Gravitational physics is the study of the physical laws that govern how objects move in response to gravity. It is a branch of classical mechanics, which is concerned with the motion of bodies under the influence of forces. In gravitational physics, these forces are caused by mass and energy.
Gravity is a force that every object in the universe exerts on every other object. It is the force that keeps us glued to the ground and prevents us from floating off into space. The strength of gravity depends on two things: the mass of the objects involved and the distance between them. The more massive an object, the stronger its gravitational pull. And, as you might expect, the closer two objects are to each other, the stronger their mutual gravitational attraction will be.
The first person to develop a theory of gravity was Isaac Newton. In his 1687 book Philosophiæ Naturalis Principia Mathematica (often called simply The Principia), Newton showed that gravity was a force between masses. He also showed that it was responsible for some surprising phenomena, such as why apples fall from trees and why planets orbit around stars.
Newton’s theory of gravity worked well for many years. But it had one big problem: it could not explain what happened when objects moved very fast or were very close together—such as when two stars orbit each other or when light bends as it passes close to a star or black hole. To solve these problems, physicists had to develop a new theory of gravity—one that would work not only in everyday situations but also in extreme cases like these.