ISSN:0031-9228    

DOI:10.1063/1.2808514

出版商:AIP    

年代:1994

数据来源: AIP

ISSN:0031-9228    

DOI:10.1063/1.2808515

出版商:AIP    

年代:1994

数据来源: AIP

摘要:

The evidence from Fermilab's Collider Detector Facility group for a174‐GeV/c2top quark (seePHYSICS TODAY, May, page 20) has been received with cautious enthusiasm by the particle physics community. Since most physicists still have not seen the 153‐page preprint submitted on 22 April toPhysical Review D, the demand for speakers on the result exceeds even CDF's abundant supply of experimenters. Still, it is unlikely that new developments will suppant CDF's present results before we've had time to digest them. the low top‐production rate, the large backgrounds—events that mimic top decay—and the complicated topologies of t‐quark decays all but ensure that the discovery of the t quark will be a protracted process rather than a single dramatic event. While awaiting new results from CDF and DO (the other detector at Fermilab's 1.8‐TeV pp¯ collider), it is appropriate to evaluate CDF's present evidence and to anticipate possible future developments.

ISSN:0031-9228    

DOI:10.1063/1.2808516

出版商:AIP    

年代:1994

数据来源: AIP

摘要:

If comets are like “dirty snowballs,” as Fred Whipple proposed in the early 1950s, then Jupiter is about to suffer the embarrassment of being hit by a boomerang snowball as astronomers around the world watch. Like many snowballs, Comet Shoemaker‐Levy 9 broke apart in mid‐flight. Comet SL9 was first seen, already in orbit around Jupiter, in March 1993, by a trio of avid comet hunters: Carolyn and Gene Shoemaker of the US Geological Survey in Flagstaff, Arizona, and David Levy, a contributing editor toSky & Telescopemagazine. By May of last year the comet's orbit had been determined. It was realized by Brian Marsden (Smithsonian Astrophysical Observatory, Cambridge, Massachusetts) that in July 1992, SL9 had come within 95 000 km of Jupiter's center of mass, where it experienced tidal forces sufficient to rip it apart. On its next pass, SL9 will aim to come within 30 000 km of Jupiter's center of mass. Because the planet's radius is about 71 000 km, Jupiter will suffer a direct hit. Astronomers will be on hand to evaluate its injuries, if any.

ISSN:0031-9228    

DOI:10.1063/1.2808517

出版商:AIP    

年代:1994

数据来源: AIP

摘要:

In most metals, the electrons behave as if they were independent of one another. Although each electron really does interact with the other electrons and phonons, the net effect is felt only as a kind of molasses through which the otherwise freely moving electron must slog. Thus one an usually treat metallic systems as a low‐density gas of weakly interacting particles, accounting for the average interactions simply by assigning an effective mass to the electrons. Such a model is commonly called a Fermi liquid. In one‐dimensional systems, however, the Coulomb forces between the electrons intervene more strongly and produce quite a different behavior.

ISSN:0031-9228    

DOI:10.1063/1.2808518

出版商:AIP    

年代:1994

数据来源: AIP

摘要:

The development of compact, reliable and inexpensive short‐wavelength lasers is certain to have profound effects on virtually any technology that uses coherent visible light. Although the impact of such devices will be far‐reaching, the primary driving force behind efforts to develop blue‐green diode lasers is without question optical recording. The demand for increased data storage capabilities is continually forcing the recording industry to increase storage densities.

ISSN:0031-9228    

DOI:10.1063/1.881438

出版商:AIP    

年代:1994

数据来源: AIP

摘要:

The older I get, the more I am afflicted by fits of nostalgia. Even when they recall the best days of my youth, they nonetheless weigh heavy, because it's impossible to go back. I think the best way to deal with these memories is to convey them to paper. So I'd like to share some of my recollections of a great man, my unforgettable teacher Lev Davidovich Landau, to whom I was close for several decades until his tragic death in 1968. (See also the articles by I. M. Khalatnikov and Vitaly Ginzburg inPHYSICS TODAY, May 1989.)

ISSN:0031-9228    

DOI:10.1063/1.881434

出版商:AIP    

年代:1994

数据来源: AIP

摘要:

February 1994 saw the centenary of the birth of Yakov Il'ich Frenkel, a distinguished Russian theoretical physicist. His was one of the well‐known names among physicists in the first half of the century. He belonged to the generation of universalists, and his contributions range from condensed matter to nuclear physics, and from classical electrodynamics to geophysics and biophysics. He was a prolific writer, and his books, translated into German and English, were widely used texts. He educated many graduate students and played an important part in building up physics institutions in the Soviet Union in the late 1920s and '30s

ISSN:0031-9228    

DOI:10.1063/1.881435

出版商:AIP    

年代:1994

数据来源: AIP

ISSN:0031-9228    

DOI:10.1063/1.2808519

出版商:AIP    

年代:1994

数据来源: AIP

ISSN:0031-9228    

DOI:10.1063/1.2808520

出版商:AIP    

年代:1994

数据来源: AIP