| Lee Smolin | |
|---|---|
at Harvard
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| Born | 1955 New York City |
| Nationality | American |
| Fields | Physicist |
| Institutions | Perimeter Institute, University of Waterloo |
| Alma mater | Hampshire College, Harvard University |
| Doctoral advisor | Sidney Coleman, Stanley Deser |
Lee Smolin (born 1955) is an American theoretical physicist, a researcher at the Perimeter Institute for Theoretical Physics, and an adjunct professor of physics at the University of Waterloo. He is married to Dina Graser, a communications lawyer in Toronto. His brother is David M. Smolin.
Smolin is best known for devising several different approaches to quantum gravity, in particular 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.[1]
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Smolin was born in New York City to Michael Smolin, an engineer, and Pauline Smolin, a playwright. His brother, David M. Smolin, became a professor in the Cumberland School of Law in Birmingham, Alabama.[2] He was educated at Hampshire College. He received his Ph.D in theoretical physics from Harvard University in 1979.[1]
The fecund universes theory of cosmology advanced by Lee Smolin, also called cosmological natural selection theory, suggests that a process analogous to biological natural selection applies at the grandest scales. Smolin summarized the idea in a book aimed at a lay audience called The Life of the Cosmos.
The theory surmises that a collapsing black hole causes the emergence of a new universe on the "other side", whose fundamental constant parameters (speed of light, Planck length and so forth) may differ slightly from those of the universe where the black hole collapsed. Each universe therefore gives rise to as many new universes as it has black holes. Thus the theory contains the evolutionary ideas of "reproduction" and "mutation" of universes, but has no direct analogue of natural selection. However, given any universe that can produce black holes that successfully spawn new universes, it is possible that some number of those universes will reach heat death with unsuccessful parameters. So, in a sense, fecundity cosmological natural selection is one where universes could die off before successfully reproducing, just as any biological being can die without having offspring.[3]
Leonard Susskind, who promotes a similar string theory landscape, stated:
"I'm not sure why Smolin's idea didn't attract much attention. I actually think it deserved far more than it got"[4]
Smolin has noted that the string theory landscape is not Popper falsifiable if other universes are not observable. This is the subject of the Smolin-Susskind debate. There are then only two ways out: traversable wormholes connecting the different parallel universes and "signal nonlocality", as described by Antony Valentini, a scientist at the Perimeter Institute.
In a critical review of The Life of the Cosmos, the astrophysicist Joe Silk suggested that our universe falls short by about four orders of magnitude of being maximal for the production of black holes.[5] In his book Questions of Truth, the particle physicist John Polkinghorne has another difficulty with Smolin's thesis, in that one cannot impose the consistent multiversal time which would be required to make the evolutionary dynamics work, since otherwise short-lived universes with few descendants would dominate long-lived universes with many.[6]
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. If a more massive neutron star was ever observed, it would show that our universe's natural laws were not tuned for maximum black hole production, because the mass of the strange quark could be retuned to lower the mass threshold for production of a black hole. A 2-solar-mass pulsar was discovered in 2010,[7] so that cosmological natural selection has been falsified according to Smolin's own criteria.
The 2006 publication of The Trouble with Physics generated debate about the merits of string theory. The book was criticized by physicists Joseph Polchinski[8] and Luboš Motl.[9]
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.
Smolin's thesis found support in one corner. In the same year as that in which The Trouble with Physics was published, Peter Woit also published a book for nonspecialists, whose conclusion was similar to Smolin's, namely that string theory was a fundamentally flawed research program.[10]
The Smolin-Susskind debate refers to the series of intense postings in 2004 by Lee Smolin and Leonard Susskind, concerning Smolin’s argument: "[The] Anthropic Principle cannot yield any falsifiable predictions, and therefore cannot be a part of science".[4]
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 has articulated the following philosophical views (the sentences in italics are quotations):
Smolin is non-religious, believing that "there never was a God, no pilot who made the world by imposing order on chaos and who remains outside, watching and proscribing." [12] He also opposes the anthropic principle, which he claims "cannot help us to do science." [13]
The following books are relatively non-technical, and can be appreciated by those who are not physicists.
Smolin was recently named as #21 on Foreign Policy Magazine's list of Top 100 Public Intellectuals.[14] He is also one of many physicists dubbed the "New Einstein" by the media.[15]