Leonard Susskind
Theoretical Physicist, Stanford
Trace a path from Leonard Susskind →Portrait painted after an image by Acmedogs · CC BY-SA 3.0
About
Leonard Susskind (b. 1940) is a theoretical physicist who grew up in the South Bronx, trained at City College of New York and Cornell, and has taught at Stanford since 1979, where he holds the Felix Bloch professorship and was founding director of the Stanford Institute for Theoretical Physics. Around 1970 he was one of three physicists, with Yoichiro Nambu and Holger Bech Nielsen, who independently saw that the Veneziano model describes vibrating strings — one of the founding moments of string theory. His long argument with Stephen Hawking over whether black holes destroy information, told in The Black Hole War (2008), drove him to black hole complementarity and to the holographic principle, which Gerard 't Hooft proposed and Susskind refined. In the last decade he has argued that geometry itself may be made of quantum information: with Juan Maldacena he proposed ER=EPR, linking wormholes to entanglement, and with Adam Brown and others the conjecture that a black hole's interior grows with the quantum complexity of its state.
Key Contributions
- Co-discovered around 1970, independently of Nambu and Nielsen, that the Veneziano dual resonance model describes quantum strings — a founding step of string theory
- Developed black hole complementarity and gave the first precise string-theoretic interpretation of the holographic principle (1995), the idea that a region's information lives on its boundary
- Argued against Stephen Hawking's claim that black holes destroy information, and told that decades-long dispute in The Black Hole War (2008)
- Proposed ER=EPR with Juan Maldacena and the Complexity Equals Action conjecture with Adam Brown and colleagues, recasting spacetime geometry in terms of entanglement and computation
- Introduced the string theory landscape (2003) and wrote The Cosmic Landscape (2005), then taught physics to non-specialists through his Stanford Continuing Studies courses, published as The Theoretical Minimum series (2013–2023)
Connections
Adam R. Brown
CollaboratedFounder/lead of Blueshift, Google DeepMind
Before Brown turned to AI at Google DeepMind, he and Susskind spent years at Stanford asking what fills the inside of a black hole. With Roberts, Swingle and Zhao they conjectured in 'Complexity Equals Action' (2015) that a black hole's quantum complexity is dual to the action of a region of spacetime, and the two of them followed it with 'The Second Law of Quantum Complexity' — a thermodynamics in which complexity, not entropy, keeps climbing. That a physicist of computation now builds reasoning machines is not as far a step as it looks.
arxiv.org · arxiv.org
Richard Feynman
In conversationTheoretical Physicist & Nobel Laureate
Susskind calls Feynman his friend — they did physics together without ever publishing a paper, and Feynman became convinced the two shared a temperament because both had fathers who taught them to use tools. In his TEDxCaltech talk Susskind recalls a mid-1980s dinner where, with Sidney Coleman, they argued with two philosophers of mind over 'Can a machine become a mind?', and Feynman demolished the jargon. What Susskind took from him was a rule: if you cannot explain something simply, you do not understand it.
youtube.com · ted.com
Brian Greene
In conversationTheoretical Physicist & Science Communicator
In a long World Science Festival conversation, Greene and Susskind walk from Hawking radiation through holography to the firewall paradox. Asked what string theory has actually achieved, Susskind's answer is modest and exact: not the particle spectrum, but a mathematically precise existence proof that quantum mechanics and gravity can coexist — and Greene, string theory's best-known popularizer, agrees that this alone justifies the program.
youtube.com
Sean Carroll
In conversationHomewood Professor of Natural Philosophy, Johns Hopkins University
On Mindscape in 2019, Carroll — who introduces him as a leader in reconciling general relativity with quantum mechanics — draws out the ideas Susskind is known for: black hole complementarity, the hologram, the landscape. The richest thread is the newest: Susskind's claim that the computational complexity of a black hole's evolution has a direct geometric meaning, the volume of its interior.
preposterousuniverse.com
