Replacing the classical physics in use since the end of the scientific revolution, modern physics arose in the early 20th century with the advent of quantum physics, substituting mathematical studies for experimental studies and examining equations to build a theoretical structure.[citation needed] The old quantum theory was a collection of results which predate modern quantum mechanics, but were never complete or self-consistent. The collection of heuristic prescriptions for quantum mechanics were the first corrections to classical mechanics. Outside the realm of quantum physics, the various aether theories in classical physics, which supposed a "fifth element" such as the Luminiferous aether, were nullified by the Michelson-Morley experiment—an attempt to detect the motion of earth through the aether. In biology, Darwinism gained acceptance, promoting the concept of adaptation in the theory of natural selection. The fields of geology, astronomy and psychology also made strides and gained new insights. In medicine, there were advances in medical theory and treatments.