I know because E=(n+1/2)*h-bar*omega , and n is an integer , with the integers ranging from zero, to all positive values. Photons are said to be massless physical quantities and according Einstein's theory of special relativity (or general relativity) mass and energy are equivalent. So if a photon is massless, then why wouldn't the energy for a photon be zero? I know that in vacuum states, that their are still oscillations occurring, so technically there is no vacuous state ; is that the explanation for why there are zero energies states at the atomic level? Bose einstein condensate , says that an energy state can get close to a temperature equivalent to the absolute value of zero but not exactly at absolute zero. Could n0n-zero temperature be the explanation for a non-zero energies. Why do oscillations at the atomic level never cease?