Sir Isaac Newton has come first in the PhysicsWeb survey to find out which scientists have made the most important contributions to physics. Not only does Newton's work on mechanics and gravitation form the basis of much of classical physics, but Newton also made major contributions to the studies of optics, light and heat. Second place goes to Albert Einstein, who developed the theories of special and general relativity and discovered the photoelectric effect. He is followed by James Clerk Maxwell, who unified electricity and magnetism within a single theoretical framework - electromagnetism. The man who paved the way for Newton's laws of gravitation and helped develop the telescope, Galileo, is fourth. And in fifth place is Paul Dirac, one of the founders of quantum mechanics.