ISSN:0031-9228    

DOI:10.1063/1.2914008

出版商:AIP    

年代:1980

数据来源: AIP

ISSN:0031-9228    

DOI:10.1063/1.2913980

出版商:AIP    

年代:1980

数据来源: AIP

ISSN:0031-9228    

DOI:10.1063/1.2913987

出版商:AIP    

年代:1980

数据来源: AIP

摘要:

As radio astronomers survey our galaxy for the millimeter wavelengths characteristic of molecular rotations at low temperature, it is becoming clear that much of the interstellar gas in the galaxy is molecular rather than atomic. Furthermore, this molecular gas, mostlyH2,appears to be concentrated in giant molecular clouds, tens of parsecs across. With masses typically several hundred thousand times that of the Sun, these giant clouds appear to be the most massive objects in the galaxy.

ISSN:0031-9228    

DOI:10.1063/1.2913989

出版商:AIP    

年代:1980

数据来源: AIP

摘要:

When the earthquake struck the Lawrence Livermore Laboratory laser‐fusion facility on 24 January, most of the damage it inflicted was to the buildings and support facilities, according to John Emmett, who directs the program. Out of the $8 million in optical components in the two‐armed Argus laser and 20‐armed Shiva laser, only $13 000 worth of damage occured. Repair of the support equipment will cost $126 000, a figure that includes electrical and mechanical equipment and the expense of repositioning the laser and target frames. (The target frame, for instance, weighs 400 000 pounds and had to be jacked up and shifted back into place to ensure optimal alignment of beams.)

ISSN:0031-9228    

DOI:10.1063/1.2913990

出版商:AIP    

年代:1980

数据来源: AIP

摘要:

The demonstration of break‐even fusion power production for brief pulses is a realistic prospect for the large deuterium–tritium tokamaks scheduled for completion in the early 1980's. But they are not likely to achieve plasma ignition. Before one can begin building practical fusion reactors, it will be necessary to build at least one significantly larger experimental tokamak—one that can achieve and control an ignited plasma for minutes at a time, with fusion neutrons bombarding the walls at power levels exceeding a megawatt per square meter.

ISSN:0031-9228    

DOI:10.1063/1.2913991

出版商:AIP    

年代:1980

数据来源: AIP

ISSN:0031-9228    

DOI:10.1063/1.2913993

出版商:AIP    

年代:1980

数据来源: AIP

摘要:

Dense fluids, defined to include both dense gases and liquids, have the reputation of being especially difficult to deal with theoretically. This reputation is not undeserved. Unlike dilute gases and crystalline solids, which can be thought of as deviants from well understood ideal states, the ideal gas and the ideal harmonic crystal, the dense fluid lies far from any recognizable landmark. This rules out the use of straightforward, convergent or asymptotic, expansions—the all‐purpose tool of the theoretical physicist—and makes even the hardy wince.

ISSN:0031-9228    

DOI:10.1063/1.2913994

出版商:AIP    

年代:1980

数据来源: AIP

摘要:

When I landed in Peking one cold night last November I was warmly greeted by Kuan Wei‐yen, a low‐temperature physicist who runs Academia Sinica's Institute of Physics. It was the start of a three‐week tour of the People's Republic of China as the guest of Academia Sinica, in which I met with Vice‐Premier Fang Yi and other leading science officials, visited six physics institutes and five university physics departments.

ISSN:0031-9228    

DOI:10.1063/1.2913995

出版商:AIP    

年代:1980

数据来源: AIP

摘要:

Henri Poincare´ is well known today for his contributions to many areas of mathematics and his popular writings on science. His attempts to apply physical theories to the evolution of the solar system and the rest of the universe are largely forgotten, except by a few specialists. Yet the crisp lucid prose of this brilliant thinker can still help the modern reader to appreciate the worldview of nineteenth‐century science, and provides a useful introduction to a fascinating historical phenomenon that I will call “the mathematician as naturalist” (see the box on page 44).

ISSN:0031-9228    

DOI:10.1063/1.2913996

出版商:AIP    

年代:1980

数据来源: AIP