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They are not space time diagrams, they are Feynman graphs. Technically they are a clever way to write down the terms of a series expansion. In the convention us
by yk 12y ago
They are not space time diagrams, they are Feynman graphs. Technically they are a clever way to write down the terms of a series expansion. In the convention used, on the left hand side are the incoming particles and the outgoing particles are on the right. The internal lines and vertices are just representations of formulas, and the important thing is only the topology of the graph.
However one of the really great things of Feynman graphs is, that they admit a easy interpretation about what is happening. Then the interior lines are interpreted as virtual particles that are created during the reaction, but since they are virtual they do not really have a defined speed, so the lines are just drawn like that.
- jessriedel 12y agoIn fact, Feynman diagrams are spacetime diagrams. (They are commonly computed in momentum space, i.e. Fourier space, but you can also do them in normal position space.) When you draw a Feynman diagram, the vertices correspond to actual points in spacetime, which are then integrated over a la the path integral.