Gravitational lenses
For several years astronomers have devoted considerable effort to finding and studying a class of celestial phenomena whose very existence depends on rare cosmic accidents. These are gravitational-lens events, which occur when two or more objects at different distances from the earth happen to lie along the same line of sight and so coincide in the sky. The radiation from the more distant object, typically a quasar, is bent by the gravitational field of the foreground object. The bending creates a cosmic mirage: distorted or multiple images of the background object. Such phenomena may reveal many otherwise undetectable features of the image source, of the foreground object and of the space lying between them. Such observations could help to resolve several fundamental questions in cosmology. In the past decade theoretical and observational research on gravitational lenses has grown rapidly and steadily. At this writing at least 17 candidate lens systems have been discussed in the literature. Of the 17 lens candidates reported so far in professional literature, only five are considered to have been reliably established by subsequent observations. Another three are generally regarded as weak or speculative cases with less than 50 percent chance of actually being lens systems. In the remaining nine cases the evidence is mixed or is sparse enough so that the final judgment could swing either way. As might be concluded, little of the scientific promise of gravitational lenses has yet been realized. The work has not yielded a clear value for the proportionality constant or any of the other fundamental cosmological parameter. 7 figs.
- OSTI ID:
- 7163643
- Journal Information:
- Scientific American; (USA), Vol. 259:1; ISSN 0036-8733
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
GENERAL PHYSICS
GRAVITATIONAL LENSES
RESEARCH PROGRAMS
ALIGNMENT
COSMOLOGY
ELECTROMAGNETIC RADIATION
EXPLORATION
GALAXIES
GENERAL RELATIVITY THEORY
GRAVITATION
GRAVITATIONAL INTERACTIONS
IDENTIFICATION SYSTEMS
IMAGES
MASS
NONLUMINOUS MATTER
RADIOWAVE RADIATION
TESTING
UNIVERSE
VISIBLE RADIATION
BASIC INTERACTIONS
FIELD THEORIES
INTERACTIONS
LENSES
RADIATIONS
640106* - Astrophysics & Cosmology- Cosmology