Gravity can be either "artificial gravity" or natural gravity. This effect can cause liquids to flow against the force of gravity. Then it curves downward due to gravity. String theory is a theoretical framework that attempts to reconcile gravity and quantum mechanics. The flow of water depended on gravity alone. Let formula 12 be the acceleration of gravity. Heavy refers to oil that has higher density and therefore lower API gravity. They are sensitive to gravity and linear acceleration. Water inside the aqueducts depended entirely on gravity. Rivers flow downhill with their power derived from gravity. There are a number of other approaches to quantum gravity. Candidates for a future theory of quantum gravity include string theory. They are relevant in research on unified theories such as quantum gravity. Beginning in 1973, Hawking moved into the study of quantum gravity and quantum mechanics. Pushing behavior has shown that perception of body posture in relation to gravity is altered.