For a man who as a child found "learning arithmetic mildly painful," Manhattan Project mathematician Stan Ulam turned that discomfort level into an outstanding career at several American universities as well as at Los Alamos from 1943 until 1967.
Born in Lwow, Poland, where mathematics was discussed in coffee houses and on park benches, Ulam said in his autobiography, Adventures of a Mathematician, that collaboration among famous mathematicians in his home town "was on a scale and with an intensity that I have never seen surpassed, equaled, or approximated anywhere, except perhaps at Los Alamos during the war years."
Unfortunately, the rise of Hitler and the accompanying threat to Poland's sovereignty cast a shadow over the mathematicians who gathered in Lwow's Scottish Cafe for long discussions, one of which lasted, according to Ulam, without interruption for 17 hours except for meals.
LOS ALAMOS SCIENCE
Facing Political Realities
Being of Jewish descent, Ulam knew that the 1930 political realities indicated he had to leave his hometown for his own safety. But the mathematical excellence he participated in as a student at the University of Lwow and the Polytechnic Institute created a tie to world-famous mathematicians that he found hard to break.
At age 23, Ulam gave a talk at the International Mathematical Congress in Zurich where his exposure to mathematicians and new ideas from all over Europe and America broadened his mathematical horizons. He returned to Lwow to earn his master's and doctorate degrees, realizing by 1934 that for mainly political but also personal economic reasons he should leave Poland.
He began a tour of Vienna, Zurich, Paris, and England, meeting with famous mathematicians and spending time at Cambridge University. On his return to Lwow in 1936, Ulam received an offer from famous mathematician John von Neumann to go to America to the Institute of Advanced Studies at Princeton University for a few months.
Princeton, according to Ulam, had become a "way station for displaced Europe scientists." While there, Ulam put his finger on a trend that von Neumann and other scientists were following. As Ulam noticed about von Neumann, "He began to think of problems away from pure mathematics". He was thinking now more about classical problems in physics. For example, he studied problems of turbulence in hydrodynamics."
Turning to the Practical
This turn to the practical was one that Ulam and others in the Manhattan Project would have to make less than a decade later when that wartime effort geared up to face a most practical problem; the building of a weapon more powerful than any other previously conceived.
In 1939 he became a member of the Harvard University Society of Fellows where with another young mathematician he completed in 1941 a long paper on ergodic transformation for The Annals of Mathematics, then considered the most prestigious mathematics journal.
When his Fellows appointment at Harvard ended in 1941, he became an instructor at the University of Wisconsin. Yet with the war in full swing, Ulam said he was dismayed at the detached view of the conflict among many colleagues at Wisconsin and the isolationist attitude of many Americans. Once Ulam became an American citizen in 1941, he hoped he could become more active in the war effort.
In his autobiography, Ulam commented about his relationship at this time with other colleagues, especially von Neumann, and noted, "The tone of our mathematical correspondence changed from the abstract to the more applied, physics-related topics." Many scientists wanted to contribute to the war effort, and finally in 1943, Ulam was invited to join what he described as "an unidentified project that was doing important work, the physics having something to do with the interior of the stars."
Von Neumann played an influential role in Ulam's receiving this invitation to join this project in New Mexico. Ulam soon noted that people whom he knew well at Wisconsin began to vanish one after the other without saying where they were going.
Heading to a Secret City
Once he learned he was headed for New Mexico, he went to the University of Wisconsin library to check out a guidebook on that state. The list of borrowers included the very people who had been leaving mysteriously. With the pieces falling into place, Ulam took a train with his wife to Lamy, New Mexico, and traveled from there to Santa Fe and Los Alamos.
Beginning his work with colleagues such as von Neumann and others he had known in Europe, Ulam admitted that the "long equations on the blackboard of a Los Alamos office scared me." But he remembered the words of von Neumann's invitation to Ulam to join the secret project. "If you want war work, this is probably a quite exceptional opportunity". The project in question is exceedingly important, probably beyond all adjectives I could affix to it....
At Los Alamos, Ulam noticed that it was "one thing to know about physics abstractly and another to have a practical encounter with problems directly connected with experimental data such as the very novel technology that was to come from Los Alamos."
Ulam's work on the Manhattan Project involved the statistics of neutron multiplication and calculating the hydrodynamics problem involved in the implosion process. His interests revolved around applied rather than abstract mathematics. Of this new work, Ulam said, "I found my purely abstract intellectual habits as a mathematician immediately useful in the work with these more practical, special, and tangible problems." He described working in "a visual, almost tactile way to imagine the physical situations, rather than a merely logical picture of the problem."
Focusing on Complexity to Achieve Success
The complexity of these problems demanded computing capabilities unavailable at that time. It was this need for electronic computers that motivated Ulam to participate with fellow Los Alamos mathematician Nick Metropolis and von Neumann in developing the Monte Carlo method, which greatly aided in solving many of the complex problems involved in creating the atomic weapon.
As a member of the Theoretical Division, Ulam worked alongside Division Director Hans Bethe, who had signed the letter inviting Ulam to Los Alamos. Fellow physicist Richard Feynman described Bethe's role in T Division. "Bethe was like a battleship moving steadily forward, surrounded by a flotilla of smaller vessels, the younger theoretical workers of the Laboratory." In fact, Ulam, himself only 34 when he arrived at Los Alamos, had described working with so many young scientists as like "looking at an encyclopedia."
Having so many brilliant scientists focused on one project contributed to the successful testing of the atomic device and the possibility of using the other two available weapons to bomb Nagasaki and Hiroshima. With the surrender of Japan, Los Alamos had to chart a new course of scientific activities.
Looking Toward the Next Challenge: the "Super"
In the midst of this redirection, Ulam left Los Alamos for a brief teaching stint at the University of Southern California in Los Angeles, an assignment and location not to his liking. In California he encountered a medical challenge that would affect the rest of his life. A bout with encephalitis required brain surgery that would shed doubt on his future work. Luckily, his memory and cognitive abilities were not affected.
After realizing that he could continue to work effectively, he accepted an invitation to return to Los Alamos in the midst of a political and scientific controversy over the decision to develop the "super" or hydrogen bomb.
Ulam looked at all aspects of this project but concluded, "I sincerely felt it was safer to keep these matters in the hands of scientists and people who are accustomed to objective judgements rather than in the hands of demagogues or jingoists. Or even well meaning but technically uniformed politicians."
He worked with his former Wisconsin colleague C.J. Everett in proving that their methods of developing the hydrogen bomb were more effective than those of Ulam's longtime rival Edward Teller. In the end, Ulam came up with the idea that actually made the H-bomb work. Teller and Ulam submitted the patent application for the bomb jointly.
Exploring the Scientific Frontiers of the 1960s
Though this work catapulted Ulam's name beyond the boundaries of Los Alamos, Ulam remained as research advisor to the Los Alamos Scientific Laboratory director from 1957 until 1967. He received attention from the Kennedy administration in Washington and explored many technical areas popular in the 1960s space issues, nuclear propulsion, and electronic computing.
When he retired from the Lab, Ulam moved back to academia, but not to Harvard, MIT, and University of California, where he had been a visiting professor. Instead he chose the University of Colorado at Boulder that had a growing mathematics department and spectacular scenery that would remind him of his days at Los Alamos .He remained there until he retired in 1975, continuing to make academic rounds as a visiting professor until a few months before his death in Santa Fe on May 13, 1984.
The words of his wife Franoise capture the breadth of this impressive mathematician: