This was supposed to be an action-packed summer for me. After my semester ended in mid-May, I would fly to Namibia, Africa, for a three-week wilderness trek with two other old guys, Robert and Marc, and my son Mac. Then I was heading to New Mexico for a fellowship at the Santa Fe Institute, with which I have a complex history. I couldn’t wait!
When the pandemic shattered these summer plans, I started casting about for something to do. Seek enlightenment on another Buddhist retreat? Hike the Appalachian Trail? Track research on COVID-19 vaccines and treatments? None of these ideas gripped me. I felt listless, restless.
Then, on May 15, iconoclastic physicist Sabine Hossenfelder posted a video on YouTube, “Understanding Quantum Mechanics #2: Superposition and Entanglement.” I’m a Hossenfelder fan, and I’ve always been fascinated by quantum weirdness, so I watched the video. And I felt the same frustration I’ve felt for decades when I’ve tried to understand quantum mechanics. When the “explanations” become mathematical, I hit a wall.
In college, my degrees were in English and journalism. I took one class in physics and two in calculus, but I remember little from those courses. Ignorance hasn’t stopped me from writing about science, as my critics like pointing out. I’m a generalist, who goes wherever my curiosity takes me. I’ve written about physics, the mind-body problem, cancer, mental illness, war, you name it. I have twinges of imposter syndrome, especially when reporting on highly mathematical fields—including mathematics itself! But I’ve convinced myself that my job as a journalist isn’t to know what experts know. It’s to know enough, learn enough, to judge which experts and theories are credible.
But Hossenfelder’s video triggered something in me. Quantum mechanics is our most fundamental account of reality. I’ve written about it a lot, for example, in 1992 in “Quantum Philosophy,” an in-depth report on experimental probes of nonlocality and other quantum oddities. I’ve also interviewed great quantum theorists, such as John Wheeler and David Bohm, and modern philosophers of physics, like David Albert and Tim Maudlin. But I understand the theory only in a half-assed, metaphorical, physics-for-poets way.
Then I wondered: What would it take for me to grasp quantum mechanics the way that physicists do, math and all? I’ve entertained this question before, but only in an idle, day-dreamy kind of way. After seeing Hossenfelder’s video, the question kept nagging me—maybe because I lacked excuses to dismiss it. I just finished my sixth book, and my summer break is only beginning.
The more I thought about learning quantum mechanics, the more excited I got. But would it be possible at my age and with my lack of training? How long would it take, and how should I start? I ran these questions by a few friends with quantum expertise, including three physicists, a philosopher of physics and a science writer with a strong math and physics background.
They were almost too enthusiastic about my project (perhaps, I couldn’t help suspecting, because they want to see me suffer). Several recommended that I begin by reading Quantum Mechanics, The Theoretical Minimum: What you Need to Know to Start Doing Physics, by Stanford physicist Leonard Susskind and a former student. The back-cover blurb says the book “provides a tool kit for amateur scientists to learn physics at their own pace.” Perfect.
There’s an irony here. Leonard Susskind and I butted heads in 2006 after The New York Times published my essay “In Defense of Common Sense.” Many modern scientists, my essay pointed out, have disparaged common sense, contending that it can thwart comprehension of nature. I contested this position, arguing that common sense, which I defined as “ordinary, nonspecialized knowledge and judgment,” is often “indispensable for judging scientists' pronouncements.”
As examples, I pointed to physicists’ quest for a unified theory, which has led them to postulate the existence of infinitesimal strings, extra dimensions and extra universes. “All these theories are preposterous,” I wrote, “but that's not my problem with them. My problem is that no conceivable experiment can confirm the theories, as most proponents reluctantly acknowledge. The strings… are too small to be discerned by any buildable instrument, and the parallel universes are too distant. Common sense thus persuades me that these avenues of speculation will turn out to be dead ends.”
Susskind, a string and multiverse enthusiast, went after me on The Edge, a website for hifalutin intellectual chitchat. He concluded: “Instead of dyspeptically railing against what he plainly does not understand, Horgan would do better to take a few courses in algebra, calculus, quantum mechanics, and string theory. He might then appreciate, even celebrate, the wonderful and amazing capacity of the human mind to find uncommon ways to comprehend the incomprehensible.”
At the time, I shrugged off Susskind’s attack, which I’d heard many times. Experts often insist that only other experts are qualified to judge them. In other words, you must become indoctrinated into a field before you can criticize it. No journalist can accept such a rule. But here I am, 14 years later, taking Susskind’s advice. And not only that, I’m trying to learn quantum mechanics by reading his book! To brush up on calculus, which I last studied in college, I’m also reading Quick Calculus.
Susskind urged me to study string theory, too, but I’m not taking that advice. First of all, string theory looks more like a dead end now than ever. Moreover, it would take far too long to learn—at least six years of graduate-level study, one of my quantum advisers estimated--and my old brain would probably never grasp it. Edward Witten, whom some say is the smartest physicist since Newton, told me that when he read early papers on string theory in the 1970s, he found them “opaque.” (String theory’s hardness could explain its persistence. Those who master it can’t admit they have wasted their time on a dead end.)
I have no idea whether my quantum experiment will succeed. Almost as soon as I started Susskind, I started bogging down. I had to check Wikipedia to remind myself what sines and cosines are, not to mention complex numbers, Euler’s constant and matrices. Now I’m struggling to grok Hamiltonians, eigenvectors, Hermitians, kets and bras—and the infernal notations! I’m skipping Susskind’s math exercises for now. I’ll give them a shot after another reading or two, or three or four, and after I finish Quick Calculus.
But I’m enjoying myself in spite, no, because of my sense of disorientation. I feel as though I’m on the border of a strange new territory—far stranger than Namibia would have been--that is already challenging my preconceptions and forcing me to see the world anew.
What might happen as a result of my quantum experiment (assuming I don’t give up in frustration before I make any real progress)? If I get to the point where I can pontificate cockily about eigenvectors and wave functions (an enormous if), will my view of physics change? More specifically, will I have insights into the meaning of quantum mechanics? And perhaps its potential role in consciousness and free will?
That’s hard to say. Those who know quantum mechanics intimately--that is, mathematically--disagree on its implications. Clearly, mathematical knowledge in itself does not steer you toward a predetermined viewpoint. That’s appropriate, since, as Susskind notes, quantum mechanics shatters conventional notions of determinism.
Also, learning quantum mechanics poses a paradox. Richard Feynman famously said of quantum mechanics, “I don’t understand it. Nobody does.” So even if my quantum experiment fulfills my wildest expectations, I’ll never arrive at a point where I can say, “Ah, I get it.” The best I can hope for is to know a little more about what I don’t know. I’ll happily settle for that. Then, as our world descends into chaos, I can sit back in my apartment contemplating the wave function of it all.
Postscript: This is my last column for my blog “Cross-check,” which I started writing in 2010. My old pal Robert Hutchinson, who organized our canceled trip to Namibia, suggested the name “Cross-check,” an allusion to my passion for hockey. I’ve posted one piece per week on average for more than a decade now, and I've never enjoyed writing more. Scientific American is retiring its blog network this weekend, and I and other bloggers will henceforth write for the column “Observations.” So that’s where I’ll appear next. I hope to see you there.
See also my free, online book Mind-Body Problems: Science, Subjectivity & Who We Really Are.