  According to this principle, the relativistic changes occurring to the
bodies, after velocity changes, cannot be detected by observers moving with
them because bodies and stationary radiations change in identical proportion
after identical circumstances, i.e, because bodies and stationary radiations
have identical relativistic laws with respect to any fixed observer.
Effectively the theoretical properties of particle models made up of stationary
radiations agree with special relativity, quantum mechanics and the
gravitational (G) tests. They fix lineal properties for all of them: the G
fields, the black holes (BHs) and the universe. The BHs, after absorbing
radiation, must return to the gas state. An eventual universe expansion cannot
change any relative distance because the G expansion of matter occurs in
identical proportion. This fixes a new kind of universe. In it matter evolves
in closed cycles, between gas and BH states and vice versa, indefinitely.
Galaxies and clusters must evolve rather cyclically between luminous and black
states. Most of the G potential energy of a matter cycle must be released
around neutron star and black hole boundaries. Nuclear stripping reactions
would transform G energy into nuclear and kinetic energies. This accounts for
many non well explained phenomena in astrophysics. This work has been
published, in more detail, in a book.
