I dont believe expanding space. Space is nothing and it cant change any way! Photons have density and size. If photon is density, Photon time is slowly and thats why new light dont interactive so much what old light! Old light photons are not so density and that why old photons time moving faster than new photons time. Old photons get light expanding / red shifting faster. We dont need dark energy, because there is no expanding space at all! Also all kind of particle expanding all a time! Photons never glint like biljardball! Photon interactive with particle who pushing out from expanding nucleus of atom and get that particle entropy working faster and then we have a new photon. Also very old photons interactive with particle who pushing out from expanding nucleus of atoms and get that particle expanding very fast. All expanding particle recycle all at time eternal thing! Only real force is pushing force! Space is eternal, infinity place who is nothing! Thanks! Black holes are very density "stars" who emit very density particle who dont workin like photons! Maybe we can found out how we get this particle entropy start working faster and if we can, then we mide can see black holes?

Actually we can't say that a photon has Density, because theoretically a photon has no mass but according to "wave particle duality" photons have mass. This is a contradiction. Now coming to the universe, think universe as a particle then if the particle is traveling at the speed of light, then according to relativistic mechanics the mass also increases, thus it could be that this is the cause of expansion of universe.