Book review: The Trouble with Physics, by Lee Smolin

This controversial book (Smolin, 2006) is an attack on string theory and its dominance in theoretical physics. The author has worked in string theory himself, as well as in a major competing approach, loop quantum gravity. He argues that string theory has led nowhere despite being the dominant approach in the field for a long time. His scientific criticisms of string theory are heavily disputed in the community, and he may have overstated the case. However, he also makes a sociological criticism, that (in the U.S.) string theory has suffocated funding and employment opportunities for physicists who pursue alternative theories. Here Smolin's case seems more compelling.

The book has four parts. The first, "The Unfinished Revolution", is an enjoyable capsule history of unification in theoretical physics. Here the author proposes his list of the five great unsolved problems in physics: (1) Combining quantum theory with general relativity, (2) Resolving the difficulties in the foundations of quantum theory, perhaps by replacing it, (3) finding a theory unifying particles and forces, (4) explain the values of the free constants in the Standard Model of Particle Physics, and (5) explain dark matter and dark energy; alternatively explain the values of the constants in the Standard Model of Cosmology. The second part of the book, "A Brief History of String Theory", is precisely that. Here is where Smolin presents his assessment of the successes and alleged failures of string theory. I found this to be the toughest going and least enjoyable part of the book. The third part, "Beyond String Theory", has three chapters. The first discusses experimental and observational anomalies--for me, this was the most exciting part of the book. The other two chapters discuss speculative theories of physics, alternatives to both currently established theory and string theory. The final part of the book, "Learning from Experience", delves into the philosophy and sociology of physics. This is perhaps the most important part of the book. He feels that theoretical physics has run aground and is ripe for a paradigm shift. The "shut up and calculate" mentality that has been successful for the last 60 years has run its course, and it may be time for radical new ideas. The structure and sociology of the physics community is currently an obstacle to any such radicalism. Although I cannot go all the way along with Smolin in this section, I too am a critic of the academic tenure system and the funding mechanisms for science in the U.S.

Smolin has thought a great deal about the history, philosophy, and sociology of the physics profession. This is unusual for a physicist nowadays. His book presents an opportunity for the rest of us to do so too.

Reference

Lee Smolin, 2006: The Trouble with Physics: The Rise of String Theory, the Fall of a Science, and What Comes Next. Houghton Mifflin.