THEORY OF "TIME OF RELAXATION"

CHANDRASEKHAR, S. [SUBRAMANYAN] (+) RALPH E. WILLIAMSON

The Time of Relaxation of Stellar Systems.

USA, [No printer], 1941. Lex8vo. In the original printed wrappers. "Reprinted for private circulation from The Astrophysical Journal, Vol. 93, No. 2, March, 1941". Previous owner's name, the famous English physicist, astronomer and mathematician, [J. H. Jeans] to top right corner of front wrapper. A very fine and clean copy. Pp. 285-326.

Scarce offprint issue, from the library of the influential English physicist and astronomer James Hopwood Jeans, of Chandrasekhar's important paper in which he developed his theory of "time of relaxation". In the 1983 he was awarded the Nobel Prize in physic for key discoveries that led to the currently accepted theory on the later evolutionary stages of massive stars.

Chandresekhar is famous for showing that the final fate of a star depends on its mass, furthermore he calculated that massive stars would be unable to evolve into white dwarfs, the limiting size called the Chandresekhar Limit.
"An important question from the point of view of what can be observed is how the cumulative effect of chance encounters affects the orbit of a star measured by what is called "time of relaxation" of the stellar system. Conventional wisdom assumed it could be theoretically calculated by considering the cumulative effect of a large number of two-body encounters. A closer analysis convinced Chandrasekhar that such an idealization did not provide a good approximation to the physical situation in the stellar system. The gravitational field fluctuated in space and time. New methods of treating the problem based on statistics were required. He laid the foundations of such new methods in one of his most celebrated and widely quoted papers, "Stochastic and Statistical Problems in Astronomy," published in 1943. The probability methods reviewed in this paper have found application beyond astronomy in a wide variety of problems and fields as different as colloidal chemistry and stellar dynamics." (DSB)


James Hopwood Jeans (1877 -1946) made several important contributions in many areas of physics, including quantum theory, the theory of radiation and stellar evolution. His analysis of rotating bodies led him to conclude that Laplace's theory that the solar system formed from a single cloud of gas was incorrect, proposing instead that the planets condensed from material drawn out of the sun by a hypothetical catastrophic near-collision with a passing star. This theory is not accepted today. Furthermore he is the founder of British cosmology.

Order-nr.: 46600