Although physics was not considered a distinct field of science until the early nineteenth century, people have been studying the motion, energy, and forces that are at play in the universe for thousands of years. The earliest documented accounts of serious thought toward physics, specifically the motion of the planets, dates back to the years of the Chinese, Indians, Egyptians, Mesoamericans, and the Babylonians. The Greek philosophers Plato and Aristotle analyzed the motion of objects, but did not perform experiments to prove or disprove their ideas.