This brain drain appears to be real. I spoke to Jared Kaplan, co-founder of Anthropic, the company behind the chatbot Claude. He was a physicist the last time we spoke. As a grad student at Harvard in the 2000s, he worked with the renowned theorist Nima Arkani-Hamed to open up the new directions in amplitude research that are being actively pursued today. But Kaplan left the field in 2019. “I started working on AI because it seemed plausible to me that … AI was going to make progress faster than almost any field in science historically,” he said. AI would be “the most important thing to happen while we’re alive, maybe one of the most important things to happen in the history of science. And so it seemed obvious that I should work on it.”
As for the future of particle physics, AI makes worrying about it now rather pointless, in Kaplan’s view. “I think that it’s kind of irrelevant what we plan on a 10-year timescale, because if we’re building a collider in 10 years, AI will be building the collider; humans won’t be building it. I would give like a 50% chance that in two or three years, theoretical physicists will mostly be replaced with AI. Brilliant people like Nima Arkani-Hamed or Ed Witten, AI will be generating papers that are as good as their papers pretty autonomously. … So planning beyond this couple-year timescale isn’t really something I think about very much.”
Cari Cesarotti, a postdoctoral fellow in the theory group at CERN, is skeptical about that future. She notices chatbots’ mistakes, and how they’ve become too much of a crutch for physics students. “AI is making people worse at physics,” she said. “What we need is humans to read textbooks and sit down and think of new solutions to the hierarchy problem.”
Cesarotti was a high school junior when the Higgs boson was discovered. She grew up near Fermilab, the U.S. national lab in Illinois that houses the Tevatron, which was the world’s highest-energy particle collider before the LHC. (The top quark was discovered there in 1995.) This proximity taught her that a particle physicist was a thing you could be. Later, it turned out to be her thing. “What are the fundamental building blocks of the universe — those were the questions that I was most interested in knowing the answer to,” she told me. “But what people said was, ‘Particle physics is dead. Don’t do this.’”
It may have been a fair warning; Cesarotti has yet to land a permanent job as a rising particle physicist. The subfield has continued to shrink, she and others said, as faculty hiring committees and grad students go in other directions. “Definitely all this rhetoric that there was nothing to be found and you should give up on it — people listened,” she said. “And of course that means there are fewer people. It becomes a self-fulfilling prophecy. If you’re pushing all these talented people out of trying to solve these problems into a field that it’s easier to make an impact on, then you’re setting yourself up for failure.”
Cesarotti echoed a sentiment I’d heard from others, which sounds correct to me as well: “Particle physics isn’t dead; it’s just hard.” It’s hard to know what to think about or look for. But the most devoted particle physicists are thinking and looking all the same.
“It was easy for 125 years,” Strassler said. “One thing led to the next. That lucky century has, for now, at least in the medium term, come to an end. That could change tomorrow, or next century, or who knows.”
A hint of a new lightweight particle could, in theory, show up at the LHC, or in some other experiment. Strassler is particularly excited about the study of radioactive thorium-229 decay, which could reveal variations in the fundamental constants. I’m slightly partial to experiments looking for “axions,” dark matter candidates that are so lightweight that they can act a little like light itself.
On the theory side, an obvious solution to the hierarchy problem could drop naturally out of the geometry behind scattering amplitudes. Or, if Kaplan is right, AI systems might someday suggest powerful new ideas for how the 25 particles of the Standard Model fit into a more comprehensive pattern — a possibility I didn’t foresee back when the crisis began.
Clearly, further progress toward the truth remains possible in particle physics. But there’s no discovery guarantee. I’ve had more than 13 years to think about it, and it remains a disturbing prospect: All the empirical clues we can glean about nature’s fundamental laws and building blocks might already be in hand. The universe may plan on keeping the rest of its secrets.