Theory of Gravity (Civ3)/Civilopedia

In the 17th century, Sir Isaac Newton developed the law of universal gravitation. This law recognized that every mass in the universe exerts 
an attraction on every other mass. Newton postulated that gravity was a universal force that affected all matter. Newton's theory served to 
explain the forces of attraction between the Earth and nearby objects, as well as the forces that affect the motion of planets and other 
astronomical bodies. In the early 20th century, Albert Einstein's special theory of relativity led to a major reinterpretation and clarification of 
Newton's theory of gravity. Scientists now believe that gravity affects energy as well as matter, and that gravity is actually a fundamental 
warping of the fabric of space-time. Some theorize that the force of this warping is transmitted by as-yet-unobserved particles called 
gravitons.