The term \"annihilate\" literally means \"turn into nothing\". However, when a p
ID: 1391993 • Letter: T
Question
The term "annihilate" literally means "turn into nothing". However, when a particle and antiparticle collide, they clearly do not turn into nothing; they simply transform into different particles.
Did the term originate at a time when physicists thought that matter + antimatter really did turn into nothing? Does anyone else find the term confusing and/or misleading? Can we introduce a better term?
(I find it especially irritating to hear physicists say that an electron and a positron annihilate into two photons... that's an oxymoron!)
Explanation / Answer
Elementary particles are characterized by quantum numbers, some of them esoteric, which have organized the known particles and resonances into specific multiplets of SU(3) or SU(2).
Different interactions conserve different quantum numbers, but the term "annihilation" is reserved for the annihilation of specific quantum numbers.
In the case of proton antiproton, baryon number is annihilated and becomes zero.
In the case of electron positron it is lepton number that is annihilated and becomes 0.
The energy released by these annihilations rearranges itself in different outgoing particles, conserving the quantum numbers of the given interactions.
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