[swansont]

Widdekind, on 18 January 2012 - 08:05 AM, said:

Is the photon's "obliviousness", to the Weak interaction, what "shields" photons, from decay, into neutrinos, i.e. ? Otherwise, if neutrinos mass <1eV, then every photon more energetic than infra-red would be unstable to neutrino decay ?

AFAIK, yes. Gell-Mann put it as something like "That which is not forbidden is mandated". Conversely, if it doesn't happen at all (given enough chances, of course), it must be forbidden in some way.

[Widdekind]

swansont, on 18 January 2012 - 11:33 AM, said:

AFAIK, yes. Gell-Mann put it as something like "That which is not forbidden is mandated". Conversely, if it doesn't happen at all (given enough chances, of course), it must be forbidden in some way.

For clarity, then, the Z^O neutral Weak boson has been dubbed "heavy light", and like light, is only able to alter another 'particle's' momentum / energy & spin. Yet, the Z⁰ couples to, and can decay into, neutrinos. So, then, the Z⁰ is "more than merely massive light" ?

[immijimmi]

Everything is made of energy. When things release photons it is because photons are made of energy and not much else, therefore they are easy to create as an outlet for spare energy. One reason photons can't be the fundamental constituents of matter would be that they don't have color charge, electric charge or mass, and most components of matter possess these qualities.