Freeman Dyson (carrying briefcase) at the Point Loma test site, summer 1959. Clockwise from top, surrounding the meter model: Ed Day, Walt England, Brian Dunne, Perry Ritter, Jim Morris, Michael Feeney, W B McKinney, Michael Ames.
In September of 1932, about the time that seven-year-old Ted Taylor began experimenting with chemical explosives in Mexico City, Freeman Dyson, then eight, was sent away from home in Winchester, England, to attend the Twyford School. "It was an abominable school but had an excellent library so that was my refuge," he says. "There was lots and lots of stuff about electrons and electricity and radio waves and all sorts of things, but nobody ever mentioned protons. I remember asking people, 'Why is it that they only talk about electrons and not about protons?' Nobody seemed to know."
Among the books that captured Freeman's imagination was From the Earth to the Moon and a Trip Around It by Jules Verne. Shortly before his ninth birthday—December 15, 1932—Freeman began to write a sequel, Sir Phillip Roberts's Erolunar Collision, concerning a predicted collision between the asteroid Eros and the Moon. Freeman's unfinished account of South African astronomer Sir Phillip's preparations for a voyage to observe the collision closely followed the precedent of Jules Verne. " 'Accounting for delays,' said Sir Phillip, when General Mason had told him of his idea, 'and the journey, and preparations on the Moon, we will still have well over ten years to make our cannon, projectile, and gun-cotton, we will use gun-cotton, it is much better than ordinary powder, therefore we can make our expedition much larger than Barbicane's; don't worry about money, subscriptions will be almost infinite.' "[87]
While Ted was learning how to make gun-cotton, Freeman was theorizing about propelling a 15-foot diameter spaceship to the Moon. Gun-cotton, or nitrocellulose, detonates at nearly twice the speed of dynamite and was introduced in 1865, the year that Jules Verne published the first installment of his book. Freeman estimated that Sir Phillip's launching gun—or Columbiad, as Verne referred to it—would be two miles in length, uncannily close to the dimensions of more recent proposals for chemical-fueled space-launching guns. Sir Phillip's ten-year development schedule corresponds exactly to the plans for a 1968 Mars mission that accompanied Freeman and Ted's sales pitch for Project Orion in 1958.
Freeman first estimated how large a Moon-based Columbiad it would take to escape from the Moon's gravitational field for the return to Earth. He then estimated how large a terrestrial Columbiad it would take to send the lunar Columbiad to the Moon. The second-stage Columbiad would be left on the Moon for future use, a strategy quite different from the single-use, multiple-stage rockets in which the Apollo astronauts finally did make the trip. Orion goes one step better, dispensing with the Columbiad entirely—though when they built their flying model, the Orioneers used a shallow tub and a one-pound charge of gunpowder for the initial kick.
The progenitor of Orion was not Wernher, but Verne. "When I thought about space travel in those days, I was thinking about the huge guns that I read about in the stories of Jules Verne," Freeman explains. "Rockets had nothing to do with it. The Martians in Wells's War of the Worlds did not come in rockets. They came in artillery shells."[88] On December 19, 1934, Freeman witnessed his first rocket launch, reinforcing his conviction that Verne's was the better approach. A German entrepreneur, Gerhard Zucker, had arrived in England to promote postal rocketry, supporting his venture by selling collectible Rocket Mail stamps. "Herr Zucker stated that he hoped to construct a large rocket here in England," the British Interplanetary Society reported, with a view to establishing a regular rocket postal service between England and the continent. After which, he envisions the formation of a company for the manufacture of postal rockets for world distribution."[89]
The Dysons had a weekend cottage near Lymington, almost exactly where Zucker decided to launch. "They had this very impressive-looking rocket," Freeman remembers. "They set it up with great ceremony on this rather derelict piece of land where we lived, which was sort of a mudflat on the coast opposite the Isle of Wight. They had some dignitaries from London who came down, and ceremoniously put this bag of mail with special stamps into the rocket. Then they launched and the thing zoomed up into the sky very beautifully. But then it turned around and came back almost exactly where it took off and landed with a big splash in the mud. So they went out and retrieved it and the mail went over later on the boat."
Within ten years, Zucker's successors were routinely sending rockets across the English Channel, having switched from delivering letters to delivering bombs. Freeman was working as a civilian statistician for the Royal Air Force Bomber Command when he first encountered the rockets of Wernher von Braun. "In London we were very grateful to Wernher von Braun," he explains. "We knew that each V-2 cost as much to produce as a high-performance fighter aircraft."[90] German airplanes were inflicting heavy Allied losses, whereas V-2s exploded haphazardly and only once. It was when V-2s began falling on southern England at 3,500 miles per hour that Freeman first thought about rockets, not guns, as vehicles for reaching space. "I remember being very delighted to learn that the V-2 really existed. It was a big step forward. It went 50 miles up and 250 miles horizontal. If you could do that much you could get into space. And then I was rather disappointed. If the Germans could do that well, I expected that we would have our own secret projects. Probably we would be doing much better. At the end of the war I found out there was really nothing on our side. We had to start over again from scratch."
In 1947 Freeman left England to study physics with Hans Bethe at Cornell. Theoretical physics and experimental physics were separate trades, but graduate students were expected to become familiar with both. Millikan's oil drop experiment, which had drawn Ted into physics six years earlier, did not go as well in Freeman's hands. Millikan had shown how to measure the charge of the individual electron by balancing microscopic droplets of oil between the force of gravity pulling them downward and the force of an electric field pulling them up. "I had my oil drops floating nicely, and then I grabbed hold of the wrong knob to adjust the electric field," says Freeman. "They found me stretched out on the floor, and that finished my career as an experimenter."[91]
Many of the physicists who had spent the war building the bomb with Bethe at Los Alamos were now reassembled under Bethe's leadership at Cornell. Freeman became familiar with the Manhattan Project's chief protagonists and the political forces in which their work had become enmeshed. He felt a moral and technical kinship with those who had spent the war calculating how to build atomic weapons, just as he had spent the war calculating how to maximize the destructive effects of conventional bombs. "The sin of the physicists at Los Alamos did not lie in their having built a lethal weapon," he later explained. "They did not just build the bomb. They enjoyed building it. They had the best time of their lives building it. That, I believe, is what Oppenheimer had in mind when he said that they had sinned."[92]
Of all the Los Alamos gang, Richard Feynman influenced Freeman the most. Bethe assigned Freeman to work on a problem known as quantum electrodynamics, or QED. In 1947, there was a quagmire of incomplete and contradictory approaches to the relation between matter and electromagnetic fields. "The problem," according to Freeman, "was simply that there existed no accurate theory to describe the everyday behavior of atoms and electrons emitting and absorbing light."[93] In the aftermath of the war physicists had returned to their laboratories, built new equipment, and were making new observations and discoveries with unprecedented precision but without a consistent mathematical framework to explain the results. Feynman had developed a system of QED that produced all the right answers, but his unorthodox techniques were viewed by the physics establishment as mathematically opaque. "Dick was using his own private quantum mechanics that nobody else could understand," Freeman later explained.[94] "He was struggling, more intensely than I had seen anyone struggle, to understand the workings of nature by rebuilding physics from the bottom up."[95]
Freeman
Dyson (carrying briefcase) at the Point Loma test site, summer 1959.
Clockwise
from top, surrounding the meter model: Ed Day, Walt England, Brian
Dunne, Perry
Ritter, Jim Morris, Michael Feeney, W B McKinney, Michael Ames.
Feynman revealed his methods to Freeman, who then went to Ann Arbor to attend a series of lectures by mathematical physicist Julian Schwinger, whose approach to QED was as precise, orderly, and complicated as Dick's "Feynman diagrams" were simple and unexplained. "Dyson was probably the only person who thoroughly understood both methods," Bethe observed.[96] The third piece in the puzzle came from Sin-Itiro Tomonaga in Japan, who had developed a parallel theory of QED in complete isolation during the war. This arrived unexpectedly in Hans Bethe's mailbox at Cornell, and thus Freeman found himself in the middle of a deep mathematical conflict in the spring and summer of 1948. Tomonaga, Schwinger, and Feynman had each arrived at the same physics by taking a different mathematical approach. In September, while Freeman was returning by Greyhound bus from Berkeley to Chicago, the puzzle was suddenly resolved. "The roads were too bumpy for me to read, and so I sat and looked out of the window and fell into a comfortable stupor," he remembers. "As we were droning across Nebraska on the third day, something suddenly happened. Feynman's pictures and Schwinger's equations began sorting themselves out in my head with a clarity they had never had before. For the first time I was able to put them all together. I had no pencil and paper, but everything was so clear I did not have to write it down."[97]
On October 6, 1948, Freeman submitted "The Radiation Theories of Tomonaga, Schwinger, and Feynman" to The Physical Review. This demonstrated the mathematical equivalence of the Feynman and Schwinger theories and presented a simpler method of applying Schwinger and Tomonaga's theory to specific problems, "the simplification being the greater the more complicated the problem."[98] Soon after the paper appeared on February 1, 1949, Freeman was offered a professorship at Cornell by Bethe and a permanent membership at the Institute for Advanced Study by Robert Oppenheinier. He never obtained a Ph.D.
The mathematical elucidation of QED advanced our understanding of how the strange workings of quantum mechanics constitute the universe in which we live. "The picture of the world that we have finally reached is the following," Freeman explained in 1953. "Some 10 or 20 qualitatively different quantum fields exists. Each fills the whole of space and has its own particular properties. There is nothing else except these fields; the whole of the material universe is built of them.... Even to a hardened theoretical physicist it remains perpetually astonishing that our solid world of trees and stones can be built of quantum fields and nothing else. The quantum field seems far too fluid and insubstantial to be the basic stuff of the universe. Yet we have learned gradually to accept the fact that the laws of quantum mechanics impose their own peculiar rigidity upon the fields they govern, a rigidity which is alien to our intuitive conceptions but which nonetheless effectively holds the earth in place."[99]
QED's mathematical precision could be applied to a wide spectrum of physical events—from the behavior of an individual electron to the behavior of a 4,000-ton spaceship propelled by exploding bombs. To describe the extent of the domain of QED, Freeman divided the whole of physics into three compartments: "In the first compartment we put our knowledge of nuclear structure, protons, neutrons, mesons, neutrinos, and the interactions of these particles with one another. In the second compartment we put theories of the large-scale structure and geometry of the universe, including Einstein's general theory of gravitation. In the third compartment we put our knowledge of all other phenomena, everything intermediate in scale between an atomic nucleus and a massive star. The third compartment includes the whole of classical mechanics, optics and electrodynamics, special relativity and extra-nuclear atomic physics. The first two compartments are full of undigested experimental information, empirical rules, and mutually contradictory assumptions. These fields are only beginning to be explored and organized. On the other hand, the third compartment is unified by a logically consistent theory... quantum electrodynamics.... It is the only field in which we can choose a hypothetical experiment and predict the result to five places of decimals, confident that the theory takes into account all the factors that are involved."[100]
This view of the world was mathematically abstract—the perfect complement to the hands-on technical imagination that was Ted's. Freeman might grab the wrong knob in an experiment, but he could calculate exactly how the electrons, if not the physicist, should behave. The question of Orion's feasibility—once the rearrangement of nuclei in the first few microseconds of the bomb's explosion was completed—fell within the domain of QED. When Freeman said he believed that Orion would work as Ted Taylor hoped, skeptics listened. They knew that Ted could design the bombs and that Freeman could calculate what would happen next. Driving a 4,000-ton ship with nuclear explosions would be difficult. "What you need is momentum and not energy," Freeman explains. "A nuclear explosion gives you a lot of energy but very little momentum."[101] This was the basic problem, and Freeman's job was to help decide whether making the translation from the energy of a bomb to the momentum of a ship was feasible or not.
The way the numbers turned out, he believed the answer was yes. Problems as diverse as the opacity of a stagnating plasma, stability of the ship, convective ablation of the pusher, optimum launch trajectory through the atmosphere, effects of fallout, design of test containment facilities, mission planning to the outer planets, and military implications received Freeman's attention over the project's first twelve months. "We skimmed the cream off a multitude of technical problems in the most diverse branches of physics and engineering," he said.[102] "In the early days of the project we were all amateurs. Everybody did a little of everything. There was no division of the staff into physicists and engineers. The ethos of engineering is very different from that of physics. A good physicist is a man with original ideas. A good engineer is a man who makes a design that works with as few original ideas as possible."[103]
"He had a good sense of what he was good at," says Ted. "In the course of his deciding whether to stay with the project and resign from the Institute, he said he had to make a choice between being a very good theoretical physicist or the best engineer ever. He was not sitting on the side doing esoteric plasma physics calculations, or simply dreaming about what kind of a bed he'd sleep in. He was doing the real engineering, providing a framework so it could all fit together as Orion evolved." In the end, Freeman chose to return to physics, after fifteen months that he remembers as the most exciting of his scientific life. "When I left the project in September 1959, the number of employees had risen to fifty; we had together solved to our satisfaction most of the basic problems of vehicle design, the technical feasibility of our concept had been clearly established, and the government had decided not to take us seriously. Wernher von Braun and his chemical rockets had won the battle for government support, and the pattern of the space program was set in a way that left no place for us."[104]
Project Orion spanned all three compartments into which Freeman had divided our knowledge of the world. The third compartment, encompassing most of the design and operation of Orion, lay within the bounds of QED. From there, Orion offered a window into the other two compartments where so much remained to be explored and understood: the mysteries of the atomic nucleus, which Ted and his colleagues were fiddling with by designing and exploding bombs, and the mysteries of the large-scale structure of the universe, being revealed by the expansion of science into space. "The general feeling when I arrived was one of great enthusiasm from Freeman and Ted," says Pierre Noyes, who consulted part-time for Orion during the summer of 1958. "Freeman said one of the reasons he was pushing Orion was it could take a lot of people, including older people like himself." As Bruno Augenstein describes it, the allure of Orion's high performance is that "even quite adventurous missions may well be realistically accomplishable in times commensurate with the productive lives of individual scientists."[105]
"I saw in half-an-hour that it was the thing all the space-flight projects had been praying for," Freeman wrote in July 1958, when his optimism was at its height. "I have never had any reason to change this opinion. It will work, and it will open the skies to us. The problem is of course to convince oneself that one can sit on top of a bomb without being fried. If you do not think about it carefully, it looks obvious that you can't do it. Ted's genius was the courage that led him to question the obvious impossibility. Ted and I will fly together to Los Alamos this evening. We travel like Paul and Barnabas. Golly, this life is good."[106]