In the original Newtonian concept, gravity was a force between point masses. Following Newton, Laplace attempted to model gravity as some kind of radiation field or fluid. Since the 19th century explanations for gravity have in terms of a field model, rather than a point attraction. This revolution was brought about by Einstein's general theory of relativity. Most scientists believe that the gravitational field and its gravitational waves are the physical interpretations of Einstein's equations of general relativity.