The New Super – the Mike event

The Mike event, the world’s first test of a thermonuclear device

Well, when we left off last blog, Teller and Ulam wrote a physics paper that laid down the foundation for the hydrogen bomb. It was March 1951. What is painfully obvious to many of us involved in research, it’s one thing to write a theoretical paper; it’s quite another thing to turn theory into reality. To make that happen you need first class people, so we’re going to see John Wheeler pop up again in this story; didn’t I tell you so four or five blogs ago? And now, a word about a man I call Wheeler’s assistant—Ken Ford. 

Ford worked closely with Wheeler through their years at Princeton, and later at the University of Texas. He did the hardcore calculations for the design of the Mike device—the world’s first hydrogen bomb. He wrote his code and did calculations on “antique” computers that looked like something out of the props for the movie 2001: A Space Odyssey—well, lots of buttons and blinking lights but maybe not as sophisticated as Hal. He had to do his calculations at night at IBM headquarters in New York, after IBM closed its offices to its regular employees. Ken is an exceptional world-class physicist, and human being. He won the Oersted Award in 2006 from the Association of American Science Teachers. He’s in his nineties, and he’s still working!

As you will see in this blog, the Mike event was the first explosion of a thermonuclear device, an H-bomb. That event literally changed military thinking. The atomic bomb was an awesome weapon that ended a world war in its tracks, but military services saw it as a powerful addition to their arsenal of weapons for future battles. As I mention in this blog, after the Mike event, military strategists had to rethink what nuclear war meant, and that train of thought will be played on later in this story. 

One final word: several authors have made arguments that once Wheeler gave his presentation at the GAC meeting shown in this blog, Oppenheimer expressed his support for the Super. That, they say, makes arguments that he tried to sabotage thermonuclear research bogus. These arguments are based on his saying to Wheeler the physics behind the New Super was “technically sweet.” I’m afraid Oppenheimer’s behavior throughout the course of his tenure as chairman of the GAC simply does not bear that out. We’ll see more about that in a later blog. 

Enjoy the next segment of our blog series based on my upcoming book, From Berkeley to Berlin:

April 1951 marked one year since Wheeler had arrived at Los Alamos. He longed for more stability for his family; he wanted to return home to New Jersey. He proposed a contract with the AEC to create a laboratory at Princeton to do calculations of a thermonuclear device. To make his proposal more attractive, he collaborated with a fellow member of the Princeton physics faculty, astrophysicist Lyman Spitzer, to make a joint proposal. Spitzer’s portion of the contract involved producing energy with a fusion reactor, using an invention he called a stellerator, a star making machine. Later, the stellerator would take on the form of a Russian invention called the Tokomak.  

Spitzer, a mountain climbing enthusiast, suggested the name Matterhorn for the project. Subsequently, the project was split in two with Spitzer’s part called Matterhorn-S, the “S” standing for stellerator, and Wheeler’s part called Matterhorn-B, the “B” standing for bomb. Bradbury accepted Wheeler’s proposal and agreed to support Matterhorn-B, and the AEC granted Wheeler the contract. Spitzer’s portion of the program eventually led to founding the Princeton Plasma Physics Laboratory.

Project Matterhorn-B found a home in a small metal shack on property newly acquired by Princeton, and Wheeler set about recruiting physicists. He wrote and called 120 prominent theoretical physicists around the nation. Some were astrophysicists who were important to him because they were specialists in radiative transport calculations (essential for understanding the Super). Only one colleague responded to Wheeler’s request for help, Louis Henyey, a professor of astrophysics at UC Berkeley. 

For the rest of the Matterhorn-B crew, Wheeler recruited physicists who had not yet had a chance to establish themselves. Among them was his assistant, Ken Ford, who wrote a radiative transport computer code to calculate reactions for the Teller-Ulam thermonuclear model, the New Super. Ford wrote the code on a primitive machine created by IBM Corporation called the card-programmed calculator, or IBM-CPC.* With an IBM-CPC, the programmer fed punched computer cards into the computer that were read at a rate of about one per second. Wheeler procured permission for Ford to use an IBM-CPC at the IBM offices in New York City during off hours. Ford took the train from Princeton to New York in the evening and returned to Princeton in the morning with the results of the night’s work. His calculations looked promising.

Ken Ford, with the snazzy tie, his wife Joanne, and me, Tom, at their old home in Philadelphia

Despite having written a well-received paper with Ulam, Teller was agitated. He felt the leadership of Los Alamos did not enthusiastically support a Super program. Bradbury had expanded the role of the Theoretical Division to devote more time to thermonuclear research, but that did not satisfy Teller. Frustrated, on April 4, 1951, Teller took his case to Gordon Dean, the new chairman of the AEC. Teller said he was frustrated working at Los Alamos and turned in his resignation. He wanted to create a separate and independent laboratory and place it in Chicago where he could recruit scientists from a nearby university—and where he could be close to Fermi. Dean got Teller to postpone his resignation.

Dean was now curious about developments in the Super program and he scheduled a meeting of the GAC with AEC commissioners to discuss thermonuclear research. Oppenheimer arranged for the meeting to take place at the Institute for Advanced Study in Princeton. Dean was clear about what he expected from the meeting: a recommendation from the GAC whether or not to proceed with a test of a thermonuclear device.

The GAC meeting began on June 16, 1951, a Saturday; LASL Theoretical Division leader, Carson Mark, gave a progress report on laboratory research. Mark made no mention of the Teller-Ulam breakthrough with the Super and Teller became disheartened. On Sunday, Wheeler briefed the GAC on the feasibility of the Teller-Ulam principle:

Ford brought the data back on an early train and went to the Matterhorn building, where he made graphs of the principal results on sheets of paper about two feet by three feet in size. He approached a window of the first-floor conference room where we were meeting, tapped on the window, and caught my eye. I had just started my presentation, I opened the window and accepted the roll. There was time only for him to say, “Looks good.” I unrolled the graphs, taped them to the blackboard, and explained their meaning. 

The reaction was electric. Here, for the first time, was convincing evidence that a thermonuclear flame, spreading in a device based on the Ulam-Teller principle, would propagate, sustain itself, and burn up a significant fraction of the fuel. The clear sense of the scientists present was that we had a sure route to success, and that there was no longer any technical reason to delay the program.

In a dramatic reversal from its findings in October 1949, the GAC recommended a thermonuclear device should be tested. Bradbury would have to organize LASL to quickly develop a device based on the Teller-Ulam document. Its test would be called the Mike event. Teller was a visionary, not a manager, so Bradbury assigned responsibility of day-to-day activities for the test to his W (Weapons) Division, led by a no-nonsense engineer named Marshall Holloway. Teller was not a happy man. He felt more estranged from Bradbury than ever.

In a series of meetings, Teller and Bradbury had heated exchanges and LASL scientists made acrimonious remarks directed at Teller and his wild accusations.[9] Teller’s disenchantment with the management at Los Alamos was complete and he resigned from LASL a second time. By November 1951, he was back in Chicago.

* * *

The Mike event was part of Operation Ivy, a series of nuclear tests scheduled for the fall of 1952. The Matterhorn-B Program supported the effort with calculations, as Wheeler and his physicists made regular trips back to Los Alamos by train, in reserved Pullman cars—a two-day trip. Those travel days were filled with Wheeler interacting freely with his charges who in turn got to enjoy highly rewarding experiences. The train from Chicago to New Mexico was called the Chief, and not surprisingly, Matterhorn-B computer codes carried names from the old American West: Chief and Squaw being two examples.

The Mike device was not a usable weapon: it was the size of a small house—it could hardly be carried by a bomber. Nevertheless, it was a thermonuclear device, the first to ever exist, and Bradbury felt a sense of accomplishment about completing his assignment to build it. Despite Teller’s warnings to the contrary, the LASL-Matterhorn team completed its work on schedule. 

The Mike event occurred on Halloween, 1952, American time, November 1, western Pacific time, at Eniwetok Atoll. To anyone observing the detonation, it must have seemed like Armageddon had arrived.

The yield of a device is the amount of nuclear energy released by the device—the yield of the Mike device was about 10 megatons (10MT), almost a thousand times more powerful than the Hiroshima bomb. After the atomic blasts of the 1940s, the military services had thought that an atomic bomb was just a new, albeit powerful, weapon in their fighting arsenal. After the Mike event, the Services had to rethink what nuclear war meant.

America’s feat of being the sole country in the world with a thermonuclear weapon did not last long. On August 8, 1953, Soviet Premier Georgy Malenkov notified the world that, just as the United States had no monopoly on the atomic bomb, it had no monopoly on the hydrogen bomb either. In the Soviet Union’s fourth nuclear test, dubbed by American intelligence as “Joe 4,” in reference to Josef Stalin, Soviet weapons scientists detonated their first hydrogen bomb. 

Although the blast was larger than any of America’s early atomic bombs, it only had a fraction of the yield of the Mike device. The Russian device did not share the sophistication brought out by the Teller-Ulam article; even so, it was clear they were intent on developing a thermonuclear weapon, and they had made a significant start. It had taken Soviet scientists only four years, versus seven years for the United States, to develop and test a thermonuclear warhead once they had successfully tested the atomic bomb. To anyone associated with America’s nuclear program, it was clear the Soviets had an excellent nuclear weapons program of their own.


*Von Neumann’s MANIAC in Princeton was undergoing development at the time, so Ford used an IBM-CPC, a machine he was familiar with from his work at LASL. He supplemented his work using the Standards Eastern Automatic Computer (SEAC) housed at the National Bureau of Standards in Washington, DC.

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