  We solve Klein-Gordon equation for massless scalars on d+1 dimensional
Minkowski (Euclidean) space in terms of the Cauchy data on the hypersurface
t=0. By inserting the solution into the action of massless scalars in Minkowski
(Euclidean) space we obtain the action of dual theory on the boundary t=0 which
is exactly the holographic dual of conformally coupled scalars on d+1
dimensional (Euclidean anti) de Sitter space obtained in (A)dS/CFT
correspondence. The observed equivalence of dual theories is explained using
the one-to-one map between conformally coupled scalar fields on Minkowski
(Euclidean) space and (Euclidean anti) de Sitter space which is an isomorphism
between the hypersurface t=0 of Minkowski (Euclidean) space and the boundary of
(A)dS space.
