ISSN:0031-9228    

DOI:10.1063/1.2814519

出版商:AIP    

年代:1985

数据来源: AIP

ISSN:0031-9228    

DOI:10.1063/1.2814520

出版商:AIP    

年代:1985

数据来源: AIP

ISSN:0031-9228    

DOI:10.1063/1.2814521

出版商:AIP    

年代:1985

数据来源: AIP

摘要:

The output wavelength of a free‐electron laser varies as the inverse square of the energy of the electrons whose undulation through the FEL generates the laser light. Accelerators and storage rings of the kind one uses for highenergy physics have provided FEL researchers with electron beams of sufficient energy to yield laser output in the near infrared and even in the visible (seePHYSICS TODAY, December 1983, page 17). But such rf linacs and storage rings are typically limited to rather low electron currents, thus seriously limiting the peak output power of the freeelectron lasers that depend on them.

ISSN:0031-9228    

DOI:10.1063/1.2814522

出版商:AIP    

年代:1985

数据来源: AIP

摘要:

Is Jupiter as large as a planet can be? Are the Sun's faint neighbors, with roughly 10&percent; of its mass, the smallest stars? There is no apparent physical reason that objects in the mass range of 5 to 50 times the mass of Jupiter should not exist, and although the properties of such objects have not been well explored theoretically, their existence has important implications for a number of fields in physics and astronomy.

ISSN:0031-9228    

DOI:10.1063/1.2814523

出版商:AIP    

年代:1985

数据来源: AIP

摘要:

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 Schro¨dinger 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.

ISSN:0031-9228    

DOI:10.1063/1.881019

出版商:AIP    

年代:1985

数据来源: AIP

摘要:

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.

ISSN:0031-9228    

DOI:10.1063/1.880968

出版商:AIP    

年代:1985

数据来源: AIP

摘要:

Rudolph Minkowski was born in Germany near the end of the last century and died in California during the final quarter of this century. He was trained as a laboratory physicist, but worked most of his life as an observational astronomer. Using the largest optical telescopes in the world, he made important contributions to nearly every branch of nebular and extragalactic astronomy, but his most important contribution was to the identification and interpretation of cosmic radio sources. His monument is the National Geographic Society‐Palomar Observatory Sky Survey. He guided, encouraged and counseled a generation of radio and optical astronomers.

ISSN:0031-9228    

DOI:10.1063/1.880969

出版商:AIP    

年代:1985

数据来源: AIP

ISSN:0031-9228    

DOI:10.1063/1.2814524

出版商:AIP    

年代:1985

数据来源: AIP

摘要:

It has been 25 years since Max Perutz and John Kendrew, working in Cambridge, England, used x‐ray crystallography to determine in three dimensions the molecular structure of the oxygen‐transport proteins hemoglobin and myoglobin. Their technique—xray diffraction from crystallized samples—continues to be one of the central sources of structural information for biology at the molecular level. Now, however, the advent of powerful new synchrotron x‐ray sources based on multi‐GeV electron storage rings is opening up new ways in which one can probe biological structure at the subcellular level.

ISSN:0031-9228    

DOI:10.1063/1.880970

出版商:AIP    

年代:1985

数据来源: AIP