In the 1930’s and the 1970’s astronomers discovered that the outer regions of spiral galaxy clusters moved much faster than their combined mass could explain. This led to the supposition that there must be a huge amount of some invisible/dark mass/matter, that amounts up to 85% of all matter in the universe! After more than fifty years, no ‘dark’ matter has however been found. On the contrary, irregularities among galaxies have been found that even dark matter cannot explain, such as: the Tully-Fisher relation between the brightness of a galaxy and the velocity of its outermost stars, and the strange gamma ray signals from the center of the milky way. In this paper the author demonstrates that, when 3-dimensional mass particles accelerate to a black hole, due to the Lorentz-Fitzgerald contraction, their length in their direction of motion is gradually contracted, until they reach the Schwarzschild radius where they obtain the speed of light and where they are compressed into 2-dimensional wave-particles. This means that they simply have become light particles, with no longitudinal mass but only transverse mass characteristics, such as variable velocity, linear momentum and gravitational interaction, in a plane perpendicular to their invariable speed, which explains the cylindrical photon ring gradually circulating into a black hole. This means that light is strong enough to survive the most extreme conditions in the universe, at the event horizon of a Black Hole, which is confirmed by the recent Chinese cosmic ray observatory ‘LHAASO’ that has demonstrated that ultra-high-energy photons can attain energies up to 1,4.109MeV, which is 140 times the energy that can be produced by the Large Hadron Collider! And it is also in line with the so-cold “gamma ray burst” that emit the same amount of energy as a supernova, but in seconds or minutes instead of weeks! This allows the author to demonstrate that the high velocities in the outer regions of spiral galaxy clusters, is not caused by some invisible ‘dark’ matter, but that it is caused by the transverse gravitational interaction of high energy photons, circulating those galaxy clusters. And it also explains the Tully-Fisher relation between the brightness of a galaxy and the velocity of its outermost stars. And this also explains the fireball of γ-rays that followed immediately after the detection of the gravity waves released by the merging of two neutron stars.