Richard Feynman American theoretical physicist, Nobel laureate in 1965. Date of Birth: 11.05.1918 Country: USA

Biography of Richard Feynman

American theoretical physicist, Nobel laureate in 1965. Richard Phillips Feynman was born in New York City, in the family of Melville Arthur Feynman and Lucille Phillips. He grew up in Far Rockaway, Queens, with his younger sister. His father, the head of the sales department at a uniform factory, had a deep interest in the natural sciences and encouraged his son to conduct experiments in their home laboratory. Along with his school friend, Feynman entertained their neighbors by performing simple chemistry tricks. Even as a high school student, he earned money by repairing radios. As the captain of the school's algebra team, Feynman displayed an ability to quickly solve complex mathematical problems by considering them as a whole, avoiding lengthy calculations.

After graduating from high school in 1935, Feynman enrolled at the Massachusetts Institute of Technology (MIT) and graduated with a bachelor's degree in physics in 1939. At MIT, he realized that "the most important problem of the time was the unsatisfactory state of quantum theory of electricity and magnetism (quantum electrodynamics)". Quantum electrodynamics is the study of interactions between elementary particles and between particles and the electromagnetic field. Many positions of the existing theory, created by Werner Heisenberg, Wolfgang Pauli, and P.A.M. Dirac, received brilliant confirmation, but there were still unclear aspects in its structure, such as the infinite mass and infinite charge of the electron.

In 1939, Feynman entered the graduate program at Princeton University and received the Proctor Fellowship. In graduate school, he continued experimenting with various approaches to quantum electrodynamics, learning from mistakes, discarding unsuccessful schemes, and trying out many new ideas, some of which arose during conversations with his advisor, John A. Wheeler. Feynman aimed to preserve the principle of delayed action of one electron on another: an electron, experiencing the influence of another electron, in turn affects it with a certain additional delay, similar to light reflecting back to its source. Following Wheeler's advice, Feynman suggested that this reflection consists not only of the usual delayed wave but also an "anticipating" wave that reaches the electron before its disturbing action begins. Feynman did not find the paradoxical course of time, running not only forward but also backward, to be a concern, as he later admitted: "By that time, I was enough of a physicist to say, 'Oh no, it's not impossible!'". After months of mathematical calculations, failures, and attempts to find new approaches, Feynman succeeded in transforming concepts and equations from different perspectives. He found original ways to incorporate quantum mechanics into classical electrodynamics and developed methods for obtaining results quickly and easily, which would require cumbersome calculations using traditional approaches. One of his most successful ideas was the use of the principle of least action, based on the assumption that nature chooses the most economical path to achieve a certain goal. Although Feynman was not satisfied with his achievements, he acknowledged that he had made significant progress in solving the problem, and his work received recognition. Feynman published his dissertation "The Principle of Least Action in Quantum Mechanics" and obtained his Ph.D. in physics in 1942.

Shortly before completing his dissertation, Feynman received a job offer from a group of Princeton physicists involved in uranium isotope separation for the Manhattan Project, i.e., the creation of an atomic bomb. From 1942 to 1945, Feynman led a group in Los Alamos, New Mexico, working in Hans A. Bethe's division. Even during these years, he found time to contemplate while riding the bus, making necessary calculations on scraps of paper, contemplating the further development of the proposed quantum electrodynamics variant. At Los Alamos, Feynman interacted with Niels Bohr, Orestes Boron, Enrico Fermi, Robert Oppenheimer, and other leading physicists. He was among those present at the first atomic bomb test in Alamogordo, New Mexico. After the war, in the summer of 1945, Feynman worked with Hans A. Bethe at General Electric in Schenectady, New York. He then became an adjunct professor of theoretical physics at Cornell University. Meanwhile, new questions arose for quantum electrodynamics. For example, in 1947, Willis E. Lamb showed through precise experiments that two energy levels, which according to Dirac's theory should correspond to the same energy value, actually differ slightly (the "Lamb shift"). Another discrepancy between theory and experiment was discovered by Polykarp Kusch, who found that the electron's intrinsic magnetic moment exceeds its orbital magnetic moment by more than 0.1%. Building on the foundational work of Bethe, Feynman began working on solving these fundamental problems, but soon he entered a period of stagnation, driven by the fact that physics no longer provided him with the intellectual pleasure it once did. After some time, he accidentally witnessed someone tossing a plate in the Cornell University cafeteria and became interested in the relationship between the plate's rotation speed and its wobbling. Feynman managed to derive equations describing the flight of the plate. This exercise rejuvenated him, and he resumed his work on quantum electrodynamics.

What he was doing seemed to have no real value," Feynman later wrote, "but, in fact, it had great importance. The diagrams and everything else for which I received the Nobel Prize had their origin in that apparently meaningless play with a spinning plate." "Everything else" was a new variant of the theory in which quantum electrodynamics interactions were considered from a new perspective - trajectories in space-time. It is said that a particle travels from its initial trajectory point to its final point; possible interactions "along the way" are expressed in terms of their relative probabilities. These probabilities are summed into series (sometimes complex) for which Feynman developed rules and graphical techniques (Feynman diagrams). Externally simple but extremely convenient, these diagrams are widely used in many areas of physics. Feynman managed to explain the "Lamb shift," the electron's magnetic moment, and other particle properties. Independently of Feynman and each other, based on different theoretical approaches, Julius S. Schwinger and Sin-Itiro Tomonaga almost simultaneously proposed their versions of quantum electrodynamics and managed to overcome the main difficulties. They used a mathematical procedure called renormalization. By postulating positive and negative infinities that almost entirely cancel each other out, and the remaining residue (such as the electron's charge) corresponds to experimentally measured values. The Feynman-Schwinger-Tomonaga quantum electrodynamics is considered the most accurate physical theory known today. Its correctness has been experimentally confirmed over a wide range of scales - from subatomic to astronomical.

Together with Schwinger and Tomonaga, Feynman was awarded the Nobel Prize in Physics in 1965 "for their fundamental work in quantum electrodynamics, with deep-ploughing consequences for the physics of elementary particles." In his speech at the award ceremony, Ivar Waller of the Swedish Royal Academy of Sciences noted that the laureates had introduced new ideas and methods into an old theory and created a new one that now occupies a central position in physics. It not only explains previous discrepancies between theory and experiment but also allows for a deeper understanding of the behavior of mu mesons and other particles in nuclear physics, solid-state physics, and statistical mechanics. Feynman remained at Cornell University until 1950 and then moved to the California Institute of Technology as a professor of theoretical physics. In 1959, he assumed the prestigious Richard Chace Tolman Professorship, established in memory of Richard Chase Tolman. In addition to his work on quantum electrodynamics, Feynman proposed an atomic explanation for the theory of liquid helium, developed by Soviet physicist Lev Landau. Helium, which undergoes liquefaction at 4°K (-269°C), becomes superfluid at around 2°K. The dynamics of superfluid helium sharply contrast with the laws that ordinary liquids obey: it cools rather than heats up when flowing, freely flows through microscopic narrow openings, "defying" gravity, and creeps up the walls of a container. Feynman derived the rotons postulated by Landau to explain the unusual behavior of superfluid helium atoms. His explanation suggests that the atoms of very cold helium aggregate into rotons, forming something akin to smoke rings.

Together with his colleague Murray Gell-Mann, Feynman made significant contributions to the theory of weak interactions, such as the emission of beta particles by radioactive nuclei. This theory emerged from Feynman diagrams, which graphically represent interactions between elementary particles and their possible transformations. Feynman's last works were devoted to strong interactions, i.e., the forces that hold nucleons in the nucleus and act between subnuclear particles, or "partons" (such as quarks) that make up protons and neutrons.

Feynman's originality of thought and his artistry as a lecturer influenced a whole generation of physics students. His method of intuitively guessing a formula and subsequently proving its correctness has more imitators than critics. The influence of both his theories and his personality is felt in every branch of modern elementary particle physics.

Feynman was married three times. Arline Greenbaum, whom he married in 1941, died of tuberculosis in 1945 while Feynman was in Los Alamos. His marriage to Mary Louise Bell, entered into in 1952, ended in divorce. In 1960, he married Gwyneth Howarth in England. They had a son and a daughter. Honest and irreverent toward authority, Feynman served on the presidential commission investigating the circumstances of the explosion of the reusable space shuttle "Challenger" in 1986. He composed his own thirteen-page report, criticizing the responsible officials of the National Aeronautics and Space Administration (NASA) for being "foolish" and not noticing significant flaws in the design of the spacecraft. A person of tireless curiosity and diverse interests, Feynman enjoyed playing the bongos, studying the Japanese language, drawing and painting, participating in deciphering Mayan texts, and showing a lively interest in the wonders of parapsychology, although he approached them with a healthy dose of skepticism.

In addition to the Nobel Prize, Feynman received the Albert Einstein Memorial Award from the Lewis and Rosa Strauss Memorial Fund (1954), the Ernest Orlando Lawrence Prize in Physics from the United States Atomic Energy Commission (1962), and the Niels Bohr Gold Medal from the Danish Society of Engineers, Electricians, and Mechanics (1973). Feynman was a member of the American Physical Society, the Brazilian Academy of Sciences, and the Royal Society of London. He was elected a member of the National Academy of Sciences of the United States, but later resigned.