Astronomers do not do experiments. They observe the universe primarily through detect ing light emitted by stars and other luminous objects. Since this light must travel through space to reach us, variations in the metric of space affects the appearance of astronomical objects. These variations lead to dramatic changes in the shape and brightness of astronom ical sources. Because these variations are sensitive to mass rather than to light, observations of gravitational lensing enable astronomers to probe the mass distribution of the universe. With gravitational lensing observations,...

In this book, 11 leading scholars contribute to the understanding of the scientific and philosophical works of Moses Maimonides (1135-1204), the most luminous Jewish intellectual since Talmudic times. Deeply learned in mathematics, astronomy, astrology (which he strongly rejected), logic, philosophy, psychology, linguistics, and jurisprudence, and himself a practising physician, Maimonides flourished within the high Arabic culture of the 12th century, where he had momentous influence upon subsequent Jewish beliefs and behavior, upon ethical demands, and upon ritual traditions. For him,...