Proton decay into neutron by negative pion (anti up quark plus down quark) which decay into neutrino plus muon (205.7 Mev/c^2) which make proton has 8.4087*10^-16 meter radius, it predict decay time 881(second)=(8.4087*10^-16)^2*(1.602*10^-19)/(137.036*0.938*10^9*10), by symmetry of time neutron decay into proton take same time.