Who is Sir Isaac Newton from A Brief History of Time and what is their importance?

Newton formulates several laws of physics that still hold to this day. The law of gravity is the most famous, and the tale about Newton coming up with the idea from an apple falling may have some truth to it. Another important law is the second law of thermodynamics. This introduces the concept of entropy in any closed system, where movement is from the organized to the disorganized. General relativity and quantum gravity make Newton's law of gravity less important while Hawking attempts to unify physics, yet the author finds the second law of thermodynamics useful for sifting through other theories.