PHYSICIST LEAVES A LEGACY AS WIDE-RANGING VISIONARY

Freeman Dyson, a visionary physicist and technophile who helped crack the secrets of the subatomic world, tried to build a spaceship that could carry humans across the solar system, worked to dismantle nuclear arsenals and wrote elegantly about science and human destiny, died Friday at a hospital near his home in Princeton, N.J. He was 96.

The cause was complications from a fall, said a son, George Dyson.

Dyson, born in England between the world wars, spent most of his professional life as a kind of geniusin-residence at the Institute for Advanced Study in Princeton, overlapping in his early years with Albert Einstein.

In recent years, Dyson spent many winters in La Jolla, and he could often be found in the physics department at UC San Diego, chatting up professors.

“He took everybody under his wing,” said Brian Keating, a UCSD physicist and Dyson confidante. “He was always charitable and gracious and really incisive in what he had to say. He was never negative or down. It was eternally cheerful. It was great to have this giant of physics here.”

During a 2016 interview with the Union-tribune, Dyson, was asked about the changing lives of physicists.

“I think theoretical physicists sort of have a midlife crisis — an extreme case of it.

You lose the ability to do physics quickly,” Dyson said. “The really great theoretical physicists are mostly in their 20s and 30s. So when you arrive at 40, there’s a midlife crisis; you don’t compete anymore with the brilliant people.

“The question is: What do you do with the second part of your life?

“For many people, it is quite simple — you go into administration, where you can do a lot of useful things. Or you become a teacher, if you have a gift for that. I decided that my gift is to be a writer. In the second half of my life, science has been a hobby. My real job is writing.”

In a career spent traversing fields as diverse as physics, biology, astronomy, nuclear energy, arms control, space travel and science ethics, Dyson was always obliging when a journalist called him for a grabby quote about the trajectory of humanity.of all his notions, his most famous was that alien civilizations, seeking to maximize their supply of energy, would build elaborate megastructures around their parent stars to capture much of the solar radiation. Astronomers periodically see something that they speculate might be one of these “spheres,” although Dyson freely admitted he lifted the idea from sciencefiction writer Olaf Stapledon.

Long before he became an oracle, he labored in the trenches of mathematics and physics. He succeeded in the late 1940s in developing an early landmark synthesis of the latest thinking in the theory known as quantum electrodynamics. His resulting paper, “The Radiation Theories of Tomonaga,

Schwinger and Feynman,” was regarded as an instant classic and gave Dyson lifelong credibility in the sciences even as he went on to tackle more speculative interests.

That included the interplanetary spaceship. Project Orion, initiated in the late 1950s, was an effort to design a spacecraft powered by nuclear explosions, rather than traditional fuels, and capable of carrying people throughout the solar system.

A 1-meter-tall model seemed to work fine, and the Orion team decided they could send humans to Mars by 1968 and to the moons of Jupiter and Saturn two years later. But the government was not keen on nuclear bombs as a form of propulsion, and the project, taken over by the Air Force, was eventually terminated.

He contributed to the design of what became known as neutron bombs, work he later regretted bitterly. He became an advocate for arms control and served as outside counsel to decision-makers in Washington.

At age 45, Dyson told The Washington Post in 2014, he had a midlife crisis. He decided to do science as a hobby and become more of a sage, writing books and magazine articles on science, technology and the future.

Freeman John Dyson was born in Crowthorne, England, on Dec. 15, 1923, the son of George Dyson, a composer who was later knighted, and the former Mildred Atkey, a lawyer.