This wouldn't be to do with neutrinos would it?
This idea has been around since the 70's but has been gaining ground recently.
A neutrino or anti-neutrino in produced every time a photon is. There are a lot of photons in the Universe!
There are reasons to believe that the neutrino might not actually be massless as we normally consider it to be but might have a really, really tiny mass.
Now we've not managed to measure a mass this small but there are 3 types of neutrino, the normal one the muon and the Tau. If they have mass they should swap identity - like a strange quick change routine -it's called mixing or oscilation .
Is it anything to do with that?