... then emitting a fast moving electron or by converting a proton to a neutron and then emitting a fast moving positron. The most famous is the decay of 14C to 14N, used by archaeologists. If this is all that happens then we should expect the energy before and afterwards to be the same (as energy is not destroyed, just changed from one form to another.) In fact the electrons energies ranges from zero to nearly the mass difference. In a letter written by Wolfgang Pauli, he suggested that this happened because another particle was emitted. As this particle did not have any electric charge, it managed to escape from the reaction undetected carrying with it the missing energy. The name Neutrino (Italian for 'little neutral one') was given to this particle. The neutrino is very difficult to observe, hence Pauli saying he thought it would never be observed. Although this had ...

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