Cosmic coincidence or graviton mass?
  Using the quantum corrected Friedmann equation, obtained from the quantum
Raychudhuri equation, and assuming a small mass of the graviton (but consistent
with observations and theory), we propose a resolution of the smallness
problem(why is observed vacuum energy so small?) and the coincidence
problem(why does it constitute most of the universe, about 70%, in the current
epoch?).
