This assumes a minimum energy from each photon.  If you could red-shift indefinitely you could end up with ex: 1 + 1&#x2F;2 + 1&#x2F;4 + 1&#x2F;8 +... which sums to 2.<p>I believe the minimum energy of a photon is directly bound by the age of the universe, so if the universe was twice as old you could have photons at 1&#x2F;2 the energy.  You do get more light sources as you increase distance, but the inverse square law balances that.  So Sum (1&#x2F;n) from 1 to N which really slowly grows to infinity.  As in 10^100 = 230.84