  The method of covariant perturbation theory allowed for the computation of
the kernel of the evolution equation on a spin Riemannian manifold. The
proposed axiomatic definition of the covariant effective action introduces the
universal scale parameter, with the length square dimensionality, into a
dimensionless mathematical theory. It is shown that this geometrical result has
a physical meaning of the action of field theory, including gravity. Two lowest
tensor order terms of this functional are independent of a spin group and
local. They reproduce the action of general relativity with the cosmological
constant. The current value of the universal scale can be determined with the
measured Hubble constant. This scale parameter considered as a physical
variable can let us build cosmological theories axiomatically.
