# Leonard Susskind

Leonard Susskind (born January 1, 1940) is an American physicist, who is a professor of theoretical physics at Stanford University, and founding 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 US 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. He was the first to give a precise string-theoretic interpretation of the holographic principle in 1995 and the first to introduce the idea of the string theory landscape in 2003.

## Quotes

* The standard SU(3)×SU(2)×U(1) theory of strong, electromagnetic, and weak interactions appears to correctly describe physics down to the smallest distance scales yet probed.
** (1984). "The gauge hierarchy problem, technicolor, supersymmetry, and all that". Physics Reports 104 (2–4): 181–193. DOI:10.1016/0370-1573(84)90208-4.
* (Jokingly) Sex in ten dimensions is impossible... topologically.
** Lecture "Cosmic landscape and illusion of intelligent design", DESY Hamburg (28 September, 2006).
* The problem with general relativity is that the principles are pretty simple and the computations are always ugly.
** General Relativity Lecture 5, YouTube, published 30 October 2012 (quote at 1:21:46 of 1:39:06)
* A straight line is a special case of a curve. It's a curve which is uncurved.
** Einstein's General Theory of Relativity Lecture 7, YouTube, published 12 March 2009 (quote at 1:27 of 1:56:43)
* Elegance requires that the number of defining equations be small. Five is better than ten, and one is better than five. On this score, one might facetiously say that String Theory is the ultimate epitome of elegance. With all the years that String Theory has been studied, no one has found even a single defining equation! The number at present count is zero. We know neither what the fundamental equations of the theory are nor even if it has any.
** The Cosmic Landscape: String Theory and the Illusion of Intelligent Design. Little, Brown. 2008.
* Most constants are adjusted with a deviation of one percent, which means that if the value differs by one percent everything collapses. Physicists can certainly claim that this is a fluke, but it must be acknowledged that this cosmological constant is adjusted to an accuracy of 1/10120. No one thinks that this is solely a fluke. It is the most extreme example of hyperfine regulation...
** La maggior parte delle costanti è regolata con uno scarto dell’uno per cento, il che significa che se il valore differisce dell’uno per cento tutto collassa. I fisici possono certo affermare che si tratta di un colpo di fortuna ma bisogna riconoscere che questa costante cosmologica è regolata con una precisione di 1/10120. Nessuno pensa che si tratti unicamente di un caso. E’ l’esempio più estremo di regolazione iperfine...
*** As quoted in Francesco De Martini, Le tante prove del “Disegno intelligente” che ha creato l’Universo, Il Foglio (March 13, 2004)
* My physics has been extremely mainstream, ... It's not true that I'm some sort of a [radical thinker], not at all.
** During an interview with Y Combinator - Published on Dec 6, 2018.

## Quotes about Susskind

* ... Lenny Susskind ... is very well known for his technical work, for his popular work, for his semi-technical books, The Theoretical Minimum, and, within the physics community, as a storyteller, a mentor, and a guiding visionary of the field.
** Sean M. Carroll, Episode 45: Leonard Susskind on Quantum Information, Quantum Gravity, and Holography. YouTube (6 May 2019).
* Dozens of other popular authors have written about black holes and string theory, but Gefter’s excitement makes even such overdone subjects seem fresh. And through the whole process, she and her father remain awed by the physicists whose work they’re studying—late in the book, her father even asks Susskind for an autograph.
** Chad Orzel in (May 2014)"Review of Trespassing on Einstein's Lawn: A Father, a Daughter, the Meaning of Nothing, and the Beginning of Everything by Amanda Gefter". Physics Today 67 (5): 52-53. DOI:10.1063/PT.3.2385.