In this article, it was shown that the Josephson effect can be used to measure smaller low-frequency voltages and magnetic fields than can be measured with any other methods, and is also being investigated as possible high-frequency detectors and mixers, as thermometers and as computer elements.
Abstract: Josephson tunneling, an effect predicted and discovered within the last decade, has already formed the basis of a new technology. The “Josephson devices” are ultrasensitive electronic measuring devices that operate at liquid‐helium temperatures (1–4K) and exploit the macroscopic‐scale quantum properties of superconducting junctions. They have been used to measure, for example, smaller low‐frequency voltages and magnetic fields than can be measured with any other methods, and are also being investigated as possible high‐frequency detectors and mixers, as thermometers and as computer elements. One of the most important applications of the Josephson effect has been in the precision measurement of e/h in an experiment that avoids any assumptions from quantum electrodynamics (QED); results from this experiment give a convenient and accurate way to express the standard of electromotive force.