Nearly Forty years ago I worked out how gravity works.  In short it is a direct pull on empty space. For a long time it has been accepted fact that the universe is entirely empty, only a microscopical amount of energy makes the universe we see and feel. This energy is formed by the motion of space. Energy is only motion more complex variations are made after Billions of years of accretions of mass. Tiny individual units of space begin  to spin and this permanent spin is the pull of gravity. Thus the redshift of light from distant stars is because the light moves against the pull of gravity the further the travel the greater the redshift.
Not expansion without explanation. Penzias & Wilson we’re puzzled by radiation that came from all directions. This was adjudged by Dicke of Harvard as the remains of light from Big  Bang. The only known motion coming from all directions for sure is Gravity Dare we say New Gravity? —- The route from the complicated to the transparently obvious is a path towards the ‘True ‘ picture of Nature’
James Clark Maxwell,,