Hard Science Gone Soft

A review of The Trouble with Physics: The Rise of String Theory, the Fall of a Science, and What Comes Next by Lee Smolin

Physics, according to Smolin, has hit a wall. The last time a fundamental theory of physics successfully explained a new observation from the real world was 1981. No twenty-five-year period in the past two hundred years, by Smolin’s reckoning, has been as fallow for physics as the one we’ve just lived through. Having spent several years of my career in elementary particle physics, the field from which Smolin harkens, I know he’s right.

This period coincides with the rise of string theory to a level of hegemony in fundamental physics generally reserved for only the most successful theories in the past, even though it hasn’t convincingly shown itself to be consistent with reality. Smolin’s head count of the last two decades worth of hiring into top academic physics posts bears this out especially strikingly. Many young physicists feel they must work on string theory even if they don’t believe it, because they can’t get a job otherwise. What gives?

Most reactions to Smolin’s book that I’ve seen in the popular press say some version of “Extra! String Theory Might Be Wrong!” or worse, “Smolin Pronounces String Theory Wrong!” These miss his point, as I see it, entirely. Of course any theory as unproven as string theory stands today might be wrong. The relevant question is, why are the press, the public, and most significantly, the physics community, so surprised by that possibility? What caused so many people to think string theory was so right in the first place? Smolin thinks in big-picture terms, and as his title says, he is writing about the trouble with physics, not just the trouble with string theory. His take is that string theory’s strange ascendancy is merely a symptom of a larger problem.

He begins his explanation of the Trouble with a question: What makes a successful theory of physics? His answer comes from recounting the long history that brought us to 1981, theoretical physicists’ last successful year. Unlike most accounts of that history, which includes familiar icons like Kepler and Galileo, Smolin tells of the failures as well as the successes. Kepler pursued incorrect theories of the solar system for years before hitting upon the one we know today. His failed ideas were superior to his successful ones in both mathematical beauty and in unifying a broad range of phenomena in the solar system. What distinguished the right idea from the wrong ones in Kepler’s case, and every other as well, was neither of these things, but rather agreement with experimental observations – that is, grounding in the real world. We’re well-advised to remember this history when listening to modern theorists wax adoring about the beauty of mathematical symmetry and unification of physical laws, because those leave the relevant (and harder) question completely unanswered.

Smolin’s most close-up view of physics history is that part, starting in 1976, in which he has participated. He interweaves his explanations of the ideas of string theory – all designed for lay readers – with personal stories of interactions among the people involved. His accounts of those relationships demonstrate both his command of the subject and his sympathy, and often, affection for the physicists and their ideas. In Smolin’s story as many insights develop over beer and pizza as at professional conferences. Once, during a dinner-table discussion of a possible modification to the theory of relativity between Smolin and three culturally diverse young colleagues, a fiery-tempered Italian man holds a knife to his own throat, threatening to cut it if another’s theory is right. Fortunately it turns out to be a joke, and leads to a more relaxed and frank discourse than before. The Trouble with Physics is a book of stories, all of which unite to tell a larger story. They make the book fun to read and also give it the scope needed to explain the Trouble.

Smolin’s explanations of theoretical concepts of physics are among the best I’ve seen in a book for lay readers. I do wish he had used passive voice less liberally, and avoided starting nearly every other sentence or clause with the vague “It is…” “There are…” or variations thereof. These add a layer of verbal abstraction to the already abstract concepts of string theory, and contribute to that chapter’s tough reading in some places. But a sense of confusion is partly appropriate; one of Smolin’s points is how long and complex the chain of reasoning separating us from the last direct experimental observation has become. (“Rube Goldberg” comes not only to my mind, but some of the string theorists themselves.) And he overcomes his linguistic imprecision by sticking mostly to visualizable explanations. When he uses analogies as explanatory aids, he respects the reader’s intelligence enough to say exactly how the analogy applies to physics. His explanation of spontaneous symmetry breaking, for instance, is the best non-technical account I’ve seen of one of the most abstract ideas in physics. His analogy in this case – to the evolving interactions among a group of people meeting each other for the first time – also reminds us to keep the inextricable human element of science firmly in mind.

While string theorists’ ideas may seem arcane and convoluted, Smolin’s portrayal of their social structure will sound familiar to anyone who has witnessed a hot fashion combined with a hierarchical power structure. The arrogance of many string theorists towards outsiders seems more reminiscent of Hollywood or Washington, D.C. than the halls of academic physics. String theorists tend to view alternative ideas and their advocates with an “us versus them” derisiveness. Young scientists feel pressured to pursue research topics sanctioned by the mainstream, or suffer career-ending critique from the senior hiring authorities. Even a tenured researcher with a long track record of success, including a Nobel Prize, tells Smolin of being pushed to switch his research or risk losing his funding.

Smolin believes string theorists are not to blame for this Trouble. Rather, the universities and other research institutions of modern science have endowed one school of thought with too much power, and thus allowed alternatives to be shoved aside. This withering of diversity in physics is a new phenomenon. When society’s view of college professors was codified by the cliche “Those who can, do; those who can’t, teach,” the university served as a sort of bohemian outpost. Administration was minimal, leaving researchers to ponder as they pleased. Creative individuals, free to pursue outrageous ideas, gave us the past revolutions in physics that now fill our standard textbooks. But two transformative trends converged on science simultaneously: It became popular and funding for it stopped growing. Competition for jobs and funding stiffened. Professorships acquired status and prestige, and universities’ research programs suddenly had reputations to protect and grant money to chase after. Administration grew explosively. Thus, the explanation for the Trouble resides not in individuals, but rather in the system.

Alternatives to string theory aren’t the only casualty to suffer from the new system. An entire style of doing science is dying of starvation. Independent-minded creative thinkers who question the basic assumptions which current theories are built upon get weeded out by the hierarchical hiring and funding apparatus. These deeply creative “seers,” as Smolin calls them, are outliers because they are much rarer than the highly-skilled, mathematically-minded problem solvers who make up most of the physics community. Einstein, as well as Niels Bohr and the other architects of quantum theory were examples of this type of scientist. In fact, the originators of string theory were themselves seers, and suffered from it in their early days. The academic tenure system presents seers with a Catch-22: It protects intellectually independent people once they are established, but militates against their becoming established in the first place. The seers’ expansive ideas also tend to be riskier and take longer to reach fruition than those of the problem solvers. Although Smolin doesn’t doubt the high talent of people who tend to be successful under the current system, he wonders if they have the right type of talents to launch the kind of revolution theoretical physics now needs to move forward. The current roadblock in physics may need seers instead of expert problem-solvers.

Smolin’s solution is simple, if unlikely to be realized: Change the system. He proposes we physicists look no further than our neighbors in the business community for a simple and proven alternative. Conservative, established businesses productively coexist with risky, venture capital-funded new technology firms. Smolin finds a direct analogy between conservative versus risky business styles and the dichotomy of master problem solver-type scientists versus seers. If one duo can thrive together, why not the other? One venture capitalist’s dictum suggests a working principle academic science might also apply to seers: “If more than ten percent of the firms I fund succeed, I know I’m not taking enough risks.”

Sure, it could happen. Just like Microsoft might give up its monopolies. But a federal court order hasn’t made that happen, and neither does any miracle seem likely to persuade academics to preside over their own surrender of power. Not that Smolin is holding his breath; he has bypassed the academic mainstream, and now directs an independently funded research institute to find and nurture seers. After experiencing the academic system he describes, I’d say that he was smart to take that tack. More bluntly, he has simply recorded the end of the era of university-based innovation in science. Applied research will probably continue apace under the present system, possibly even benefit from it. And I’ve seen no indication that this system renders scientific results untrustworthy, as some anti-science crusaders will no doubt accuse. But the fundamental leaps of insight that brought us relativity, quantum physics, and other true revolutions will have to spring from a different source, or dry up completely.

I’m encouraged that an insider like Smolin (who received his Ph.D. from Harvard, carried out research at the Princeton Institute for Advanced Study and at Yale University, and contributed to string theory) acknowledges what’s happening. For three hundred years the world lauded physics as king of the sciences. So powerful and intimidating was its aura that other disciplines often suffered from “physics envy,” and tried, superficially in most cases, to emulate its numerical precision and mathematical rigor. Now that same focus on mathematical rigor – the specialty of master problem-solvers – to the exclusion of deeper physical insight puts the field in danger of becoming less-than-rigorous science. Suddenly physics seems to find itself lost in the same uncertain fog in which the social sciences have often been mired: Lots of different theories capable of explaining certain parts of the observed world, but none that explains all of it, and no unique theory that explains reality better than all the others. Worst of all, some leading string theorists have responded to this state of affairs by suggesting the standard scientific requirement of real-world testing should be relaxed to accommodate the uncertainties in string theory.

Perhaps physicists just got lucky in the centuries from Isaac Newton to 1981. What distinguished physicists from sociologists and other “soft” scientists was that we had loads of direct and simple observational evidence with which to weed out theories. Physical laws were few enough and simple enough to fit mathematical equations we could solve. Maybe nature’s supply of such easy evidence and simple laws is exhaustible, and we used it up. Particle physicists have echoed this sentiment over the last two decades in their lament over the inability of giant particle accelerators, their bread and butter theory-checker for the past fifty years, to reach the energies needed to test current ideas like string theory. I held this view when I started reading The Trouble with Physics. But Smolin convinced me that nature still gives us evidence that’s good enough to narrow down our theories as well as we did in the past, if only we had generated even one theory that could claim to account for any of that evidence. If the brute-force approach of high energy accelerators is out of steam, we need only look elsewhere. Astronomical observations over the last ten years have flooded us with unexpected phenomena, including an apparent problem with the law of gravity, crying out for explanation. If anything, theoretical physicists have used the notion of unachievable observations to sustain the theories they like most; tweak the theory a little, and the experiments that might falsify it drift safely out of observational reach.

Whatever the real source of the Trouble in theoretical physics, we should at least be honest with ourselves that it exists, according to twenty-five years worth of evidence. Changing the rules to dismiss that evidence is the solution least likely to help. Whatever the impetus behind our theories, and whether or not they come from people or institutions we consider well-motivated, only one thing makes for sound science: rigorous experimental checks of how well our explanations match reality. It’s true that some ideas are worthwhile for what they teach us about how to live life, or just for fun. If we bypass the real-world test, we haven’t committed any sin. But we have quit being scientists.