ISSN:0031-9228    

DOI:10.1063/1.2915002

出版商:AIP    

年代:1982

数据来源: AIP

ISSN:0031-9228    

DOI:10.1063/1.2914958

出版商:AIP    

年代:1982

数据来源: AIP

摘要:

Ferromagnetism and superconductivity are two forms of long‐range order that may exist in a material at low temperature. When both are present, they compete with one another, and many have wondered under what conditions they might coexist. The answer has been emerging in recent years, primarily through studies of two materials in which a compromise settlement is reached. The latest in a series of experiments—this one on a single crystal—has confirmed and further elucidated the properties of the coexistence phase seen in earlier work: This phase seems to accommodate within a single crystal both superconducting regions with sinusoidally modulated magnetic moments and normal ferromagnetic domains.

ISSN:0031-9228    

DOI:10.1063/1.2914960

出版商:AIP    

年代:1982

数据来源: AIP

摘要:

The often‐quoted remark of I. I. Rabi, made when the muon was discovered—“Who ordered that?”—is again an apt commentary about the third charged lepton to be found, the tau. A recent experiment, by Gary Feldman, George Trilling and their collaborators at the PEP electron‐positron collider at SLAC has determined the lifetime of the tau. They find it to be(4.6±1.9)×10−13sec, a value entirely consistent with the universality of the weak interaction. That is, the weak interaction between the tau and other particles appears, within experimental limits, to be the same as that of the electron and muon. They're all spin‐1/2, charged, pointlike particles, differing only in mass: the electron with 0.511003 MeV, the muon with 105.6595 MeV and the tau with 1782 MeV.

ISSN:0031-9228    

DOI:10.1063/1.2914961

出版商:AIP    

年代:1982

数据来源: AIP

摘要:

A steady‐state scheme for plasma‐current drive would greatly enhance the attractiveness of the tokamak as a fusion reactor. The fact that a conventional tokamak reactor would have to operate in a pulsed mode presents serious engineering difficulties. Even though the length of such pulses could be as long as an hour (followed by a recovery time of less than a minute), pulsed operation raises the problem of thermal fatigue.

ISSN:0031-9228    

DOI:10.1063/1.2914962

出版商:AIP    

年代:1982

数据来源: AIP

摘要:

The nuclear physicists at the Indiana University Cyclotron Facility are proposing to enhance considerably the capabilities of this light‐ion cyclotron by appending to it an electron‐cooling storage ring. Electron cooling has been developed over the last decade at Novosibirsk, CERN and Fermilab primarily as a technique for “cooling” antiproton beams—reducing their spread in transverse and longitudinal momentum—for high‐energy physics experiments (PHYSICS TODAY, August 1980, page 44). The IUCF would be the first attempt to exploit beam cooling for nuclear‐physics ion beams.

ISSN:0031-9228    

DOI:10.1063/1.2914963

出版商:AIP    

年代:1982

数据来源: AIP

摘要:

We complimentPHYSICS TODAYfor its stimulating guest comment in the April ‘81 issue by Frank J. Tipler (“Extraterrestrial beings do not exist,” April, page 9). As research physicists in specialties far removed from astrophysics and extraterrestrial biology, but intrigued by Carl Sagan's (and others') unquestioned assertion that numberless intelligent civilizations exist elsewhere in the universe, we have been struck by the paucity of critical response to this hypothesis. This lack being quite an uncharacteristic reaction by the scientific community to what is a controversial proposition. However, with Tipler's counterpoint, it now appears that an opposite view is alive and well,PHYSICS TODAYand Tipler have provided the required first step for the scientific community's consideration, and the usual and absolutely necessary polemics may now proceed.

ISSN:0031-9228    

DOI:10.1063/1.2914964

出版商:AIP    

年代:1982

数据来源: AIP

摘要:

In the Guest Comment in April (page 9), Frank Tipler argues that if extraterrestrial beings existed, our galaxy would be so full of their Von Neumann machine proxies that we could not have missed them. Tipler replaces Michael Hart's and James Trefil's humanoid colonizers with machines, to circumvent the costs of humanoid support and humanoid fragility. Francis Crick and Leslie Orgel replace them with cargoes of microorganisms in a revival of Svante Arrhenius' century‐old “Panspermia” hypothesis.

ISSN:0031-9228    

DOI:10.1063/1.2914965

出版商:AIP    

年代:1982

数据来源: AIP

摘要:

The above criticisms of my views can be divided into two classes: (1) those of a technical nature, and (2) those which deal with the sociology of possible extraterrestrial intelligent beings. Most of these criticisms I have discussed in the threeQuarterly Journalarticles of which thePHYSICS TODAYpaper was but a pre´cis. Here I will reply briefly to those criticisms that were answered in theQuarterly Journal; my critics are referred to those papers for more detail on the points in question.

ISSN:0031-9228    

DOI:10.1063/1.2914966

出版商:AIP    

年代:1982

数据来源: AIP

摘要:

Among intellectual disciplines, mathematics occupies a unique position. It is in many respects an art, but it is also the language of science. Although a great deal of mathematics can be traced directly to external influences, much of its creativity is motivated internally: “pour la gloire de l'esprit humain,” as Carl G. T. Jacobi put it. Often the mathematician lets the imagination soar, constrained only by logic, intrinsic structure, and a sense of historical continuity. Yet from time to time these abstract deliberations have important applications in other fields.

ISSN:0031-9228    

DOI:10.1063/1.2914967

出版商:AIP    

年代:1982

数据来源: AIP