ISSN:0031-9228    

DOI:10.1063/1.3034944

出版商:AIP    

年代:1968

数据来源: AIP

ISSN:0031-9228    

DOI:10.1063/1.3034901

出版商:AIP    

年代:1968

数据来源: AIP

ISSN:0031-9228    

DOI:10.1063/1.3034914

出版商:AIP    

年代:1968

数据来源: AIP

ISSN:0031-9228    

DOI:10.1063/1.3034916

出版商:AIP    

年代:1968

数据来源: AIP

摘要:

A degree becomes a kelvin; Miscounted those fringes; Astronomer's stamp; Clarity, justice, confusion; What is c if not a speed?; Toward better retrieval; Don't; listen to my opinion; Keeping builders up to date.

ISSN:0031-9228    

DOI:10.1063/1.3034917

出版商:AIP    

年代:1968

数据来源: AIP

摘要:

THE DEFINITIONof the newly coined word “rheology” in the constitution of the Society of Rheology, when it was founded in 1929 under Eugene C. Bingham of Lafayette College, was “fundamental and practical knowledge concerning the deformation or flow of matter.” As Markus Reiner recalled telling Bingham at the time, this word would appear to have the same meaning as the termcontinuum mechanics. An operational definition obtained by an examination of what most rheologists actually do would more likely lead to the conclusion that, as accurately as any scientific discipline can be defined, “rheology—a branch of mechanics—is the study of those properties of materials which determine their response to mechanical force,” a statement that appears in a brochure recently issued by the Society of Rheology. This more restricted view, the one that I shall take in delineating the area covered in this historical review, removes from consideration the more complicated flow and deformation problems usually discussed in fluid mechanics, hydrodynamics and elasticity.

ISSN:0031-9228    

DOI:10.1063/1.3034918

出版商:AIP    

年代:1968

数据来源: AIP

摘要:

IN THE SECOND“golden” decade of this century Albert Einstein unified physics and geometry and fulfilled a long cherished dream of Karl Friedrich Gauss, Bernhard Riemann and William K. Clifford. This geometrical theory of gravitation had “magnetic” types of velocity‐dependent forces and a finite velocity of gravitational interactions; it apparently predicted gravitational radiation. The equations describe gravitation in terms of the curvature of space‐time. Riemann gave the concept of the curvature ofn‐dimensional space as a logical generalization of the concept of curvature of a two‐dimensional surface. Radii of curvature for such a surface are easy to visualize. There is a simple connection (given in the box on p. 39) between these radii and the sum of the angles of a small triangle made up of geodesic lines (figure 1).

ISSN:0031-9228    

DOI:10.1063/1.3034919

出版商:AIP    

年代:1968

数据来源: AIP

摘要:

INFORMATION CONTENTof physics has been influenced dramatically by vigorous developments in research and education since 1946. These developments are the direct result of two federal science policies.

ISSN:0031-9228    

DOI:10.1063/1.3034920

出版商:AIP    

年代:1968

数据来源: AIP

摘要:

CERTAIN AREAS OF RESEARCHthat used to be actively pursued by people called physicists in physics laboratories have now to a large extent, although not entirely, migrated to chemistry laboratories. Among the most prominent of the areas that have moved from physics toward chemistry are molecular spectroscopy, the theory of molecular structure and spectra and certain related areas, for example molecular mass spectroscopy. All these various areas are usually called “molecular physics” if carried on in physics departments or “chemical physics” if in chemistry departments.

ISSN:0031-9228    

DOI:10.1063/1.3034921

出版商:AIP    

年代:1968

数据来源: AIP

摘要:

THE SECOND WORLD WARinterrupted work in the quantum theory almost completely, and yet it furnished a stimulus that had the most profound effect on postwar work. First, there was the effect of the microwave radar research that was carried on at the Massachusetts Institute of Technology radiation laboratory, Bell Telephone Laboratories and other institutions. Physicists who had been converted into radar engineers during the war went back to their laboratories with a greatly enhanced knowledge of electronics and microwave techniques. This situation resulted in the development of new and powerful experimental techniques of high‐frequency experimentation on solids, leading to the methods of paramagnetic resonance, radiofrequency spectroscopy, cyclotron resonance, and a myriad of other ways of investigating atoms, molecules and solid state. Another outgrowth of the radar work was the increased interest in solid‐state electronics. Radar techniques of the wartime period used silicon crystals as rectifiers much as early radio had used galena crystals. Toward the end of the war remarkable properties of germanium, similar chemically to silicon, were beginning to be appreciated, and an intensive research program to understand these substances was started at Purdue University under Karl Lark‐Horovitz. It was realized that these substances were semiconductors, and those working on them began to recall what had almost been forgotten during the war; namely, the way in which the energyband theory of solids explained semiconductor properties. Bell Telephone Laboratories had the foresight to realize that the electrical properties of semiconductors might have great practical value in more everyday applications than radar and put a team of their best men, including William Shockley, John Bardeen and others, to work.

ISSN:0031-9228    

DOI:10.1063/1.3034922

出版商:AIP    

年代:1968

数据来源: AIP