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Mathematically, QED has the structure of an Abelian gauge theory with a U(1) gauge group. The gauge field which mediates the interaction between the charged spin-1/2 fields is the electromagnetic fieldThe electromagnetic field EMF is composed of two related vectorial fields, the electric field and the magnetic field. This means that the vectors E and B that characterize the field each have a value defined at each point of space and time. If only E the.
Physically, this translates to the picture of charged particles (and their antiparticleFor each kind of particle, there is an associated antiparticle with the same mass but opposite electromagnetic, weak, and strong charges, as well as spin. Some particles, notably photons, have no distinct antiparticle, or, put in another way, are identicas) interacting with each other by the exchange of photonFor the Japanese anime video, see Photon (anime). In physics, the photon (from Greek φοτος, meaning light is a quantum of excitation of the quantised electromagnetic field and is one of the elementary particles studied by qus. These interactions can be described pictorially with Feynman diagramA Feynman diagram is a bookkeeping device for performing calculations in quantum field theory, invented by American physicist Richard Feynman. The problem of calculating scattering cross sections in particle physics reduces to summing over the amplitudess, and QED was historically the theory to which Feynman diagrams were first applied.
QED was the first quantum field theory in which the difficulties of building a consistent, fully quantum description of fields and creation and annihilation of quantum particles were satisfactorily resolved. Sin-Itiro TomonagaSin-Itiro Tomonaga or Shinichiro Tomonaga ( Tomonaga Shin'ichiro March 31, 1906 July 8, 1979) was a Japanese physicist, influential in the development of quantum electrodynamics, work for which he was jointly awarded the Nobel Prize in Physics in 1965 alo, Julian SchwingerJulian Seymour Schwinger ( February 12, 1918 July 16, 1994) was an American theoretical physicist. He formulated the theory of renormalization and posited a phenomenon of electron-positron pairs known as the Schwinger effect. He was jointly awarded the No and Richard FeynmanRichard Phillips Feynman ( May 11, 1918 February 15, 1988) ( surname pronounced "fine-man") was one of the most influential American physicists of the 20th century, expanding greatly the theory of quantum electrodynamics. As well as being an inspiring lec received the 19651965 was a common year starting on Friday (the link is to a full 1965 calendar). Events January-February January 4 United States President Lyndon Johnson proclaims his " Great Society" during his State of the Union address. January 14 Prime Ministers of N Nobel Prize in Physics for its development, their contributions involving a covariant and gauge invariant prescription for the calculation of observable quantities. Feynman's mathematical technique, based on his diagrams, initially seemed very different from the field-theoretic, operator-based approach of Schwinger and Tomonaga, but was later shown to be equivalent. The renormalization procedure for making sense of some of the infinite predictions of quantum field theory also found its first successful implementation in quantum electrodynamics.
The QED Lagrangian for the interaction of electrons and positrons through photons is
The part of the Lagrangian containing the electromagnetic field tensor describes the free evolution of the electromagnetic field, whereas the Dirac-like equation with the gauge covariant derivative describes the free evolution of the electron and positron fields as well as their interaction with the electromagnetic field.