Brian Randolph Greene (born February 9, 1963) is an American theoretical physicist and string theorist. He has been a professor at Columbia University since 1996 and chairman of the World Science Festival since co-founding it in 2008. Greene has worked on mirror symmetry, relating two different Calabi–Yau manifolds (concretely, relating the conifold to one of its orbifolds). He also described the flop transition, a mild form of topology change, showing that topology in string theory can change at the conifold point.
Greene has become known to a wider audience through his books for the general public, The Elegant Universe, Icarus at the Edge of Time, The Fabric of the Cosmos, The Hidden Reality, and related PBS television specials. He also appeared on The Big Bang Theory episode "The Herb Garden Germination", as well as the films Frequency and The Last Mimzy.
Early life
Greene was born in New York City. His father, Alan Greene, was a one-time vaudeville performer and high school dropout who later worked as a voice coach and composer. He stated in an interview with Lawrence Krauss that he is of Jewish heritage. After attending Stuyvesant High School,[2] Greene entered Harvard in 1980 to concentrate in physics. After completing his bachelor's degree, Greene earned his doctorate from Oxford University as a Rhodes Scholar, graduating in 1987. While at Oxford, Greene also studied piano with the concert pianist Jack Gibbons.
Career
Greene joined the physics faculty of Cornell University in 1990, and was appointed to a full professorship in 1995. The following year, he joined the staff of Columbia University as a full professor. At Columbia, Greene is co-director of the university's Institute for Strings, Cosmology, and Astroparticle Physics (ISCAP), and is leading a research program applying superstring theory to cosmological questions. He is also one of the FQXi large grant awardees, his project title being "Arrow of Time in the Quantum Universe". His co-investigators are David Albert and Maulik Parikh.
Research
Greene's area of research is string theory, a candidate for a theory of quantum gravity. String theory attempts to explain the different particle species of the standard model of particle physics as different aspects of a single type of one-dimensional, vibrating string. One peculiarity of string theory is that it postulates the existence of extra dimensions of space: instead of the usual four dimensions, there must be ten spatial dimensions and one dimension of time to allow for a consistently defined string theory. The theory has several explanations to offer for why we do not perceive these extra dimensions, one being that they are "curled up" (compactified, to use the technical term) and are hence too small to be readily noticeable.
In the field, Greene is best known for his contribution to the understanding of the different shapes the curled-up dimensions of string theory can take. The most important of these shapes are so-called Calabi–Yau manifolds; when the extra dimensions take on those particular forms, physics in three dimensions exhibits an abstract symmetry known as supersymmetry.
Greene has worked on a particular class of symmetry relating two different Calabi–Yau manifolds, known as mirror symmetry (concretely, relating the conifold to one of its orbifolds). He is also known for his research on the flop transition, a mild form of topology change, showing that topology in string theory can change at the conifold point.
Currently, Greene studies string cosmology, especially the imprints of trans Planckian physics on the cosmic microwave background, and brane-gas cosmologies that could explain why the space around us has three large dimensions, expanding on the suggestion of a black hole electron, namely that the electron may be a black hole.

World Science Festival
In 2008, together with Tracy Day (former ABC News producer), Greene co-founded the World Science Festival, whose mission is to cultivate a general public informed by science, inspired by its wonder, convinced of its value, and prepared to engage with its implications for the future. He is currently the Chairman of the Board.

The World Science Festival’s signature event is a five-day festival in New York City, typically falling at the May. Hailed a “new cultural institution”, by The New York Times, the Festival has featured such luminaries as: Stephen Hawking, Edward O. Wilson, Sir Paul Nurse, James Watson, Anna Deavere Smith, Francis Collins, Philip Glass, Yo-Yo Ma, Oliver Sacks, Mary-Claire King, William Phillips, Paul Davies, Elizabeth Vargas, Sir Roger Penrose, Charlie Rose, Lisa P. Jackson, John Lithgow, Vinton Cerf, Glenn Close, Jeffrey Eugenides, Bill T. Jones, Joyce Carol Oates, Elaine Fuchs. The first six Festivals have drawn close to a million visitors, and millions more have explored the year round content available online.
Communicating science
Greene is well known to a wider audience for his work on popularizing theoretical physics, in particular string theory and the search for a unified theory of physics. His first book, The Elegant Universe: Superstrings, Hidden Dimensions, and the Quest for the Ultimate Theory, published in 1999, is a popularization of superstring theory and M-theory. It was a finalist for the Pulitzer Prize in nonfiction, and winner of The Aventis Prizes for Science Books in 2000.[3] The Elegant Universe was later made into a PBS television special of the same name, hosted and narrated by Greene, which won a 2003 Peabody Award.
Greene's second book, The Fabric of the Cosmos: Space, Time, and the Texture of Reality (2004), is about space, time, and the nature of the universe. Aspects covered in this book include non-local particle entanglement as it relates to special relativity and basic explanations of string theory. It is an examination of the very nature of matter and reality, covering such topics as spacetime and cosmology, origins and unification, and including an exploration into reality and the imagination. The Fabric of the Cosmos was later made into a PBS television special of the same name, hosted and narrated by Greene.
Greene's third book, The Hidden Reality: Parallel Universes and the Deep Laws of the Cosmos, published in January 2011, deals in greater depth with multiple universes, or, as they are sometimes referred to collectively, the multiverse.
A book for a younger audience, Icarus at the Edge of Time ISBN 978-0-307-26888-4, which is a futuristic re-telling of the Icarus myth, was published September 2, 2008.[4] In addition to authoring popular-science books, Greene is an occasional Op-Ed Contributor for The New York Times, writing on his work and other scientific topics.
The popularity of his books and his natural on-camera demeanor have resulted in many media appearances, including Charlie Rose, The Colbert Report, The NewsHour with Jim Lehrer, The Century with Peter Jennings, CNN, TIME, Nightline in Primetime, Late Night with Conan O'Brien, and the Late Show with David Letterman. It has also led to Greene helping John Lithgow with scientific dialogue for the television series 3rd Rock from the Sun, and becoming a technical consultant for the film Frequency, in which he also had a cameo role. He was a consultant on the 2006 time-travel movie Déjà Vu. He also had a cameo appearance as an Intel scientist in 2007's The Last Mimzy. Greene was also mentioned in the 2002 Angel episode "Supersymmetry" and in the 2008 Stargate Atlantis episode "Trio". Through his film credits, combined with his research publications in mathematical physics, Greene is one of the few people to have a defined Erdős–Bacon number.[citation needed] In April 2011 he appeared on The Big Bang Theory in the episode "The Herb Garden Germination" as himself, speaking to a small crowd about the contents of his most recent book.

Greene often lectures outside of the collegiate setting, at both a general and a technical level, in more than twenty-five countries. In 2012 his teaching prowess was recognized when he received the Richtmyer Memorial Award, which is given annually by the American Association of Physics Teachers.[5]
In May 2013, the Science Laureates of the United States Act of 2013 (H.R. 1891; 113th Congress) was introduced into Congress. Brian Greene was listed by one commentator as a possible nominee for the position of Science Laureate, if the act were to pass.[6]