photons photons photons photons photons photons photons photons photons photons photons photons photons photons photons. photons photons photons photons http://en.wikipedia.org/wiki/Photons photons photons photons. photons photons photons photons Photons photons photons photons photons photons photons photons photons photons Photons photons photons photons photons photons photons photons photons photons photons photons photons photons photons photons photons photons photons photons photons photons photons photons photons photons photons photons photons photons photons photons photons photons photons photons photons photons photons photons photons photons Photons photons photons Photons photons photons photons transitions between their energy levels Photons photons photons