Three-body problem could avoid nuclear war – 06/29/2023 – Science

Isaac Newton was perplexed. He was already famous for discovering how gravity holds the universe together and for using that knowledge to predict the motions of celestial bodies, such as the moon’s path around the Earth. So, by taking the sun’s gravitational forces into account, he sought to improve his lunar predictions. Instead, he made them worse.

The failure, as Newton’s friend Edmond Halley reported, “made his head ache and kept him awake so often that he thought no more of it.” Newton felt his defeat so deeply that he remembered it more than once in his old age.

Today it is called the three-body problem. Famous in science and science fiction for orbital perturbations and chaotic phenomena, it has recently become a concern of atomic experts and military planners. As Beijing rapidly expands its nuclear arsenal, they warn that the world of atomic superpowers is about to escalate from two to three. The result, they add, compared with the Moscow-Washington standoff, now 70 years old, could pose a new danger.

The looming era could encourage “states to resort to nuclear weapons in a crisis,” warned Andrew F. Krepinevich Jr., a senior fellow at the Center for a New American Security, recently. He cited natural instabilities observed by physicists and astronomers as an omen.

Experts say the tripolar era could endanger human survival. But they also cite a series of lessons from three bodies in nature — starting with Newton — that shed light on the issue and suggest possible ways forward. So far, though, no answer stands out. The world’s nuclear thinkers are finding the complex issue as intractable as it was for Newton.

“We have a conceptual problem,” said Ernest J. Moniz, a physicist who, as energy secretary in the Obama administration, oversaw the US nuclear arsenal. “We have to change the traditional approach of equalizing weapons or strategic delivery systems, but it’s still not clear how to do that.”

France A. Córdova, an astrophysicist and former director of the National Science Foundation, said studying three-body phenomena in the natural sciences could help reveal military risks. “Things are changing very quickly,” she said. “Anything that helps to understand this is great.”

The security-conscious hawks want to expand the US arsenal in response to China’s nuclear rise and Beijing’s threat to close ranks with Moscow. Pigeons see a window to reduce the size of the three bodies. They want to break the problem down into smaller, more manageable pieces. For example, they argue that Washington should deal with the two superpowers independently and seek diplomatic ties that reinforce stability between the two bodies.

Recently, the Biden administration called for more simplification. Jake Sullivan, the national security adviser, argued that the American response should focus less on the quantity of the country’s nuclear weapons than on their quality. To successfully deter attacks, he said in a speech, the US military does not need weapons that “outnumber the combined total of our competitors.”

In everyday life, groups of twos and threes can seem inconsequential. Two friends joining another brings the total to three. It’s the sum of the parts—what scientists call linear increase.

But in many aspects of nature the three have an almost magical power to sow chaos, to become more than the sum of their parts. Scientists call them nonlinearities. In short, the range from two to three can produce a counterintuitive leap in complexity, as Newton discovered, much to his dismay.

“Our intuitions deceive us,” said Michael Weisberg, a philosopher of science at the University of Pennsylvania, of the three-body tumult. Steven Strogatz, an applied mathematician at Cornell University, agrees: “Three is inherently problematic. Things get complicated.”

Surprisingly, the jump in disorganization also appears in the world’s oceans and atmosphere—in eddies and turbulences, tornadoes and hurricanes. If two of the whirling bodies approach each other, they move straight ahead or circle each other.

“With three, things immediately get more complicated,” said Michael J. Shelley, an expert in fluid dynamics at New York University. “They can collapse into each other. It gets very messy and unpredictable. There’s a big difference.”

Remarkably, the leap also appears in human life when groups of three cause social complexities to escalate—notably in young families. Two brothers have a relationship. But a third child results in seven types of sibling bonds—three one-to-one relationships, three one-to-two relationships, and one group relationship. Parents, by definition, are outnumbered and confusion can occur.

The Cold War — for all its terrors and crises — avoided nuclear war in part because its mature structures echoed the binary stability that astronomers see in the skies and that young families see in the relatively simple games of two children.

The era of the most serious nuclear tension began when the world’s first thermonuclear weapons were tested by Washington in 1952 and by Moscow in 1955. By nature, weapons could produce explosions a thousand times more powerful than the Hiroshima bomb. The ensuing arms race fueled Cold War fears of mutual annihilation—mocked in “Dr. Strangelove” [Dr. Fantástico]the classic 1964 film.

Soon, the antagonists took advantage of the parity of forces as a way to reduce the risk of conflict. Negotiated agreements put Moscow and Washington on an equal footing, with the aim of replacing war with tense stalemates — as is the case in Russia and the United States today.

“We’re on a stable footing,” said William I. Newman, a professor of astrophysics at the University of California, Los Angeles, who helps run the Los Alamos weapons lab for the University of California. “Any departure from that will increase instability.”

The imminent departure is Beijing’s plan to produce 1,500 nuclear warheads by 2035, as assessed by the Pentagon. If achieved, that would represent a five-fold increase over the “minimum deterrent” that Beijing had more than half a century ago and would make it a nuclear pair of Moscow and Washington.

Newman calls the tripolar state “much less resilient” than the bipolar stalemate. Even so, three-body theorists see many ways to avoid the unthinkable.

For example, Krepinevich, in an article in Foreign Affairs last year, argued that Moscow could fade into economic and strategic insignificance, leaving a strong pairing of Beijing and Washington to “navigate towards a new bipolar equilibrium”.

The armed uprising over the weekend in Russia shows not just Moscow’s weakness, but the threat of new instability in an atomic superpower.

On a different note, Siegfried S. Hecker, former director of the Los Alamos, New Mexico, weapons laboratory, argued that Washington should try to deal with the rival superpowers as separate entities.

“I don’t see Russia and China coming together” on atomic strategies, he said. “I see it as two bipolar.” As the war in Ukraine rages on and Washington has little interaction with Moscow, Hecker added, now is a good time “to work with the Chinese” on building a two-body relationship.

The main concern of military planners is that Beijing not only achieve parity of arms with Washington, but also form a military pact with Moscow.

“We’re still not seeing a solid, really consolidated, lasting, resilient geopolitical alliance,” Gen. Mark Milley, the outgoing chairman of the Joint Chiefs of Staff, told Foreign Affairs magazine last month. “Could this happen in the future? It could, and we need to be careful, and we need to do what we can to make sure it doesn’t happen.”

Translated by Luiz Roberto M. Gonçalves