ISSN:0031-9228    

DOI:10.1063/1.2890032

出版商:AIP    

年代:1982

数据来源: AIP

ISSN:0031-9228    

DOI:10.1063/1.2889991

出版商:AIP    

年代:1982

数据来源: AIP

ISSN:0031-9228    

DOI:10.1063/1.2889993

出版商:AIP    

年代:1982

数据来源: AIP

ISSN:0031-9228    

DOI:10.1063/1.2889994

出版商:AIP    

年代:1982

数据来源: AIP

摘要:

Surveying the redshifts of bright galaxies out to 800 megaparsecs, a group of astronomers has found preliminary evidence for the existence of a gigantic void—a million‐cubic‐megaparsec volume devoid of bright galaxies—in the northern sky. In a recentAstrophysical Journal Letter, Robert Kirshner (University of Michigan), Augustus Oemler (Yale), Paul Schechter (Harvard–Smithsonian and Kitt Peak) and Stephen Shectman (Mount Wilson and Las Campanas Observatories) report that their deep redshift surveys of three small angular regions in the constellation Boo¨tes show identical 6000‐km/second gaps in the velocity distribution of galaxies down to 16th magnitude. The three sampled regions, each 1.4° square, form a roughly equilateral triangle on the celestial sphere, about 35° on a side. Assuming that the entire triangular region will ultimately prove to be “empty” in this same 6000‐km/second velocity interval, centered at 15 000 km/second, one would deduce the existence of a void more than 100 megaparsecs across, about 300 Mpc (109light years) distant from us.

ISSN:0031-9228    

DOI:10.1063/1.2889995

出版商:AIP    

年代:1982

数据来源: AIP

摘要:

Take an excited hydrogen atom, add a second excited electron, and you change the calculation of energy levels from an easy problem to a formidable task. In such doubly excited atoms, the dominance of electron correlations considerably alters the single‐particle shell structure. Alternative formulations of the electronic states in terms of hyperspherical coordinates have greatly elucidated the angular and radial correlations. That progress was recently boosted by the insight from dynamical group theory: A supermultiplet classification gives striking order to the energy spectrum and predicts which electron states become mixed. This supermultiplet classification visually depicts the doubly excited atom as a linear triatomic molecule having the electrons across the nucleus from one another and exhibiting collective rotational and bending motions. This new view is compatible with that of the hyperspherical approach. All the varying perspectives were discussed last month at the meeting of the APS Division of Electron and Atomic Physics in New York.

ISSN:0031-9228    

DOI:10.1063/1.2889996

出版商:AIP    

年代:1982

数据来源: AIP

ISSN:0031-9228    

DOI:10.1063/1.2890000

出版商:AIP    

年代:1982

数据来源: AIP

摘要:

I have always been unhappy about science history because it so often skirts what I think is the most important element in a new observation or theory—how did this person happen to be doing this thing or happen to be thinking along these new lines? So, in writing here about my involvement in the early days of accelerator mass spectroscopy, I want to take you behind the scenes, to help you understand how I happened to be mixed up in three unusual projects.

ISSN:0031-9228    

DOI:10.1063/1.2890001

出版商:AIP    

年代:1982

数据来源: AIP

摘要:

The phenomenal growth of physics as a science over the past half century has been paralled, breakthrough for breakthrough, by the explosion of physics as a marketable commodity. Technology has followed close on the heels of research, and has sometimes even taken the lead and acted as a stimulus for research.

ISSN:0031-9228    

DOI:10.1063/1.2890002

出版商:AIP    

年代:1982

数据来源: AIP

摘要:

We all know that blue skies and red sunsets are due to the “Rayleigh scattering” of sunlight. But beyond that, Rayleigh scattering means different things to different scientists.

ISSN:0031-9228    

DOI:10.1063/1.2890003

出版商:AIP    

年代:1982

数据来源: AIP