# Richard Feynman

Richard Phillips Feynman

Richard Feynman,
Los Alamos National Laboratory, wartime ID badge
Born

May 11 1918
Far Rockaway, Queens, New York

Died February 15 1988 (aged 69)
Residence United States
Nationality  United States
Field Physics
Institutions Manhattan Project
Cornell University
California Institute of Technology
Alma mater Massachusetts Institute of Technology
Princeton University
Notable students  Al Hibbs
George Zweig
Mark Kislinger
Finn Ravndal
Thomas Curtright
Known for Quantum electrodynamics
Particle theory
Feynman diagrams
Notable prizes Nobel Prize in Physics (1965)
Oersted Medal (1972)
Religious stance None (Atheist)

Richard Phillips Feynman (May 11, 1918 – February 15, 1988; IPA: /ˈfaɪnmən/) was an American physicist known for expanding the theory of quantum electrodynamics, the physics of the superfluidity of supercooled liquid helium, and particle theory. For his work on quantum electrodynamics, Feynman was a joint recipient of the Nobel Prize in Physics in 1965, together with Julian Schwinger and Sin-Itiro Tomonaga; he developed a widely-used pictorial representation scheme for the mathematical expressions governing the behavior of subatomic particles, which later became known as Feynman diagrams.

He assisted in the development of the atomic bomb and was a member of the panel that investigated the Space Shuttle Challenger disaster. In addition to his work in theoretical physics, Feynman has been credited with pioneering the field of quantum computing,[1] and introducing the concept of nanotechnology (creation of devices at the molecular scale)[2]. He held the Richard Chace Tolman professorship in theoretical physics at Caltech.

Feynman was a keen popularizer of physics in both his books and lectures, notably a 1959 talk on top-down nanotechnology called There's Plenty of Room at the Bottom [3]and The Feynman Lectures on Physics[4]. Feynman is also known for his semi-autobiographical books Surely You're Joking, Mr. Feynman![5] and What Do You Care What Other People Think?[6], and through books about him, such as Tuva or Bust![7] He was also known as a prankster, a proud amateur painter, and a bongo player. Richard Feynman was regarded as an eccentric and a free spirit. He liked to pursue multiple seemingly independent paths, such as biology, art, percussion, Maya hieroglyphs, and lock picking. Freeman Dyson once wrote that Feynman was "half-genius, half-buffoon," but later revised this to "all-genius, all-buffoon".[8]

 Quantum physics $\Delta x \, \Delta p \ge \frac{\hbar}{2}$ Quantum mechanics Introduction to... Mathematical formulation of... Fundamental concepts Decoherence · Interference Uncertainty · Exclusion Transformation theory Ehrenfest theorem · Measurement Experiments Double-slit experiment Davisson-Germer experiment Stern–Gerlach experiment EPR paradox · Popper's experiment Schrödinger's cat Equations Schrödinger equation Pauli equation Klein-Gordon equation Dirac equation Advanced theories Quantum field theory Wightman axioms Quantum electrodynamics Quantum chromodynamics Quantum gravity Feynman diagram Interpretations Copenhagen · Ensemble Hidden variables · Transactional Many-worlds · Consistent histories Quantum logic Consciousness causes collapse Scientists Planck · Schrödinger Heisenberg · Bohr · Pauli Dirac · Bohm · Born de Broglie · von Neumann Einstein · Feynman Everett · Others

## Science Legacy

Feynman's major contribution to science was to complete the basic edifice of quantum physics, at least in outline, by developing the method of deriving the wave aspect of things from the fundamental law of science called the Principle of Least Action. While technically this method is call 'path integration over all possible histories,' Feynman almost always called his method 'adding little arrows.'[9]

## Biography

Richard Phillips Feynman was born on May 11, 1918,[10] in Far Rockaway, Queens, New York.[11] His family was Jewish and, while not ritualistic in their practice of Judaism, his parents attended synagogue every Friday. Feynman (in common with other famous physicists, Edward Teller and Albert Einstein) was a late talker; by his third birthday he had yet to utter a single word. The young Feynman was heavily influenced by his father, Melville, who encouraged him to ask questions to challenge orthodox thinking. From his mother, Lucille, he gained the sense of humor that endured throughout his life. As a child, he delighted in repairing radios and had a talent for engineering. His sister Joan also became a professional physicist.[12]

### Education

In high school he was bright, with a measured IQ of 123:[13] high, but "merely respectable" according to biographer Gleick.[13] He would later scoff at psychometric testing. By 15, he had mastered differential and integral calculus. Before entering college, he was experimenting with and re-creating mathematical topics, such as the half-derivative, utilizing his own notation. Thus, while in high school, he was developing the mathematical intuition behind his Taylor series of mathematical operators. His habit of direct characterization would sometimes disconcert more conventional thinkers; for example, one of his questions when learning feline anatomy was: "Do you have a map of the cat?" (referring to an anatomical chart).

A member of the Arista Honor Society, in his last year at Far Rockaway High School, Feynman won the New York University Math Championship; the large difference between his score and his closest runners-up shocked the judges.[14] He applied to Columbia University; however, because he was Jewish, and Columbia still had a quota for Jews, he was not accepted.[15] Instead he attended the Massachusetts Institute of Technology, where he received a bachelor's degree in 1939, and in the same year was named a Putnam Fellow. While there, Feynman took every physics course offered, including a graduate course on theoretical physics while only in his second year. He obtained a perfect score on the entrance exams to Princeton University in mathematics and physics—an unprecedented feat—but did rather poorly on the history and English portions. Attendees at Feynman's first seminar included the luminaries Albert Einstein, Wolfgang Pauli, and John von Neumann. He received a Ph.D. from Princeton University in 1942; his thesis advisor was John Archibald Wheeler. Feynman's thesis applied the principle of stationary action to problems of quantum mechanics, laying the ground work for the "path integral" approach and Feynman diagrams.

This was Richard Feynman nearing the crest of his powers. At twenty-three … there was no physicist on earth who could match his exuberant command over the native materials of theoretical science. It was not just a facility at mathematics (though it had become clear … that the mathematical machinery emerging from the Wheeler-Feynman collaboration was beyond Wheeler's own ability). Feynman seemed to possess a frightening ease with the substance behind the equations, like Albert Einstein at the same age, like the Soviet physicist Lev Landau—but few others.

James Gleick , Genius: The Life and Science of Richard Feynman

While researching his Ph.D., Feynman married his first wife, Arline Greenbaum. (Arline's name is often spelled Arlene). Arline was diagnosed with tuberculosis, a terminal illness at that time, but she and Feynman were careful, and he never contracted the disease.

### The Manhattan Project

Feynman (center) with Robert Oppenheimer (right) relaxing at a Los Alamos social function during the Manhattan Project.

At Princeton, the physicist Robert R. Wilson encouraged Feynman to participate in the Manhattan Project—the wartime U.S. Army project at Los Alamos developing the atomic bomb. Feynman said he was persuaded to join this effort to build it before Nazi Germany. He was assigned to Hans Bethe's theoretical division, and impressed Bethe enough to be made a group leader. Together with Bethe, he developed the Bethe-Feynman formula for calculating the yield of a fission bomb, which built upon previous work by Robert Serber. Until his wife's death on June 16, 1945, he visited her in a sanatorium in Albuquerque each weekend. He immersed himself in work on the project, and was present at the Trinity bomb test. Feynman claimed to be the only person to see the explosion without the very dark glasses provided, reasoning that it was safe to look through a truck windshield, as it would screen out the harmful ultraviolet radiation.

As a junior physicist, he was not central to the project. The greater part of his work was administering the computation group of human computers in the Theoretical division (one of his students there, John G. Kemeny, would later go on to co-write the computer language BASIC). Later, with Nicholas Metropolis, he assisted in establishing the system for using IBM punch cards for computation. Feynman succeeded in solving one of the equations for the project that were posted on the blackboards.

Feynman's other work at Los Alamos included calculating neutron equations for the Los Alamos "Water Boiler," a small nuclear reactor, to measure how close an assembly of fissile material was to criticality. On completing this work he was transferred to the Oak Ridge facility, where he aided engineers in calculating safety procedures for material storage, so that inadvertent criticality accidents (for example, storing subcritical amounts of fissile material in proximity on opposite sides of a wall) could be avoided. He also did theoretical work and calculations on the proposed uranium-hydride bomb, which later proved to be infeasible.

Feynman was sought out by physicist Niels Bohr for one-on-one discussions. He later discovered the reason: most physicists were too in awe of Bohr to argue with him. Feynman had no such inhibitions, vigorously pointing out anything he considered to be flawed in Bohr's thinking. Feynman said he felt as much respect for Bohr as anyone else, but once anyone got him talking about physics, he would forget about anything else.

Due to the top secret nature of the work, Los Alamos was isolated. In his own words, "There wasn't anything to do there." Bored, Feynman indulged his curiosity by learning to pick the combination locks on cabinets and desks used to secure papers. Feynman played many jokes on colleagues. In one case he found the combination to a locked filing cabinet by trying the numbers a physicist would use (it proved to be 27-18-28 after the base of natural logarithms, e = 2.71828…), and found that the three filing cabinets where a colleague kept a set of atomic bomb research notes all had the same combination. He left a series of notes as a prank, which initially spooked his colleague into thinking a spy or saboteur had gained access to atomic bomb secrets (coincidentally, Feynman once borrowed the car of physicist Klaus Fuchs who was later discovered to be a spy for the Soviet Union).

On occasion, Feynman would find an isolated section of the mesa to drum in the style of American natives; "and maybe I would dance and chant, a little." These antics did not go unnoticed, and rumors spread about a mysterious Indian drummer called "Injun Joe." He also became a friend of laboratory head J. Robert Oppenheimer, who unsuccessfully tried to court him away from his other commitments to work at the University of California, Berkeley after the war.

Feynman alludes to his thoughts on the justification for getting involved in the Manhattan Project in his book The pleasure of finding things out. As mentioned earlier, he felt the possibility of Nazi Germany developing the bomb before the Allies was a compelling reason to help with its development for the U.S. However he goes on to say that it was an error on his part not to reconsider the situation when Germany was defeated. In the same publication Feynman also talks about his worries in the atomic bomb age, feeling for some considerable time that there was a high risk that the bomb would be used again soon so that it was pointless to, for example, build for the future. Later he describes this period as a 'depression.'

### Early career

After the project concluded, Feynman began work as a professor at Cornell University, where Hans Bethe (who proved that the sun's source of energy was nuclear fusion) worked. However, he felt uninspired there; despairing that he had burned out, he turned to less useful, but fun problems, such as analyzing the physics of a twirling, nutating dish, as it is being balanced by a juggler. (As it turned out, this work served him well in future research.) He was therefore surprised to be offered professorships from competing universities, eventually choosing to work at the California Institute of Technology at Pasadena, California, despite being offered a position near Princeton, at the Institute for Advanced Study (which included such distinguished faculty members as Albert Einstein).

Feynman rejected the Institute on the grounds that there were no teaching duties. Feynman found his students to be a source of inspiration and, during uncreative times, comfort. He felt that if he could not be creative, at least he could teach. Another major factor in his decision was a desire to live in a mild climate, a goal he chose while having to put snow chains on his car's wheels in the middle of a snowstorm in Ithaca, New York.

Feynman has been called the "Great Explainer"; he gained a reputation for taking great care when giving explanations to his students, and for assigning himself a moral duty to make the topic accessible. His principle was that if a topic could not be explained in a freshman lecture, it was not yet fully understood. Feynman gained great pleasure [16]from coming up with such a "freshman level" explanation of the connection between spin and statistics (that groups of particles with spin 1/2 "repel," whereas groups with integer spin "clump," i.e., Fermi-Dirac statistics and Bose-Einstein statistics as consequence of how fermions and bosons behave under a rotation of 360 degrees), a question he pondered in his own lectures and to which he demonstrated the solution in the 1986 Dirac memorial lecture.[17] In the same lecture he explained that antiparticles exist since if particles only had positive energies they would not be restricted to a light cone. He opposed rote learning and other teaching methods that emphasized form over function, everywhere from a conference on education in Brazil to a state commission on school textbook selection. Clear thinking and clear presentation were fundamental prerequisites for his attention. It could be perilous to even approach him when unprepared, and he did not forget the fools or pretenders.[18]

During one sabbatical year, he returned to Newton's Principia Mathematica to study it anew; what he learned from Newton, he passed along to his students, such as Newton's attempted explanation of diffraction.

### The Caltech years

Feynman did significant work while at Caltech, including research in:

• Quantum electrodynamics. The theory for which Feynman won his Nobel Prize is known for its accurate predictions.[19][20] He helped develop a functional integral formulation of quantum mechanics, in which every possible path from one state to the next is considered, the final path being a sum over the possibilities (also referred to as Sum-over-paths or Sum over histories).[21]
• Physics of the superfluidity of supercooled liquid helium, where helium seems to display a lack of viscosity when flowing. Applying the Schrödinger equation to the question showed that the superfluid was displaying quantum mechanical behavior observable on a macroscopic scale. This helped with the problem of superconductivity; however, the solution eluded Feynman. It was solved with the BCS theory.
• A model of weak decay, which showed that the current coupling in the process is a combination of vector and axial (an example of weak decay is the decay of a neutron into an electron, a proton, and an anti-neutrino). Although E.C. George Sudharsan and Robert Marshak developed the theory nearly simultaneously, Feynman's collaboration with Murray Gell-Mann was seen as seminal because the weak interaction was neatly described by the vector and axial currents. It thus combined the 1933 beta decay theory of Fermi with an explanation of parity violation.

He also developed Feynman diagrams, a bookkeeping device which helps in conceptualizing and calculating interactions between particles in spacetime, notably the interactions between electrons and their antimatter counterparts, positrons. This device allowed him, and later others, to approach time reversibility and other fundamental processes. Feynman famously painted Feynman diagrams on the exterior of his van.

Feynman diagrams are now fundamental for string theory and M-theory, and have even been extended topologically. Feynman's mental picture for these diagrams started with the hard sphere approximation, and the interactions could be thought of as collisions at first. It was not until decades later that physicists thought of analyzing the nodes of the Feynman diagrams more closely. The world-lines of the diagrams have developed to become tubes to allow better modelling of more complicated objects such as strings and M-branes.

From his diagrams of a small number of particles interacting in spacetime, Feynman could then model all of physics in terms of those particles' spins and the range of coupling of the fundamental forces.[22] Feynman attempted an explanation of the strong interactions governing nucleons scattering called the parton model. The Parton model emerged as a rival to the quark model developed by his Caltech colleague Murray Gell-Mann. The relationship between the two models was murky; Gell-Mann referred to Feynman's partons derisively as "put-ons." Feynman did not dispute the quark model; for example, when the fifth quark was discovered, Feynman immediately pointed out to his students that the discovery implied the existence of a sixth quark, which was duly discovered in the decade after his death.

After the success of quantum electrodynamics, Feynman turned to quantum gravity. By analogy with the photon, which has spin 1, he investigated the consequences of a free massless spin 2 field, and was able to derive the Einstein field equation of general relativity, but little more.[23] However, a calculational technique that Feynman developed for gravity in 1962 — "ghosts" — later proved invaluable for explaining the quantum theory of the weak and strong forces, the other two fundamental interactions in nature. In 1967, Fadeev and Popov quantized the particle behavior of the spin 1 theories of Yang-Mills-Shaw-Pauli, that are now seen to describe the weak and strong interactions, using Feynman's path integral technique but including also Feynman's "ghost" particles to conserve probability.

At this time, in the early 1960s Feynman exhausted himself by working on multiple major projects at the same time, including his Feynman Lectures on Physics: while at Caltech, Feynman was asked to "spruce up" the teaching of undergraduates. After three years devoted to the task, he produced a series of lectures that would eventually become the Feynman Lectures on Physics, one reason that Feynman is still regarded as one of the greatest teachers of physics. He wanted a picture of a drumhead sprinkled with powder to show the modes of vibration at the beginning of the book. Outraged by many Rock and Roll and drug connections that one could make from the image, the publishers changed the cover to a picture of him playing drums. Feynman later won the Oersted Medal for teaching, of which he seemed especially proud. His students competed keenly for his attention; one night he was awakened when a student solved a problem and dropped it in his mailbox; glimpsing the student sneaking across his lawn, he could not go back to sleep, and he read the student's solution. The next morning his breakfast was interrupted by another triumphant student, but Feynman informed him that he was too late.

Partly as a way to bring publicity to progress in physics, Feynman offered $1000 prizes for two of his challenges in nanotechnology, claimed by William McLellan and Tom Newman, respectively.[24] He was also one of the first scientists to conceive the possibility of quantum computers. Many of his lectures and other miscellaneous talks were turned into books, including The Character of Physical Law and QED: The Strange Theory of Light and Matter. He gave lectures which his students annotated into books, such as Statistical Mechanics and Lectures on Gravity. The Feynman Lectures on Physics[25] required two physicists, Robert B. Leighton and Matthew Sands as full-time editors for several years. Even though they were not adopted by the universities as textbooks, these books continue to be bestsellers because they provide a deep understanding of physics. As of 2005, The Feynman Lectures on Physics have sold over 1.5 million copies in English, an estimated one million copies in Russian, and an estimated half million copies in other languages. In 1974 Feynman delivered the Caltech commencement address on the topic of cargo cult science, which has the semblance of science but is only pseudoscience due to a lack of "a kind of scientific integrity, a principle of scientific thought that corresponds to a kind of utter honesty" on the part of the scientist. He instructed the graduating class that "The first principle is that you must not fool yourself—and you are the easiest person to fool. So you have to be very careful about that. After you've not fooled yourself, it's easy not to fool other scientists. You just have to be honest in a conventional way after that."[26] In the late 1970s, according to "Richard Feynman and the Connection Machine," Feynman played a critical role in developing the first parallel processing computer and finding innovative uses for it in numerical computing and building neural networks, as well as physical simulation with cellular automata (such as turbulent fluid flow), working with Stephen Wolfram at Caltech.[27] Shortly before his death, Feynman criticized string theory in an interview: "I don't like that they're not calculating anything," he said. "I don't like that they don't check their ideas. I don't like that for anything that disagrees with an experiment, they cook up an explanation—a fix-up to say, 'Well, it still might be true.'" These words have since been much-quoted by opponents of the string-theoretic direction for particle physics. ### Personal life He was married a second time in June 1952, to Mary Louise Bell of Neodesha, Kansas; this marriage was brief and unsuccessful. He later married Gweneth Howarth from the United Kingdom, who shared his enthusiasm for life and spirited adventure. Besides their home in Altadena, California, they had a beach house in Baja California, that latter of which was purchased with the prize money from Feynman's Nobel Prize, at that time$55,000 (of which Feynman was entitled to a third). They remained married until Feynman's death. They had a son, Carl, in 1962, and adopted a daughter, Michelle, in 1968.[28]

Feynman had a great deal of success teaching Carl using discussions about ants and Martians as a device for gaining perspective on problems and issues; he was surprised to learn that the same teaching devices were not useful with Michelle. Mathematics was a common interest for father and son; they both entered the computer field as consultants and were involved in advancing a new method of using multiple computers to solve complex problems—later known as parallel computing. The Jet Propulsion Laboratory retained Feynman as a computational consultant during critical missions. One coworker characterized Feynman as akin to Don Quixote at his desk, rather than at a computer workstation, ready to do battle with the windmills.

According to his colleague, Professor Steven Frautschi, Feynman was the only person in the Altadena region to buy flood insurance after the massive 1978 fire, predicting correctly that the fire's destruction would lead to land erosion, causing mudslides and flooding. The flood occurred in 1979 after winter rains and destroyed multiple houses in the neighborhood. Feynman's use of insurance, an inherently future-looking device, was not only fortunate but ironic in light of his depiction of his outlook following the Manhattan Project. Feynman wrote that in the years following the development and use of the atomic bomb, whenever seeing the construction of a bridge or a new building, he was unavoidably struck by the thought that the labor was futile and in vain, as the human race would soon be undone by the bomb.

Feynman traveled a great deal, notably to Brazil, and near the end of his life schemed to visit the Russian land of Tuva, a dream that, due to Cold War bureaucratic problems, never became reality.[29] Ironically, the day after he died, a letter arrived for him from the Soviet government giving him authorization to travel to Tuva. During this period he discovered that he had a form of cancer, but, thanks to surgery, he managed to hold it off. Out of his enthusiastic interest in reaching Tuva came the phrase "Tuva or Bust" (also the title of a book about his efforts to get there), which was tossed about frequently amongst his circle of friends in hope that they, one day, could see it firsthand. The documentary movie Genghis Blues (1999) mentions some of his attempts to communicate with Tuva and chronicles the journey when some of his friends did make it there. His attempts to circumvent the complex Soviet bureaucratic system which kept Tuva sealed, and also his attempts to write and send a letter using an English-Russian and Russian-Tuvan dictionary, as well as his earlier efforts to translate Mayan hieroglyphics, all demonstrate his life-long addiction to solving puzzles, locks, and cyphers. At the time, they also earned him a reputation for eccentricity.

Feynman did not work only on physics, and had a large circle of friends from all walks of life, including the arts. He took up drawing at one time and enjoyed some success under the pseudonym "Ofey," culminating in an exhibition dedicated to his work. He learned to play drums (frigideira) in a samba style in Brazil by dint of persistence and practice, and participated in a samba school. Apparently Feynman did not much appreciate orchestral music, but he had a keen sense of rhythm and timing which extended to a personal timekeeping center in his brain which let him operate without ever needing a watch. In addition, he had some degree of synesthesia for numbers and equations, explaining that certain mathematic functions appeared in color for him, even though invariably actually printed in standard black-and-white.

According to the James Gleick biography, Genius, Richard Feynman experimented with LSD during his professorship at Caltech.[13] Somewhat embarrassed by his actions, Feynman sidestepped the issue when dictating his anecdotes; consequently, the "Altered States" chapter in Surely You're Joking, Mr. Feynman! describes only marijuana and ketamine experiences at John Lilly's famed sensory deprivation tanks, as a way of studying consciousness. Feynman gave up alcohol when he began to show early signs of alcoholism, as he did not want to do anything that could damage his brain.

In Surely You're Joking, Mr. Feynman!, he gives advice on the best way to pick up a girl in a hostess bar. At Caltech, he used a nude/topless bar as an office away from his usual office, making sketches or writing physics equations on paper placemats. When the county officials tried to close the locale, all visitors except Feynman refused to testify in favor of the bar, fearing that their families or patrons would learn about their visits. Only Feynman accepted, and in court, he affirmed that the bar was a public need, stating that craftsmen, technicians, engineers, common workers "and a physics professor" frequented the establishment. While the bar lost the court case, it was allowed to remain open as a similar case was pending appeal.

Feynman served on the presidential commission investigating the 1986 Challenger disaster. He concluded that NASA management's space shuttle reliability estimate was fantastically unrealistic. He warned in his appendix to the commission's report: "For a successful technology, reality must take precedence over public relations, for nature cannot be fooled."

## Challenger Disaster

Feynman was requested to serve on the Presidential Rogers Commission which investigated the Challenger disaster of 1986. Feynman devoted the latter half of his book What Do You Care What Other People Think? to his experience on the Rogers Commission, straying from his usual convention of brief, light-hearted anecdotes to deliver an extended and sober narrative. Feynman's account reveals a disconnect between NASA's engineers and executives that was far more striking than he expected. His interviews of NASA's high-ranking managers revealed startling misunderstandings of elementary concepts.

In one example, early tests resulted in some of the booster rocket's o-rings burning a third of the way through. These o-rings provided the gas-tight seal needed between the vertically stacked cylindrical sections that made up the solid fuel booster. NASA managers recorded this result as demonstrating that the o-rings had a "safety factor" of 3. Feynman incredulously explains the magnitude of this error: a "safety factor" refers to the practice of building an object to be capable of withstanding more force than it will ever conceivably be subjected to. To paraphrase Feynman's example, if engineers built a bridge that could bear 3000 pounds without any damage, even though it was never expected to bear more than 1000 pounds in practice, the safety factor would be 3. If, however, a truck drove across the bridge and it cracked at all, the safety factor is now zero: the bridge is defective.

Feynman was clearly disturbed by the fact that NASA management not only misunderstood this concept, but in fact inverted it by using a term denoting an extra level of safety to describe a part that was actually defective and unsafe. Feynman continued to investigate the lack of communication between NASA's management and its engineers and was struck by the management's claim that the risk of catastrophic malfunction on the shuttle was 1 in 105; i.e., 1 in 100,000. Feynman immediately realized that this claim was risible on its face; as he described, this assessment of risk would entail that we could launch a shuttle every day for the next 274 years without an accident. Investigating the claim further, Feynman discovered that the 1 in 105 figure was reached by the highly dubious method of attempting to calculate the probability of failure of every individual part of the shuttle, and then adding these estimates together. This method is erroneous by standard probability theory: the correct way to calculate such risk is to subtract each individual factor's failure risk from unity and then multiply all differences. The product will be the net safety factor and the difference between it and unity, the net risk factor.

Feynman was disturbed by two aspects of this practice. First, NASA management assigned a probability of failure to each individual bolt, sometimes claiming a probability of 1 in 108; that is, one in one hundred million. Feynman pointed out that it is impossible to calculate such a remote possibility with any scientific rigor. Secondly, Feynman was bothered not just by this sloppy science but by the fact that NASA claimed that the risk of catastrophic failure was "necessarily" 1 in 105. As the figure itself was beyond belief, Feynman questioned exactly what "necessarily" meant in this context—did it mean that the figure followed logically from other calculations, or did it reflect NASA management's desire to make the numbers fit?

Feynman suspected that the 1/100,000 figure was wildly fantastical, and made a rough estimate that the true likelihood of shuttle disaster was closer to 1 in 100. He then decided to poll the engineers themselves, asking them to write down an anonymous estimate of the odds of shuttle explosion. Feynman found that the bulk of the engineers' estimates fell between 1 in 50 and 1 in 100. Not only did this confirm that NASA management had clearly failed to communicate with their own engineers, but the disparity engaged Feynman's emotions. When describing these wildly differing estimates, Feynman briefly lapses from his damaging but dispassionate detailing of NASA's flaws to recognize the moral failing that resulted from a scientific failing: he was clearly upset that NASA presented its clearly fantastical figures as fact to convince a member of the public, schoolteacher Christa McAuliffe, to join the crew. Feynman was not uncomfortable with the concept of a 1/100 risk, but felt strongly that the recruitment of laypeople required an honest portrayal of the real risk involved.

Feynman's investigation eventually suggested to him that the cause of the Challenger explosion was the very part to which NASA management so mistakenly assigned a safety factor. The o-rings were rubber rings designed to form a seal in the shuttle's solid rocket boosters, preventing the rockets' super-heated gas from escaping and damaging other parts of the vehicle. Feynman suspected that despite NASA's claims, the o-rings were unsuitable at low temperatures and lost their resilience when cold, thus failing to expand and maintain a tight seal when rocket pressure distorted the structure of the solid fuel booster. Feynman's suspicions were corroborated by General Kutyna also on the commission who cunningly provided Feynman with a broad hint by asking about the effect of cold on o-ring seals after mentioning that the temperature on the day of the launch was far lower than had been the case with previous launches: below freezing at 28 or 29 Fahrenheit (-2.2 to -1.6 °C); previously, the coldest launch had been at 53 °F (12°C).

Feynman obtained samples of the seals used on the Challenger by dismantling a model supplied to the commission intending to test the resilience of the seals at low temperature in front of the TV cameras, but in an act that he claims to have been ashamed of, ran the test first in private to ensure that it was indeed the case that low temperature reduced the resilience of the rubber as he suspected.

When testifying before Congress, Feynman questioned a NASA manager with seeming innocence, focusing on the cold temperatures that the o-rings could be subjected to while remaining resilient (i.e., effective). The NASA manager insisted that o-rings would retain their resilience even in extreme cold. But Feynman managed to obtain a glass of iced water, and used it to cool a section of o-ring seal clamped flat with a small clamp he had purchased earlier at a hardware store.

After receiving repeated assurances that the o-rings would remain resilient at subzero temperatures, and at an opportune moment selected by Kutyna during a particular NASA slide-show, Feynman took the o-ring out of the water and removed the vise, revealing that the o-ring remained flattened, demonstrating a lack of resilience at 32 °F (0 °C), warmer than the launch temperature.[30] While Feynman worried that the audience did not realize the importance of his action, The New York Times picked the story up, crediting Feynman for his ruse, and earning him a small measure of fame.

Feynman's investigations also revealed that there had been many serious doubts raised about the o-ring seals by engineers at Morton Thiokol, which made the solid fuel boosters, but communication failures had led to their concerns being ignored by NASA management. He found similar failures in procedure in many other areas at NASA, but singled out its software development for praise due to its rigorous and highly effective quality procedures which were under threat from NASA management which wished to reduce testing to save money since the tests were always passed.

Based on his experiences with NASA's management and engineers, Feynman concluded that the serious deficiencies in NASA management's scientific understanding, the lack of communication between the two camps, and the gross misrepresentation of the shuttle's dangers required that NASA take a hiatus from shuttle launches until it could resolve its internal inconsistencies and present an honest picture of the shuttle's reliability. Feynman soon found that, while he respected the intellects of his fellow Commission members, they universally finished their criticisms of NASA with clear affirmations that the Challenger disaster should be addressed by NASA internally, but that there was no need for NASA to suspend its operations or to receive less funding. Feynman felt that the Commission's conclusions were not compatible with its findings, and could not in good conscience recommend that such a deeply flawed organization should continue without a suspension of operations and a major overhaul. His fellow commission members were alarmed by Feynman's dissension, and it was only after much petitioning that Feynman's minority report was included at all: as an appendix to the official document. Feynman's book What Do You Care What Other People Think? included a copyedited version of the appendix in addition to his narrative account.

It was announced in May 2006 that a movie would be made about the disaster. Challenger, directed by Philip Kaufman—whose 1983 film The Right Stuff chronicled the early history of the space program—will focus on the role of Feynman in the ensuing investigation. David Strathairn will play Dr. Feynman.[31]

## Commemorations

On May 4, 2005 the United States Postal Service issued the American Scientists commemorative set of four 37-cent self-adhesive stamps in several configurations. The scientists depicted were Richard Feynman, John von Neumann, Barbara McClintock, and Josiah Willard Gibbs. Feynman's stamp, sepia-toned, features a photograph of a 30-something Feynman and eight small Feynman diagrams.

A shuttlecraft named after Feynman appeared in two episodes of the science fiction television show Star Trek: The Next Generation ("The Nth Degree," 1991; "Chain of Command, Part 1," 1992). An error in the art department, however, caused the shuttle name to be misspelled, "FEYMAN."

Feynman appears in the fiction book The Diamond Age as one of the heroes of the world where nanotechnology is ubiquitous.

His relationship with his first wife Arline, who died during the Manhattan Project, is portrayed in the 1996 movie Infinity.

Apple's "Think Different" ad campaign featured photo portraits of Feynman that appeared in magazines and on posters and billboards. One showed him in his early days as a teacher at Caltech. The other showed him toward the end of his life. That ad shows Feynman wearing a Thinking Machines T-shirt (see the photo which heads this article), a company where he had served as a consultant.

The main building for the Computing Division at Fermilab, the FCC, is named in his honor: The "Feynman Computing Center."

The play "QED," written by Peter Parnell, portrays Feynman near the end of his life. Alan Alda played Feynman in a series of productions of the play in 2001 and 2002.

• Feynman point
• Feynman diagram
• Feynman Long Division Puzzles
• Feynman sprinkler
• Foresight Nanotech Institute Feynman Prize
• List of physicists
• List of theoretical physicists
• Stückelberg–Feynman interpretation
• Wheeler–Feynman absorber theory
• Hellmann–Feynman theorem
• Flexagon
• One-electron universe

## Notes

1. Jacob West, 2000-04-28, The Quantum Computer. accessdate 2007-09-20
2. Steven Alan Edwards. The Nanotech Pioneers. (Germany: WILEY-VCH, 2006), 15-17. ISBN 978-3527312900
3. Richard Phillips Feynman and Jeffrey Robbins. 1999. The pleasure of finding things out: the best short works of Richard P. Feynman. (Cambridge, MA: Perseus Books. ISBN 0738201081).
4. Richard Phillips Feynman, Robert B. Leighton, and Matthew L. Sands. 1963. The Feynman lectures on physics. (Reading, MA: Addison-Wesley Pub. Co. ISBN 0201020106)
5. Feynman, Richard Phillips, Ralph Leighton, and Edward Hutchings. 1985. "Surely you're joking, Mr. Feynman!": adventures of a curious character. (New York: W.W. Norton. ISBN 0393019217).
6. Richard Phillips Feynman and Ralph Leighton. 1988. What do YOU care what other people think?: further adventures of a curious character. (New York: Norton. ISBN 0393026590.)
7. Ralph Leighton. 1991. Tuva or bust!: Richard Feynman's last journey. (New York: W.W. Norton. ISBN 0393029530.)
8. Richard Phillips Feynman, Christopher Skyes. 1996. No Ordinary Genius: The Illustrated Richard Feynman. (New York, NY: W.W. Norton & Co. ISBN 039331393X). Retrieved September 26, 2007.
9. Richard Phillips Feynman. QED: the strange theory of light and matter. (Alix G. Mautner memorial lectures.) (Princeton, NJ: Princeton University Press, 1988. ISBN 0691024170).
10. 1972. Richard P. Feynman: The Nobel Prize in Physics 1965, Biography. Nobelprize.org. Retrieved September 26, 2007.
11. J.J. O'Connor, E.F. Robertson. 2002. Richard Phillips Feynman. University of St. Andrews. Retrieved September 26, 2007.
12. Feynman and Leighton, 1985; Feynman and Leighton, 1988
13. 13.0 13.1 13.2 James Gleick. Genius: The Life and Science of Richard Feynman. (Pantheon, 1992. ISBN 0679408363), 30
14. Gleick.
15. "He [Feynman] had also applied for entrance to Columbia University but it seems that because of the Jewish quota prevalent at the time he was not accepted…" Kimball A. Milton, Jagdish Mehra. Climbing the Mountain: The Scientific Biography of Julian Schwinger. (Oxford University Press, 2003, ISBN 0198506589), 218.
16. Tony Hey and Patrick Walters. The quantum universe. (Cambridge University Press, 1987, ISBN 0521318459)
17. Richard P. Feynman and Steven Weinberg. Elementary Particles and the Laws of Physics: The 1986 Dirac Memorial Lectures. (Cambridge University Press, 1987, ISBN 0521340004
18. Hans A. Bethe. The Road from Los Alamos. (Masters of Modern Physics vol. 2) (New York: Simon and Schuster, 1991, ISBN 0671740121), 241.
19. Cecilia Jarlskog, Background information on the 1999 Nobel Prize in Physics, the Royal Swedish Academy of Sciences. Retrieved September 23, 2007.
20. Bethe, Bloch, Dirac, Dyson, Feynman, Fermi, Heisenberg, Jordan, Klein, Lamb, Oppenheimer, Pauli, Rutherford, Schwinger, Tomonaga, Weisskopf, Wigner, et al. Selected Papers on Quantum Electrodynamics, edited by Julian Schwinger, (New York: Dover, 1958, ISBN 0486604446)
21. Feynman and Albert R. Hibbs. Quantum Mechanics and Path Integrals. (New York: McGraw Hill, 1965. ISBN 0070206503)
22. Richard P. Feynman. Theory of Fundamental Processes. (Series of lectures given at California Institute of Technology, 1959-1960) (Addison Wesley, 1961. ISBN 0805325077)
23. Richard P. Feynman. Feynman Lectures on Gravitation, edited by Fernando Morinigo. (1995) (Boulder, CO: Westview Press, 2002. ISBN 0813340381)
24. John Gribbin. Richard Feynman: A Life in Science. (Dutton, 1997), 170.
25. The Feynman Lectures on Physics: The Definitive and Extended Edition. (with Leighton and Sands). Originally published as separate volumes in 1964 and 1966, and as a set since 1970. 3 vols., (Addison Wesley, 2nd edition 2005, ISBN 0805390456). Includes "Feynman’s Tips on Physics," a set of four previously unreleased lectures on problem solving.
26. Richard P. Feynman, 1974. Cargo Cult Science. Engineering and Science 37:7. Retrieved September 26, 2007.
27. W. Daniel Hillis, Richard Feynman and The Connection Machine. Physics Today (1989) accessdate September 20, 2007
28. Richard P. Feynman. Perfectly Reasonable Deviations from the Beaten Track: The Letters of Richard P. Feynman, edited by Michelle Feynman, foreword by Timothy Ferris, (New York: Basic Books, 2005. ISBN 0738206369).
29. Tuva Or Bust!, Ralph Leighton, (New York: W. W. Norton & Company, 2000. ISBN 0393320693)
30. James Gleick,"Richard Feynman Dead at 69; Leading Theoretical Physicist" New York Times, February 17, 1988.
31. Media 8 To Produce "Challenger" Directed by Philip Kaufman. May 24, 2006, accessdate 2007-09-21.

## References

• Bethe, Hans A. The Road from Los Alamos. (Masters of Modern Physics vol. 2) New York: Simon and Schuster, 1991, ISBN 0671740121.
• Edwards, Steven Alan. The Nanotech Pioneers. Germany: WILEY-VCH, 2006, ISBN 978-3527312900.
• Feynman, Christopher Skyes. 1996. No Ordinary Genius: The Illustrated Richard Feynman. New York, NY: W.W. Norton & Co. ISBN 039331393X.
• Feynman, Richard. 1967. The Character of Physical Law, The 1964 Messenger Lectures. Cambridge, MA: MIT Press. ISBN 0262560038.
• __________. Perfectly Reasonable Deviations from the Beaten Track: The Letters of Richard P. Feynman, edited by Michelle Feynman, foreword by Timothy Ferris. New York: Basic Books, 2005. ISBN 0738206369.
• __________. 1985. Quantum Electrodynamics. Upper Saddle River, NJ: Addison Wesley. ISBN 0805325018.
• __________. 1997. Six Not So Easy Pieces: Einstein’s Relativity, Symmetry and Space-Time. Upper Saddle River, NJ: Addison Wesley. ISBN 0201150263.
• __________. Theory of Fundamental Processes. (Series of lectures given at California Institute of Technology, 1959-1960) Addison Wesley, 1961. ISBN 0805325077.
• Feynman, Robert B. Leighton, and Matthew L. Sands. 1963. The Feynman lectures on physics. Reading, MA: Addison-Wesley Pub. Co. ISBN 0201020106.
• Feynman, Richard, and Steven Weinberg. 1987. Elementary Particles and the Laws of Physics: The 1986 Dirac Memorial Lectures. Cambridge, UK: Cambridge University Press. ISBN 0521340004.
• Feynman, Richard, Robert B. Leighton, and Matthew Sands. 1994. Six Easy Pieces: Essentials of Physics Explained by Its Most Brilliant Teacher. Jackson, TN: Perseus Books. ISBN 0201409550.
• Feynman and Albert R. Hibbs. Quantum Mechanics and Path Integrals. (New York: McGraw Hill, 1965. ISBN 0070206503
• Feynman, and Jeffrey Robbins. 1999. The pleasure of finding things out: the best short works of Richard P. Feynman. Cambridge, MA: Perseus Books. ISBN 0738201081.
• Gleick, James. 1992. Genius: The Life and Science of Richard Feynman. Pantheon, ISBN 0679408363.
• Gribbin, John, and Mary Gribbin. 1997. Richard Feynman: A Life in Science. New York, NY: Dutton (Penguin). ISBN 052594124X.
• Leighton, Ralph. 1991. Tuva or bust!: Richard Feynman's last journey. New York: W.W. Norton. ISBN 0393029530.
• Milton, Kimball A., and Jagdish Mehra. Climbing the Mountain: The Scientific Biography of Julian Schwinger. Oxford University Press, 2003, ISBN 0198506589.

The Feynman Lectures on Physics are perhaps his most accessible work for anyone with an interest in physics, compiled from lectures to Caltech undergraduates in 1962. As news of the lectures' lucidity grew, a large number of professional physicists began to drop in to listen. Physicist Robert B. Leighton edited them into book form. The work has endured, and is useful to this day. They were edited and supplemented in 2005 with "Feynman's Tips on Physics: A Problem-Solving Supplement to the Feynman Lectures on Physics" by Michael Gottlieb and Ralph Leighton (Robert Leighton's son), with support from Kip Thorne and other physicists.

### Popular works by and about Feynman

• Feynman, Richard. 1994. The Character of Physical Law. New York, NY: Modern Library. ISBN 0679601279. - A book of some of Feynman's lectures on the Laws of Physics.
• Dyson, Freeman J., 1979. Disturbing the Universe. New York, NY: Harper and Row. ISBN 0-06-011108-9. Dyson’s autobiography. The chapters “A Scientific Apprenticeship” and “A Ride to Albuquerque” describe his impressions of Feynman in the period 1947-48 when Dyson was a graduate student at Cornell.
• Physics Today, American Institute of Physics magazine. February 1989 Issue. 42:2. Special Feynman memorial issue containing non-technical articles on Feynman's life and work in physics.
• Feynman, Richard, Ralph Leighton, ed. 2005. Classic Feynman: All the Adventures of a Curious Character. New York, NY: W.W. Norton. ISBN 0-393-06132-9. Chronologically reordered omnibus volume of Surely You’re Joking, Mr. Feynman and What Do You Care What Other People Think?, with a bundled CD containing one of Feynman’s signature lectures.
• Feynman, Richard, Michelle Feynman. 2005. Don't You Have Time to Think?. New York, NY: Allen Lane. ISBN 0-7139-9847-4.
• Mlodinow, Leonard. 2003. Feynman's Rainbow, A Search For Beauty In Physics And In Life. Clayton, AU: Warner Books. ISBN 0-446-69251-4
• Gribbin, John, Mary Gribbin. 1997. Richard Feynman, A Life in Science. New York, NY: Plume. ISBN 0452276314.

### Audio recordings

• Safecracker Suite (a collection of drum pieces interspersed with Feynman telling anecdotes)
• Six Easy Pieces (original lectures upon which the book is based)
• Six Not So Easy Pieces (original lectures upon which the book is based)
• The Feynman Lectures on Physics: The Complete Audio Collection
• Quantum Mechanics, Volume 1
• Advanced Quantum Mechanics, Volume 2
• From Crystal Structure to Magnetism, Volume 3
• Electrical and Magnetic Behavior, Volume 4
• Feynman on Fundamentals: Energy and Motion, Volume 5
• Feynman on Fundamentals: Kinetics and Heat, Volume 6
• Feynman on Science and Vision, Volume 7
• Feynman on Gravity, Relativity and Electromagnetism, Volume 8
• Basic Concepts in Classical Physics, Volume 9
• Basic Concepts in Quantum Physics, Volume 10
• Feynman on Science and Vision, Volume 11
• Feynman on Sound, Volume 12
• Feynman on Fields, Volume 13
• Feynman on Electricity and Magnetism, Part 1, Volume 14
• Feynman on Electricity and Magnetism, Part 2, Volume 15
• Feynman on Electromagnetism, Volume 16
• Feynman on Electrodynamics, Volume 17
• Feynman on Flow, Volume 18
• Masers and Light, Volume 19
• The Very Best Lectures, Volume 20
• Samples of Feynman's drumming, chanting and speech are included in the songs "Tuva Groove (Bolur Daa-Bol, Bolbas Daa-Bol)" and "Kargyraa Rap (Dürgen Chugaa)" on the album Back Tuva Future, The Adventure Continues by Kongar-ol Ondar. The hidden track on this album also includes excerpts from lectures without musical background.

### Video recordings

• The Messenger Lectures (1964)
• The Law of Gravitation
• The Relation of Mathematics to Physics
• The Great Conservation Principles
• Symmetry in Physical Law
• The Distinction of Past and Future
• Probability and Uncertainty - The Quantum Mechanical View of Nature
• Seeking New Laws
• Take the world from another point of view [videorecording] / with Richard Feynman ; Films for the Hu (1972)
• QED in New Zealand (1979)
• Elementary Particles and the Laws of Physics (1986)
• The Last Journey of a Genius [videorecording] / a BBC TV production in association with WGBH Boston (1989)