Space is the medium of radiation particle movement

pace is the medium for the movement of radiation particles. Only the speed at which the medium changes radiation can the medium have quality. There are two forms of media: 1. Vacuum, absolutely still, and without mass. Radiation particles move at the speed of light, and there is no mass in vacuum space. 2. Non-vacuum, relative movement, and mass. The non-vacuum range is very wide. The microscopic appearance is: atomic nuclei, electrons, quarks and even more basic particles, the macroscopic appearance is: satellites, planets, stars, galaxies, black holes and even dark matter and other celestial bodies. Obviously there is mass in non-vacuum space. Non-vacuum space slows down the speed of radiation particles, thus forming mass. Dark matter (this special medium) can stop any radiation particles from moving, so the mass of dark matter is extremely huge, and the mass of dark matter is extremely huge