It is a prerequisite of atomic theory.
The attracting force that exists between any two particles of matter is called gravity. This force exists throughout the universe and explains the behavior of both the apple that fell on Newton's head and the orbit of the Earth around the Sun. The Theory of Gravity is credited to Sir Isaac Newton, who first recognized that gravitation was universal. His work opened the door to later scientists including Albert Einstein, who developed the Theory of Relativity, and the men who developed Atomic Theory.