Quasars and Gravitational Lenses

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Science  23 Mar 1984:
Vol. 223, Issue 4642, pp. 1255-1259
DOI: 10.1126/science.223.4642.1255


Despite the expenditure of large amounts of telescope time and other resources, most of the fundamental questions concerning quasi-stellar objects (quasars) remain unanswered. A complex phenomenology of radio, infrared, optical, and x-ray properties has accumulated but has not yielded even a satisfactory classification system. The large red shifts (distances) of quasars make them very valuable tools for studying cosmology and the properties of intervening matter in the Universe through observations of absorption lines and gravitational lenses.