In this video Dr.Lincoln says that the weak interaction is weak in low energies because the particles cannot emit the Z and W bosons easily. He mentions the decay of a neutron to a proton an electron and an electron antineutrino.He says the beta decay through the weak interaction happens slowly because for it to happen a W boson with mass 0.002 billion eV/c^2 must be emmited and the W boson has an average mass of 90 billion eV/c^2 -> it is very rare to find a W boson with such low mass which will cause the decay.
He made another video about quantum gravity which highlights some of the properties graviton must have:
averagely massless ( averagely moving at c , does not decay(infinite range) )
quantum spin = 2 ( gravity is only attractive )
I was wondering according to his first video if gravitons were massless then it would be easy to be emmited from a particle ( fermion) and gravity should be really strong.But on the other hand gravitons must be massless because gravitational waves propagate at c ( special relativity).
So what's the point here?