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Ideas of comparison of scientific theories on a specific data set are at the fundamental level of statistics of model selection.  These can be extended to total theories although there is no solid theory that I know of.  Given the difficulty in simply producing any models that fit all known empirical facts in physics might imply that methods for comparison of total theories is a mere curiosity.  But the effort might still be justified on the grounds that there is an explosion of widely differing theories of physics unifying gravity and other forces including monumental efforts such as quantum gravity and string theories.  One of the attractive qualities in efforts toward an ‘S4 physics’ in which the shape of the universe is fixed to $1/h$ where $h$ is Planck constant is that the identification of radius of the universe to observed quantum spacing of energy reduces parameters for any theory describing the subatomic phenomena with macroscopic phenomena.  This is an old note which requires for its validity the observation that the Einstein’s equation with a cosmological constant $h^2$ appears as the Euler-Lagrange equation for the Einstein-Hilbert action over hypersurfaces.