ISSN:0031-9228    

DOI:10.1063/1.2435629

出版商:AIP    

年代:1906

数据来源: AIP

ISSN:0031-9228    

DOI:10.1063/1.2435630

出版商:AIP    

年代:1906

数据来源: AIP

ISSN:0031-9228    

DOI:10.1063/1.2435631

出版商:AIP    

年代:1906

数据来源: AIP

ISSN:0031-9228    

DOI:10.1063/1.2435632

出版商:AIP    

年代:1906

数据来源: AIP

摘要:

What is the ultimate sensitivity with which one can continually measure an object's position? Sensitivity is often limited by thermal noise, and in some situations amplifiers set the noise floor. But classical physics argues that, with proper experimental design, the position uncertainty can be made arbitrarily small. Nearly 80 years ago, though, Werner Heisenberg posited his now‐famous uncertainty relation, in which quantum mechanics places a fundamental limit on measurement precision: The product of the uncertainties in an object's position and momentum must be at leastℏ/2.A single position measurement will cast an object into a position eigenstate, but the resulting uncertain momentum will make the next position measurement uncertain.

ISSN:0031-9228    

DOI:10.1063/1.2435633

出版商:AIP    

年代:1906

数据来源: AIP

摘要:

Cosmology'swidely accepted “concordance model” presumes that some still unknown form of dark matter overwhelms the cosmic abundance of ordinary baryonic matter by a factor of about six. Powerful evidence of dark matter has been accumulating since the 1930s from an impressive variety of observational realms: gas temperature and the random motion of galaxies in large galaxy clusters, galaxy rotation, the distribution of clusters, the abundances of the lightest elements, the anisotropy of the microwave background, and the redshifts of distant supernovae.

ISSN:0031-9228    

DOI:10.1063/1.2435634

出版商:AIP    

年代:1906

数据来源: AIP

ISSN:0031-9228    

DOI:10.1063/1.2435635

出版商:AIP    

年代:1906

数据来源: AIP

摘要:

Heike Geislerreceived tenure in August 2005. Two weeks later, Hurricane Katrina hit, and she has been back to her office only once—to pack her things. The chemistry professor was sacked, along with most of the faculty of Xavier University in New Orleans, in the wake of Katrina.

ISSN:0031-9228    

DOI:10.1063/1.2435636

出版商:AIP    

年代:1906

数据来源: AIP

摘要:

Citing the dramaticallyincreasing economic costs of hurricanes that have hit the US in recent years, often reaching into the tens of billions of dollars, the National Science Board has proposed a $300 million per year initiative to more deeply involve the federal government in hurricane research.

ISSN:0031-9228    

DOI:10.1063/1.2435637

出版商:AIP    

年代:1906

数据来源: AIP

摘要:

The race is onto pinpoint&thgr;13,the last unknown mixing angle and a key parameter needed to decode neutrino oscillation. The Double Chooz experiment being constructed in northern France is poised to get results first, while a rival experiment at southern China's Daya Bay will aim for greater sensitivity.

ISSN:0031-9228    

DOI:10.1063/1.2435638

出版商:AIP    

年代:1906

数据来源: AIP