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Q & A: Unstable particles

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Most recent answer: 10/15/2009
Dear Sir what is the most unstable particle of the universe and why such kind of particle is unstable?
- Ali (age 32)
Hello Ali,
Particles can be unstable because there are certain interactions, or forces, that can transmute one particle into an equivalent  or equivalent collection of other particles.  One restriction is that the various conservation laws must hold.  For example charge, baryon number, lepton number, angular momentum, energy, etc.  A classic example is the decay of a neutron into a proton plus electron plus anti-neutrino.  The speed of the decay is determined by the strength of the interaction.  The three relevant interactions are the strong, electromagnetic, and weak (the latter two are intertwined and represent different manifestations of a single theory, the electro-weak).   
The most unstable?  Hard to say.
Clearly the rho meson is in the running. For more information look at:


(published on 10/15/2009)

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