ISSN:0031-9228    

DOI:10.1063/1.2914154

出版商:AIP    

年代:1980

数据来源: AIP

ISSN:0031-9228    

DOI:10.1063/1.2914109

出版商:AIP    

年代:1980

数据来源: AIP

摘要:

Helium‐3 has revealed yet another quirk in the complex pattern of its behavior at low temperatures. The latest surprise is that the nuclear spins in its magnetically ordered solid phase are not arranged according to the simplest symmetries one would associate with its underlying body‐centered‐cubic lattice. This conclusion comes from two simultaneous but independent nuclear magnetic resonance studies done by Douglas D. Osheroff, Michael C. Cross and Daniel S. Fisher at Bell Telephone Laboratories and by Dwight Adams, Erwin A. Schubert, Greg E. Haas and Donovan M. Bakalyar at the University of Florida (at Gainesville). Interpretation of the Bell Labs data is exceptionally clear because the experimenters there succeeded in growing a single crystal of solidHe3below its transition temperature to a magnetically ordered state. The two studies probe behavior at different regions of the applied magnetic field and thus complement one another.

ISSN:0031-9228    

DOI:10.1063/1.2914110

出版商:AIP    

年代:1980

数据来源: AIP

摘要:

The strong attraction between hydrogen atoms of opposite electron spin would seem to make it impossible to have stable monatomic hydrogen gas, except in interstellar space. But the force between hydrogen atoms of parallel spin is predominantly repulsive. Isaac Silvera and Jook Walraven of the University of Amsterdam have taken advantage of the absence of bound states for spin‐polarized hydrogen to produce a monatomic hydrogen gas that showed no sign of reverting to ordinaryH2after almost an hour in a high magnetic field at low temperature, despite its very considerable density—more than1016 atoms/cm3.

ISSN:0031-9228    

DOI:10.1063/1.2914111

出版商:AIP    

年代:1980

数据来源: AIP

摘要:

PEP celebrated its first stored electron beam on 21 April. On 5 May both positron and electron beams were stored, each at 8 GeV; since then beam currents of 2 mA for electrons and 1.5 mA for positrons have been reached. PEP director John Rees explained that the currents were deliberately kept low to avoid the incoherent beam‐beam limit. As commissioning continues, the PEP team will bring the beams to 15 GeV each, where peak performance is expected. The maximum design energy is 18 GeV/beam.

ISSN:0031-9228    

DOI:10.1063/1.2914112

出版商:AIP    

年代:1980

数据来源: AIP

摘要:

Materials research and electronic computers are two of the eight fields China has chosen to emphasize during the next several years. So it was not surprising that some of the most advanced research and development that I saw during my recent visit to China (PHYSICS TODAY, March, page 32) was related to solid‐state physics and electronic circuitry.

ISSN:0031-9228    

DOI:10.1063/1.2914113

出版商:AIP    

年代:1980

数据来源: AIP

摘要:

The von Laue–Langevin Institute, at Grenoble in the French Alps, is getting its second wind. This much we are told by the appellationDeuxieme Souffle, the name given to the 104‐million‐franc renewal program recently approved by the steering committee of this joint French–German–British neutron‐beam laboratory. The planned expansion of neutron sources and instrumentation should add significantly to the experimental capabilities of what is already the most powerful source of continuous neutron beams in Europe—and the leading source of cold and ultra‐cold neutrons in the world.

ISSN:0031-9228    

DOI:10.1063/1.2914114

出版商:AIP    

年代:1980

数据来源: AIP

摘要:

Some physicists have recently begun to voice their expectations that the “grand synthesis” of all physics is almost within our grasp. If only we had a little more of this or that, and if only some of the remaining nagging difficulties would go away… Here, however, I would like to turn from this sublime ambition to more down‐to‐earth considerations. Physics remains a science based on experience. How do we acquire that experience to determine whether or not particle physics is indeed on the right track to the “grand synthesis?”

ISSN:0031-9228    

DOI:10.1063/1.2914115

出版商:AIP    

年代:1980

数据来源: AIP

摘要:

One of the most serious energy problems faced by our nation during the remainder of this century will be shortages of liquid fuels for transportation. It may be possible to reduce the magnitude of this problem by developing smaller, more efficient vehicles, by reducing non‐essential travel, by producing synthetic fuels from coal or biomass, or by exploiting oil shales or tar sands. Each of these is only a partial solution, however, and serious liquid‐fuel shortages are possible even with dramatic successes in each of them.

ISSN:0031-9228    

DOI:10.1063/1.2914116

出版商:AIP    

年代:1980

数据来源: AIP

摘要:

There occurred in the early years of this century three conceptual revolutions that profoundly changed Man's understanding of the physical universe: the special theory of relativity (in 1905), the general theory of relativity (1915) and quantum mechanics (1925). Einstein personally was responsible for the first two of these revolutions, and influenced and helped to shape the third. But it is not about his work in these conceptual revolutions that I shall write here. Much has been written about that work already. Instead, I shall discuss, in general terms, Einstein's insights on the structure of theoretical physics and their relevance to the development of physics in the second half of this century. I shall divide the discussion into four sections which are, of course, very much related.

ISSN:0031-9228    

DOI:10.1063/1.2914117

出版商:AIP    

年代:1980

数据来源: AIP