Inertia

Copernicus conjectured that the earth spins on its axis and orbits the sun. Considering its implications, this was a dangerous assumption that prompted risky questions: Why do objects fall to earth rather than hurtle off into space? And in this heretical scheme of things in which the earth wasn't at the center, where is God? Risking more than his favored status in Rome, Galileo helped to answer such questions with the law of inertia.