RIP Freeman Dyson

Ken AshfordIn PassingLeave a Comment

The father of a friend of mine — a seminal thinker for the ages.

NY Times:

In 1979, Freeman Dyson came up with a plan to live forever.

There was no fanciful elixir. It was not a matter of theological speculation. Mr. Dyson was, for all his eccentric, maverick tendencies, a theoretical physicist — one of the most brilliant and insightful of his age.

In a mathematically rigorous manuscript, sprinkled with commentary and philosophical quotations, he wrote the formulas by which some advanced consciousness could encode itself into a form of matter that would persist indefinitely into the cosmic future, after the last star is snuffed out in the darkness.

He postulated that this eternal machine might be an amorphous cloud of particles, passing electromagnetic signals back and forth to emulate human thought. He made sure to spend a few paragraphs outlining a detailed plan for unlimited memory storage, since “it seems hardly worthwhile to be immortal if one must ultimately erase all trace of one’s origins in order to make room for new experience.”

It was this paper, “Time Without End: Physics and Biology in an Open Universe,” that brought me to Mr. Dyson’s office at the Institute for Advanced Study in Princeton last May, four decades after its publication. I was working on a book about the end of the universe and seeking his expertise. How will it happen? How can we know? Should we hold on to anything like hope?

By this time, Mr. Dyson was a legend, known as much for his intellectual breadth as for his groundbreaking work in physics and mathematics.

At the age of only 24, he had an insight that proved the equivalency between two seemingly disparate theories of particle physics that would lead three of his colleagues to a Nobel Prize.

To the public, he’s more famous for giving science fiction the “Dyson Sphere,” a hypothetical structure a future civilization could build to harness the entire power of its sun. As a professor at the institute in 1965, he won the prestigious Dannie Heinemann Prize for Mathematical Physics for his work in quantum field theory, just a few years after taking leave to try to develop an interplanetary spacecraft powered by nuclear explosions.

He worked with such luminaries as Richard Feynman and Wolfgang Pauli, and wrote books speculating about religion, biology, and the future of human society. His early achievements landed him an offer of a professorship before he even finished his Ph.D., so he never bothered to complete it — he felt that being a perpetual student gave him license to explore more freely.

Of course, being a genius and visionary helped with that, too. By the time he was pondering eternal life, he had already firmly established his scientific legacy, so he could risk working on topics he knew would be considered frivolous. In the introduction of his 1979 paper, he pushed back against the idea that eschatology, the study of end times, should be avoided by serious scientists: “If our analysis of the long-range future leads us to raise questions related to the ultimate meaning and purpose of life, then let us examine these questions boldly and without embarrassment.”

At our meeting last year, I asked if he still felt that these topics were considered “disreputable” in physics.

“Yes, of course,” he replied. Proof, he said, was “the fact that everything I wrote was wrong.”

I should be clear here that there was no mistake with his calculations, given the knowledge of the cosmos at the time. Mr. Dyson was betrayed by the universe.

By the 1970s, it was firmly established that the universe was expanding, so the next big question was whether the cosmos was fated to recollapse, destroying us all in a Big Crunch, or to simply expand forever.

The latter possibility might sound more appealing — Mr. Dyson himself wrote that the concept of a recollapsing universe was “a rather dismal story” — but it seemed that it would still doom us to a bleak future cosmos of gradual cooling in which all sources of light and heat would fade away by degrees.

When Mr. Dyson turned his attention to an eternally growing cosmos, though, he found hope. He calculated that a machine built to gradually slow its computations, periodically entering states of hibernation, could persist, subjectively, forever.

The discovery in the late 1990s that the universe is not just expanding, but accelerating in its expansion, ruined everything. If this acceleration continues, even a carefully engineered calculation machine will eventually come apart.

“The universe just disperses into disconnected volumes, which are essentially empty,” Mr. Dyson told me. “Essentially nothing happens after a finite time.”

This seems to be where we’re headed. The current scientific consensus is that far in the future, long after our own sun dies, whether or not we have evolved from fragile biological humanity to spacefaring, self-replicating machines, we will all eventually succumb. The distant galaxies will be pulled beyond the limits of our sight; stars will die; all light will fade. We will end our cosmic existence alone, in the dark.

“It would be disappointing,” Mr. Dyson said. “I mean, you have to accept what nature provides. But it’s like the fact that we have finite lifetimes. It’s not so tragic. In many, many ways it makes the universe more interesting. It’s always evolving to something different. But having a finite lifetime for the whole thing …” His voice trailed off.

“Maybe that’s our fate. But certainly, I would prefer to have evolution going on forever.”

Whether or not the accelerated expansion will continue is not a settled question. It may never be one. As a theoretical cosmologist myself, I’m searching for answers, but I have to concede we may never figure them out. Maybe it’s the journey that will be worthwhile; maybe we’ll learn something useful along the way.

At the end of our discussion, I asked Mr. Dyson whether he thinks we’ll someday say with certainty where we’re all going, how it’s all going to end.

“It’ll be more interesting if it turns out to be unanswerable,” he said. “Nature always has more imagination than we have. So, I think it’s quite likely.”

Freeman Dyson passed away last week, at the age of 96. He knew no one could have all the answers, but I got the impression that he liked it that way.

“The beauty of science is that all the important things are unpredictable,” he told me. “The optimistic view in me is that nature is designed to make the universe as interesting as possible.”