Illustration of Feynman diagram

1948 Feynman diagram

The book of science

Tom Sharp

Richard Feynman quantum mechanics Illustration of Feynman diagram

Feynman diagram

A Feynman diagram graphs paths of subatomic particles against time, in which lines entering from the left and leaving to the right carry energy, momentum, and spin, in which each vertex represents where particles interact or split, and internal lines are propagators. Straight lines are fermions, wavy lines are bosons, and helical lines are gluons.

Antiparticles seem to go backward in time

Ernst Stueckelberg interpreted the positron, the electron’s antiparticular mate, as though it were an electron moving backward in time.


A Feynman diagram represents a possibility for a set of interacting particles, but it doesn’t represent all possibilities, which would be almost all of an infinite number of diagrams, which would be like . . . like . . .

One difference between a theorist and an experimentalist in the field of quantum chromodynamics is that the theorist simplifies to essential interactions, when the actual interactions can be far more complex, containing a profusion of gluons sprouting off quarks and antiquarks and decaying into hadrons.

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