The theory of gravity was not "cleared" by any individual in the sense of being proven completely correct or validated by a single person. Instead, our understanding of gravity has developed over centuries through the work of numerous scientists and thinkers.
One of the key figures in the development of the theory of gravity was Sir Isaac Newton, who formulated the law of universal gravitation in the late 17th century. Newton's law described gravity as a force of attraction between objects with mass, and it provided a mathematical framework for understanding and predicting the motion of celestial bodies.
However, our understanding of gravity underwent a significant transformation in the early 20th century with the advent of Albert Einstein's theory of general relativity. Einstein's theory proposed a new understanding of gravity, describing it as the curvature of spacetime caused by the presence of mass and energy. General relativity provided a more comprehensive and accurate explanation of gravity, particularly in extreme conditions and situations involving strong gravitational fields.
Since Einstein's formulation, scientists have continued to study and refine our understanding of gravity through observations, experiments, and theoretical advancements. Various experiments, such as the Eötvös experiment, the Pound-Rebka experiment, and more recent experiments involving gravitational waves, have provided empirical support for the predictions of general relativity.
It's important to note that while our current understanding of gravity is primarily based on general relativity, there are ongoing efforts to reconcile gravity with quantum mechanics, giving rise to the field of quantum gravity. However, a complete and unified theory of quantum gravity is still an active area of research and remains a challenge in theoretical physics.