Our lives are secretly ruled by transistors. They power our computers and, with them, modern society. Today’s most advanced microchips pack more than 21 billion transistors onto a single piece of silicon slightly larger than your thumbnail.
But in the 1950s, when computers were still in their infancy, the transistor’s dominance was far from settled. In an age of bulky and power-hungry vacuum tubes, the U.S. military and American industry searched desperately for some way to speed up and shrink computers for defense and commercial applications. In “The Cryotron Files,” Iain Dey and Douglas Buck tell the story of a little-known invention called the cryotron—a liquid-helium-cooled superconducting competitor to the transistor that was, for a time, the front-running technology in the quest to build the fastest, smallest computers. Their interesting book weaves together the biography of the cryotron’s inventor, Dudley Buck of MIT (the father of one of the book’s authors), with a history of key aspects of Cold War defense programs. Along the way we are given an insider’s look at the 1950s military-industrial complex and the ease and informality with which academia, the military, intelligence agencies and industry collaborated.
Born in 1927 in San Francisco, Dudley Buck as a teenager fit the now-stereotypical mold of an engineering and scientific prodigy: He built his own radio transmitters, cooked up homemade explosives and played clever pranks on anyone he could. By 1944, with World War II in full swing, the 17-year-old Buck enrolled in a program designed to attract the nation’s best students to become naval officers. He graduated in 1948 from the University of Washington as Ensign Buck and was assigned to the Navy’s cryptography and code-breaking team. There he was set to work on an early computer called ABEL; his inventiveness and enthusiasm impressed a number of senior people who would wind up at the future National Security Agency and who would support him throughout his career.
In 1950 Buck completed his naval service and became a graduate student in electrical engineering at MIT, working for Prof. Jay Forrester on Whirlwind, a massive Pentagon-sponsored computer that took up 2,500 square feet of floor space and comprised 5,000 vacuum tubes. Whirlwind was intended to track enemy aircraft, predict their course, and vector fighters to intercept them. Buck found himself swept up in the project and made strong contributions. He stayed in touch with his friends in the Navy, passing on groundbreaking research from MIT. “There was nothing unusual in this flow of information,” Messrs. Dey and Buck write. “In 1950, ideas moved fluidly across academia, the military, and a handful of emerging computer giants—such as IBM and Raytheon. . . . The line that marked where the state ended and the private sector began was blurry at best.”
It was in 1952 that the National Security Agency was founded, and Buck—while still a graduate student at MIT—began consulting with many of his former naval colleagues, now at the NSA, on the technology that would underlie future computers. The transistor was an option, of course, but, in the words of one historian, “even the people who made the transistor were thinking, ‘Okay, what’s next, what’s the next device?’ Clearly the transistor was better than the vacuum tube. Obviously, there’s going to be something that’s better than the transistor.”
Buck’s time at MIT, the authors write, “coincided with a period in history where no idea was deemed too wild.” One of Buck’s wild ideas was based on a property called superconductivity: the disappearance of electrical resistance in some materials when they are cooled to an extremely low temperature (think -450 Fahrenheit). He realized that both a basic memory circuit and an electrical switch could be made by twisting together wires made from two different superconductors. By placing an electrical current through one wire, its magnetic field could be used to turn on or off the flow of current in the other. This could in theory be done very rapidly, using extremely little power. Of course, the circuits would have to be operated in a bath of liquid helium—inconvenient but perhaps not insurmountably so.
By 1954 he had managed to make such a circuit in his laboratory, and his soon-to-be wife provided the name: the cryotron. Buck worked feverishly, first to make it reliable and then to miniaturize it. He and his team came up with the idea of using electron beams to “write” tiny cryotrons onto thin films of material, dramatically reducing their size and foreshadowing the way silicon integrated circuits would eventually be manufactured. Word of the cryotron and its possibilities spread rapidly; indeed, publicity seems to have seriously outpaced the development of the device itself. By 1958 it seemed as if everyone was trying to build computers out of cryotrons—IBM, RCA, Raytheon, GE, and the NSA most especially.
The field was jolted when Buck died suddenly in 1959 at the age of 32, a few days after falling ill with a high fever and a bad cough. Some think his death was due to exposure to toxic chemicals used in his research. Other theories are more sinister: On the day he died, a colleague of Buck’s, Louis Ridenour, a former chief scientist of the U.S. Air Force and vice president at Lockheed, died of a sudden brain hemorrhage at age 47. Both were scheduled to attend a meeting four days later of the NSA’s Scientific Advisory Board—a program review of Project Lightning, the NSA’s secret project to dramatically increase the speed of digital computers. The authors raise the idea that both individuals might have been targeted by the Russians but provide no substantive evidence for such a claim.
Buck’s death derailed cryotron research at MIT, but other organizations pressed on. IBM had hundreds of people working on cryotron-based computers and is said to have invested some $250 million in the effort. But it was not to be: Cryotrons proved tricky to make work at scale, and the silicon integrated circuit surpassed them—all without the need for tanks of liquid helium.
The book is marred by the authors’ tendency toward breathless overstatement in their effort to give Dudley Buck what they think is his rightful place in history. And at times they dramatize their work by pushing the reader to view events as connected that could just as easily be coincidences. Despite such matters, however, “The Cryotron Files” sheds warmth on an unappreciated bit of low-temperature Cold War technological history.