by Peter Byrne
One aim of unified field theory has always been the notion that fields are more fundamental than particles, and that it should be possible to construct all particles from the purely geometrical representation of the field.7
Treating particles as fields, Misner, in his dissertation, suggested a way to think about summing over field histories à la Feynman until the ordinary probabilities of quantum mechanics jelled.8 He recalled,
My Feynman path integral approach to quantum gravity is mostly considered an attempt to calculate the operations necessary to evolve the wave function of the universe forward in time. A rigid adherent of the Bohr observer-driven collapse of the wave function would have anathematized any attempt to evolve a wave function which served no observer. Thus the awareness that Hugh’s alternative view of quantum mechanics existed left me free to think about formulating the dynamics of quantum gravity.9
Several different approaches to quantizing gravity were presented at Chapel Hill, but the hottest debate centered around how wave functions might be assigned to yet-to-be-discovered gravity particles (gravitons), and how the superposition principle and the idea of wave function collapse might be treated in a unified field theory. Microscopic gravitons would, presumably, exist in quantum superpositions while, at the same time, obeying the classical laws of general relativity: How could this be so?, asked the physicists. How could the gravitational mass (energy) of an atomic object be computed when the uncertainty principle forbids the simultaneous measurement of its position and momentum?10
Wheeler advised his colleagues, as an exercise, to forget about the measurement problem and quantum uncertainty and,
Imagine what sort of ideas scientists might come up with if they were ‘put under torture’ to develop a theory that would fully explain all the elementary particles and their interactions solely in terms of gravitation and electromagnetism alone!11
He suggested that, under those conditions, Feynman’s sum over histories method was capable of solving these problems.12 However, many participants were convinced that it was not theoretically possible to quantize gravity in this manner. DeWitt summed up a common concern: if gravity is quantized, then it will be subject to superposition and wave function collapse. Consequently, “the gravitational field suddenly changes because of a measurement performed on the system.” In other words, the theory of general relativity will not hold up if gravitons are allowed to jump around like electrons. Part of the debate (then as now) revolved around the question of whether the wave function is physically real, or simply epistemic, i.e. a description of knowledge.
Feynman speaks
Feynman sketched an experiment on a blackboard showing a ball influenced by a gravitational field while entangled with a superposed quantum system. Taking up Wheeler’s suggestion to ignore the collapse postulate, he concluded, “If you believe in quantum mechanics up to any level then you have to believe in gravitational quantization in order to describe this experiment.”13
Furthermore, said Feynman, he could conceive of the ball existing in a reversible quantum mechanical superposition. To say that such a thing is not possible:
There would [have to be] be a new principle! It would be fundamental! … I haven’t thought out how to say it properly…. I’m trying to feel my way. We know that in any piece of apparatus that has ever been built it would be a phenomenally difficult thing to arrange the experiment so as to be reversible. But is it impossible? There’s nothing in quantum mechanics which says that you can’t get interference [superposition] with a mass of 1-5 gram—or one gram…. At the moment all I can say is that we’d better quantize the gravitational field, or else find a new principle.14
In effect, Feynman was saying that the Schrödinger equation should apply to macroscopic objects unless a newly invented set of equations could show otherwise!15 By the end of the conference, Feynman was in agreement with Wheeler and Misner that summing over histories was a key to quantizing gravity, but, he said,
Historically, the rigorous analysis of whether what one says is true or not comes many years later after the discovery of what is true. And, the discovery of what is true is helped by experiments. The attempt at mathematical rigorous solutions without guiding experiments is exactly the reason the subject is difficult, not the equations. The second choice of action is to ‘play games’ by intuition and drive on…. You have nothing to lose: there are no experiments…. In this field since we are not pushed by experiments we must be pulled by imagination.16
He drew the line, however, at following after Everett’s imaginative leap.
During the last few minutes of the conference, Wheeler returned to the measurement paradox. Knowing that Everett’s unpublished long thesis had been privately circulating among physicists during the past year, he suggested a way to simplify quantizing gravity without resorting to wave function collapse:
However, there exists the proposal that there is one ‘universal wave function.’ This function has already been discussed by Everett, and it might be easier to look for this ‘universal wave function’ than to look for all the [Feynman] propagators [the particular amplitudes that would be summed over in a theory of quantum gravity].17
Feynman was not pleased. He retorted,
The concept of a ‘universal wave function’ has serious difficulties. This is so since the function must contain amplitudes for all possible worlds depending upon all quantum mechanical possibilities in the past and thus one is forced to believe in the equal reality of an infinity of possible worlds.18
And on that credulous note, the conference ended.
Misner speaks
Fifty years after the Chapel Hill meeting, Misner recalled, “I was the first one to use the words ‘quantum cosmology.’”19 Now that’s fairly popular. However, that meant you were suddenly tempted to talk about the wave function of the universe. Well, in Bohr’s viewpoint this was nonsensical. It was impossible because for Bohr the wave function was something about the information available to an experimenter after he defined an experiment. Well, there were no experimenters or experiments when the Big Bang was going off. Therefore, people had to seriously worry, how could you have quantum mechanics rule the universe at the early times.20
Misner explained that, years after Everett’s theory was published, discoveries in astrophysics, including cosmic microwave background information about the early state of the universe, caused some cosmologists to become many worlders.
He observes,
To interpret that kind of thing and make sense of it, they really had to say what do you mean by the wave function of the universe? That started a bunch of things, not all of which are the same as Hugh’s. But, they’re all within the viewpoint of believing, as Hugh did, that the standard equations always work and then you just have to understand within that framework how our human, everyday experiences arise.21
And that means understanding why we should believe in only one universe, even though Everett could explain why we experience only one universe.22
BOOK 5
POSSIBLE WORLD FUTURES
20 Preparing for World War III
The armament race … assumes hysterical character…. The ghostlike character of this development lies in its apparently compulsory trend. Every step appears as the unavoidable consequence of the preceding one. In the end, there beckons more and more clearly general annihilation…. Within the country: concentration of tremendous financial power in the hands of the military; militarization of the youth; close supervision of the loyalty of citizens, in particular, of the civil servants, by a police force growing more conspicuous every day. Intimidation of people of independent political thinking. Subtle indoctrination of the public by radio, press, and schools. Growing restriction of range of public information under the pressure of military secrecy.
Albert Einstein, 19501
Leaving Princeton
Upon graduation, Everett was scheduled to begin his new job as a Scientific Warfare Analyst with the Weapons Systems Evaluation Grou
p (WSEG) at a top-notch salary of $8,520. But having a PhD in hand was a requirement of the job. He had hoped to receive his degree in the spring of 1956. But after Bohr frowned on his thesis, Wheeler postponed its acceptance, contingent upon it being rewritten. In fact, Wheeler was urging him to forego a career in operations research and “to start working towards a first class academic position.” He wrote, “You have something original and important to contribute and I feel you ought not to let yourself be distracted from it.”2 Princeton offered Everett an instructorship, but he declined to accept it as working in academia did not appeal to him.3
He was attracted to operations research, and had first interviewed with WSEG in the summer of 1955, mid-way through writing his dissertation. The job required a doctorate because “While such a degree is no absolute measure of the type of man we are seeking, it is a selection device on brain power.” Brilliance in applied mathematics and “patriotism … or other constructive motives are desirable.” WSEG’s ongoing projects were,
Weapons certificate, 1956.
Various war-gaming computations. Economic, biological, military and engineering effects of installing atomic power in submarines. The application of nuclear power to aircraft. Physical and physiological effects of atomic weapons. These are only a few of the areas involved in our studies. Actually WSEG problems encompass practically all disciplines.4
Eager to keep Everett in tow, WSEG allowed him to start with the proviso that he win his degree within the year. By early summer, Everett had received his security clearances and was working at the Pentagon, having been granted an occupational draft deferment after his student deferment expired.5 In August he took a four day course in “special weapons and guided missile orientation” at Fort Bliss, Texas; and in October he received a certificate engraved with the image of an atomic mushroom cloud for attending the “special weapons orientation advanced class” at Sandia Base, New Mexico.
He was in his element.
Reeling in her man
Meanwhile, Nancy was sunning herself at summer camp in Vermont. She sailed, rode horses, made notes for writing a novel, and conducted a long-distance relationship with her handsome lover. They fought about their future as a couple over the telephone, and reconciled a few days later by letter. In July they enjoyed a cozy weekend in Nancy’s Princeton apartment while her roommates were away. But Everett was thriving in his new job, whereas Nancy had no job prospects beyond the clerical work she hated. The final entry in the diary of her Princeton years reads:
Hugh – fish or cut bait – but we must define situ[ation] clearly in order to act on it. Everyone else seems to take for granted we are getting married. I try – but can’t lose doubts.
She was pregnant.
Everett asked her to get an abortion, but she told him that she was going to have the baby whether they got married or not, and that she didn’t want to marry him just because she was pregnant.6 In November, they married in a small ceremony at the Chevy Chase Assembly of God in Bethesda. Everett’s father and step-mother attended; he told Katharine about it a few weeks later.
Nancy returned to Princeton to wind up her affairs. In December, they were scheduled to move into Arlington Towers apartments, not far from the Pentagon. While she was away, Everett wrote her a charming letter:
Dear No. 1 wife, … I wish you were here with me now. I miss you very much…. I think we had best wait till after Christmas for our major purchases (e.g. TV) when the prices should be lower and we have collected more green stamps. In the meantime we can live on love, and maybe an occasional hamburger…. Still haven’t completed work for Wheeler, but hope to have something whomped up to talk to him about. The trouble is I have been working (at work) on a very interesting problem, and have been unable to resist working on mathematical parts at home.
Commenting that a dinner party was coming up, he queried, “What dress will you wear? Lets really put on the dog.” And he signed the letter, “I miss you. I miss you. I miss you. I love you. I love you. I love you.”
The WSEG problem that he was working on after hours—at the expense of rewriting his thesis—was calculating kill ratios from radioactive fallout. Death rates were calculated per megaton of hydrogen bomb dropped on American and Russian cities. This soon-to-be famous study in operations research was to significantly affect the structure of the nuclear war fighting machine. Plus, he was working on a project to ferret out how many ballistic missiles and atom bombs the Soviet Union had on hand.
Operations research comes of age
During the Second World War, Anglo-American scientists questioned the Navy’s rule that German submarines dove to depths of 100 feet after spotting airborne threats. Using probability theory, researchers, especially Bell Lab’s resident genius, William Shockley, determined that this figure was an overestimate, and that depth charges should be set for 30 feet.7 The Allied kill ratio quickly fattened, and military brass was sold on science. At MIT, physicists on war-footing used quantum mechanics and information theory to develop radar detection systems. Wiener’s cybernetics gave birth to gun and bomb sight servomechanisms that could pinpoint targets from moving vehicles and airplanes. The tactic of using conventional bombs to ignite annihilatory firestorms over enemy cities was fine-tuned by operations researchers; the Manhattan Project was a massive operations research project; and the Cold War itself was a product of “OR.”
As the nuclear arms race ramped up, researchers at MIT’s Lincoln Labs conceived the Whirlwind analogue computer system. It evolved into a digital command and control system labeled the Semi-Automatic Ground Environment (SAGE). SAGE was designed to track and intercept enemy airplanes, and by the late 1950s the computerized surveillance network was operated by the newly created North American Air Defense Command located deep inside Cheyenne Mountain, near Colorado Springs.
Each SAGE computer weighed 300 tons, contained 58,000 vacuum tubes, and sprawled over 20,000 square feet inside a massive building powered by diesel generators and cooled by huge water towers. Each building contained two of the digital monsters as mutual back-ups. Two dozen of these SAGE control centers graced the North American landmass. They continually processed radar data, weather reports, missile and airbase status reports, flight plans of civilian aircraft, and reports from the Ground Observer Corps. Feeding information into Cheyenne Mountain, the centers tracked all aircraft traversing North American airspace and were ready to provide interception coordinates to fighter pilots when needed, or so the theory went. In reality, SAGE was massively inefficient and prone to error; nor was it designed to survive a surprise nuclear strike.8
Although SAGE was rapidly made obsolete by the invention of intercontinental ballistic missiles, transistors, and integrated circuits, it remained the business template for Cold War command, control, and communication systems. IBM Corporation earned hundreds of millions of dollars building computers for SAGE during the 1950s. RAND programmed SAGE, (eventually spinning off a for-profit company, Systems Development Corporation, to keep it up to date). Working on SAGE, contractors invented (and profited from inventing) many of the core concepts of modern computing, including magnetic memory, graphic display techniques, simulation techniques, parallel processing, digital data transmission, and machine networking.9
In a few short years, the science of “OR” had come a long way from outsmarting German U-boat skippers.
Origin of WSEG
In the afterglow of Hiroshima and Nagasaki, the Department of War was rechristened a “defense” department, although it still operated primarily in offensive mode, engaging in military adventures from Korea to the Middle East. The Pentagon set out to recruit the brightest scientists and computer programmers, but quickly found itself stymied by the ability of private industry to pay higher salaries than federal regulations allowed. And there were scads of industrial corporations vying for contracts to design and build advanced weaponry for the armed services.
Each military service had their own war plan and proprietary weapons systems
. And each service jealously guarded access to “their” operations researchers: RAND was tied to the Air Force; the Operations Research Office served the Navy; and Research Analysis Corporation was contracted to the Army. Research reports issued by each “think tank” almost invariably supported the parochial interests of its military sponsor. Science was for sale as each service plotted to influence strategic policy in favor of funding weapons systems that would give it the largest slices of the atomic procurement pie.
Not surprisingly, the Joint Chiefs of Staff were having a difficult time overseeing the technology of war planning because they were getting conflicting scientific advice from the rival services. In 1947, the chiefs had created their own private think-tank, the Weapons Systems Evaluation Group, called by its acronym, pronounced “wessegg.” Staffed by military officers from all of the services, and a roster of civilian scientists, WSEG had been expected to deliver research free of the machinations of inter-service rivalry. Questions of the day concerned the relative feasibilities of radiological, biological and chemical warfare, how to fight a “limited” nuclear war, how to decide which of the 35 separate ballistic missile programs currently in production was worth keeping.10 Unfortunately, the ranking military officers running WSEG also favored the agendas of their own services, and they dominated the group.
