In July 2012, physicists at the Large Hadron Collider (LHC) in Europe triumphantly announced the discovery of the Higgs boson, the long-sought linchpin of the subatomic world. Interacting with Higgs bosons imbues other elementary particles with mass, making them slow down enough to assemble into atoms, which then clump together to make everything else.
A couple of months later, I took a job as the first staff reporter at the nascent science magazine that would become Quanta. Turns out I was starting on the physics beat just as the drama was picking up.
The Quanta Podcast Columnist Natalie Wolchover asks particle physicists whether the field is facing a profound crisis. All episodes Your browser does not support the audio element. / APPLE SPOTIFY
The drama wasn’t about the Higgs particle; by the time it materialized at the LHC there was already little doubt about its existence. The Higgs was the last piece of the Standard Model of particle physics, the 1970s-era set of equations governing the 25 known elementary particles and their interactions.
More striking was what did not emerge from the data.
Physicists had spent billions of euros building the 27-kilometer supercollider not only to confirm the Standard Model but also to supersede it by uncovering components of a more complete theory of nature. The Standard Model doesn’t include particles that could comprise dark matter, for instance. It doesn’t explain why matter dominates over antimatter in the universe, or why the Big Bang happened in the first place. Then there’s the inexplicably enormous disparity between the Higgs boson’s mass (which sets the physical scale of atoms) and the far higher mass-energy scale associated with quantum gravity, known as the Planck scale. The chasm between physical scales — atoms are vastly larger than the Planck scale — seems unstable and unnatural. In 1981, the great theorist Edward Witten thought of a solution for this “hierarchy problem”: Balance would be restored by the existence of additional elementary particles only slightly heavier than the Higgs boson. The LHC’s collisions should have been energetic enough to conjure them.
But when protons raced both ways around the tunnel and crashed head-on, spraying debris into surrounding detectors, only the 25 particles of the Standard Model were observed. Nothing else showed up.
In philosophy, “qualia” refers to the subjective qualities of our experience: what it’s like for Alice to see blue or for Bob to feel delighted. Qualia are “the ways things seem to us,” as the late philosopher Daniel Dennett put it. In these essays, our columnists follow their curiosity, and explore important but not necessarily answerable scientific questions.
The absence of any “new physics” — particles or forces beyond the known ones — fomented a crisis. “Of course, it is disappointing,” the particle physicist Mikhail Shifman told me that fall of 2012. “We’re not gods. We’re not prophets. In the absence of some guidance from experimental data, how do you guess something about nature?”
Once the standard reasoning about the hierarchy problem had been shown to be wrong, there was no telling where new physics might be found. It could easily lie beyond the reach of experiments. The particle physicist Adam Falkowski predicted to me at the time that, without a way to search for heavier particles, the field would undergo a slow decay: “The number of jobs in particle physics will steadily decrease, and particle physicists will die out naturally.”
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