Theoretical physics is a branch of physics that employs mathematical models and abstractions of physical objects and systems to rationalize, explain, and predict natural phenomena . This is in contrast to experimental physics , which uses experimental tools to probe these phenomena.
118-424: Richard Phillips Feynman ( / ˈ f aɪ n m ə n / ; May 11, 1918 – February 15, 1988) was an American theoretical physicist . He is best known for his work in the path integral formulation of quantum mechanics , the theory of quantum electrodynamics , the physics of the superfluidity of supercooled liquid helium , and in particle physics , for which he proposed the parton model . For his contributions to
236-549: A luminiferous aether . Conversely, Einstein was awarded the Nobel Prize for explaining the photoelectric effect , previously an experimental result lacking a theoretical formulation. A physical theory is a model of physical events. It is judged by the extent to which its predictions agree with empirical observations. The quality of a physical theory is also judged on its ability to make new predictions which can be verified by new observations. A physical theory differs from
354-504: A mathematical theorem in that while both are based on some form of axioms , judgment of mathematical applicability is not based on agreement with any experimental results. A physical theory similarly differs from a mathematical theory , in the sense that the word "theory" has a different meaning in mathematical terms. R i c = k g {\displaystyle \mathrm {Ric} =kg} The equations for an Einstein manifold , used in general relativity to describe
472-401: A working hypothesis . Joan Feynman Joan Feynman (March 31, 1927 – July 21, 2020) was an American astrophysicist and space physicist . She made contributions to the study of solar wind particles and fields, sun-Earth relations, and magnetospheric physics. In particular, Feynman was known for developing an understanding of the origin of auroras . She was also known for creating
590-422: A "bum". The young Feynman was heavily influenced by his father, who encouraged him to ask questions to challenge orthodox thinking, and who was always ready to teach Feynman something new. From his mother, he gained the sense of humor that he had throughout his life. As a child, he had a talent for engineering, maintained an experimental laboratory in his home, and delighted in repairing radios. This radio repairing
708-477: A bunch of professional soldiers," Wilson later recalled, "we signed up, en masse, to go to Los Alamos." Like many other young physicists, Feynman soon fell under the spell of the charismatic Oppenheimer, who telephoned Feynman long distance from Chicago to inform him that he had found a Presbyterian sanatorium in Albuquerque, New Mexico for Arline. They were among the first to depart for New Mexico, leaving on
826-498: A businessman. Her parents, both Ashkenazi Jews , originated from Minsk , Belarus (then in Russian Empire) and Poland. Joan was an inquisitive child, and she exhibited an interest in understanding the natural world from an early age. However, her mother and grandmother both dissuaded her from pursuing science, since they believed that women's brains were not physically capable of understanding complex scientific concepts in
944-585: A car from his friend Klaus Fuchs to drive to Albuquerque to see Arline. Asked who at Los Alamos was most likely to be a spy, Fuchs mentioned Feynman's safe-cracking and frequent trips to Albuquerque; Fuchs himself later confessed to spying for the Soviet Union . The FBI would compile a bulky file on Feynman, particularly in view of Feynman's Q clearance . Informed that Arline was dying, Feynman drove to Albuquerque and sat with her for hours until she died on June 16, 1945. He then immersed himself in work on
1062-404: A certain economy and elegance (compare to mathematical beauty ), a notion sometimes called " Occam's razor " after the 13th-century English philosopher William of Occam (or Ockham), in which the simpler of two theories that describe the same matter just as adequately is preferred (but conceptual simplicity may mean mathematical complexity). They are also more likely to be accepted if they connect
1180-538: A complement to the quark model developed by Gell-Mann. The relationship between the two models was murky; Gell-Mann referred to Feynman's partons derisively as "put-ons". In the mid-1960s, physicists believed that quarks were just a bookkeeping device for symmetry numbers, not real particles; the statistics of the omega-minus particle , if it were interpreted as three identical strange quarks bound together, seemed impossible if quarks were real. Theoretical physicist The advancement of science generally depends on
1298-653: A critical discovery about the nature and cause of auroras . Using data collected by NASA spacecraft Explorer 33 , she demonstrated that the occurrence of auroras is a product of the interaction between the Earth's magnetosphere and the magnetic field of the solar wind. Feynman helped to develop a model for estimating the environmental hazards of the local space environment . High-velocity coronal mass ejections are known to cause geomagnetic storms , which can have dangerous effects on both spacecraft and on humans in space. Fast-moving coronal mass ejections cause shock waves in
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#17327655389991416-443: A dinner plate in the air. He read the work of Sir William Rowan Hamilton on quaternions , and tried unsuccessfully to use them to formulate a relativistic theory of electrons. His work during this period, which used equations of rotation to express various spinning speeds, ultimately proved important to his Nobel Prize–winning work, yet because he felt burned out and had turned his attention to less immediately practical problems, he
1534-566: A father of the Xbox , bought the van. Qantum was the license plate ID. At Caltech, Feynman investigated the physics of the superfluidity of supercooled liquid helium , where helium seems to display a complete lack of viscosity when flowing. Feynman provided a quantum-mechanical explanation for the Soviet physicist Lev Landau 's theory of superfluidity. Applying the Schrödinger equation to
1652-500: A form of protoscience and others are a form of pseudoscience . The falsification of the original theory sometimes leads to reformulation of the theory. "Thought" experiments are situations created in one's mind, asking a question akin to "suppose you are in this situation, assuming such is true, what would follow?". They are usually created to investigate phenomena that are not readily experienced in every-day situations. Famous examples of such thought experiments are Schrödinger's cat ,
1770-569: A graph based on research by astronomer Cecilia Payne-Gaposchkin . In 1948 Feynman earned a bachelor's degree in physics from Oberlin College . She later attended Syracuse University , where she studied solid state theory in the physics department under Melvin Lax . During her graduate years, Feynman took a year off to live with her husband in Guatemala, where they studied the anthropology of
1888-493: A junior physicist, he was not central to the project. He administered the computation group of human computers in the theoretical division. With Stanley Frankel and Nicholas Metropolis , he assisted in establishing a system for using IBM punched cards for computation. He invented a new method of computing logarithms that he later used on the Connection Machine . An avid drummer, Feynman figured out how to get
2006-494: A model that predicts the number of high-energy particles likely to hit a spacecraft over its lifetime, and for uncovering a method for predicting sunspot cycles . Feynman was raised in the Far Rockaway section of Queens , New York City , along with her elder brother, Richard Feynman (who became a Nobel Prize-winning physicist ). Her parents were Lucille Feynman (née Phillips), a homemaker, and Melville Arthur Feynman,
2124-498: A new branch of mathematics: infinite, orthogonal series . Modern theoretical physics attempts to unify theories and explain phenomena in further attempts to understand the Universe , from the cosmological to the elementary particle scale. Where experimentation cannot be done, theoretical physics still tries to advance through the use of mathematical models. Mainstream theories (sometimes referred to as central theories ) are
2242-465: A physical system might be modeled; e.g., the notion, due to Riemann and others, that space itself might be curved. Theoretical problems that need computational investigation are often the concern of computational physics . Theoretical advances may consist in setting aside old, incorrect paradigms (e.g., aether theory of light propagation, caloric theory of heat, burning consisting of evolving phlogiston , or astronomical bodies revolving around
2360-684: A point of dating other men, but Feynman proposed in early 1960. They were married on September 24, 1960, at the Huntington Hotel in Pasadena . They had a son, Carl, in 1962, and adopted a daughter, Michelle, in 1968. Besides their home in Altadena, they had a beach house in Baja California , purchased with the money from Feynman's Nobel Prize. Feynman tried marijuana and ketamine at John Lilly 's sensory deprivation tanks , as
2478-411: A relativistic version. Feynman thought that he could do this, but when he went back to Bethe with his solution, it did not converge. Feynman carefully worked through the problem again, applying the path integral formulation that he had used in his thesis. Like Bethe, he made the integral finite by applying a cut-off term. The result corresponded to Bethe's version. Feynman presented his work to his peers at
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#17327655389992596-578: A spacecraft over its functional lifetime. Her work in this area led to important new developments in spacecraft design. Later in her career, Feynman studied climate change . She was particularly interested in transient solar events and solar cycle variations. She studied the influence of the sun on patterns of wintertime climate anomalies known as the Arctic oscillation or North Annular Mode (NAM). Together with her colleague and husband Alexander Ruzmaikin, she found that during periods of lower solar activity,
2714-510: A train on March 28, 1943. The railroad supplied Arline with a wheelchair, and Feynman paid extra for a private room for her. There they spent their wedding anniversary. At Los Alamos, Feynman was assigned to Hans Bethe's Theoretical (T) Division, and impressed Bethe enough to be made a group leader. He and Bethe developed the Bethe–Feynman formula for calculating the yield of a fission bomb , which built upon previous work by Robert Serber . As
2832-653: A way of studying consciousness . He gave up alcohol when he began to show vague, early signs of alcoholism , as he did not want to consume anything that could damage his brain. Despite his curiosity about hallucinations , he was reluctant to experiment with LSD . Feynman had synesthesia , and said that mathematical symbols had different colors for him: "When I see equations, I see the letters in colors. I don't know why. I see vague pictures of Bessel functions with light-tan j's, slightly violet-bluish n's, and dark brown x's flying around." There had been protests over his alleged sexism in 1968, and again in 1972. Although there
2950-469: A wide range of phenomena. Testing the consequences of a theory is part of the scientific method . Physical theories can be grouped into three categories: mainstream theories , proposed theories and fringe theories . Theoretical physics began at least 2,300 years ago, under the Pre-socratic philosophy , and continued by Plato and Aristotle , whose views held sway for a millennium. During
3068-539: Is either a Communist or very strongly pro-Communist—and as such is a very definite security risk. This man is, in my opinion, an extremely complex and dangerous person, a very dangerous person to have in a position of public trust ... In matters of intrigue Richard Feynman is, I believe immensely clever—indeed a genius—and he is, I further believe, completely ruthless, unhampered by morals, ethics, or religion—and will stop at absolutely nothing to achieve his ends. The U.S. government nevertheless sent Feynman to Geneva for
3186-658: Is known as the Hellmann–Feynman theorem . In 1939, Feynman received a bachelor's degree and was named a Putnam Fellow . He attained a perfect score on the graduate school entrance exams to Princeton University in physics—an unprecedented feat—and an outstanding score in mathematics, but did poorly on the history and English portions. The head of the physics department there, Henry D. Smyth , had another concern, writing to Philip M. Morse to ask: "Is Feynman Jewish? We have no definite rule against Jews but have to keep their proportion in our department reasonably small because of
3304-626: Is no evidence he supported discrimination against women in science, protestors "objected to his use of sexist stories about 'lady drivers' and clueless women in his lectures." Feynman recalled protesters entering a hall and picketing a lecture he was about to make in San Francisco, calling him a "sexist pig". Seeing the protesters, as Feynman later recalled the incident, he addressed institutional sexism by saying that "women do indeed suffer prejudice and discrimination in physics, and your presence here today serves to remind us of these difficulties and
3422-490: Is not to be expected according to Vallarta and Feynman". When they next met, Feynman asked gleefully whether Vallarta had seen Heisenberg's book. Vallarta knew why Feynman was grinning. "Yes," he replied. "You're the last word in cosmic rays." The other was his senior thesis, on "Forces in Molecules", based on a topic assigned by John C. Slater , who was sufficiently impressed by the paper to have it published. Its main result
3540-480: The frigideira , a metal percussion instrument based on a frying pan. He was an enthusiastic amateur player of bongo and conga drums and often played them in the pit orchestra in musicals. He spent time in Rio with his friend Bohm, but Bohm could not convince Feynman to investigate Bohm's ideas on physics. Feynman did not return to Cornell. Bacher, who had been instrumental in bringing Feynman to Cornell, had lured him to
3658-517: The Physical Review . One of these, which was co-written with Manuel Vallarta , was entitled "The Scattering of Cosmic Rays by the Stars of a Galaxy". Vallarta let his student in on a secret of mentor-protégé publishing: the senior scientist's name comes first. Feynman had his revenge a few years later, when Heisenberg concluded an entire book on cosmic rays with the phrase: "such an effect
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3776-589: The Arista Honor Society , in his last year in high school he won the New York University Math Championship. His habit of direct characterization sometimes rattled 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). Feynman applied to Columbia University but was not accepted because of its quota for
3894-539: The EPR thought experiment , simple illustrations of time dilation , and so on. These usually lead to real experiments designed to verify that the conclusion (and therefore the assumptions) of the thought experiments are correct. The EPR thought experiment led to the Bell inequalities , which were then tested to various degrees of rigor , leading to the acceptance of the current formulation of quantum mechanics and probabilism as
4012-475: The Maya peoples who lived there. She was a co-author, along with her husband and Betty J. Meggers , of a 1957 paper on anthropology. Feynman eventually earned her doctorate in physics in 1958. Her thesis was on the "absorption of infrared radiation in crystals of diamond-type lattice structure". She also completed postdoctoral work at Columbia University 's Lamont Geological Observatory . Joan Feynman spent
4130-539: The Pocono Conference in 1948. It did not go well. Julian Schwinger gave a long presentation of his work in quantum electrodynamics, and Feynman then offered his version, entitled "Alternative Formulation of Quantum Electrodynamics". The unfamiliar Feynman diagrams , used for the first time, puzzled the audience. Feynman failed to get his point across, and Paul Dirac , Edward Teller and Niels Bohr all raised objections. To Freeman Dyson , one thing at least
4248-572: The Scientific Revolution gathered pace, the concepts of matter , energy, space, time and causality slowly began to acquire the form we know today, and other sciences spun off from the rubric of natural philosophy . Thus began the modern era of theory with the Copernican paradigm shift in astronomy, soon followed by Johannes Kepler 's expressions for planetary orbits, which summarized the meticulous observations of Tycho Brahe ;
4366-600: The University of Wisconsin–Madison as an assistant professor of physics, but was on unpaid leave during his involvement in the Manhattan Project. In 1945, he received a letter from Dean Mark Ingraham of the College of Letters and Science requesting his return to the university to teach in the coming academic year. His appointment was not extended when he did not commit to returning. In a talk given there several years later, Feynman quipped, "It's great to be back at
4484-525: The ferry to Staten Island , where they were married in the city office. The ceremony was attended by neither family nor friends and was witnessed by a pair of strangers. Feynman could kiss Arline only on the cheek. After the ceremony he took her to Deborah Hospital , where he visited her on weekends. In 1941, with World War II occurring in Europe but the United States not yet at war, Feynman spent
4602-577: The principle of stationary action to problems of quantum mechanics, inspired by a desire to quantize the Wheeler–Feynman absorber theory of electrodynamics, and laid the groundwork for the path integral formulation and Feynman diagrams. A key insight was that positrons behaved like electrons moving backwards in time. James Gleick wrote: This was Richard Feynman nearing the crest of his powers. At twenty-three ... there may now have been no physicist on earth who could match his exuberant command over
4720-603: The quantum mechanical idea that ( action and) energy are not continuously variable. Theoretical physics consists of several different approaches. In this regard, theoretical particle physics forms a good example. For instance: " phenomenologists " might employ ( semi- ) empirical formulas and heuristics to agree with experimental results, often without deep physical understanding . "Modelers" (also called "model-builders") often appear much like phenomenologists, but try to model speculative theories that have certain desirable features (rather than on experimental data), or apply
4838-428: The synagogue every Friday. However, by his youth, Feynman described himself as an "avowed atheist ". Many years later, in a letter to Tina Levitan , declining a request for information for her book on Jewish Nobel Prize winners, he stated, "To select, for approbation the peculiar elements that come from some supposedly Jewish heredity is to open the door to all kinds of nonsense on racial theory", adding, "at thirteen I
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4956-461: The two-fluid theory of electricity are two cases in this point. However, an exception to all the above is the wave–particle duality , a theory combining aspects of different, opposing models via the Bohr complementarity principle . Physical theories become accepted if they are able to make correct predictions and no (or few) incorrect ones. The theory should have, at least as a secondary objective,
5074-589: The "Mathematical Formulation of the Quantum Theory of Electromagnetic Interaction" in 1950 and "An Operator Calculus Having Applications in Quantum Electrodynamics" in 1951, he developed the mathematical basis of his ideas, derived familiar formulae and advanced new ones. While papers by others initially cited Schwinger, papers citing Feynman and employing Feynman diagrams appeared in 1950, and soon became prevalent. Students learned and used
5192-454: The 1954 Oppenheimer security hearing ("Where there's smoke there's fire") offended him. They separated on May 20, 1956. An interlocutory decree of divorce was entered on June 19, 1956, on the grounds of "extreme cruelty". The divorce became final on May 5, 1958. He begins working calculus problems in his head as soon as he awakens. He did calculus while driving in his car, while sitting in the living room, and while lying in bed at night. In
5310-429: The 19th century. Another important event in the 19th century was the discovery of electromagnetic theory , unifying the previously separate phenomena of electricity, magnetism and light. The pillars of modern physics , and perhaps the most revolutionary theories in the history of physics, have been relativity theory and quantum mechanics . Newtonian mechanics was subsumed under special relativity and Newton's gravity
5428-719: The American Geophysical Union. In 2002, Feynman was named as one of the Jet Propulsion Laboratory's elite senior research scientists. In 2000, she was awarded NASA's Exceptional Achievement Medal . Feynman had one daughter, Susan Hirshberg, and two sons, Charles Hirshberg and Matt Hirshberg, from her first marriage, to anthropologist Richard Irwin Hirshberg (born 1924). Feynman met Hirshberg at Oberlin College, and they married in 1948, separated in 1974, and later divorced. Feynman
5546-586: The California Institute of Technology (Caltech). Part of the deal was that he could spend his first year on sabbatical in Brazil. He had become smitten by Mary Louise Bell from Neodesha, Kansas . They had met in a cafeteria in Cornell, where she had studied the history of Mexican art and textiles. She later followed him to Caltech, where he gave a lecture. While he was in Brazil, she taught classes on
5664-476: The Dutchmen Snell and Huygens. In the 18th and 19th centuries Joseph-Louis Lagrange , Leonhard Euler and William Rowan Hamilton would extend the theory of classical mechanics considerably. They picked up the interactive intertwining of mathematics and physics begun two millennia earlier by Pythagoras. Among the great conceptual achievements of the 19th and 20th centuries were the consolidation of
5782-535: The Earth ) or may be an alternative model that provides answers that are more accurate or that can be more widely applied. In the latter case, a correspondence principle will be required to recover the previously known result . Sometimes though, advances may proceed along different paths. For example, an essentially correct theory may need some conceptual or factual revisions; atomic theory , first postulated millennia ago (by several thinkers in Greece and India ) and
5900-471: The Jet Propulsion Laboratory as a senior scientist in 2003. However, she continued to work, publishing in 2009 on the influence of solar activity on the climate of the first millennium. During her career, Feynman was an author or co-author of more than 100 scientific publications. She also edited three scientific books. Feynman was twice elected secretary of the Solar and Interplanetary Physics Section of
6018-663: The NAM index is systematically lower. Such periods of low solar activity coincide with cooling periods for certain parts of the world, for example, in Europe during the Little Ice Age . Feynman and her colleagues also discovered a link between solar variability and climate change in ancient water levels of the Nile River . During periods of high solar activity, conditions around the Nile were found to be drier, and when solar activity
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#17327655389996136-619: The September 1958 Atoms for Peace Conference. On the beach at Lake Geneva , he met Gweneth Howarth, who was from Ripponden , West Yorkshire, and working in Switzerland as an au pair . Feynman's love life had been turbulent since his divorce; his previous girlfriend had walked off with his Albert Einstein Award medal and, on the advice of an earlier girlfriend, had feigned pregnancy and extorted him into paying for an abortion, then used
6254-513: The Talmud had evolved, and everything that was discussed was carefully recorded. Despite being impressed, Feynman was disappointed with the lack of interest for nature and the outside world expressed by the rabbis, who cared about only those questions which arise from the Talmud. Feynman attended Far Rockaway High School , which was also attended by fellow Nobel laureates Burton Richter and Baruch Samuel Blumberg . Upon starting high school, Feynman
6372-651: The University of California, but the head of the physics department, Raymond T. Birge , was reluctant. He made Feynman an offer in May 1945, but Feynman turned it down. Cornell matched its salary offer of $ 3,900 (equivalent to $ 66,000 in 2023) per annum. Feynman became one of the first of the Los Alamos Laboratory's group leaders to depart, leaving for Ithaca, New York , in October 1945. Because Feynman
6490-419: The applications of relativity to problems in astronomy and cosmology respectively . All of these achievements depended on the theoretical physics as a moving force both to suggest experiments and to consolidate results — often by ingenious application of existing mathematics, or, as in the case of Descartes and Newton (with Leibniz ), by inventing new mathematics. Fourier's studies of heat conduction led to
6608-576: The base of natural logarithms , e = 2.71828 ...), and found that the three filing cabinets where a colleague kept research notes all had the same combination. He left notes in the cabinets as a prank, spooking his colleague, Frederic de Hoffmann , into thinking a spy had gained access to them. Feynman's $ 380 (equivalent to $ 7,000 in 2023) monthly salary was about half the amount needed for his modest living expenses and Arline's medical bills, and they were forced to dip into her $ 3,300 (equivalent to $ 58,000 in 2023) in savings. On weekends he borrowed
6726-537: The biography Genius: The Life and Science of Richard Feynman by James Gleick . Feynman was born on May 11, 1918, in New York City, to Lucille ( née Phillips ; 1895–1981), a homemaker , and Melville Arthur Feynman (1890–1946), a sales manager. Feynman's father was born into a Jewish family in Minsk , Russian Empire , and immigrated with his parents to the United States at the age of five. Feynman's mother
6844-514: The body of knowledge of both factual and scientific views and possess a usual scientific quality of the tests of repeatability, consistency with existing well-established science and experimentation. There do exist mainstream theories that are generally accepted theories based solely upon their effects explaining a wide variety of data, although the detection, explanation, and possible composition are subjects of debate. The proposed theories of physics are usually relatively new theories which deal with
6962-486: The bulk of her career studying the interactions between the solar wind and the Earth's magnetosphere . While working at the NASA Ames Research Center in 1971, Feynman discovered that the periodic spouting of solar material known as a solar coronal mass ejection (CME) could be identified by the presence of helium in the solar wind. This was an important find because, although CME's were known at
7080-622: The calutron, but Feynman and Paul Olum struggled to determine whether it was practical. Ultimately, on Lawrence's recommendation, the isotron project was abandoned. At this juncture, in early 1943, Robert Oppenheimer was establishing the Los Alamos Laboratory , a secret laboratory on a mesa in New Mexico where atomic bombs would be designed and built. An offer was made to the Princeton team to be redeployed there. "Like
7198-426: The conditions of Feynman's scholarship to Princeton was that he could not be married; nevertheless, he continued to see his high school sweetheart, Arline Greenbaum, and was determined to marry her once he had been awarded his PhD despite the knowledge that she was seriously ill with tuberculosis . This was an incurable disease at the time, and she was not expected to live more than two years. On June 29, 1942, they took
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#17327655389997316-441: The curvature of spacetime A physical theory involves one or more relationships between various measurable quantities. Archimedes realized that a ship floats by displacing its mass of water, Pythagoras understood the relation between the length of a vibrating string and the musical tone it produces. Other examples include entropy as a measure of the uncertainty regarding the positions and motions of unseen particles and
7434-481: The development of quantum electrodynamics, Feynman received the Nobel Prize in Physics in 1965 jointly with Julian Schwinger and Shin'ichirō Tomonaga . Feynman developed a widely used pictorial representation scheme for the mathematical expressions describing the behavior of subatomic particles , which later became known as Feynman diagrams . During his lifetime, Feynman became one of the best-known scientists in
7552-469: The difficulty of placing them." Morse conceded that Feynman was indeed Jewish, but reassured Smyth that Feynman's "physiognomy and manner, however, show no trace of this characteristic". Attendees at Feynman's first seminar, which was on the classical version of the Wheeler–Feynman absorber theory , included Albert Einstein , Wolfgang Pauli , and John von Neumann . Pauli made the prescient comment that
7670-413: The engineers there in devising safety procedures for material storage so that criticality accidents could be avoided, especially when enriched uranium came into contact with water, which acted as a neutron moderator . He insisted on giving the rank and file a lecture on nuclear physics so that they would realize the dangers. He explained that while any amount of unenriched uranium could be safely stored,
7788-399: The enriched uranium had to be carefully handled. He developed a series of safety recommendations for the various grades of enrichments. He was told that if the people at Oak Ridge gave him any difficulty with his proposals, he was to inform them that Los Alamos "could not be responsible for their safety otherwise". Returning to Los Alamos, Feynman was put in charge of the group responsible for
7906-808: The field of quantum computing and introducing the concept of nanotechnology . He held the Richard C. Tolman professorship in theoretical physics at the California Institute of Technology. Feynman was a keen popularizer of physics through both books and lectures, including a 1959 talk on top-down nanotechnology called There's Plenty of Room at the Bottom and the three-volume publication of his undergraduate lectures, The Feynman Lectures on Physics . Feynman also became known through his autobiographical books Surely You're Joking, Mr. Feynman! and What Do You Care What Other People Think? , and books written about him such as Tuva or Bust! by Ralph Leighton and
8024-407: The groundwork for the path integral formulation and Feynman diagrams. With Murray Gell-Mann , Feynman developed a model of weak decay , which showed that the current coupling in the process is a combination of vector and axial currents (an example of weak decay is the decay of a neutron into an electron, a proton, and an antineutrino ). Although E. C. George Sudarshan and Robert Marshak developed
8142-416: The highest order, writing Principia Mathematica . In it contained a grand synthesis of the work of Copernicus, Galileo and Kepler; as well as Newton's theories of mechanics and gravitation, which held sway as worldviews until the early 20th century. Simultaneously, progress was also made in optics (in particular colour theory and the ancient science of geometrical optics ), courtesy of Newton, Descartes and
8260-472: The history of furniture and interiors at Michigan State University . He proposed to her by mail from Rio de Janeiro, and they married in Boise, Idaho , on June 28, 1952, shortly after he returned. They frequently quarreled and she was frightened by what she decided was "a violent temper". Their politics were different; although he registered and voted as a Republican , she was more conservative, and her opinion on
8378-670: The house's convenience and said that "it's there that I did the fundamental work" for which he won the Nobel Prize. Feynman spent several weeks in Rio de Janeiro in July 1949. That year, the Soviet Union detonated its first atomic bomb , generating concerns about espionage. Fuchs was arrested as a Soviet spy in 1950 and the FBI questioned Bethe about Feynman's loyalty. Physicist David Bohm
8496-455: The idea of energy (as well as its global conservation) by the inclusion of heat , electricity and magnetism , and then light . The laws of thermodynamics , and most importantly the introduction of the singular concept of entropy began to provide a macroscopic explanation for the properties of matter. Statistical mechanics (followed by statistical physics and Quantum statistical mechanics ) emerged as an offshoot of thermodynamics late in
8614-570: The interplay between experimental studies and theory . In some cases, theoretical physics adheres to standards of mathematical rigour while giving little weight to experiments and observations. For example, while developing special relativity , Albert Einstein was concerned with the Lorentz transformation which left Maxwell's equations invariant, but was apparently uninterested in the Michelson–Morley experiment on Earth 's drift through
8732-675: The late 1920s. In the aftermath of World War 2, more progress brought much renewed interest in QFT, which had since the early efforts, stagnated. The same period also saw fresh attacks on the problems of superconductivity and phase transitions, as well as the first applications of QFT in the area of theoretical condensed matter. The 1960s and 70s saw the formulation of the Standard model of particle physics using QFT and progress in condensed matter physics (theoretical foundations of superconductivity and critical phenomena , among others ), in parallel to
8850-611: The machine to click in musical rhythms. 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, Feynman was sent to the Clinton Engineer Works in Oak Ridge, Tennessee , where the Manhattan Project had its uranium enrichment facilities. He aided
8968-627: The money to buy furniture. When Feynman found that Howarth was being paid only $ 25 a month, he offered her $ 20 (equivalent to $ 202 in 2022) a week to be his live-in maid. Feynman knew that this sort of behavior was illegal under the Mann Act , so he had a friend, Matthew Sands , act as her sponsor. Howarth pointed out that she already had two boyfriends, but decided to take Feynman up on his offer, and arrived in Altadena, California , in June 1959. She made
9086-417: The native materials of theoretical science. It was not just a facility at mathematics (though it had become clear ... that the mathematical machinery emerging in the Wheeler–Feynman collaboration was beyond Wheeler's own ability). Feynman seemed to possess a frightening ease with the substance behind the equations, like Einstein at the same age, like the Soviet physicist Lev Landau —but few others. One of
9204-478: The need to remedy them". In 1975, in Long Beach, CA , Feynman bought a Dodge Tradesman Maxivan with a bronze-khaki exterior and yellow-green interior, with custom Feynman diagram exterior murals. After Feynman's death, Gweneth sold the van for $ 1 to one of Feynman's friends, film producer Ralph Leighton, who later put it into storage, where it began to rust. In 2012, video game designer Seamus Blackley ,
9322-580: The number of Jews admitted . Instead, he attended the Massachusetts Institute of Technology , where he joined the Pi Lambda Phi fraternity. Although he originally majored in mathematics, he later switched to electrical engineering, as he considered mathematics to be too abstract. Noticing that he "had gone too far", he then switched to physics, which he claimed was "somewhere in between". As an undergraduate, he published two papers in
9440-525: The only university that ever had the good sense to fire me." As early as October 30, 1943, Bethe had written to the chairman of the physics department of his university, Cornell , to recommend that Feynman be hired. On February 28, 1944, this was endorsed by Robert Bacher , also from Cornell, and one of the most senior scientists at Los Alamos. This led to an offer being made in August 1944, which Feynman accepted. Oppenheimer had also hoped to recruit Feynman to
9558-458: The powerful new tool that Feynman had created. Computer programs were later written to evaluate Feynman diagrams, enabling physicists to use quantum field theory to make high-precision predictions . Marc Kac adapted Feynman's technique of summing over possible histories of a particle to the study of parabolic partial differential equations , yielding what is now known as the Feynman–Kac formula ,
9676-419: The process of becoming established and some proposed theories. It can include speculative sciences. This includes physics fields and physical theories presented in accordance with known evidence, and a body of associated predictions have been made according to that theory. Some fringe theories go on to become a widely accepted part of physics. Other fringe theories end up being disproven. Some fringe theories are
9794-528: The project and was present at the Trinity nuclear test . Feynman claimed to be the only person to see the explosion without the very dark glasses or welder's lenses provided, reasoning that it was safe to look through a truck windshield, as it would screen out the harmful ultraviolet radiation. The immense brightness of the explosion made him duck to the truck's floor, where he saw a temporary "purple splotch" afterimage . Feynman nominally held an appointment at
9912-500: The question showed that the superfluid was displaying quantum mechanical behavior observable on a macroscopic scale. This helped with the problem of superconductivity , but the solution eluded Feynman. It was solved with the BCS theory of superconductivity, proposed by John Bardeen , Leon Neil Cooper , and John Robert Schrieffer in 1957. Feynman, inspired by a desire to quantize the Wheeler–Feynman absorber theory of electrodynamics, laid
10030-607: The rise of medieval universities , the only acknowledged intellectual disciplines were the seven liberal arts of the Trivium like grammar , logic , and rhetoric and of the Quadrivium like arithmetic , geometry , music and astronomy . During the Middle Ages and Renaissance , the concept of experimental science, the counterpoint to theory, began with scholars such as Ibn al-Haytham and Francis Bacon . As
10148-414: The solar wind, speeding up solar particles and instigating geomagnetic storms as the particles arrive at the outer edge of Earth's magnetosphere. Often, the commencement of such storms is coupled with a high influx of protons , which can wreak havoc on communications systems and space flight activities. Feynman's model ultimately helped engineers determine the flux of high-energy particles that would affect
10266-484: The study of physics which include scientific approaches, means for determining the validity of models and new types of reasoning used to arrive at the theory. However, some proposed theories include theories that have been around for decades and have eluded methods of discovery and testing. Proposed theories can include fringe theories in the process of becoming established (and, sometimes, gaining wider acceptance). Proposed theories usually have not been tested. In addition to
10384-621: The summer working on ballistics problems at the Frankford Arsenal in Pennsylvania . After the attack on Pearl Harbor brought the United States into the war, Feynman was recruited by Robert R. Wilson , who was working on means to produce enriched uranium for use in an atomic bomb , as part of what would become the Manhattan Project . At the time, Feynman had not earned a graduate degree. Wilson's team at Princeton
10502-443: The techniques of mathematical modeling to physics problems. Some attempt to create approximate theories, called effective theories , because fully developed theories may be regarded as unsolvable or too complicated . Other theorists may try to unify , formalise, reinterpret or generalise extant theories, or create completely new ones altogether. Sometimes the vision provided by pure mathematical systems can provide clues to how
10620-706: The theoretical work and calculations on the proposed uranium hydride bomb , which ultimately proved to be infeasible. He was sought out by physicist Niels Bohr for one-on-one discussions. He later discovered the reason: most of the other physicists were too much 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. He said he felt as much respect for Bohr as anyone else, but once anyone got him talking about physics, he would become so focused he forgot about social niceties. Perhaps because of this, Bohr never warmed to Feynman. At Los Alamos, which
10738-511: The theoreticians were completely overshadowed by the achievements of the experimentalists, who reported the discovery of the Lamb shift , the measurement of the magnetic moment of the electron, and Robert Marshak 's two-meson hypothesis. Bethe took the lead from the work of Hans Kramers , and derived a renormalized non-relativistic quantum equation for the Lamb shift. The next step was to create
10856-472: The theories like those listed below, there are also different interpretations of quantum mechanics , which may or may not be considered different theories since it is debatable whether they yield different predictions for physical experiments, even in principle. For example, AdS/CFT correspondence , Chern–Simons theory , graviton , magnetic monopole , string theory , theory of everything . Fringe theories include any new area of scientific endeavor in
10974-435: The theory nearly simultaneously, Feynman's collaboration with 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 Enrico Fermi with an explanation of parity violation . Feynman attempted an explanation, called the parton model , of the strong interactions governing nucleon scattering. The parton model emerged as
11092-571: The theory would be extremely difficult to quantize, and Einstein said that one might try to apply this method to gravity in general relativity , which Sir Fred Hoyle and Jayant Narlikar did much later as the Hoyle–Narlikar theory of gravity . Feynman received a PhD from Princeton in 1942; his thesis advisor was John Archibald Wheeler . In his doctoral thesis entitled "The Principle of Least Action in Quantum Mechanics", Feynman applied
11210-490: The theory, which Feynman and Wheeler had tried, unsuccessfully, to work around. "Theoreticians", noted Murray Gell-Mann , "were in disgrace". In June 1947, leading American physicists met at the Shelter Island Conference . For Feynman, it was his "first big conference with big men ... I had never gone to one like this one in peacetime." The problems plaguing quantum electrodynamics were discussed, but
11328-953: The time, they had until then been difficult to detect. After her time at NASA Ames, Feynman moved on to research posts with the High Altitude Observatory ; the National Center for Atmospheric Research in Boulder, Colorado; the National Science Foundation in Washington, DC; and Boston College in Massachusetts. In 1985 Feynman accepted a position at the Jet Propulsion Laboratory in Pasadena , California, where she remained until her retirement. Feynman made
11446-511: The use of which extends beyond physics to many applications of stochastic processes . To Schwinger, however, the Feynman diagram was "pedagogy, not physics". By 1949, Feynman was becoming restless at Cornell. He never settled into a particular house or apartment, living in guest houses or student residences, or with married friends "until these arrangements became sexually volatile". He liked to date undergraduates, hire prostitutes, and sleep with
11564-468: The wake of the 1957 Sputnik crisis , the U.S. government's interest in science rose for a time. Feynman was considered for a seat on the President's Science Advisory Committee , but was not appointed. At this time, the FBI interviewed a woman close to Feynman, possibly his ex-wife Bell, who sent a written statement to J. Edgar Hoover on August 8, 1958: I do not know—but I believe that Richard Feynman
11682-477: The way that men's brains could. Despite this, her brother Richard always encouraged her to be curious about the universe. It was he who originally introduced young Joan to auroras when, one night, he coaxed her out of bed to witness the northern lights flickering above an empty golf course near their home. Later, Feynman found comfort in an astronomy book given to her by her brother. She became convinced that she could, in fact, study science, when she came across
11800-673: The wives of friends. He was not fond of Ithaca's cold winter weather, and pined for a warmer climate. Above all, he was always in the shadow of Hans Bethe at Cornell. Despite all of this, Feynman looked back favorably on the Telluride House , where he resided for a large period of his Cornell career. In an interview, he described the House as "a group of boys that have been specially selected because of their scholarship, because of their cleverness or whatever it is, to be given free board and lodging and so on, because of their brains". He enjoyed
11918-530: The works of these men (alongside Galileo's) can perhaps be considered to constitute the Scientific Revolution. The great push toward the modern concept of explanation started with Galileo , one of the few physicists who was both a consummate theoretician and a great experimentalist . The analytic geometry and mechanics of Descartes were incorporated into the calculus and mechanics of Isaac Newton , another theoretician/experimentalist of
12036-686: The world. In a 1999 poll of 130 leading physicists worldwide by the British journal Physics World , he was ranked the seventh-greatest physicist of all time. He assisted in the development of the atomic bomb during World War II and became known to the wider public in the 1980s as a member of the Rogers Commission , the panel that investigated the Space Shuttle Challenger disaster . Along with his work in theoretical physics, Feynman has been credited with having pioneered
12154-486: Was arrested on December 4, 1950 and emigrated to Brazil in October 1951. Because of the fears of a nuclear war, a girlfriend told Feynman that he should also consider moving to South America. He had a sabbatical coming for 1951–1952, and elected to spend it in Brazil, where he gave courses at the Centro Brasileiro de Pesquisas Físicas . In Brazil, Feynman was impressed with samba music, and learned to play
12272-418: Was born and the family moved to Far Rockaway, Queens . Though separated by nine years, Joan and Richard were close, and they both shared a curiosity about the world. Though their mother thought women lacked the capacity to understand such things, Richard encouraged Joan's interest in astronomy, and Joan eventually became an astrophysicist. Feynman's parents were both from Jewish families, and his family went to
12390-548: Was born in the United States into a Jewish family. Lucille's father had emigrated from Poland, and her mother also came from a family of Polish immigrants. She trained as a primary school teacher but married Melville in 1917, before taking up a profession. Feynman was a late talker and did not speak until after his third birthday. As an adult, he spoke with a New York accent strong enough to be perceived as an affectation or exaggeration, so much so that his friends Wolfgang Pauli and Hans Bethe once commented that Feynman spoke like
12508-414: Was clear: Shin'ichirō Tomonaga , Schwinger and Feynman understood what they were talking about even if no one else did, but had not published anything. He was convinced that Feynman's formulation was easier to understand, and ultimately managed to convince Oppenheimer that this was the case. Dyson published a paper in 1949, which added new rules to Feynman's that told how to implement renormalization. Feynman
12626-448: Was experimenting with mathematical topics such as the half-derivative using his own notation. He created special symbols for logarithm , sine , cosine and tangent functions so they did not look like three variables multiplied together, and for the derivative , to remove the temptation of canceling out the d {\displaystyle d} 's in d / d x {\displaystyle d/dx} . A member of
12744-422: Was given a kinematic explanation by general relativity . Quantum mechanics led to an understanding of blackbody radiation (which indeed, was an original motivation for the theory) and of anomalies in the specific heats of solids — and finally to an understanding of the internal structures of atoms and molecules . Quantum mechanics soon gave way to the formulation of quantum field theory (QFT), begun in
12862-403: Was isolated for security, Feynman amused himself by investigating the combination locks on the cabinets and desks of physicists. He often found that they left the lock combinations on the factory settings, wrote the combinations down, or used easily guessable combinations like dates. He found one cabinet's combination by trying numbers he thought a physicist might use (it proved to be 27–18–28 after
12980-786: Was low, conditions were wetter. In 1974, Feynman became the first woman to be elected as an officer of the American Geophysical Union (AGU). She organized an AGU committee charged with advancing the fair treatment of women within the geophysics community. Feynman was a long-standing member of the International Astronomical Union . She was a member of a number of the IAU's subdivisions, including Division E Sun and Heliosphere, Division G Stars and Stellar Physics, and Division E Commission 49 Interplanetary Plasma & Heliosphere. Feynman retired from
13098-487: Was no longer working at the Los Alamos Laboratory, he was no longer exempt from the draft . At his induction physical, Army psychiatrists diagnosed Feynman as suffering from a mental illness and the Army gave him a 4-F exemption on mental grounds. His father died suddenly on October 8, 1946, and Feynman suffered from depression. On October 17, 1946, he wrote a letter to Arline, expressing his deep love and heartbreak. The letter
13216-611: Was not only converted to other religious views, but I also stopped believing that the Jewish people are in any way 'the chosen people '". Later in life, during a visit to the Jewish Theological Seminary , Feynman encountered the Talmud for the first time. He saw that it contained the original text in a little square on each page, and surrounding it were commentaries written over time by different people. In this way
13334-496: Was probably the first job Feynman had, and during this time he showed early signs of an aptitude for his later career in theoretical physics, when he would analyze the issues theoretically and arrive at the solutions. When he was in grade school, he created a home burglar alarm system while his parents were out for the day running errands. When Richard was five, his mother gave birth to a younger brother, Henry Phillips, who died at age four weeks. Four years later, Richard's sister Joan
13452-604: Was prompted to publish his ideas in the Physical Review in a series of papers over three years. His 1948 papers on "A Relativistic Cut-Off for Classical Electrodynamics" attempted to explain what he had been unable to get across at Pocono. His 1949 paper on "The Theory of Positrons" addressed the Schrödinger equation and Dirac equation , and introduced what is now called the Feynman propagator . Finally, in papers on
13570-640: Was quickly promoted to a higher math class. An IQ test administered in high school estimated his IQ at 125—high but "merely respectable", according to biographer James Gleick . His sister Joan, who scored one point higher, later jokingly claimed to an interviewer that she was smarter. Years later he declined to join Mensa International , saying that his IQ was too low. When Feynman was 15, he taught himself trigonometry , advanced algebra , infinite series , analytic geometry , and both differential and integral calculus . Before entering college, he
13688-442: Was sealed and only opened after his death. "Please excuse my not mailing this," the letter concluded, "but I don't know your new address." Unable to focus on research problems, Feynman began tackling physics problems, not for utility, but for self-satisfaction. One of these involved analyzing the physics of a twirling, nutating disk as it is moving through the air, inspired by an incident in the cafeteria at Cornell when someone tossed
13806-487: Was surprised by the offers of professorships from other renowned universities, including the Institute for Advanced Study , the University of California, Los Angeles , and the University of California, Berkeley . Feynman was not the only frustrated theoretical physicist in the early post-war years. Quantum electrodynamics suffered from infinite integrals in perturbation theory . These were clear mathematical flaws in
13924-474: Was working on a device called an isotron, intended to electromagnetically separate uranium-235 from uranium-238 . This was done in a quite different manner from that used by the calutron that was under development by a team under Wilson's former mentor, Ernest O. Lawrence , at the Radiation Laboratory of the University of California . On paper, the isotron was many times more efficient than
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