Nuclear war may keep humanity from finding a ‘theory of everything,’ top physicist says

April 28, 2026

13 min read

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Nuclear war may keep humanity from finding a ‘theory of everything,’ top physicist says

After winning a Breakthrough Prize, the world’s most lucrative science award, theoretical physicist David Gross is using the moment to warn of nuclear war’s existential threat—and how we can escape it

By Lee Billings edited by Clara Moskowitz

Theoretical physicist David J. Gross attends the 12th Breakthrough Prize Ceremony at Barker Hangar on April 18, 2026 in Santa Monica, California, where he received a Special Breakthrough Prize in Fundamental Physics.

Taylor Hill/FilmMagic/Getty Images

David Gross, a celebrated U.S. theoretical physicist, calls himself an optimist—especially concerning the future of his field. He’s certain that somewhere out there lurks a final, unified theory of nature, just waiting to be discovered. But he’s pessimistic about our chances of actually discovering it; on balance, he estimates, it’s more likely that we’ll destroy ourselves in nuclear warfare first. And as the latest recipient of a $3-million Special Breakthrough Prize in Fundamental Physics, he’s using the opportunity to warn the world of this dire peril.

When Gross speaks, especially about prospects of a unified theory, people tend to listen—after all, he’s responsible for some of the biggest steps we’ve taken toward devising one.

Such a theory would, by definition, unify three known fundamental forces—electromagnetism and the strong and weak nuclear forces—with a fourth, gravity, reconciling a long-standing schism between these domains. In the early 1970s Gross co-discovered a phenomenon called asymptotic freedom—a counterintuitive property of the strong nuclear force showing that interactions between quarks (the subatomic constituents of neutrons and protons) weaken at shorter distances and strengthen at longer ones. In other words, the farther apart you try to pull quarks, the harder they’ll resist. But if you pile them together inside a proton, they will frolic freely, almost as if they have no resistance at all.

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The idea has been exhaustively confirmed in high-energy experiments, and it helped establish a theory of the strong force called quantum chromodynamics (QCD), which became a cornerstone of the Standard Model of particle physics. It also netted Gross a share of the 2004 Nobel Prize in Physics. In the aftermath of QCD’s ascendance, his quest for unification turned more speculative as he formulated foundational aspects of string theory, specifically a mathematically elegant hybrid type he co-developed in the 1980s called heterotic string theory, which mixes other types to describe fundamental particles. Unlike asymptotic freedom, however, heterotic string theory (and string theory in general) has yet to be validated by experiments.

Although the connection between these technical contributions and the existential threat of nuclear warfare may seem tenuous, Gross maintains it’s quite clear: Centuries of further theoretical and experimental progress may be required to find and verify a final theory—but planning for such a future is shortsighted when global nuclear war could effectively end human civilization itself in a single afternoon. Reducing that risk, he says, is therefore at least as important for discovering a unified theory as performing the fundamental physics work itself.

In a conversation with Scientific American, Gross discussed his Breakthrough Prize, the reasons for slow progress toward a unified theory and the folly of ballistic missile defense. And he explained why the current status quo means everyone now on Earth still faces the threat of nuclear annihilation.

[An edited transcript of the interview follows.]

You’ve won several major awards during your long career—the Dirac Medal in 1988, the Harvey Prize in 2000 and of course the Nobel Prize in Physics in 2004. Now you’ve won this year’s $3 million Breakthrough Prize in Fundamental Physics as well. Do you consider this the capstone?

Nothing really compares to the Nobel Prize, but this one is certainly the most lucrative. I’ve been heavily involved in raising money for my institute, the Kavli Institute for Theoretical Physics at the University of California, Santa Barbara, and for many others like it around the world. So with this Breakthrough Prize, it’s nice to finally have some money to give to other people!

You know, this is a “lifetime achievement” prize, which carries the suggestion that my lifetime is drawing to a close. So that’s