|Born||1940 (age 72–73)
South Bronx, New York City, USA
University of Tel Aviv
Stanford Institute for Theoretical Physics
Korea Institute for Advanced Study
Perimeter Institute for Theoretical Physics
|Alma mater||City College of New York
|Doctoral advisor||Peter A. Carruthers|
|Known for||Holographic principle
String theory landscape
Hamiltonian lattice gauge theory
|Notable awards||American Institute of Physics' Science Writing Award
Sakurai Prize (1998)
Boris Pregel Award, New York Academy of Science (1975)
Leonard Susskind (born 1940) is the Felix Bloch Professor of Theoretical Physics at Stanford University, and Director of the Stanford Institute for Theoretical Physics. His research interests include string theory, quantum field theory, quantum statistical mechanics and quantum cosmology. He is a member of the National Academy of Sciences, and the American Academy of Arts and Sciences, an associate member of the faculty of Canada's Perimeter Institute for Theoretical Physics, and a distinguished professor of the Korea Institute for Advanced Study.
Susskind is widely regarded as one of the fathers of string theory, having, with Yoichiro Nambu and Holger Bech Nielsen, independently introduced the idea that particles could in fact be states of excitation of a relativistic string. He was the first to introduce the idea of the string theory landscape in 2003.
Early life and education 
Susskind was born to a poor Jewish family from the South Bronx section of New York City, and now resides in Palo Alto, California. He began working as a plumber at the age of 16, taking over from his father who had become ill. Later, he enrolled in the City College of New York as an engineering student, graduating with a B.S. in physics in 1962. In an interview in the Los Angeles Times, Susskind recalls the moment he discussed with his father this change in career path: "When I told my father I wanted to be a physicist, he said, ‘Hell no, you ain’t going to work in a drug store.’ I said no, not a pharmacist. I said, ‘Like Einstein.’ He poked me in the chest with a piece of plumbing pipe. ‘You ain’t going to be no engineer,’ he said. ‘You’re going to be Einstein.’" Susskind then studied at Cornell University under Peter A. Carruthers where he earned his Ph.D. in 1965. He has been married twice, first in 1960, and has four children.
Susskind was an Assistant Professor of Physics, then an Associate Professor at Yeshiva University (1966–1970), after which he went for a year at the University of Tel Aviv (1971–72), returning to Yeshiva to become a Professor of Physics (1970–1979). Since 1979 he has been Professor of Physics at Stanford University, and since 2000 has held the Felix Bloch Professorship of Physics.
Susskind was awarded the 1998 J. J. Sakurai Prize for his "pioneering contributions to hadronic string models, lattice gauge theories, quantum chromodynamics, and dynamical symmetry breaking." Susskind's hallmark, according to colleagues, has been the application of "brilliant imagination and originality to the theoretical study of the nature of the elementary particles and forces that make up the physical world."
In 2007, Susskind joined the Faculty of Perimeter Institute for Theoretical Physics in Waterloo, Ontario, Canada, as an Associate Member. He has been elected to the National Academy of Sciences and the American Academy of Arts and Sciences. He is also a distinguished professor at Korea Institute for Advanced Study.
Scientific career 
Susskind was one of at least three physicists who independently discovered during or around 1970 that the Veneziano dual resonance model of strong interactions could be described by a quantum mechanical model of strings, and was the first to propose the idea of the string theory landscape. Susskind has also made contributions in the following areas of physics:
- The independent discovery of the string theory model of particle physics
- The theory of quark confinement
- The development of Hamiltonian lattice gauge theory
- The theory of scaling violations in deep inelastic electroproduction
- The theory of symmetry breaking sometimes known as "technicolor theory"
- The second, yet independent, theory of cosmological baryogenesis (Sakharov's work was first, but was mostly unknown in the Western hemisphere.)
- String theory of black hole entropy
- The principle of black hole complementarity
- The causal patch hypothesis
- The holographic principle
- M-theory, including development of the BFSS matrix model 
- Kogut-Susskind fermions
- Introduction of holographic entropy bounds in physical cosmology
- The idea of an anthropic string theory landscape
- The Census Taker's Hat
||The neutrality of this article is disputed. (January 2013)|
The story goes that "In 1970, a young physicist named Leonard Susskind got stuck in an elevator with Murray Gell-Mann, one of physics' top theoreticians, who asked him what he was working on. Susskind said he was working on a theory that represented particles ' as some kind of elastic string, like a rubber band.' Gell-Mann responded with loud, derisive laughter.", story told in The Cosmic Landscape, p. 218.
Susskind is the author of two popular science books, The Cosmic Landscape: String Theory and the Illusion of Intelligent Design published in 2005, and The Black Hole War: My Battle with Stephen Hawking to Make the World Safe for Quantum Mechanics published in 2008.
Susskind is also currently writing a series of companion books to his lecture series The Theoretical Minimum. The first of these, The Theoretical Minimum: What You Need to Know to Start Doing Physics, was published in 2013 and presents the modern formulations of classical mechanics.
The Cosmic Landscape 
The Cosmic Landscape: String Theory and the Illusion of Intelligent Design is Susskind's first popular science book, published by Little, Brown and Company on December 12, 2005. It is Susskind's attempt to bring his idea of the anthropic landscape of string theory to the general public. In the book, Susskind describes how the string theory landscape was an almost inevitable consequence of several factors, one of which was Steven Weinberg's prediction of the cosmological constant in 1987. The question addressed here is why our universe is fine-tuned for our existence. Susskind explains that Weinberg calculated that if the cosmological constant was just a little different, our universe would cease to exist.
The Black Hole War 
The Black Hole War: My Battle with Stephen Hawking to Make the World Safe for Quantum Mechanics is Susskind's second popular science book, published by Little, Brown, and Company on July 7, 2008. The book is his most famous work and explains what he thinks would happen to the information and matter stored in a black hole when it evaporates. The book sparked from a debate that started in 1981, when there was a meeting of physicists to try to decode some of the mysteries about how particles of particular elemental compounds function. During this discussion Stephen Hawking stated that the information inside a black hole is lost forever as the black hole evaporates. It took 28 years for Leonard Susskind to formulate his theory that would prove Hawking wrong. He then published his theory in his book, The Black Hole War. Like The Cosmic Landscape, The Black Hole War is aimed at the lay reader. He writes: "The real tools for understanding the quantum universe are abstract mathematics: infinite dimensional Hilbert spaces, projection operators, unitary matrices and a lot of other advanced principles that take a few years to learn. But let's see how we do in just a few pages."
Susskind teaches a series of courses about modern physics referred to as The Theoretical Minimum. Collectively these courses teach the basic but rigorous theoretical foundations required to study each area of physics from classical mechanics through cosmology and string theory.
These courses are presented on the The Theoretical Minimum website and are also available on iTunes from "Stanford on iTunes U" and YouTube from "Stanford University's Channel". The courses are intended for the general public as well as students.
The Theoretical Minimum 
Core Sequence 
In the core sequence, each course builds upon the prior courses to lay the foundation for an understanding of the advanced theories of modern physics.
- Classical Mechanics (Fall 2007) iTunes YouTube
- Quantum Mechanics (Winter 2008) iTunes YouTube
- Special Relativity and Classical Field Theory (Spring 2008) iTunes YouTube
- Einstein's General Theory of Relativity (Fall 2008) iTunes YouTube
- Cosmology (Winter 2009) iTunes YouTube
- Statistical Mechanics (Spring 2009) iTunes YouTube
Core Sequence Repeated 
- Classical Mechanics (Fall 2011) iTunes YouTube
- Quantum Mechanics (Winter 2012) iTunes YouTube
- Special Relativity and Classical Field Theory (Spring 2012) iTunes YouTube
- General Relativity (Fall 2012) iTunes YouTube
- Cosmology (Winter 2013) iTunes YouTube
- Statistical Mechanics (Spring 2013 - In Progress) iTunes YouTube
Other Lectures 
- Particle Physics: 1 Basic Concepts (Fall 2009) iTunes YouTube
- Particle Physics: 2 Standard Model (Winter 2010) iTunes YouTube
- Particle Physics: 3 Supersymmetry, Grand Unification, String Theory (Spring 2010) iTunes YouTube
- String Theory and M-Theory (Fall 2010) iTunes YouTube
- Topics in String Theory (Winter 2011) iTunes YouTube
- Physics of the Higgs Boson (Single lecture: July 30, 2012) iTunes YouTube
A separate series of lectures on Quantum Mechanics and Relativity 
- Quantum Entanglements Part 1 (Fall 2006) iTunes YouTube
- Quantum Entanglements Part 2 (Not available online)
- Relativity (Spring 2007) iTunes YouTube [videos are mistakenly titled Quantum Entanglements Part 3]
(Note that some of the lecture names are a little mixed-up: "Quantum Entanglements Part 3" is in fact a lecture series on special relativity and electromagnetic theory, and the order in which the lectures were given is 1, 4, 5, 6, 7, 2&3, 8 and 9 (in terms of the numbers given on the videos). There is no mention of string theory in the series "Supersymmetry, Grand Unification, String Theory")
Smolin–Susskind Debate 
The Smolin-Susskind debate refers to the series of intense postings in 2004 between Lee Smolin and Susskind, concerning Smolin’s argument that the "Anthropic Principle cannot yield any falsifiable predictions, and therefore cannot be a part of science." It began on July 26, 2004, with Smolin's publication of "Scientific alternatives to the anthropic principle". Smolin e-mailed Susskind asking for a comment. Having not had the chance to read the paper, Susskind requested a summarization of his arguments. Smolin obliged, and on July 28, 2004, Susskind responded, saying that the logic Smolin followed "can lead to ridiculous conclusions". The next day, Smolin responded, saying that "If a large body of our colleagues feels comfortable believing a theory that cannot be proved wrong, then the progress of science could get stuck, leading to a situation in which false, but unfalsifiable theories dominate the attention of our field." This was followed by another paper by Susskind which made a few comments about Smolin's theory of "cosmic natural selection". The Smolin-Susskind debate finally ended with each of them agreeing to write a final letter which would be posted on Edge, with three conditions attached: (1) No more than one letter each; (2) Neither sees the other's letter in advance; (3) No changes after the fact.
Political Positions 
Same-sex marriage 
See also 
- Superstring theory
- Quantum chromodynamics
- Susskind-Glogower operator
- List of theoretical physicists
- Kogut-Susskind fermions
- Fischler-Susskind mechanism
- Boris Pregel
- Faculty information sheet. Stanford University. Retrieved 2009-09-01
- "Lennyfest". May 20–21, 2000: his 60th birthday was celebrated with a special symposium at Stanford University.
- 60 New Members Chosen by Academy. National Academy of Sciences (press release). May 2, 2000. Retrieved 2009-09-01
- Edge.org Leonard Susskind - A Biography (last accessed August 12, 2007).
- "Leonard Susskind Joins PI". October 15, 2007.
- "Susskind, Leonard: Distinguished Professor / School of Physics : Theoretical Particle Physics". Korea Institute for Advanced Study.
- "A Walk Across the Landscape". NYAS Publication.
- http://www.veccal.ernet.in/~iwlsc/qgp/Haridass_talk.ppt[dead link]
- Leonard Susskind (2003). "The Anthropic Landscape of String Theory". arXiv:hep-th/0302219 [hep-th].
- Salisbury, David F. (11 May 1997). "Susskind wins prestigious Sakurai Prize in theoretical physics" (Press release). Stanford University.
- "Leonard Susskind discusses duel with Stephen Hawking". LA Times. July 26, 2008.
- Welcome To Kias
- Schwarz (2000). "String Theory: The Early Years". arXiv:hep-th/0007118 [hep-th].
- Susskind, Leonard (1979). "Lattice models of quark confinement at high temperature". Physical Review D 20 (10): 2610. doi:10.1103/PhysRevD.20.2610.
- Kogut, John; Susskind, Leonard (1975). "Hamiltonian formulation of Wilson's lattice gauge theories". Physical Review D 11 (2): 395. Bibcode:1975PhRvD..11..395K. doi:10.1103/PhysRevD.11.395.
- Yao, W-M; et al (2006). "Review of Particle Physics". Journal of Physics G: Nuclear and Particle Physics 33 (1). doi:10.1088/0954-3899/33/1/001.
- Biography at APS J. J. Sakurai Prize website (last accessed August 12, 2007)
- Leonard Susskind (1993). "Some Speculations about Black Hole Entropy in String Theory". arXiv:hep-th/9309145 [hep-th].
- Susskind, Leonard (1993). "String theory and the principle of black hole complementarity". Physical Review Letters 71 (15): 2367–2368. arXiv:hep-th/9307168. doi:10.1103/PhysRevLett.71.2367. PMID 10054662.
- Bousso, Raphael (2002). "The holographic principle". Reviews of Modern Physics 74 (3): 825. arXiv:hep-th/0203101. doi:10.1103/RevModPhys.74.825.
The insistence on unitarity in the presence of black holes led 't Hooft (1993) and Susskind (1995b) to embrace a more radical, holographic interpretation of ...
- Banks, T.; Fischler, W.; Shenker, S. H.; Susskind, Leonard (1997). "M theory as a matrix model: A conjecture". Physical Review D 55 (8): 5112. arXiv:hep-th/9610043. doi:10.1103/PhysRevD.55.5112.
- L. Susskind (2005). The Cosmic Landscape: String Theory and the Illusion of Intelligent Design. Little, Brown. ISBN 0-316-15579-9. 
- L. Susskind (2008). The Black Hole War: My battle with Stephen Hawking to make the world safe for quantum mechanics. Little, Brown. ISBN 0-316-01640-3. 
- Susskind, Leonard; Hrabovsky, George (2013). The Theoretical Minimum: What You Need to Know to Start Doing Physics. Basic Books. ISBN 0-465-02811-X. 
- Smolin vs. Susskind: The Anthropic Principle. Edge Institute. August 2004. Retrieved 2009-09-01
- http://www.youtube.com/watch?v=D1RzvXDXyqA 40:23
Further reading 
- Chown, Marcus, "Our world may be a giant hologram", New Scientist, 15 January 2009, magazine issue 2691. "The holograms you find on credit cards and banknotes are etched on two-dimensional plastic films. When light bounces off them, it recreates the appearance of a 3D image. In the 1990s physicists Leonard Susskind and Nobel prize winner Gerard 't Hooft suggested that the same principle might apply to the universe as a whole. Our everyday experience might itself be a holographic projection of physical processes that take place on a distant, 2D surface."
|Wikiquote has a collection of quotations related to: Leonard Susskind|
- Leonard Susskind's Homepage (Stanford University)
- Susskind's Blog: Physics for Everyone
- The Theoretical Minimum website
- The Edge:
- Radio Interview from This Week in Science March 14, 2006 Broadcast
- "Father of String Theory Muses on the Megaverse": Podcast.
- Leonard Susskind at the Internet Movie Database
- Leonard Susskind: My friend Richard Feynman - A Ted talk