My Encounter with String Theorist and Naïve Realist Edward Witten
Edward Witten told me in 1991: “Good wrong ideas are extremely scarce, and good wrong ideas that even remotely rival the majesty of string theory have never been seen.” This photo was shot in 2015.
String theory has been on my mind lately, perhaps because I’ve been brooding over our struggles to make sense of this weird, weird world. That’s why I’m posting this profile, adapted from my 1996 book The End of Science, of string theorist Edward Witten, whom some say is the smartest physicist alive. -- John Horgan
In the late 1980s, I was eating lunch in the cafeteria of the Institute for Advanced Study in Princeton when a man walking by caught my eye. He had a lantern jaw and strikingly high forehead, bounded by think black glasses across the bottom and thick black hair across the top.
Who's that? I asked my lunchmate. Oh, that's Ed Witten, he replied. He's a particle physicist.
Witten, I learned later, is an ardent advocate of string theory. Proponents hope string theory is the long-sought unified theory of physics, so-called because it encompasses electromagnetism and the nuclear forces as well as gravity, which are now described by quantum theory and general relativity, respectively. String theory posits that all the forces spring from infinitesimal string-like particles wriggling in 10 (or more) dimensions.
The theory poses problems. Its mathematical underpinnings are hideously arcane and difficult to master. It comes in many different versions, and it’s not clear which, if any, is correct. Moreover, the theory can’t be experimentally tested. Probing the microscale where strings supposedly wriggle would require a particle accelerator 1,000 light years around. Our solar system is only one light day around. Nor can any instrument detect the extra dimensions needed to accommodate strings’ shenanigans. Witten has nonetheless convinced many physicists that string theory represents physics’ future.
In 1990, chitchatting between sessions at a physics conference, I asked attendees: Who is the smartest physicist of them all? Several names kept coming up, including Nobel laureates Steven Weinberg and Murray Gell-Man, but mentioned most was Witten. He is often likened to Einstein, but one admirer reached even further back for a comparison, suggesting that Witten possesses the greatest mathematical mind since Newton.
Witten is also the most spectacular specimen of naïve realist I have ever encountered. Naive realists possess an exceptionally strong faith in scientific and mathematical truths. They do not invent their theories, they discover them. The theories exist independently of any cultural or historical context or efforts to find them.
Like a Texan who thinks everyone except Texans has an accent, the naïve realist does not acknowledge he has adopted any philosophical stance (let alone one named “naïve realism”). He is just a conduit for objective truth. Background and personality have nothing to do with his scientific work.
Thus Witten, when I called to request an interview, tried to dissuade me from writing about him. He abhorred journalism that dwells on scientists' personalities. And contrary to what some reports have suggested, he did not discover string theory; he simply helped develop it.
Finally in August 1991 Witten agreed to let me visit him at the Institute for Advanced Study. He asked me to send him samples of my writings in advance. Stupidly, I included a profile of skeptical philosopher Thomas Kuhn.
When I arrived, Witten immediately lectured me on my shoddy journalistic ethics. I had done science a disservice by repeating Kuhn's view that science is an arational (not irrational) process that does not converge on the truth.
"You should be concentrating on serious and substantive contributions to the understanding of science," Witten said. Kuhn's philosophy "isn't taken very seriously except as a debating standard, even by its proponents." Does Kuhn go to a doctor when he’s sick? Does he have radial tires on his car?
I shrugged and guessed that he probably does. Witten nodded triumphantly. That proves, he declared, that not even Kuhn believes his own philosophy.
Kuhn’s views are influential and provocative, I said, and one of my aims as a science writer is not only to inform readers but also to provoke them.
“Aim to report on some of the truths that are being discovered, rather than aiming to provoke. That should be the aim of a science writer," Witten said.
I try to do both, I replied.
"Well, that's a pretty feeble response," Witten said. "Provoking people, or stimulating them intellectually, should be a byproduct of reporting on some of the truths that are being discovered."
This is another mark of the naïve realist: when he says "truth," there is never any ironic inflection or smile; the word is implicitly capitalized.
Finally, I managed to get Witten to recount how he became entangled by strings. He spoke so softly that I worried my tape recorder wouldn't pick him up over the air conditioner. He paused frequently--for 51 seconds at one point--casting his eyes down and squeezing his lips together like a bashful teenager.
Witten seemed to strive for the same precision and abstraction in his speech that he achieves in physics papers. Now and then he broke into convulsive, hiccupping laughter as some private joke flitted through his consciousness.
Witten first learned of string theory in 1975, just before he got his doctorate at Princeton, but his initial efforts to understand it were stymied by the "opaque" literature. (Yes, the smartest physicist of them all had a hard time grasping strings.)
In 1982, however, a paper by string pioneer John Schwarz gave Witten a crucial insight: Rather than simply allowing for the possibility of gravity, string theory requires gravity. Witten called this realization "the greatest intellectual thrill of my life."
By the mid-1980's, Witten had no doubts about the theory's potential. "It was clear that if I didn't spend my life concentrating on string theory,” he said, “I would simply be missing my life's calling.” He began publicly proclaiming the theory a "miracle" and predicting that it would "dominate physics for the next 50 years." He generated a flood of papers on the theory, including 19 in 1985 alone.
Early on, Witten concentrated on creating a string-based model of the real world, but eventually he focused on excavating the theory's "core geometric principles." These principles, he said, might be analogous to the non-Euclidian geometry that Einstein employed to construct general relativity.
Witten's pursuit of these principles led him deep into topology, the study of the fundamental geometric properties of objects in three or more dimensions. Witten created a technique that combines topology with the mathematical tools of quantum field theory. As a result of this work, Witten won the 1990 Fields Medal, the most prestigious prize in mathematics. (This honor feeds concerns that Witten is more a mathematician than physicist.)
I asked Witten about the complaint that string theory is not testable and therefore is not really physics at all. Witten replied that the theory had predicted gravity. "Even though it is, properly speaking, a post-prediction, in the sense that the experiment was made before the theory, the fact that gravity is a consequence of string theory, to me, is one of the greatest theoretical insights ever."
Witten acknowledged that string theory might not yield a precise description of nature for decades. He was nonetheless serenely confident that the theory would lead to a profound new understanding of reality. "Good wrong ideas are extremely scarce," he said, "and good wrong ideas that even remotely rival the majesty of string theory have never been seen."
When I continued to press him on the theory’s testability, Witten grew exasperated. "I don't think I've succeeded in conveying to you its wonder, its incredible consistency, remarkable elegance and beauty." In other words, string theory is too beautiful to be wrong.
Witten then revealed the depths of his naïve realism. "Generally speaking, all the really great ideas of physics are really spinoffs of string theory," he began. “Some of them were discovered first, but I consider that a mere accident of the development on planet earth. On planet earth, they were discovered in this order."
Stepping up to his blackboard, Witten wrote down general relativity, quantum field theory, string theory and supersymmetry (a concept that serves a vital role in string theory). "But I don't believe, if there are many civilizations in the universe, that those four ideas were discovered in that order in each civilization."
He paused. "I do believe, by the way, that those four ideas were discovered in any advanced civilization."
I could not believe my good fortune. Who's being provocative now? I asked.
"I'm not being provocative," Witten retorted. "I'm being provocative in the same way as someone who says the sky is blue is being provocative, if there is a writer somewhere who has said that the sky has pink polka dots."
Witten assumes that, in lieu of experimental evidence, mathematical consistency and beauty can guide physicists to the final truth. Critics have cast doubt on that assumption. Physicists Paul Ginsparg and Sheldon Glashow have compared string theorists to “medieval theologians.”
Another problem: Let's say Witten finds an infinitely pliable geometry that generates all known forces and particles. In what sense will such a theory "explain" the world? The meaning of string theory is embedded in the theory's arcane mathematics, which even Witten needed years to comprehend.
When I was in college, a literature professor likened James Joyce's gobbledygookian novel Finnegans Wake to the gargoyles atop Notre Dame Cathedral, built solely for God's amusement. I suspect that if Witten ever finds the theory he so desires, only he and God will grok it.
Postscript: In 2002 I bet string enthusiast Michio Kaku $2,000 that by 2020 no one will win a Nobel Prize for work on string theory or other unified theory. I won the bet, as string critic Peter Woit noted in a blog post headlined “2019 Physics Nobel Prizes Announced, John Horgan Wins.” Although string theory has been mathematically fruitful, it is now widely viewed—even by former advocates--as a dead end for physics. But Witten, I am strangely gratified to discover, continues to promote the theory.
Further Reading:
Is Ultimate Truth an Equation? Nah
Physicists Teleport Bullshit Through “Wormhole”!
Multiverses Are Pseudoscientific Bullshit
Moby Dick and Hawking’s “Ultimate Theory”
Defending My Naïve Realism
I also gripe about string theory in my free, online book My Quantum Experiment.