Lightman was born in Memphis Tennessee in 1948, son of Richard Lightman, a movie theater owner, and Jeanne Garretson, a dancing teacher and volunteer Braille typist. From an early age, he was entranced by both science and the arts and, while in high school, began independent science projects and writing poetry. He graduated from White Station High School in Memphis. Lightman received his AB degree in physics from Princeton University in 1970, Phi Beta Kappa and Magna Cum Laude, and his PhD in theoretical physics from the California Institute of Technology in 1974. He has received three honorary degrees.

From 1974 to 1976, Lightman was a postdoctoral fellow in astrophysics at Cornell. During this period, he began publishing poetry in small literary magazines. He was an assistant professor of astronomy at Harvard from 1976 to 1979 and from 1979 to 1989 a research scientist at the Harvard-Smithsonian Center for Astrophysics.

In 1981, Lightman began publishing essays about science, the human side of science, and the "mind of science," beginning with Smithsonian Magazine and moving to Science 82, The New Yorker, and other magazines. Since that time, Lightman's essays, short fiction, and reviews have appeared in The American Scholar, The Atlantic Monthly, Boston Review, Daedalus, Discover, Exploratorium, Granta, Harper's, Harvard Magazine, Inc Technololgy, Nature, The New Yorker, The New York Review of Books, The New York Times, Science 86, The Sciences, Smithsonian, Story, Technology Review, and World Monitor.

In 1989, Lightman was appointed professor of science and writing, and senior lecturer in physics, at the Massachusetts Institute of Technology. From 1991 to 1997, he headed the Program in Writing and Humanistic Studies at MIT. During this period, he helped create a new Communication Requirement at MIT (first instituted in 2001), which requires all MIT undergraduates to have a course equivalent in writing or speaking each of their four years. In 1995, he was appointed John E. Burchard professor of humanities at MIT, a chair named after the first dean of humanities at MIT (1948 - 1964). In 2001, Lightman cofounded the Graduate Program in Science Writing at MIT, which accepted its first students in the fall of 2002. In the same year, he resigned his chair to allow more time for his writing and became adjunct professor at MIT. In 2004, Lightman cofounded the Catalyst Collaborative at MIT, which is a collaboration between MIT and the Underground Railway Theater of Boston. The Catalyst Collaborative aims to convey science and the culture of science through theater. CC@MIT commissions new plays and produces existing plays that involve science or scientists.

As both a distinguished physicist and an accomplished novelist, Lightman is one of only a small number of people who straddle the sciences and the humanities. He was the first professor at MIT to receive a joint appointment in the sciences and the humanities. His essay "In the Name of Love?" was the first article about love and language published in Nature, the prestigious international science journal (October 8, 2001), and his "The First Law of Thermodynamics" was the first short story published in the physics journal Physics Today (May 2005). He has lectured at more than 75 universities nationwide about the similarities and differences in the ways that scientists and artists view the world.

In his scientific work, Lightman has made fundamental contributions to the theory of astrophysical processes under conditions of 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. His research articles have appeared in The Physical Review, The Astrophysical Journal, Reviews of Modern Physics, Nature, and other journals of physics and astrophysics. For his contributions to physics, he was elected a fellow of the American Physical Society in 1989 and a fellow of the American Association for the Advancement of Science the same year. In 1990, he chaired the science panel of the National Academy of Sciences Astronomy and Astrophysics Survey Committee for the 1990s. He is a past chair of the High Energy Division of the American Astronomical Society.

Lightman has also been interested in science education and the philosophy of science. His work in science studies and in science education has been published in The American Scholar, The Physics Teacher, Science, Science and Children, The Science Teacher, and Social Studies of Science.

Lightman's novel Einstein's Dreams was an international bestseller and has been translated into thirty languages. It was runnerup for the 1994 PEN New England/Boston Globe Winship Award. Einstein's Dreams was also the March 1998 selection for National Public Radio's "Talk of the Nation" Book Club. The novel has been used in numerous colleges and universities, in many cases for university-wide adoptions in "common-book" programs. More than two dozen independent theatrical and musical productions have been based on Einstein's Dreams, including a production at Chicago's National Pastime Theater in 2000, produced and directed by Patrizia Acerra and Dawn Arnold; another and different production by the same team in 2005; a production at Paradise Theater in New York in 2001, produced and directed by Paul Stancato and Brian Rhinehart; a production at the Culture Project Theater in New York in 2003, directed by Rebecca Holderness and written by Kipp Cheng, with new performances at the Burning Coal Theater in Raleigh NC in 2006; a production at the People's Branch Theater in Nashville in 2003, adapted by Brian Niece and David Alford, directed by David Alford, with new performances at the Seaside Repertory Theater in Santa Rosa Beach Florida in 2006; a musical production at the Martin Segal Theater of CUNY in New York in 2003, produced by Brian Schwartz with music and lyrics by Joshua Rosenblum and Joanne Lessner a dramatic production in March 2006 at the University of Memphis, directed by Gloria Baxter; a dance/theater production at the Dance Theater Workshop in New York City in April 2006, directed by Melinda Allen; a production by the Catalyst Collaborative and Underground Railway Theater in Cambridge in April 2007, adapted and directed by Wesley Savick; a choral production in 2006 in Baltimore, with music and lyrics by Lorraine L. Whittlesey, directed by Margaret Boudreaux; a musical composition titled "In This World" by Paul Hoffman in 2000 and performed by the Silverwood Trio on a Centaur CD; a musical composition titled "When Einstein Dreams" by Nando Michelin in 2003 and performed by the Nando Michelin Group on a Double Times Record CD. A major musical adaptation is being planned at the Prince Theater in Philadelphia, directed by Marjorie Samov.

Lightman's novel The Diagnosis was a finalist for the 2000 National Book Award in fiction, a selection of Book Sense 76, and a Barnes and Noble national college bestseller. Lightman's latest novel, Reunion, was a selection of Books Sense 76, a Boston Globe/New England bestseller, a Washington Post bestseller, a Barnes and Nobel national college bestseller, and a finalist for the Massachusetts Book Award. Lightman's collection of essays, A Sense of the Mysterious, was a finalist for the 2005 Massachusetts Book Award. Lightman's newest book, The Discoveries: Great Breakthroughs in 20th Century Science, was named by Discover Magazine as one of the ten best books on science in 2005

Other awards include the 1990 Association of American Publishers' Award for Origins as the best book of the year in physical science. In 1995 Lightman was named a Literary Light of the Boston Public Library. In 1996 he was elected a fellow of the American Academy of Arts and Sciences and also won the 1996 American Institute of Physics Andrew Gemant Award for linking science to the humanities. In 1998, he was awarded the 1998 Gyorgy Kepes Prize in the Arts from MIT's Council for the Arts. In 2003, he received a Distinguished Alumnus Award from the California Institute of Technology, that Institution's highest honor. That year, he also received the 2003 Distinguished Arts and Humanities Medal for Literature, given by the Germantown Arts Alliance (of Tennessee). In May of 2006, he received the Boston Authors' Club Julia Ward Howe Special Award. Sigma Xi, the international scientific research society, has awarded Lightman the 2006 John P. McGovern Science and Society Award. Lightman has twice been a juror for the Pulitzer Prize, for general nonfiction in 1994 and for fiction in 2004.

In 1999, Lightman founded the Harpswell Foundation a nonprofit organization whose mission is to provide educational opportunities to disadvantaged children and young people. The Foundation is funded from the donations of private individuals. All major projects of the Foundation so far have taken place in Cambodia, a country in desperate need after essentially all of its educated class were destroyed by the Khmer Rouge in the 1970s. In June 2005, the Harpswell Foundation completed a four-room school building in the village of Tramung Chrum, about 50 miles from Phnom Penh. In July 2006, the Foundation completed a dormitory for college women in Phnom Penh, which allows outstanding women to attend college. This dormitory will serve all the colleges in Phnom Penh and is one of the first dormitories in Cambodia. Not having a safe place to live while attending college has been the major obstacle preventing young women from outside Phnom Penh (over 90% of the population) to receive a college education and become leaders. Colleges in Cambodia do not provide housing for their students. Male students can live in the Buddhist temples, but female students cannot. The dormitory houses 36 women, who have been selected on the basis of their intelligence, ambition, and leadership potential. In addition to providing free housing, the Harpswell Foundation Dormitory gives these young women food; free classes in English, French, and computer skills; readings and discussion of current events in Cambodia and the world; and a weekly leadership seminar. For further information, please see the website of the Harpswell Foundation.