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Q & A: Electron-positron annihilation spectra into three photons?

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Most recent answer: 06/01/2014
When electron and positron (matter-antimatter in general) close together why there is juts annihilation, why they don't radiate energy when they spiral into eachother like charged particles would do?
- Juho (age 16)

Hello Juho,

Electrons can and do annihilate into two or more photons.  Single photon annihilation is forbidden by the laws of conservation of energy and momentum.   The relative rates of three-or-more photon annihilations agree well with the calculations of quantum electro-dynamics.   The simple picture you have in mind, that of a spiraling trajectory, is a bit old-fashioned and really gives a false impression of what's going on.  You really have to use the modern QED theory to get things right. 



(published on 06/01/2014)

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