Lee Smolin

• 1. Introduction

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  Lee Smolin dropped out of Walnut Hills High School in Cincinnati, Ohio. That might seem like an unlikely starting point for one of the most provocative theoretical physicists of the past half century. But the story of that dropout threads directly through a physics library, a French-language textbook, and a self-assigned mission taken from Albert Einstein himself.

  As a teenager, Smolin read Einstein's own reflections on the two tasks he would leave unfinished at his death: first, to make sense of quantum mechanics, and second, to unify that understanding of the quanta with gravity. Smolin decided those would be his tasks too. He called it his "mission." What followed was a career spent at the edge of theoretical physics, questioning not just the answers but the questions themselves.

  Smolin was born on the 6th of June, 1955, in New York City, to a playwright mother and an engineer father. He eventually talked his way into Hampshire College and, from there, into a graduate program. He held postdoctoral posts at some of the most prestigious institutions in the world before becoming a founding member of the Perimeter Institute for Theoretical Physics in 2001. Along the way he helped develop loop quantum gravity, proposed that universes reproduce through black holes, argued that time is the most fundamental feature of reality, and wrote a bestselling book that challenged the dominance of string theory.

  By his own account, he did not complete Einstein's mission. "Very unfortunately," he wrote, "neither has anyone else." But the attempt itself reshaped how physicists argue about the nature of space, time, and the universe.

• 2. The Mission Begins

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  Louis de Broglie's pilot wave theory, written in French, was the book that changed everything for Smolin. He found it browsing the Physics Library at the University of Cincinnati after dropping out of high school. Decades later, in his 2019 book Einstein's Unfinished Revolution, he wrote that he could still close his eyes and see a page of it, displaying the equation that relates wavelength to momentum.

  That encounter locked in his direction. Hidden inside de Broglie's framework was an early attempt to make quantum mechanics describable in precise, individual terms rather than statistical clouds of probability. Smolin would return to that project again and again throughout his career, working since the early 1980s on proposals for what physicists call hidden variables theories: non-local deterministic theories that would give a precise description of individual quantum events, not just their averages.

  His parents shaped the intellectual atmosphere he grew up in. Michael Smolin was an environmental and process engineer; Pauline Smolin was a playwright. They were Jewish followers of the Fourth Way, the spiritual movement founded by George Gurdjieff, an Armenian mystic. Smolin describes himself as Jewish. His brother, David M. Smolin, took a different path and became a law professor at the Cumberland School of Law in Birmingham, Alabama.

  After Hampshire College, Smolin was accepted into graduate school, which he credits partly to luck. His postdoctoral career moved through some of the field's most storied addresses: the Institute for Advanced Study in Princeton, New Jersey; the Kavli Institute for Theoretical Physics in Santa Barbara; and the University of Chicago. He then joined the faculties of Yale, Syracuse, and Pennsylvania State universities before a visiting professorship at Imperial College London from 1999 to 2001 set the stage for his next chapter.

• 3. Loop Quantum Gravity

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  Ted Jacobson was one of the first collaborators. Together with Jacobson, Carlo Rovelli, Louis Crane, Abhay Ashtekar, and others, Smolin contributed to what became known as loop quantum gravity, or LQG. The approach tries to unify quantum mechanics with general relativity by recasting general relativity in the language of gauge field theories, the same mathematical language used in particle physics.

  A key move in that reformulation is to express fields not as continuous values spread across space but as the dynamics of loops. With Rovelli, Smolin discovered that areas and volumes in this framework are not continuous either: they are discrete. Space itself, at the smallest scales, comes in chunks. The natural mathematical objects for describing that chunky geometry turned out to be called spin networks.

  In recent years Smolin has worked on connecting LQG to things that can actually be tested. One line of research investigates how high energy cosmic rays, photons, and neutrinos from gamma ray bursts might reveal tiny modifications to special relativity predicted by quantum gravity. He co-invented a framework called doubly special relativity with the Portuguese physicist Joao Magueijo, independently of similar work by Giovanni Amelino-Camelia. He also co-developed a related idea called relative locality, with Amelino-Camelia, Laurent Freidel, and Jerzy Kowalski-Glikman.

  Between 1999 and 2002, he also proposed several ways to give string theory a formulation that does not rely on approximate classical background spacetime models, an effort to bridge the two competing approaches to quantum gravity from within LQG's background-independent philosophy.

• 4. Universes Having Children

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  In 1992, Smolin published one of his most unusual ideas: that universes reproduce. The hypothesis, which he called cosmological natural selection and also the fecund universes theory, applies concepts from biology to cosmology at the largest possible scale.

  The mechanism is the black hole. In Smolin's picture, when a black hole collapses it gives rise to a new universe on the other side. The fundamental constants of that new universe, things like the masses of elementary particles, the Planck constant, and the elementary charge, may differ slightly from those of the parent universe. Each universe produces as many offspring as it has black holes, which means universes with more black holes leave more descendants. Over many generations, the population of universes would be dominated by those whose constants favor the formation of black holes, universes that look, in key respects, like our own.

  The theory reframes what physicists call the fine-tuning problem: why do the constants of our universe seem dialed precisely for complex structure and life? For Smolin, the answer is the same kind of answer biology gives for why organisms are well suited to their environments. It is not design; it is selection.

  The theory carried a testable prediction. When Smolin published it in 1992, he proposed that no neutron star should exist with a mass greater than 1.6 times the mass of the sun. Later, more precise modeling of neutron star interiors by nuclear astrophysicists raised the upper limit to two solar masses, which put pressure on that specific prediction. He also predicted that if cosmic inflation occurred, it must have been governed by a single field and a single parameter in its simplest form. His 1997 book The Life of the Cosmos brought these ideas to a general audience.

• 5. Time Is Real

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  Space may be an illusion, but time must be real. That line appears on page 179 of Smolin's 2013 book Time Reborn, and it captures a conviction that has organized much of his philosophical work. He argues that physical science, by treating time as a fourth dimension on equal footing with space, has drained it of its most essential character: the fact that things actually happen, in sequence, and cannot be undone.

  Time Reborn argues that an adequate description of reality would be what Smolin calls Leibnizian: it would admit no two things that are indistinguishable in every respect, and every difference between things would correspond to some other difference. The philosophical framework draws on Gottfried Wilhelm Leibniz and his principle of sufficient reason.

  Since 2006, Smolin has worked with the Brazilian philosopher and Harvard Law School professor Roberto Mangabeira Unger on the reality of time and the evolution of physical laws. In 2014 the two published a joint book, The Singular Universe and the Reality of Time, its two parts written separately by each author. The collaboration brought law, philosophy, and physics into a shared argument about what the universe is and whether its laws are fixed or themselves subject to change.

  A shorter version of Smolin's position appeared in a paper titled Temporal Naturalism, published a few months after Time Reborn. In a 2009 article he had laid out the philosophy in more systematic form: only one universe exists, nothing exists timelessly, everything real is a process leading to the next moment, and mathematics is derived from experience rather than discovered in a Platonic realm. That last point was his response to Eugene Wigner's famous essay on the unreasonable effectiveness of mathematics in the natural sciences.

• 6. The Trouble with String Theory

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  The Trouble with Physics appeared in 2006 and named a problem Smolin believed the physics community had been reluctant to confront: string theory, he argued, had acquired a near-monopoly in particle theory without ever producing an experimentally confirmed prediction.

  The book's central complaint was about falsifiability. Proponents of string theory had begun invoking the anthropic principle to explain why our universe has the properties it does, pointing to a vast landscape of possible string vacua and arguing that we happen to live in one that supports observers. Smolin contended this move placed string theory outside the reach of experimental test. The book was criticized by physicist Joseph Polchinski and other string theorists.

  What made the critique notable was that Smolin had not always been so skeptical. His 2002 book Three Roads to Quantum Gravity argued that loop quantum gravity and string theory were essentially the same concept viewed from different angles, and that book also favored the holographic principle. By 2006, his position had hardened considerably. He now argued that the premature formation of a dominant paradigm, before experimental evidence forces consensus, actively slows the progress of science.

  In the same year, Peter Woit published Not Even Wrong, a book for non-specialists that reached a similar conclusion: that string theory was a fundamentally flawed research program. The two books arrived together and amplified each other in public debate.

  Newsweek later named The Trouble with Physics number 17 on a list of fifty Books for our Time in its issue dated the 27th of June, 2009. Foreign Policy magazine named Smolin number 21 on its list of Top 100 Public Intellectuals. In 2007 he received the Majorana Prize from the Electronic Journal of Theoretical Physics.

• 7. Perimeter and Its Consequences

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  The Perimeter Institute for Theoretical Physics in Waterloo, Ontario opened in 2001, and Smolin was among its founding faculty members. The Institute was designed precisely to encourage the kind of diverse, unconventional research Smolin had argued science needed. He also held appointments as an adjunct professor of physics at the University of Waterloo and as a member of the graduate faculty of the philosophy department at the University of Toronto.

  In 2003, Smolin contributed a note to Jeffrey Epstein's birthday book. He told The Verge in 2019 that he had not been in contact with Epstein since 2008, the year Epstein pleaded guilty to charges of solicitation of prostitution and solicitation of prostitution with a minor under the age of 18. When the Epstein files were released in 2025 and 2026, however, they showed that Smolin had been in contact with Epstein as recently as 2013. Among the emails was an invitation from Epstein to the US Virgin Islands in 2011.

  In 2026, Smolin agreed to pause his relationship with the Perimeter Institute in light of those revelations.

  Outside of physics, Smolin has served as a scientific consultant for theatre productions including A Walk in the Woods by Lee Blessing, Background Interference by Drucilla Cornell, and Infinity by Hannah Moscovitch, a line of work that reflects his mother Pauline Smolin's career as a playwright. He has been a recurring guest on Through the Wormhole. In 2009 he received the Klopsteg Memorial Award from the American Association of Physics Teachers for extraordinary accomplishments in communicating the excitement of physics to the general public. In 2014 he received the Buchalter Cosmology Prize for work published in collaboration with Marina Cortes.