In addition, since a given process can be represented by many possible Feynman diagrams, the contributions of every possible diagram must be entered into the calculation of the total probability that a particular process will occur. The calculations must include terms equivalent to all the lines (representing propagating particles) and all the vertices (representing interactions) shown in the diagram. (See the figure.)įeynman diagrams are used by physicists to make very precise calculations of the probability of any given process, such as electron-electron scattering, for example, in quantum electrodynamics. In this way the path of an electron, for example, appears as two straight lines connected to a third, wavy, line where the electron emits or absorbs a photon. The basic interaction therefore appears on a Feynman diagram as a “vertex”-i.e., a junction of three lines. On a conceptual level fermions may be regarded as “matter” particles, which experience the effect of a force arising from the exchange of bosons, so-called “force-carrier,” or field, particles.Īt the quantum level the interactions of fermions occur through the emission and absorption of the field particles associated with the fundamental interactions of matter, in particular the electromagnetic force, the strong force, and the weak force. Straight lines are used to depict fermions-fundamental particles with half-integer values of intrinsic angular momentum ( spin), such as electrons ( e −)-and wavy lines are used for bosons-particles with integer values of spin, such as photons (γ). Introduced during the development of the theory of quantum electrodynamics as an aid for visualizing and calculating the effects of electromagnetic interactions among electrons and photons, Feynman diagrams are now used to depict all types of particle interactions.Ī Feynman diagram is a two-dimensional representation in which one axis, usually the horizontal axis, is chosen to represent space, while the second (vertical) axis represents time. SpaceNext50 Britannica presents SpaceNext50, From the race to the Moon to space stewardship, we explore a wide range of subjects that feed our curiosity about space!įeynman diagram, a graphical method of representing the interactions of elementary particles, invented in the 1940s and ’50s by the American theoretical physicist Richard P.Learn about the major environmental problems facing our planet and what can be done about them! Saving Earth Britannica Presents Earth’s To-Do List for the 21st Century.Britannica Beyond We’ve created a new place where questions are at the center of learning.100 Women Britannica celebrates the centennial of the Nineteenth Amendment, highlighting suffragists and history-making politicians.COVID-19 Portal While this global health crisis continues to evolve, it can be useful to look to past pandemics to better understand how to respond today. Student Portal Britannica is the ultimate student resource for key school subjects like history, government, literature, and more.Demystified Videos In Demystified, Britannica has all the answers to your burning questions.This Time in History In these videos, find out what happened this month (or any month!) in history.#WTFact Videos In #WTFact Britannica shares some of the most bizarre facts we can find.Britannica Classics Check out these retro videos from Encyclopedia Britannica’s archives.Britannica Explains In these videos, Britannica explains a variety of topics and answers frequently asked questions.
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