Physicist Frank Wilczek’s unique insights on the nature of reality

In June, at a conference set in the picturesque Italian town of Campagna, south-east of Naples, two physicists in a seemingly endless argument over a long-sought theory of fundamental reality caught my attention. From the sidelines, an unassuming figure politely interrupted them.

“I’ve got a slide that might help. Can I put it up?” asked Frank Wilczek. The slide, concisely describing the realms in which this theory may act, swiftly ended the dispute. Among the many luminaries jousting in Campagna, I realised, perhaps only Wilczek had the breadth of expertise to untangle their confusion.

Wilczek is one of the most original physicists alive today, whose achievements seem too numerous for a single mind. He revealed the true workings of one of the four fundamental forces of nature. He proposed the axion, a leading candidate for dark matter. He also predicted bizarre particles called anyons and a state of matter called a time crystal.

These landmarks fall within a familiar pattern. Wilczek immerses himself in something entirely new, makes a major contribution and then moves on, led by his curiosity. Now, at the age of 74, he is still finding new obsessions, such as gravitational waves and artificial intelligence. Though these may seem like disparate forays, they all serve Wilczek’s desire to uncover hidden layers of reality.

“The way the world works is a boundless, continuing joy and a revelation to me,” says Wilczek. “The deeper I look, the more I feel rewarded, the more I see new things to investigate, but also new things to just appreciate.”

So, on a terrace in the shadow of the Picentini mountains, we sat down to look back at his career and cast one eye to the future.

A century of quantum mechanics

The conference was held in an Augustinian convent that underwent an expansion in the 16th century and is now a working town hall. It was an unusual venue for a physics conference: posters about black holes and new kinds of elementary particles were plastered beneath medieval frescoes. The gathering was partly to celebrate how much progress there has been in quantum mechanics since the theory arose a century ago, and partly to work out how to approach the many puzzles that remain in fundamental physics. “The framework [of quantum mechanics] has gone from triumph to triumph – far beyond what the founders anticipated,” says Wilczek.

Now a theorist at the Massachusetts Institute of Technology, Wilczek has done more than most to flesh out this skeleton theory with concrete descriptions of what reality is made of. Incredibly, he made his first major contribution when he was only 21. At the time, the standard model of particle physics – our best description of the elementary particles and forces of nature – was still being forged. For decades, physicists had grappled with how the strong nuclear force holds together protons and neutrons inside an atomic nucleus. Then, in 1972, the fresh-faced Wilczek stepped in with an idea he called asymptotic freedom, which says that as you pull apart quarks, which are the building blocks of protons and neutrons, their attraction grows stronger, but if you move quarks closer together, the force grows weaker. This observation formed a pillar of what is now called quantum chromodynamics, or QCD, which is itself a pillar of the standard model.

Although Wilczek later won the 2004 Nobel prize in physics for this insight, which he shared with David Gross and David Politzer, he has one regret about this period: asymptotic freedom is, by anyone’s estimation, a bad name for a good idea. “I learned this very early the hard way,” he says. “Because we didn’t have a good name, other people kind of glommed onto it and grabbed different pieces. We didn’t wrap up the package and establish our ownership in the way we should have.”

It was a lesson that Wilczek took to heart. A few years after initially outlining the theory of QCD, he realised it was pointing towards the existence of a novel, ghostly fundamental particle. What could he call it? Wilczek’s mind wandered to an earlier shopping trip with his mother while he was home from university. “I saw [a washing powder called] Axion up on the shelf, and I said, ‘Gosh, that really sounds like a particle.’”

Since then, the axion particle has come into its own. Although axions haven’t been detected, they are a leading candidate for dark matter – the unknown substance that seems to bind galaxies together. Multiple experiments around the world are now searching for axions, which could be hundreds to billions of times smaller than the tiniest particles that we know exist. One of these detectors, which is being designed by Wilczek and his collaborators at Yale University, is called the Axion Longitudinal Plasma Haloscope, or Project ALPHA. The experiment consists of a fine-tuned wire frame capable of acting like dense plasma that should be able to detect an axion in the act of turning into a photon of light. When Project ALPHA switches on next year, it will home in on the range of masses where dark matter may still be hiding. “That should happen on the timescale of five to 10 years,” says Wilczek. “Unless something goes terribly wrong.”

Wilczek has many reasons to be optimistic about the search for axions, not least because he calls the theoretical motivations for it “profound”. But he is under no illusions about how difficult it might be and is humble about the possibility of failure. “People believe all kinds of things,” he says. Indeed, he is quick to point out to me that his conception of axions has evolved since the 1970s because it originally implied very massive particles that conflict with the observed properties of stars in our galaxy.

This humility was on display throughout the Campagna conference. Everywhere Wilczek went, he carried a small collection of coloured notecards, and many times I noticed him bending over to scribble reams of equations for a professor or student who had asked him something they didn’t understand.

His eagerness to get stuck into the topic was also tied to his urge to carefully think things through, whether it was by himself or out loud, as he peppered speakers of every background – string theorists to gravitational wave experimentalists, Nobel prizewinners to recent graduates – with questions to help improve his own understanding. Such was the respect from his fellow physicists that, whatever the subject, whenever Wilczek spoke, they patiently listened.

Wilczek’s thoughts are evidently worth listening to. It is hard to ignore the impact and relevance that QCD and axions continue to have, half a century on from their conception. The same is true of another of Wilczek’s youthful divinations: a new kind of particle that, in 1982, he christened the anyon. Technically, anyons are collective vibrations that behave as if they are particles, called quasiparticles, which can result in some unique behaviours. Elementary particles are usually indistinguishable: if you imagine swapping two particles of the same type, it would be impossible to tell that the exchange ever happened. Anyons, on the other hand, keep track of where they have been in physical space, with each swap fundamentally altering how they vibrate.

Though anyons were a theoretical oddity at first, experiments performed by other researchers soon after indicated to Wilczek that they really might exist in some quantum systems. “I thought to see this kind of behaviour should be relatively straightforward and would only take a few months,” says Wilczek. In fact, it took almost 40 years before anyons were shown to exist. Now they are an active area of research in quantum computing because each particle’s ability to keep track of its past can be used to build computer memory. “A lot of effort has gone into designing materials or implementing the ideas in other kinds of hardware,” he says. “It’s a beautiful thing to see.”

Time crystals

Another of Wilczek’s triumphs could further transform quantum computing: the exotic-sounding time crystal. This peculiar state of matter contains repeating patterns that are found not in their physical structures, as with normal crystals, but in the way their structures arrange themselves through time.

In this case, Wilczek tells me between bites of an Italian biscuit on the terrace, it was his wife who coined the term during a holiday walk in the English countryside in the early 2010s. “She asked me, ‘What are you thinking about?’ And I told her about this stuff – spontaneous breaking of time-translation symmetry. Well, she said, ‘Can you make it a little more vivid?’ And I said, ‘Well, it’s like a crystal, but in time.’ She said, ‘Oh, a time crystal. You have to call it that.’” This name “catalysed interest”, says Wilczek, so that, within a decade, researchers had made real time crystals in the lab.

All of Wilczek’s insights are rooted in quantum mechanics, and he is one of the theory’s great champions. But having dedicated his career to extending and working within the field, he is also keenly aware of its shortcomings – not least in how little progress has been made in reconciling it with gravity to reach a deeper layer of reality. “To conquer the rest of the territory is tougher because we’ve succeeded so much,” says Wilczek. “The low-hanging fruit has all been picked and the easy experiments have been done.”

New methods are emerging, though, that may help us to make inroads. This is thanks in no small part to the understanding of quantum materials spearheaded by Wilczek. “I’m very gratified that it gives us new tools for accessing subtle behaviours that we couldn’t have dreamed of accessing before,” he says. No one knows what lies beyond the frontier of quantum mechanics, but Wilczek is sure that it will be “even more beautiful and surprising”.

One promising approach, he tells me, is to pay close attention to gravitational waves, which we have been measuring with increasing sensitivity since their discovery almost a decade ago. In the same way that the field of quantum optics has thrived in distinguishing the different forms that light can take, from high-energy lasers travelling through exotic materials to everyday light emitted from a light bulb, Wilczek hopes that we can tease out whether there is some hidden structure to gravitational waves that might imply a quantum nature.

Recently, an idea from the 1960s called a Weber bar has been resurrected to search for this structure. In their original conception, Weber bars were metre-high aluminium cylinders designed to resonate when gravitational waves of certain frequencies passed through them. New experiments that use quantum technologies to control and measure the bars’ vibrations with far greater sensitivity could find the subtle imprints of hypothetical quantum particles called gravitons. “This would transcend this whole question of whether gravity is quantum mechanical,” says Wilczek.

Artificial intelligence

Wilczek is also buoyed by the possibilities of artificial intelligence and has been experimenting more and more with chatbots running on large language models as part of his scientific process. For instance, he used ChatGPT to help him design a better antenna for Project ALPHA, and even appears to be striking up a friendship with the chatbot. “Every day, I try to have a meaningful conversation with ChatGPT about science – and I’ve learned new things and had good answers to very technical questions,” he says earnestly.

This might seem like an about-turn from the open letter he penned in 2014, along with physicists Stephen Hawking and Max Tegmark, which warned of the “incalculable benefits and risks” of AI. Yet Wilczek says he hesitated before signing the final draft of the letter because it had strayed from his typically optimistic stance. “I’m not alarmist. What worries me is not so much artificial intelligence, but natural stupidity,” he says. Namely, he is concerned about AI being used for military purposes. “That’s almost the same concept as doomsday machines, where you just hand over responsibility to processes you don’t understand or control, and it’s very dangerous because you only have to make one mistake.”

Wilczek’s natural optimism has recently been shaken by the large-scale cuts to US science funding enacted by the Donald Trump administration. While obvious technological spin-offs such as quantum computing and artificial intelligence have retained government support, the wider research ecosystem is being dismantled. “This is really killing the goose that laid the golden egg,” says Wilczek. “It’s being done very thoughtlessly, just like a kid playing with matches.”

Wilczek is also angry at the tech CEOs who have benefited from the scientific research that has enabled their technology empires, but have mounted no opposition to the cuts. He puts down his coffee and looks at me seriously. “People like Elon Musk, Mark Zuckerberg, Jeff Bezos are conspicuously silent. We should call them out,” he says.

Yet even with the promise of AI and quantum technologies, Wilczek has an acute sense of how much there still seems to do – and how little time there is to do it. Aside from quantum gravity, he reels off a long list of scientific puzzles that he is toying with: dark energy, dark matter, cosmic inflation, figuring out what’s inside a neutron star. “It’s like climbing Mount Everest,” he says, smiling. “You’ve got to do it because it’s there.”

After a lifetime of climbing mountains, Wilczek’s view is nothing short of sublime. “A human lifetime is very limited in time and space, compared to the universe,” he says. “In a way, it is humbling, but it’s also a relief to know that there’s a larger structure of which we’re a part that is so grand. Our imperfections, our struggles, our travails, when you put them in perspective, they somehow don’t seem so traumatic.”