Stanislaw Ulam can be compared to some of the best mathematical minds of the 20th century but is probably somewhat less well known or remembered than many of his contemporaries. In his early career he made important contributions to ergodic theory, set theory, number theory, measure theory and algebraic topology. A few of these include the Ulam spiral, which leads to a mysterious pattern for the prime numbers; the Borsuk-Ulam theorem, an important result in topology; the Mazur-Ulam theorem and many more. Often he provided the seeds of ideas which others then developed and took the main credit for. Later, during the war, he switched over to applied mathematics and together with his friend John von Neumann was one of the first to advocate the important role computers could play in studying and solving difficult mathematical and scientific problems. He realized that one could perform powerful ‘mathematical experiments’ on a computer; for example, he was among the first to initiate a computer study of a nonlinear dynamical system in the Fermi-Pasta-Ulam experiment.

His most important work in this regard however, is the Monte Carlo method, perhaps the most powerful and versatile tool ever developed in applied mathematics, which has a plethora of applications over a very wide range of fields. These are a class of stochastic algorithms that utilize random sampling to solve otherwise intractable problems. Modern applications can now utilize the power and speed of modern computers and supercomputers. They include: computational physics and chemistry, nuclear engineering, reactor design and radiation shielding, molecular dynamics, biological physics, cancer radiation dosimetry, astrophysics, particle physics(QCD), statistical physics, simulated annealing, computer science, statistics, operations research, finance and financial engineering, image processing, traffic flow problems, aerodynamics, and engineering problems in general. The list is hardly exhaustive. But if the Monte Carlo method was his most famous contribution to science then his most infamous is one he let another man take most of the credit for. Personal tragedy and fate were to place him in a situation, at a crucial juncture in history, where his powerful abilities provided the key ideas that helped solve a dark problem; one which for the most part had totally stymied his peers–and a problem many of whom had actually hoped was a scientific and technological impossibility. But the solution changed history and made possible the construction of an awesome and terrifying weapon of virtually unlimited power.

Stan Ulam was born in 1909 in Lwow into a well-to-do family that was positioned as high in the social ladder as a Jewish family could be at that time in that part of Europe. (Lwow was part of Austria-Hungary in 1909, was part of Poland from 1918 and part of the Ukraine from 1945.) He was a privileged child from one of the richest families in Lwow and the Ulam name was synonomous with banking wealth in central Europe, much like the Rothschilds were in western Europe. He was tutored and educated at the best schools and showed an early interest in mathematics and science, easily becoming a top student with little effort. At age 17 he attended the Lwow Polytechnic Institute but soon discovered that the real mathematical action was to be found at one of the large cafes in town known as the ‘Scottish Cafe’. Here, each day Lwow mathematicians would gather to talk shop, play chess and drink coffee or brandy, and they would pose and often solve some of the most outstanding mathematical problems and conjectures of their time.

Poland between the wars had become something of a powerhouse in mathematics and there were schools or ‘intellectual gangs’ that mathematicians tended to gather in: the Warsaw school, the Lwow school and the Krakow school. The Lwow school was composed mostly of offbeat, free-thinking and undisciplined types. Perhaps the most prominent of them was Stephan Banach, of ‘Banach space’ fame, who was also Ulam’s mentor. Mark Kac also belonged to the Lwow school. The Warsaw school was somewhat more conservative minded and tended to look down on the Lwow group as either amateurs or upstarts. However, the Lwow school became better known to mathematicians outside Poland. They developed the new fields of set theory, measure theory and functional analysis. In particular, the book by Banach on linear operators where Ulam’s name is also frequently mentioned became highly regarded.

Ulam sowed the seeds of many new ideas and conjectures and could often see right to the heart of a problem. While talking one day with a Warsaw group mathematician Karol Borsuk, who was considered an outstanding topologist, he instantly realized the validity of what is now known in topology as the Borsuk-Ulam theorem. Borsuk eventually proved it using all his technical ability but needless to say he was impressed. People began to look out for the name of Ulam. Ulam at this time was clearly beginning to bloom into potentially one of the most promising mathematicians of his generation, but with the traits that were to characterize him: penetrating intuition and a playful almost irrelevant approach, combined with an impatience with details and a dislike of long drawn-out work.

Meanwhile in Princeton, the Borsuk-Ulam theorem had caught the attention of Solomon Lefschetz, a leading topologist and the chairman of the mathematics department at Princeton. In 1936 Lefschetz and John von Neumann invited Ulam to visit the Institute for Advanced Study in Princeton, now also the sanctuary and stomping ground of Albert Einstein who left Germany soon after Hitler came to power. For the next four years, Ulam was to commute between Princeton and the United States, where he lived virtually in luxury on his parents’ lavish monthly cheques; first at Princeton and then at the Harvard Society of Fellows. However, in the summer of 1939 he returned with his brother to the US from what would be his last visit to his family–later that year Poland was invaded and World War II began. The horror of Hitler’s ‘final solution’ would become a reality. Freedom of thought and the spirit of free inquiry and scholarship that had powered Polish mathematics, and European culture in general, was destroyed. The Polish mathematicians either fled or perished.

In the fall of 1939 Ulam would apparently spend hours watching the Charles river from his Harvard room, in shock from the turn of horrifying events that had changed his life forever and that of many others, but who had at least found sanctuary in the US. He learned that his family had been deported to a concentration camp and that his sister and uncles had perished in the gas chamber. The Ulam banking empire was decimated. His monthly cheques stopped and his Junior Fellowship was also on the brink of running out. He would also have to support the education of his brother at Brown University.

One glimmer of hope was that his big paper on ergodic theory had been accepted to Annals of Mathematics, the most prestigious of mathematics journals. He also became good friends with von Neumann, no doubt a very similar European background, love of mathematics and culture shock brought them together. G. D. Birkhoff, the dominant figure in American mathematics at that time and head of mathematics at Harvard, helped Ulam and began to write letters of recommendation to various universities. Ulam was then offered a post at the University of Wisconsin in Madison. The stipend was rather good for it’s time and Ulam had no choice but to accept it, despite the fact that he balked at the 12-hour weekly teaching load of calculas; something he had never had to deal with before. However, at Madison he also met the mathematician C. J. Everett, with whom he would later have an important collaboration.

After two years at Wisconsin, the US entered the war and correspondence from Von Neumann became much less frequent. Ulam felt that he was in a rut and wanted to help the war effort but unknown to him Von Neumann had already planned to take Ulam with him to Los Alamos, where the secret work on the atomic bomb would commence. Los Alamos and the Manhattan Project was a major turning point in Ulam’s career: from this time onwards applied mathematics and physics became the focus of his interests; differential equations, turbulence, hydrodynamics, diffusion theory and statistical methods would take the place of set theory, measure theory, ergodic theory and topology. Von Neumann had already made this step and had gone on beyond pure mathematics, with applied work naturally taking on a more crucial role in wartime. No longer concerned with set theory and ‘rings of operators in Hilbert space’ he developed game theory with the economist Oskar Morgenstern, and he become an authority on the mathematics of hydrodynamics, shock waves and explosions. Crucially, von Neumann, Ulam and Nicholas Metropolis where the first to realize the enormous potential of computers and computational methods. Von Neumann was aware of Alan Turing’s work on computing machines and realized how useful they could be for nonlinear problems in mathematical physics, especially turbulence. From the interplay of ideas between Ulam and Von Neumann came the powerful Monte Carlo statistical sampling method (so named because one of Ulam’s uncles had liked to gamble), numerical methods and cellular automata. Von Neumann had the clout to muster the resources to build the first computers. Every laptop on every desk today is a Von Neumann machine.

Ulam was also impressed by the physicists at Los Alamos, which by any standards were really an all-star team of outstanding scientific talent. In particular, he had been most impressed watching Enrico Fermi and the young Richard Feynman, both of whom had a genius for solving difficult physical problems with intuition and a minimum amount of mathematics. As it turned out, Ulam discovered he had this talent too, made important contributions and thrived in the company of his peers. His Monte Carlo method in particular proved to be a useful tool in numerically performing difficult integrals involved in describing fission processes. However, in 1945 their work was complete–the bombs had dropped on Japan and ended the war. Many at Los Alamos were left disturbed at the scale of the death and injury and seeing the complete destruction of Hiroshima their work had led to. About one gram of uranium, on being totally converted to energy via Einstein’s famous formula had flattened the city and wiped out most of the population. Most of the Los Alamos scientists were keen now to move on and take up academic posts and leave memories of the war and wartime work behind. Ulam, whose publication list was still not very long, took up a post at the University of Southern California. However, one man did’nt want the work on nuclear weapons to stop and for the security of the free world–against what he saw as the great potential threat posed by Stalin and Soviet Russia–did’nt think it should stop. His name was Edward Teller.

In 1941 Enrico Fermi and Edward Teller had lunch in New York. Fermi later posed the then fantastical question as to whether an atomic bomb (which was already highly feasible) might be used as a detonator for a weapon using deuterium () a form of heavy hydrogen consisting of a proton and neutron bound together. Hans Bethe had already demonstrated the nature of the proton-proton cycle of fusion reactions and nucleosynthesis that powered the sun and stars–and for which he would later receive a Nobel prize–whereby hydrogen nuclei (protons) are fused together at very high temperatures to make helium nuclei, with a release of energy. Some of the intermediatary reactions involved deuterium and tritium (), a hydrogen isotope of one proton and two neutrons bounded together. These reactions could at least in principle be reproduced on earth. To Fermi this was probably no more than a fantasy scenario for discussing interesting nuclear physics but Edward Teller took it seriously and from then on became obsessed with the idea. In fact, he came to see the atomic bomb as only a stepping stone on the way to creating a ‘hydrogen bomb’ of the type Fermi described. His design for such a device came to be called ‘The Super’. This was basically a long cylinder filled with liquid deuterium with an atomic bomb attached at one end. The ignition temperature of pure deuterium alone would be hundreds of millions of degrees, so Teller’s colleague Emil Konopinski suggested the deuterium should be mixed with tritium to lower the ignition temperature. The basic idea was that the immense heat from the atomic bomb would start fusion reactions in the mass of deuterium/tritium, which would then be self-propagating and burn along the length of the cylinder, thereby producing a megaton-range explosion. Proving whether this would work or not became known as the ‘Super Problem’.

However, the actual physics of the problem turned out to be exceedingly difficult to understand and calculate. Attempts at analytical calculations turned out to be far more complex than anyone had imagined, even Teller. To have any hope of solution, the problem really required very massive numerical-type calculations but the demands of the problem far exceeded the capabilities of any computing machine in existence at that time. During WWII, the US Army had contracted the University of Pennsylvania’s Moore School of Engineering in Philadelphia to develop a large computer–among the very first of its kind–in the hope that the machine would perform ballistic calculations. Previous computers like the differential analyzer, that could solve complex systems of nonlinear equations, were mechanical but the ENIAC (Electronic and Numerical Integrator and Calculator) were purely electronic using precision circuits (for the time) and some 18,000 vacuum tubes.

However, the machine was not completed before the end of the war and the Army were not the first to use the machine. The first calculation performed was for the Los Alamos nuclear weapons lab and the classical Super problem. Von Neumann had become interested in the prospect of a fusion weapon and he arranged to have the Super problem run on the ENIAC. The problem however was too much for the ENIAC and its 1000 bits of memory and only a very simplified version of the problem was run, giving very little realistic information on the feasibility of the design. The part of the problem that was run on 1945/46 was meant to predict the ignition and burn propagation behavior of various D-T mixtures with various initial temperatures. The calculations attempted to predict whether a self-sustaining fusion reaction would indeed occur. In 1946 the Super Conference was held at Los Alamos, taking stock of the state of the project before everyone moved on to other things. Most scientists in attendance treated it in the spirit of ‘putting your fur coat away in mothballs‘. (Quoted in Rhodes.) Except Edward Teller of course.

Meanwhile, in 1946, Ulam, who was now a professor at USC found himself one day unable to speak properly. A few hours later he underwent an emergency operation whereby his skull was partly opened and part of his brain tissue sprayed with a newly discovered antibiotic. The diagnosis was encephalitis, an inflammation of the brain. After a short convalescence he recovered apparently none the worse for his experience, but as time went on some colleagues noticed some of his personality traits seemed more pronounced than they had been. He was now seemingly haunted by the possibility that the illness might have affected his abilities and that he could have sustained some type of brain damage. He worried that what talents he had might now fade away quickly. He therefore decided that the time had come to dedicate himself to some major project that would be a true test of his abilities and one with which his name might be associated. After he recovered he resigned from USC and returned to Los Alamos, the environment that he perhaps felt best stimulated him. Once there, he invited his old friend from Wisconsin, Cornelius Everett and together they formed a powerful collaboration.

Ulam and Teller had never really liked each other since they time they had met during the Manhattan Project, but seemed to at least respect each other’s scientific abilities. In his memoirs Edward Teller writes of Ulam:

‘Stan Ulam had orginally come at the recommendation of my friend Johnny Von Neumann, but I found him difficult company. He seemed to think very highly of himself and expended much effort in demonstrating his cleverness (which was strange because his ingenuity was obvious). Although we had limited contact during the war and postwar period, I developed an allergy to him. His demeanor made it clear that his feeling about me was even stronger‘.

Ulam now felt that he could get one up on Teller by proving that his Super could not work. The ENIAC computations had never definitively established whether the Super would actually work or not. Ulam gave his opinion on the scale of the calculations involved:

‘The magnitude of the problem was staggering. In addition to all the problems of fission, neutronics, thermodynamics, hydrodynamics, new ones appeared vitally in the thermonuclear problems: the behavior of more materials, the question of time scales and the interplay of all the geometrical and physical factors…It was apparent that numerical work had to be undertaken on a vast scale.’

The immense difficulties involved were simply beyond the technology of the time. In other parts of the country construction of large electronic computers was underway, and the Los Alamos lab began working on its own version. It was meant to be a copy of the one Von Neumann was constructing at the IAS in Princeton, but construction of these would take years. However, the Super problem was soon to take on a much greater importance.

In the summer of 1949 a sequence of events occurred that left Americans in a state of shock: the communist forces of Mao Tse-Tung took control of China, and the Soviet Union tested its first atomic bomb, nicknamed ‘Joe 1′. The Soviet Union under Stalin became the new threat to the free world, and it could be argued that it was the US atomic bomb that had kept the Soviet Union out of western Europe. Truman was astonished that ‘those asiatics’ could construct something as complex as the A-bomb. How could the US stay ahead? In Washington, those in the know began to hear of Teller’s idea for a more powerful hydrogen bomb and Teller suddenly found his pet science project was gathering powerful political support. In January 1950 , after months of debate, hearings and committee meetings, President Harry Truman announced his decision: the US would accelerate “work on all forms of atomic weapons including the so-called hydrogen or superbomb”. But in only two days the hydrogen bomb was back on the front pages of the newspapers again when it was declared that Manhattan Project physicist Klaus Fuchs had been arrested in the UK for spying and handing over classified information to the Soviet Union. In all likelihood it was Fuchs who helped accelerate the Russian A-bomb project. Fuchs, a communist sympathiser and a former Los Alamos room mate of Richard Feynman, was privy to the secret work at Los Alamos including the new work on the hydrogen bomb. How much did the Soviet Union now know and could Soviet scientists succeed where the US had failed and actually solve the very considerable technical problems? The race to be the first to achieve the superbomb was now on. Los Alamos moved to a war-time schedule of a six-day work week and the Super project was given top priority and resources.

However, many scientist refused to get involved. Fermi agreed to help but his goal, like Ulam’s and Bethe’s, was essentially to demonstrate that the Super was a technological and scientific impossibility. Many seemed to share this view but felt that it was still necessary to prove the impossibility of the construction of such a weapon: then they could at least sleep at nights knowing that if they had tried everything possible and failed, then the Soviet Union would fail too. Recreating on Earth the enormous temperatures and pressure that only exist in the centre of the sun and the interiors of stars was still considered a fantasy by many. Unfazed, Teller still believed his design would work and his group hoped that the either the Von Neuman’s IAS computer or the version being built at Los Alamos would be able to do a full calculation for the Super, but construction of these machines fell behind schedule. Lack of computing facilities was proving to be the bottleneck to making any progress. Growing impatient, Ulam and Everett worked on the ignition part of the Super problem using slide rules and hand computers. They were still not certain whether the Super would work but their preliminary results, which Teller rejected, looked negative. Ulam and Everett also concluded that the amount of tritium required to lower the ignition temperature appropriately, so that the Super even had a chance to work, were impractical and was more than the US could produce in a year. The work Fermi did also suggested the Super would not work either. When the IAS computer was finally up and running Von Neumann had the Super calculation performed and reached the same conclusion. But a now distraught Teller still refused to give up on his design believing the computations were somehow all incomplete or inconclusive, or part of some conspiracy.

One key problem that had become apparent was that the design was plagued by inverse Compton scattering: photons from the fission bomb initiator would scatter off the deuterium and remove energy at a faster rate than which nuclear fusion reactions could dump heat back into the fuel. In effect, the dueterium burning never really got started before the shock wave from the atomic blast of the initiator simply blew everything apart. It was rather like having a very long and large bottle of gasoline with a stick of dynamite in place of a cork: upon lighting the dynamite everything would just blow apart without igniting very much of the gasoline if any. The US project to build the hydrogen bomb was stuck in a rut and going nowhere (as many working on it had hoped for), but by the end of 1950 Edward teller was now under political pressure to produce something workable. One thing they did do to collect data was the George Experiment part of ‘Operation Greenhouse’, whereby a small amount of fusion fuel was placed at the heart of a conventional fission bomb and used to ‘boost’ the explosion. Essentially the fuel was compressed. But this had its limitations and while some fusion was initiated it was not a true thermonuclear weapon that could ever produce a megaton-range explosion. For the most part, everyone still remained stymied by the hydrogen bomb problem– a megaton-range bomb that was powered predominantly by fusion. But then in some flash of insight Stanislaw Ulam saw the key concepts that would make it work. His wife recalls:

‘Engraved in my memory is the day when I found him at noon staring intensely out of a window in our living room with a very strange expression on his face. Peering unseeing into the garden, he said, “I found a way to make it work.” “What work?” I asked. “The Super”, he replied. “It is a totally different scheme and it will change the course of history.” ‘.

Ulam’s first insight was to separate the initiator atomic bomb and the deuterium thermonuclear fuel into stages–the primary and secondary–and encase these in a very thick outer shell or container. When the atomic bomb initiator detonated the radiation flooded into the space between the primary and secondary and was very briefly contained. The radiation pressure would then compress the thermonuclear fuel (deuterium) and start fusion reactions just before the shock wave from the initial atomic explosion had a chance to blow everything apart. His second insight was to encase the fuel in a ‘hydrodynamic lens’ such as lead or uranium. This vastly magnified the effect of the compression of the fuel and removed the inverse Compton scattering problem. The resulting scheme of ’staged radiation implosion’ was incredibly efficient and a good fraction of the thermonuclear fuel got burned. The bomb would be a true thermonuclear, or superbomb in the megaton range. The Teller-Ulam firing sequence is illustrated below.

Ulam discussed his idea with a few others before going to see Teller, and they were impressed. Teller was eventually swayed and realized it would work and he added farther refinements: he suggested that photon radiation would perform the compression rather than neutrons since they travel at speed c, which is of course considerably faster than the shock wave from the initiator atomic bomb; he also suggested that a cylindrical ’spark plug’ of plutonium could be placed within the thermonuclear fuel which would also go critical as the fuel underwent the enormous compression. Other refinements included filling the space inside the bomb with plastic or polystyrene, which instantly became a plasma and farther augmented the compression. There was also no longer any need to mix expensive and rare tritium to lower the ignition temperature. The hydrogen bomb was born. Teller and Ulam wrote joint papers, one called ‘On Radiation Mirrors and Hydrodynamic Lenses‘, still classified, and they applied for the joint patent. The arrangement became known as the Teller-Ulam configuration. (Not ‘Ulam-Teller’.) Everyone involved was convinced it would work and wondered why it had not been obvious much earlier. Even Robert Oppenheimer, who was opposed to the H-bomb (and who would later have his security clearance removed) remarked that it was ‘technically sweet’ compared to the ‘tortured thing we had in 1949‘. But Teller later downplayed Ulam’s contribution and the press later dubbed Teller ‘the father of the hydrogen bomb‘, a term Ulam was probably glad not to have anyway.

By this time the Los Alamos computer was ready, similar to the one Von Neumann had constructed in Princeton, and was appropriately named the MANIAC (Mathematical and Numerical Integrator And Calculator). Indeed the need for computing power in the hydrogen bomb problem accelerated developments in computer design and the emerging field of computer science. The new hydrogen bomb design , although still complex, was computationally much more tractable than the original Super design and encouraging results now came from the simulations. The Super Problem was essentially solved by bypassing it. A full calculation on the classical Super was not done until the late 1960s at the Control Data Corporation using the CDC6600 computer, at the time probably the most powerful machine of its kind. It proved conclusively that the classical Super would not work.

The first test of the hydrogen bomb that would utilize the Teller-Ulam firing sequence was code named Ivy Mike, to be conducted in the fall of 1952 at Eniwetok Atol in the Pacific. This was really a very impressive and complex nuclear engineering experiment and not a practical weapon in any sense. Mike was a ‘wet bomb’ using many tons of cryogenically cooled liquid deuterium. Deuterated ammonia (ND3) was originally considered but the properties of deuterium were better understood. It also had a uranium tamper to collect fusion neutrons and boost the explosion farther. This was to result in a lot of fallout. A barrage of instruments surrounded Mike to catch and transmit data in the few microseconds before the fireball punctured the outer casing. Once the deuterium fuel was compressed in the Teller-Ulam sequence, the typical fusion reactions powering the explosion were:

The resulting fireball was several miles across and vaporized the entire island and over 80 million tons of seawater. A B-36 flying 15 miles from ground zero at 40,000 feet had its wings heated 93 degrees almost instantly. A massive mushroom cloud rose into the stratosphere, and air force jets that were to fly into the cloud and collect samples had to turn back since the radiation they encountered was much too intense. At one point the mushroom was thirty-seven miles high and over a hundred miles wide. Edward Teller witnessed the event from the geology department at the University of California on an earthquake detector as he waited for the shock wave from the Pacific to reach California. The fireball was so hot that it briefly created every known element in the universe and new ‘transuranic’ artificial ones as well. The neutron density was ten million times greater than a supernova. The high-energy neutrons tacked onto the the nuclei that had comprised the uranium tamper, creating new nuclei as heavy as atomic weight 255 before decaying. New elements were named ‘Fermium’ and ‘Einsteinium’ following a radiochemistry analysis of the fallout. As well as being a fusion bomb it was also a very efficient (and dirty) way to burn large amounts of cheap uranium by using uranium as a tamper for the thermonuclear fuel.

The shot was captured on a government film that for the most part remained classified until the 1990s. The film was restored for the documentary ‘Trinity and Beyond’ . The Mike shot can be viewed below in a clip, with before and after shots of the test island.

The Ivy Mike fireball with the New York skyline to scale. The Empire State Building is at the centre. (Still from the film ‘Operation Ivy’.)

Later tests utilized solid thermonuclear fuel in the Teller-Ulam system in the form of lithium deuteride (). When captures neutrons it decays into an alpha nucleus and a tritium nucleus creating tritium ‘in situ’ within the bomb. In addition to the previous reactions, we also have

Tritium then undergoes a more energetic nuclear reaction than deuterium. In the Castle Bravo test of 1954 at Bikini Atol such solid thermonuclear fuel was used but an immense mistake was made in the assumption that the fraction was inert, when in fact the isotope behaved just like . As the lithium 7 captured neutrons and decayed it fed new tritium into the fireball. Castle Bravo turned into an inferno and was two and a half times bigger than predicted. It ran off to 15 megatons in a massive explosion that was much more fiery and ferocious than the Mike shot. It was over a 1000 times the power of the Hiroshima bomb. It blew a hole in the initially shallow ocean floor 1.6 miles across and deep enough to submerge a skyscraper. Over 100 million of tons of coral and seawater were vaporized. Later some of it began to ’snow’ down on inhabitants of near-by islands who then came down with radiation sickness. A Japanese fishing vessel, ‘The Lucky Dragon’ went unnoticed in the security zone around the blast and there was a public outcry when one of the crew later died. Bravo was the worst radiological disaster in US history (and Marshall islanders are still seeking compensation from the US government). Clip:The awesome (and scary) Castle Bravo shot, from ‘Trinity and Beyond’.

It is probably true that the solution to the hydrogen bomb problem would have been found eventually since many people were thinking about the problem. Teller’s overall excellence as scientist should still be acknowledged, but Ulam worked out the key concepts at a crucial time and juncture in history: staging, the hydrodynamic lensing, compression and the Monte Carlo method which enabled computations to be performed, where predominantly his contributions. From then on the rest was just the engineering details of putting it into practice. Years later, Hans Bethe gives Ulam the credit even though the ‘credit’ was something Ulam did not seek or want during his lifetime.

After the H-bomb was made, reporters started to call Teller the father of the H-bomb. For the sake of history, I think it is more precise to say that Ulam is the father, because he provided the seed, and Teller is the mother, because he remained with the child. As for me, I guess I am the midwife. (quoted in Schweber, p.166)

Also, the Soviet Union was never very far behind. Those in government and the military felt that if they now kept ‘the secret’ of the hydrogen bomb then only they would possess such a weapon. But what they considered a ’secret’ was really just physics, and others in the Soviet Union could and did work it out for themselves. The Bravo explosion was downplayed by the official Soviet news agency but Russian physicists were stunned by its power. Very shortly thereafter Andrei Sakharov, deduced the staged radiation implosion mechanism for himself where it was called Sakharov’s Third Idea. The Soviet union went on to test its own hydrogen bomb. (Sakharov later remarked that when it began, he was twice invited to join the Soviet weapons program and twice declined. The third time, he said, they never asked for his consent.) It has been claimed that Soviet scientists figured out the Teller-Ulam configuration from analyzing a fallout sample from Mike or Bravo but Sakharov in his autobiography denies this. Certainly, for a physicist of his calibre, he can be given the benefit of the doubt. Regardless, the arms race between two superpowers had begun. The Soviet Union would go on outdo the US in creating hydrogen bombs of ever greater power, testing them on the remote and desolate island of Novaya Zemlya in the artic circle; culminating in the colossal 57 megaton ‘Tsar Bomb‘, detonated in 1961, and which had actually been scaled down from a 100 megaton design. (It was at this test that Sakharov began to question what he was doing and to even question the Soviet Premier. Later he would become the most outspoken advocate of human rights in his country.)

Back in the US, Ulam continued to pursue science and mathematics. Leaving Los Alamos in 1965 he eventually found a place in academia that suited him at the University of Colorodo and followed the typical life of a professor at an American University, giving lectures and writing papers on subjects as diverse as the use of metrics in biology to the collapse of stars in globular clusters. He also remained a consultant to Los Alamos and was popular with the Kennedy administration. He grew particularly interested in applying mathematics to biology, and in the the peaceful use of nuclear power for spaceflight. But the hydrogen bomb was the ultimate demonstration that knowledge is power and that the state sees science mostly as a source of power that it can harness. Ulam and many others were part of this moral struggle, believing they were helping protect the free world from the kind of tyranny they had experienced first hand back in Europe. Reflecting back on the H-bomb work he remarked:

‘It still remains an endless source of surprise to me how a few scribbles on a blackboard can change the course of human affairs’.

Stan Ulam died in Santa Fe, New Mexico in 1984.

REFERENCES:

S. Ulam. Adventures of a mathematician, NY, Charles Scribner and Sons, 1983.

S. Ulam. A collection of mathematical problems, NY, Intersecience Publisher, 1960.

S. S. Schweber. In the shadow of the bomb:Bethe, Oppenheimer and the moral responsibility of the scientist. Princeton University Press, 2000.

Richard Rhodes. Dark Sun, The making of the hydrogen bomb.

Edward Teller, Memoirs of a life in Science and Politics.

Andrei Sakharov, Memoirs.

The American Experience: Race for the Superbomb. PBS video.

Trinity and Beyond–The Atomic Bomb Movie, DVD.

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