Through our actions we sense what is happening in the world. We know that we are moving around one of the stars in the Milky Way galaxy.
In the 20th century Edwin Hubble discovered that the Andromeda nebula is in fact a galaxy, one of many, we know now to be distributed in clusters. The motions of these need modified Newtonian dynamics for full comprehension.
Energies interchanges of the whole universe as the fundamental physical processes provide a way of comprehending the motions galaxies in gravitational interactions as features of large scale energy changes. The concentration of energies through the mass function of stars rotating in galaxies is the physical reality of modified Newtonian dynamics.
The dynamics galaxies superclusters may also be comprehended as functions of energies concentration through channels across the universe. These are features of overall, large scale interchanges of the cosmos that we sense.