Cosmological Constant Implementing Mach Principle in General Relativity
  We consider the fact that noticing on the operational meaning of the physical
concepts played an impetus role in the appearance of general relativity (GR).
Thus, we have paid more attention to the operational definition of the
gravitational coupling constant in this theory as a dimensional constant which
is gained through an experiment. However, as all available experiments just
provide the value of this constant locally, this coupling constant can
operationally be meaningful only in a local area. Regarding this point, to
obtain an extension of GR for the large scale, we replace it by a conformal
invariant model and then, reduce this model to a theory for the cosmological
scale via breaking down the conformal symmetry through singling out a specific
conformal frame which is characterized by the large scale characteristics of
the universe. Finally, we come to the same field equations that historically
were proposed by Einstein for the cosmological scale (GR plus the cosmological
constant) as the result of his endeavor for making GR consistent with the Mach
principle. However, we declare that the obtained field equations in this
alternative approach do~not carry the problem of the field equations proposed
by Einstein for being consistent with Mach's principle (i.e., the existence of
de Sitter solution), and can also be considered compatible with this principle
in the Sciama view.
