Galileo Galilei to Einstein's special theory of relativity. A biography by Galileo's pupil Vincenzo Viviani stated that Galileo had dropped balls of the same material, but different masses, from the Leaning Tower of Pisa to demonstrate that their time of descent was independent of their mass. This was contrary to what Aristotle had taught: that heavy objects fall faster than lighter ones, in direct proportion to weight. While this story has been retold in popular accounts, there is no account by Galileo himself of such an experiment, and it is generally accepted by historians that it was at most a thought experiment
Galileo Galilei letter to Cardinal Orsini. In 1619, Mario Guiducci, a pupil of Galileo's, published a lecture written largely by Galileo under the title "Discourse on the Comets" ("Discorso Delle Comete"), arguing against the Jesuit interpretation of comets. In 1623, Galileo published "The Assayer—Il Saggiatore", which attacked theories based on Aristotle's authority and promoted experimentation and the mathematical formulation of scientific ideas. The book was highly successful and even found support among the higher echelons of the Christian church. Following the success of "The Assayer", Galileo published the "Dialogue Concerning the Two Chief World Systems" (Dialogo sopra i due massimi sistemi del