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Freeman Dyson and the Challenges of the First Nuclear Age

Freeman Dyson and the Challenges of the First Nuclear Age

Freeman Dyson, October 2005. Credit: ioerror/Wikimedia Commons, CC BY-SA 2.0.

Two episodes from the rich and varied career of the American polymath Freeman Dyson, who passed away on February 28, illustrate the vagaries of Cold War science. They also show how top scientists of that first nuclear age balanced private misgivings, political compulsions, and deep pragmatism that followed from years of experience in military establishments.

In 1957, as an extension of his emerging reputation as a nuclear engineer – an unusual career trajectory for a pure mathematician turned theoretical physicist – Dyson started working on Orion, an ambitious project to develop rockets for planetary travel, from Earth to Mars and much beyond. The gist of the propulsion scheme was simple, feasible and utterly terrifying: hundreds of small nuclear bombs would go off in the rear of the rocket, thrusting it forward.

The impetus for what sounds like a wild idea to contemporary ears came from the US military. Research in high-velocity travel in space cut both ways. Just like Wernher von Braun’s V-2 missiles had become the American template for chemical rocket propulsion, the US Army had been keen on funding space rocketry spurred by the launch of the Soviet Sputnik in 1957.

In fact, Orion had been funded through a grant from the Army Advanced Research Projects Agency, the forerunner to the contemporary DARPA. This would not be the last time the American military establishment would be Dyson’s intellectual sponsor; Dyson would go on to have a complicated, ambivalent relationship with them. (An oblique expression of this ambivalence can be discerned in a chapter on German military conduct in his 1984 book, Weapons and Hope.)

Dyson’s contributions to Project Orion would be wide-ranging, including addressing crucial problems of keeping the spacecraft stable, designing the bombs that would produce the thrust and calculating the radioactive fallout in the process. But as much as Dyson enjoyed playing the problem-solver-in-chief of the project, Orion for him ultimately was a way to fulfil a childhood vision of planetary travel, as he explained to his IAS boss J. Robert Oppenheimer.

For Dyson – much like many other technological visionaries in the heady days of the first nuclear age – there was no dream, however ambitious, that couldn’t be fulfilled with effort. But the very dramatic advances that made those dreams seem within reach would also produce nightmares, setting in motion limits to what humans should do with them.

What ultimately happened to Project Orion illustrates this. Ten years after Dyson had ended work on it, a rocket designed by von Braun, long rehabilitated by the US despite having been a member of the Nazi Schutzstaffel, landed the first humans on the Moon. The death-knell of the alternative Orion was geopolitical. After the Cuban missile crisis of 1962, the USSR and the US agreed to discuss a proposal to ban atmospheric tests of nuclear weapons. If this proposal became a formal treaty, the nuclear-bomb propelled Orion would be a non-starter.

Phillip Schewe explained Dyson’s dilemma in his 2013 biography Maverick Genius, between his commitment to Orion (and other scientific projects that would require atmospheric nuclear explosions) and the prospects of greater cooperation with the Soviets that the treaty could bring. Ultimately, he supported the ban, even testifying in the US Senate in August 1963 in its favour.

The spectre of nuclear annihilation went on to outweigh space age’s deepest aspiration.

The nightmarish possibility of nuclear war of course didn’t vanish with the close brush of 1962. Four years later, Dyson found himself undertaking a study for JASON, an élite group of scientific advisors to the American military establishment. As the American imbroglio in Vietnam approached its crescendo, outlandish ideas surfaced in desperate efforts to contain it.

One idea, which died almost as soon as it was implemented, was for an electronic barrier between Communist North Vietnam and the US-backed South. An older version of this barrier – which came to be known as the McNamara Line, after Kennedy’s and Lyndon Johnson’s defence secretary Robert McNamara – was to also include insects to keep would-be Vietcong infiltrators from the North agitated. (As a sign of the strangely enduring power of bad ideas, US President Donald Trump proposed something similar last year: an alligator-filled moat along the US-Mexico border to deter illegal immigrants.)

The driving force behind this absurd idea was General Maxwell Taylor, the Kennedy-appointed chairman of the Joint Chiefs of Staff Committee and later the US ambassador to South Vietnam. One day in 1966, at a reception Dyson attended, Taylor – since retired though still influential – casually dropped another: the use of tactical nuclear weapons (TNWs) against the North to “keep the other side guessing”. TNWs are ‘small’ nuclear bombs like the ones Dyson had planned to use on Orion. Sufficiently alarmed by this remark, Dyson and three other JASON members who were also present, including the physicist Steven Weinberg, set to work on an unsponsored study for the Pentagon.

To say their final report, finished in 1967 and declassified with redactions in 2002, concluded this was a terrible idea is not enough. We must also look at the why, and in the process understand how Dyson sought to solve political problems with technical tools while withholding his moral judgement.

Identical in tenor with other classified military technical assessments, the report assessed the prospect of TNWs in narrow amoral terms, evaluating possible target choices and the likely military gains from each. It also examined the larger strategic consequence of local military use of nuclear weapons in terms of its potential to draw China in, or the potential use of Soviet battlefield nukes against concentrated US bases in retaliation.

One line in particular captures the document’s clinical tone:

“We estimate that any of the … games [simulations involving TNW use in Vietnam], if played on a long time scale, would end in a stalemate, with the enemy forces retiring into the forests and the US nuclear bombardment running into the law of diminishing returns.”

Later in life, when Dyson would become a vocal public advocate for nuclear abolition and his essays would repeatedly remind the world that the dangers of nuclear weapons were alive and well, he would continue to push for technical solutions. For example, a 1995 study that Dyson spearheaded advocated stabilising the US nuclear stockpile without the need for further tests, and therefore prepare the ground for eventual elimination. As he would note in a famous 1997 essay on this project, “Each of us [the study members] had private opinions about political questions, but politics was not the business of our study.”

Freeman Dyson’s life demonstrated that sound moral decisions often come at a cost of spectacular scientific advance, as his involvement in Project Orion shows. But it is equally true – as his JASON work on TNWs demonstrated – that deeply rational and pragmatic analyses often buttresses instinctive moral judgement. In the final assessment, his life demonstrates that the arc of reason that scientific advances trace is far from being unwavering, and is shaped also by the vagaries of history.

Abhijnan Rej is a New Delhi-based defence analyst. In a previous career as a mathematical physics researcher, he published papers on tools in fundamental physics that Freeman Dyson pioneered.

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