In the case of the large-scale structure of the universe, the dominant paradigm is that the dynamics of the universe are governed by the theory of general relativity, augmented by the postulation of the existence of dark matter and dark energy. Classical Newtonian theory of gravity was not believed to hold, because it could not explain many features of galaxies.

But in science, one can always come up with alternative theories to the dominant paradigm to explain any phenomenon and there have been efforts to develop what are known as MOND theories (standing for MOdified Newtonian Dynamics) to explain the properties of the universe that would dispense with general relativity and revert to Newtonian gravity with slight modifications. Via blog reader Hunter, I came across this article that says that they have tested one form of the MOND hypothesis and found that it cannot explain the measured gravitational redshift of galaxy clusters, while general relativity and dark matter can.

This does not definitely rule out MOND theories since any theory can always be tweaked to accommodate any experimental result. But such negative results do make them less plausible to scientists.