Newton discovered universal gravity precisely by combining Galileo’s physics of how things move on Earth with Kepler’s physics of the heavens. Maxwell and Faraday found the equations of electromagnetism by bringing together what was known about electricity and what was known about magnetism. Einstein found special relativity in order to resolve the apparent conflict between Newton’s mechanics and Maxwell’s electromagnetism – and then general relativity in order to resolve the resulting conflict between Newton’s mechanics and his own special relativity.
