Editing Alan Lightman (section)

==Scientific work==
In his scientific work, Lightman has made contributions to the theory of astrophysical processes under extreme temperatures and densities. In particular, his research has focused on relativistic gravitation theory, the structure and behavior of [[accretion disks]], [[stellar dynamics]], [[radiative processes]], and [[relativistic plasmas]]. Some of his significant achievements are his discovery, with [[Douglas Eardley]], of a structural instability in orbiting disks of matter, called accretion disks, that form around massive condensed objects such as [[black holes]], with wide application in astronomy;<ref>Astrophysical Journal Letters, vol. 187, pg. L1 (1974)</ref> his proof, with [[David L. Lee]], that all gravitation theories obeying the [[Equivalence principle#The weak equivalence principle|Weak Equivalence Principle]] (the experimentally verified fact that all objects fall with the same acceleration in a gravitational field) must be metric theories of gravity, that is, must describe gravity as a geometrical warping of time and space;<ref>''[[Physical Review D]]'', vol. 8, pg. 364 (1973)</ref> his calculations, with [[Stuart L. Shapiro]], of the distribution of stars around a massive black hole and the rate of destruction of those stars by the hole;<ref>''[[Astrophysical Journal]]'', vol. 211, pg. 244 (1977)</ref> his discovery, independently of Roland Svensson of Sweden, of the negative heat behavior of optically thin, hot thermal [[Plasma (physics)|plasmas]] dominated by electron-[[positron]] pairs, that is, the result that adding energy to thin hot gases causes their temperature to decrease rather than increase;<ref>''[[Astrophysical Journal]]'', vol. 253, pg. 842 (1982)</ref> and his work on unusual radiation processes, such as unsaturated [[inverse Compton scattering]], in thermal media, also with wide application in astrophysics.<ref>''[[Nature (journal)|Nature]]'', vol. 262, pg. 196 (1976)</ref>

In 1990 he chaired the science panel of the [[National Academy of Sciences]] Astronomy and Astrophysics Survey Committee. He is a past chair of the High Energy Division of the [[American Astronomical Society]].