Lee Smolin

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Lee Smolin
Lee Smolin at Harvard
Born (1955-06-06) June 6, 1955 (age 65) [1]
Alma mater Hampshire College (B.A., 1975)
Harvard University (A.M., 1978; Ph.D, 1979)
Awards Majorana Prize (2007)
Klopsteg Memorial Award (2009)
Queen Elizabeth II Diamond Jubilee Medal (2013)
Scientific career
Fields Physics
Institutions Perimeter Institute,
University of Waterloo
Doctoral advisor Sidney Coleman
Stanley Deser

Lee Smolin ( /ˈsmlɪn/ ; born June 6, 1955) is an American theoretical physicist, a faculty member at the Perimeter Institute for Theoretical Physics, an adjunct professor of physics at the University of Waterloo and a member of the graduate faculty of the philosophy department at the University of Toronto. Smolin's 2006 book The Trouble with Physics criticized string theory as a viable scientific theory. He has made contributions to quantum gravity theory, in particular the approach known as loop quantum gravity. He advocates that the two primary approaches to quantum gravity, loop quantum gravity and string theory, can be reconciled as different aspects of the same underlying theory. His research interests also include cosmology, elementary particle theory, the foundations of quantum mechanics, and theoretical biology. [2]


Early life

Smolin was born in New York City. [3] His brother, David M. Smolin, became a professor in the Cumberland School of Law in Birmingham, Alabama. [4]

Education and career

Smolin dropped out of Walnut Hills High School in Cincinnati, Ohio, and was educated at Hampshire College. He received his Ph.D in theoretical physics from Harvard University in 1979. [2] He held postdoctoral research positions at the Institute for Advanced Study in Princeton, New Jersey, the Kavli Institute for Theoretical Physics in Santa Barbara and the University of Chicago, before becoming a faculty member at Yale, Syracuse and Pennsylvania State Universities. He was a visiting scholar at the Institute for Advanced Study in 1995 [5] and a visiting professor at Imperial College London (1999-2001) before becoming one of the founding faculty members at the Perimeter Institute in 2001.

Theories and work

Loop quantum gravity

Smolin contributed to the theory of loop quantum gravity (LQG) in collaborative work with Ted Jacobson, Carlo Rovelli, Louis Crane, Abhay Ashtekar and others. LQG is an approach to the unification of quantum mechanics with general relativity which utilizes a reformulation of general relativity in the language of gauge field theories, which allows the use of techniques from particle physics, particularly the expression of fields in terms of the dynamics of loops. With Rovelli he discovered the discreteness of areas and volumes and found their natural expression in terms of a discrete description of quantum geometry in terms of spin networks. In recent years he has focused on connecting LQG to phenomenology by developing implications for experimental tests of spacetime symmetries as well as investigating ways elementary particles and their interactions could emerge from spacetime geometry.

Background independent approaches to string theory

Between 1999 and 2002, Smolin made several proposals to provide a fundamental formulation of string theory that does not depend on approximate descriptions involving classical background spacetime models.

Experimental tests of quantum gravity

Smolin is among those theorists who have proposed that the effects of quantum gravity can be experimentally probed by searching for modifications in special relativity detected in observations of high energy astrophysical phenomena. These include very high energy cosmic rays and photons and neutrinos from gamma ray bursts. Among Smolin's contributions are the coinvention of doubly special relativity (with João Magueijo, independently of work by Giovanni Amelino-Camelia) and of relative locality (with Amelino-Camelia, Laurent Freidel and Jerzy Kowalski-Glikman).

Foundations of quantum mechanics

Smolin has worked since the early 1980s on a series of proposals for hidden variables theories, which would be non-local deterministic theories which would give a precise description of individual quantum phenomena. In recent years, he has pioneered two new approaches to the interpretation of quantum mechanics suggested by his work on the reality of time, called the real ensemble interpretation and the principle of precedence.

Cosmological natural selection

Smolin's hypothesis of cosmological natural selection, also called the fecund universes theory, suggests that a process analogous to biological natural selection applies at the grandest of scales. Smolin published the idea in 1992 and summarized it in a book aimed at a lay audience called The Life of the Cosmos .

Black holes have a role in natural selection. In fecund theory a collapsing[ clarification needed ] black hole causes the emergence of a new universe on the "other side", whose fundamental constant parameters (masses of elementary particles, Planck constant, elementary charge, and so forth) may differ slightly from those of the universe where the black hole collapsed. Each universe thus gives rise to as many new universes as it has black holes. The theory contains the evolutionary ideas of "reproduction" and "mutation" of universes, and so is formally analogous to models of population biology.

When Smolin published the theory in 1992, he proposed as a prediction of his theory that no neutron star should exist with a mass of more than 1.6 times the mass of the sun.[ citation needed ] Later this figure was raised to two solar masses following more precise modeling of neutron star interiors by nuclear astrophysicists. Smolin also predicted that inflation, if true, must only be in its simplest form, governed by a single field and parameter. Both predictions have held up, and they demonstrate Smolin's main thesis: that the theory of cosmological natural selection is Popper falsifiable.

Contributions to the philosophy of physics

Smolin has contributed to the philosophy of physics through a series of papers and books that advocate the relational, or Leibnizian, view of space and time. Since 2006, he has collaborated with the Brazilian philosopher and Harvard Law School professor Roberto Mangabeira Unger on the issues of the reality of time and the evolution of laws; in 2014 they published a book, its two parts being written separately. [6]

A book length exposition of Smolin's philosophical views appeared in April 2013. Time Reborn argues that physical science has made time unreal while, as Smolin insists, it is the most fundamental feature of reality: "Space may be an illusion, but time must be real" (p. 179). An adequate description according to him would give a Leibnizian universe: indiscernibles would not be admitted and every difference should correspond to some other difference, as the principle of sufficient reason would have it. A few months later a more concise text was made available in a paper with the title Temporal Naturalism. [7]

The Trouble with Physics

Smolin's 2006 book The Trouble with Physics explored the role of controversy and disagreement in the progress of science. It argued that science progresses fastest if the scientific community encourages the widest possible disagreement among trained and accredited professionals prior to the formation of consensus brought about by experimental confirmation of predictions of falsifiable theories. He proposed that this meant the fostering of diverse competing research programs, and that premature formation of paradigms not forced by experimental facts can slow the progress of science.

As a case study, The Trouble with Physics focused on the issue of the falsifiability of string theory due to the proposals that the anthropic principle be used to explain the properties of our universe in the context of the string landscape. The book was criticized by physicist Joseph Polchinski [8] and other string theorists.

In his earlier book Three Roads to Quantum Gravity (2002), Smolin stated that loop quantum gravity and string theory were essentially the same concept seen from different perspectives. In that book, he also favored the holographic principle. The Trouble with Physics, on the other hand, was strongly critical of the prominence of string theory in contemporary theoretical physics, which he believes has suppressed research in other promising approaches. Smolin suggests that string theory suffers from serious deficiencies and has an unhealthy near-monopoly in the particle theory community. He called for a diversity of approaches to quantum gravity, and argued that more attention should be paid to loop quantum gravity, an approach Smolin has devised. Finally, The Trouble with Physics is also broadly concerned with the role of controversy and the value of diverse approaches in the ethics and process of science.

In the same year that The Trouble with Physics was published, Peter Woit published a book for nonspecialists whose conclusion was similar to Smolin's, namely that string theory was a fundamentally flawed research program. [9]


Smolin's view on the nature of time:

More and more, I have the feeling that quantum theory and general relativity are both deeply wrong about the nature of time. It is not enough to combine them. There is a deeper problem, perhaps going back to the beginning of physics. [10]

Smolin does not believe that quantum mechanics is a "final theory":

I am convinced that quantum mechanics is not a final theory. I believe this because I have never encountered an interpretation of the present formulation of quantum mechanics that makes sense to me. I have studied most of them in depth and thought hard about them, and in the end I still can't make real sense of quantum theory as it stands. [11]

In a 2009 article, Smolin articulated the following philosophical views (the sentences in italics are quotations):

Smolin views rejecting the idea of a creator as essential to cosmology on similar grounds to his objections against the multiverse. [12] He does not definitively exclude or reject religion or mysticism but rather believes that science should only deal with that of which is observable. [13] He also opposes the anthropic principle, which he claims "cannot help us to do science." [14]

He also advocates "principles for an open future" which he claims underlie the work of both healthy scientific communities and democratic societies: "(1) When rational argument from public evidence suffices to decide a question, it must be considered to be so decided. (2) When rational argument from public evidence does not suffice to decide a question, the community must encourage a diverse range of viewpoints and hypotheses consistent with a good-faith attempt to develop convincing public evidence." (Time Reborn p 265.)

Awards and honors

Smolin was named as #21 on Foreign Policy Magazine's list of Top 100 Public Intellectuals. [15] He is also one of many physicists dubbed the "New Einstein" by the media. [16] The Trouble with Physics was named by Newsweek magazine as number 17 on a list of 50 "Books for our Time", June 27, 2009. In 2007 he was awarded the Majorana Prize from the Electronic Journal of Theoretical Physics, and in 2009 the Klopsteg Memorial Award from the American Association of Physics Teachers (AAPT) for "extraordinary accomplishments in communicating the excitement of physics to the general public," He is a fellow of the Royal Society of Canada and the American Physical Society. In 2014 he was awarded the Buchalter Cosmology Prize for a work published in collaboration with Marina Cortês. [17]

Personal life

Smolin was born in New York City. His father is Michael Smolin, an environmental and process engineer and his mother is the playwright Pauline Smolin. Lee Smolin has stayed involved with theatre becoming a scientific consultant for such plays as A Walk in the Woods by Lee Blessing, Background Interference by Drucilla Cornell and Infinity by Hannah Moscovitch. [18]

Smolin is married to Dina Graser, a lawyer and urban policy consultant in Toronto, Ontario. He was previously married to Fotini Markopoulou-Kalamara. [19] His brother is law professor David M. Smolin.


Related Research Articles

Quantum gravity (QG) is a field of theoretical physics that seeks to describe gravity according to the principles of quantum mechanics, and where quantum effects cannot be ignored, such as in the vicinity of black holes or similar compact astrophysical objects where the effects of gravity are strong, such as neutron stars.

String theory Theoretical framework in physics

In physics, string theory is a theoretical framework in which the point-like particles of particle physics are replaced by one-dimensional objects called strings. String theory describes how these strings propagate through space and interact with each other. On distance scales larger than the string scale, a string looks just like an ordinary particle, with its mass, charge, and other properties determined by the vibrational state of the string. In string theory, one of the many vibrational states of the string corresponds to the graviton, a quantum mechanical particle that carries gravitational force. Thus string theory is a theory of quantum gravity.

Theory of everything Hypothetical single, all-encompassing, coherent theoretical framework of physics

A theory of everything, final theory, ultimate theory, or master theory is a hypothetical single, all-encompassing, coherent theoretical framework of physics that fully explains and links together all physical aspects of the universe. Finding a TOE is one of the major unsolved problems in physics. String theory and M-theory have been proposed as theories of everything. Over the past few centuries, two theoretical frameworks have been developed that, together, most closely resemble a TOE. These two theories upon which all modern physics rests are general relativity and quantum mechanics. General relativity is a theoretical framework that only focuses on gravity for understanding the universe in regions of both large scale and high mass: stars, galaxies, clusters of galaxies, etc. On the other hand, quantum mechanics is a theoretical framework that only focuses on three non-gravitational forces for understanding the universe in regions of both small scale and low mass: sub-atomic particles, atoms, molecules, etc. Quantum mechanics successfully implemented the Standard Model that describes the three non-gravitational forces – strong nuclear, weak nuclear, and electromagnetic force – as well as all observed elementary particles.

Eternalism is a philosophical approach to the ontological nature of time, which takes the view that all existence in time is equally real, as opposed to presentism or the growing block universe theory of time, in which at least the future is not the same as any other time. Some forms of eternalism give time a similar ontology to that of space, as a dimension, with different times being as real as different places, and future events are "already there" in the same sense other places are already there, and that there is no objective flow of time.

Loop quantum gravity Theory of quantum gravity, merging quantum mechanics and general relativity

A theory of quantum gravity, loop quantum gravity (LQG) attempts to merge quantum mechanics and general relativity, incorporating matter of the Standard Model into the framework established for the pure quantum gravity case. As a candidate for quantum gravity, LQG competes with string theory.

Julian Barbour British physicist (born 1937)

Julian Barbour is a British physicist with research interests in quantum gravity and the history of science.

Laurent Freidel is a French theoretical physicist and mathematical physicist known mainly for his contributions to quantum gravity, including loop quantum gravity, spin foam models, doubly special relativity, group field theory, relative locality and most recently metastring theory. He is currently a faculty member at Perimeter Institute for Theoretical Physics in Waterloo, Ontario, Canada.

Carlo Rovelli

Carlo Rovelli is an Italian theoretical physicist and writer who has worked in Italy, the United States and, since 2000, in France. He works mainly in the field of quantum gravity and is a founder of loop quantum gravity theory. He has also worked in the history and philosophy of science. He collaborates with several Italian newspapers, including the cultural supplements of the Corriere della Sera, Il Sole 24 Ore and La Repubblica.

Leonard Susskind American physicist

Leonard Susskind 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.

Erik Verlinde

Erik Peter Verlinde is a Dutch theoretical physicist and string theorist. He is the identical twin brother of physicist Herman Verlinde. The Verlinde formula, which is important in conformal field theory and topological field theory, is named after him. His research deals with string theory, gravity, black holes and cosmology. Currently, he works at the Institute for Theoretical Physics at the University of Amsterdam.

<i>The Fabric of the Cosmos</i> Book by Brian Greene

The Fabric of the Cosmos: Space, Time, and the Texture of Reality (2004) is the second book on theoretical physics, cosmology, and string theory written by Brian Greene, professor and co-director of Columbia's Institute for Strings, Cosmology, and Astroparticle Physics (ISCAP).

Cosmological natural selection also called the fecund universes, is a hypothesis proposed by Lee Smolin intended as a scientific alternative to the anthropic principle. It addresses the problem of complexity in our universe, which is largely unexplained. The hypothesis suggests that a process analogous to biological natural selection applies at the grandest of scales. Smolin published the idea in 1992 and summarized it in a book aimed at a lay audience called The Life of the Cosmos.

Lorentz invariance is a measure of universal features in hypothetical loop quantum gravity universes. The various hypothetical multiverse loop quantum gravity universe design models could have various Lorentz invariance results.

Loop quantum cosmology (LQC) is a finite, symmetry-reduced model of loop quantum gravity (LQG) that predicts a "quantum bridge" between contracting and expanding cosmological branches.

<i>The Trouble with Physics</i> Book by Lee Smolin

The Trouble with Physics: The Rise of String Theory, the Fall of a Science, and What Comes Next is a 2006 book by the theoretical physicist Lee Smolin about the problems with string theory. The book strongly criticizes string theory and its prominence in contemporary theoretical physics, on the grounds that string theory has yet to come up with a single prediction that can be verified using any technology that is likely to be feasible within our lifetimes. Smolin also focuses on the difficulties faced by research in quantum gravity, and by current efforts to come up with a theory explaining all four fundamental interactions. The book is broadly concerned with the role of controversy and diversity of approaches in scientific processes and ethics.

<i>Three Roads to Quantum Gravity</i> Non-fiction book by American theoretical physicist Lee Smolin

Three Roads to Quantum Gravity: A New Understanding of Space, Time and the Universe is a non-fiction book by American theoretical physicist Lee Smolin. The book was initially published on May 30, 2001 by Basic Books as a part of the Science Masters series.

Introduction to M-theory The leading contender for a universal "Theory of Everything" that unifies gravity with other forces such as electromagnetism.

In non-technical terms, M-theory presents an idea about the basic substance of the universe. As of 2020, science has produced no experimental evidence to support the concept that M-theory is a description of the real world. Although a complete mathematical formulation of M-theory is not known, the general approach is the leading contender for a universal "Theory of Everything" that unifies gravity with other forces such as electromagnetism. M-theory aims to unify quantum mechanics with general relativity's gravitational force in a mathematically consistent way. In comparison, other theories such as loop quantum gravity are considered by physicists and researchers/students to be less elegant, because they posit gravity to be completely different from forces such as the electromagnetic force.

Theoretical physics Branch of physics

Theoretical physics is a branch of physics that employs mathematical models and abstractions of physical objects and systems to rationalize, explain and predict natural phenomena. This is in contrast to experimental physics, which uses experimental tools to probe these phenomena.

<i>Time Reborn</i> Book by Lee Smolin

Time Reborn: From the Crisis in Physics to the Future of the Universe is a 2013 book by the American theoretical physicist Lee Smolin.

In theoretical physics, the problem of time is a conceptual conflict between general relativity and quantum mechanics in that quantum mechanics regards the flow of time as universal and absolute, whereas general relativity regards the flow of time as malleable and relative. This problem raises the question of what time really is in a physical sense and whether it is truly a real, distinct phenomenon. It also involves the related question of why time seems to flow in a single direction, despite the fact that no known physical laws at the microscopic level seem to require a single direction. For macroscopic systems the directionality of time is directly linked to first principles such as the Second law of thermodynamics.


  1. "The Institute for Advanced Study. Annual Report 1979/80", p. 58
  2. 1 2 Smolin's faculty page Archived 2008-07-18 at the Wayback Machine , Perimeter Institute.
  3. "Perimeter Institute Profile". Perimeter Institute. Retrieved 2015-08-17.
  4. "David Smolin's Cumberland School of Law Faculty Page". Samford University. Archived from the original on 2014-07-27. Retrieved 2015-08-17.
  5. "Institute for Advanced Study: Community of Scholars Profile". Institute for Advanced Study. Archived from the original on 2016-03-08. Retrieved 2015-08-17.
  6. Smolin L., and Roberto Mangabeira Unger R., (2014), The Singular Universe and the Reality of Time: A Proposal in Natural Philosophy, Cambridge University Press, ISBN   978-1107074064
  7. Smolin L., arXiv:1310.8539
  8. Joseph Polchinski (2007) "All Strung Out?" a review of The Trouble with Physics and Not Even Wrong, American Scientist 95(1):1.
  9. Woit, Peter (2006). Not Even Wrong: The Failure of String Theory & the Continuing Challenge to Unify the Laws of Physics. Jonathan Cape. ISBN   0-224-07605-1.
  10. Smolin, Lee. The Trouble With Physics, Houghton Mifflin Co, New York, 2006. (p. 256)
  11. Smolin's response to the question "What do you believe is true even though you cannot prove it?" "World Question Center 2005: Lee Smolin" Archived 2008-05-12 at the Wayback Machine Edge
  12. Huberman, Jack (2006). The Quotable Atheist. Nation Books. p. 282.
  13. smolin, lee (2000). Three Roads to Quantum Gravity. Basic Books. p. 1.
  14. Scientific alternatives to the anthropic principle, July 2004
  15. "Top 100 Public Intellectuals: The Final Rankings" Foreign Policy Magazine (June 27, 2008)
  16. Brockman, John. "Introduction" to Kauffman, Stuart and Smolin, Lee. "A Possible Solution For The Problem Of Time In Quantum Cosmology" Archived 2019-01-01 at the Wayback Machine on Edge (April 7, 1997)
  17. Announcement: First Prize for Dr. Marina Cortês, Dr. Lee Smolin The Universe as a Process of Unique Events, Phys. Rev. D 90, 084007 (2014)
  18. "Tarragon Theatre Profile". Tarragon Theatre. 2015. Retrieved 2015-08-17.
  19. Davies, Sally (28 July 2016). "This Physics Pioneer Walked Away from It All". Nautilus (science magazine) . Retrieved 29 July 2016.