Leonard Mlodinow

Leonard Mlodinow (; November 26, 1954) is an American theoretical physicist and mathematician, screenwriter and author. In physics, he is known for his work on the large N expansion, a method of approximating the spectrum of atoms based on the consideration of an infinite-dimensional version of the problem, and for his work on the quantum theory of light inside dielectrics.

He has also written books for the general public, five of which have been New York Times best-sellers, including The Drunkard's Walk: How Randomness Rules Our Lives, which was chosen as a New York Times notable book, and short-listed for the Royal Society Science Book Prize; The Grand Design, co-authored with Stephen Hawking, which argues that invoking God is not necessary to explain the origins of the universe; War of the Worldviews, co-authored with Deepak Chopra; and Subliminal: How Your Unconscious Mind Rules Your Behavior, which won the 2013 PEN/E. O. Wilson Literary Science Writing Award. He also makes public lectures and media appearances on programs including Morning Joe and Through the Wormhole, and debated Deepak Chopra on ABC's Nightline. Mlodinow was born in Chicago, Illinois, of parents who were both Holocaust survivors. His father, who spent more than a year in the Buchenwald concentration camp, had been a leader in the Jewish resistance in his hometown of Częstochowa, in Nazi Germany-occupied Poland. As a child, Mlodinow was interested in both mathematics and chemistry, and while in high school was tutored in organic chemistry by a professor from the University of Illinois. As recounted in his book Feynman's Rainbow, his interest turned to physics during a semester he took off from college to spend on a kibbutz in Israel, during which he had little to do at night besides reading The Feynman Lectures on Physics, which was one of the few English books he found in the kibbutz library.Mlodinow completed his doctorate at the University of California, Berkeley. It was in that PhD dissertation that he developed a new type of perturbation theory for nonrelativistic quantum mechanics, based upon solving the problem in infinite dimensions, and then correcting for the fact that we live in three. The method has become the basis of the 1/d expansion used by theoretical chemists. He has also done pioneering and innovative work in the quantum theory of nonlinear optics. The central problem of quantum nonlinear optics is how to quantize a dielectric that, as well as the usual homogeneities and anisotropy, can also have nonlinearities and dispersion, and earlier attempts in this direction, while incorporating the known linear theory, had not fully reproduced the nonlinear equations.

In 1981, Mlodinow joined the faculty at Caltech. Later, he was named an Alexander von Humboldt Fellow and worked at the Max Planck Institute for Physics and Astrophysics in Munich, Germany. In 1986, Mlodinow left full-time academia to begin a writing career. In addition to his books, he wrote many episodes for a number of television series including Star Trek: The Next Generation and MacGyver, created computer games with director Steven Spielberg and actor Robin Williams, and wrote the screenplay for the 2009 film Beyond the Horizon. He also continued to conduct research in theoretical physics, and again joined the faculty of Caltech in 2005, leaving in 2013. His latest work in physics concerns the arrow of time, quantum decoherence, and the relation between discrete quantum random walks and the relativistic equations of quantum theory.