[thatnerd]

I think it's an upper limit of around 0.2 eV^2, so √(0.2 eV^2) = 0.45 eV.

I'd like to see an experiment that's sensitive enough to eliminate the m=0 hypothesis. Their prediction of m^2 = -0.14eV^2 is a bit disconcerting.

[tlogan]

How can we prove that one of neutrinos is massless? That would be impossible - but I do not understand these things so I can be wrong.

[colanderman]

I believe GP is proposing the opposite -- a test capable of proving it is not massless. (Presumably this has never been done.)