The theory of gravity, as we understand it today, was primarily developed and clarified by Sir Isaac Newton and later expanded upon by Albert Einstein with his theory of general relativity.
Sir Isaac Newton formulated the law of universal gravitation in the late 17th century. In his book "Mathematical Principles of Natural Philosophy" (1687), Newton described gravity as a force that attracts objects with mass toward each other. According to Newton's theory, any two objects in the universe exert a gravitational force on each other, which depends on their masses and the distance between them. Newton's law of universal gravitation provided a mathematical framework for understanding and predicting the motion of celestial bodies, including the planets.
However, Newton's theory of gravity had limitations. It described gravity as an instantaneous force acting at a distance, which raised questions about the nature of gravity itself. In the early 20th century, Albert Einstein revolutionized our understanding of gravity with his theory of general relativity, published in 1915.
Einstein's general relativity proposed a new concept of gravity. According to this theory, gravity arises from the curvature of spacetime caused by mass and energy. In other words, massive objects, such as planets or stars, deform the fabric of spacetime around them, and other objects moving through this curved spacetime experience what we perceive as the force of gravity. Einstein's theory provided a more comprehensive and accurate description of gravity, especially in extreme cases where strong gravitational fields or high speeds are involved.
Since Einstein's formulation of general relativity, various experiments and observations have confirmed its predictions. For example, the bending of light around massive objects, the precession of the orbit of Mercury, and the gravitational waves detected in recent years all support the validity of general relativity.
It's important to note that our understanding of gravity continues to evolve as scientists explore its deeper aspects, such as its potential unification with quantum mechanics. Research in areas like quantum gravity and string theory aims to further refine our understanding of gravity and its fundamental nature.