Despite a debilitating life–long illness, Galileo changed physics from a purely philosophical subject into one involving mathematics and careful observation.  But his innovations didn't stop there.  He also challenged beliefs about the very structure of the universe, arguing that the earth moves around the sun at dizzying speeds.  And, using the telescope, Galileo showed philosophers that the sun, moon, and stars aren't made of an ethereal and unchangeable "fifth element" but are composed of the same stuff that ordinary terrestrial objects are. 

But suggesting such dramatic changes made philosophers uncomfortable.  And because philosophers were unable to refute Galileo on their own playing field, they sought help from theologians, sending Galileo head long into a conflict with church officials.  Galileo appealed to church fathers like St. Augustine to prevent the theologians from making what he saw as a tragic mistake.  But intrigues, personality clashes, and misunderstandings led to Galileo's famous trial and condemnation, events misinterpreted as showing a fundamental conflict between science and religion.