Machian derivation of the Friedmann equation
  Despite all fundamental objections against Newtonian concepts in cosmology,
the Friedmann equation derives from these in an astoundingly simple way through
application of the shell theorem and conservation of Newtonian energy in an
infinite universe. However, Friedmann universes in general posses a finite
gravitational horizon, as a result of which the application of the shell
theorem fails and the Newtonian derivation collapses. We show that in the
presence of a gravitational horizon the Friedmann equation can be derived from
a Machian definition of kinetic energy, without invoking the shell theorem.
Whereas in the Newtonian case total energy translates to curvature energy
density, in the Machian case total energy takes on different identities,
depending on the evolution of the horizon; we show that in the de Sitter
universe Machian total energy density is constant, i.e. appears as cosmological
constant.
