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 beside reading The Feynman Lectures on Physics, which was one of the few English books he found in the kibbutz library.
While a doctoral student at the University of California, Berkeley, and on the faculty at Caltech, he developed (with N. Papanicolaou) a new type ofperturbation theory for eigenvalue problems in quantum mechanics. Later, as an Alexander von Humboldt Fellow at the Max Planck Institute for Physics and Astrophysik in Munich, Germany, he did pioneering work (with M. Hillery) on the quantum theory of dielectric media.
Apart from his research and books on popular science, he also wrote the screenplay for the film Beyond the Horizon (currently in production) and has been a screenwriter for television series, including Star Trek: The Next Generation and MacGyver.He co-authored (with Matt Costello) a children's chapter book series entitled The Kids of Einstein Elementary.
Between 2008 and 2010, Mlodinow worked on a book with Stephen Hawking, entitled The Grand Design.A step beyond Hawking's other titles, The Grand Design is said to explore both the question of the existence of the universe and the issue of why the laws of physics are what they are.