Why did Galileo Galilei become unpopular with colleagues at the University of Pisa?

Galileo Galilei became unpopular with his colleagues at the University of Pisa primarily due to his vocal and active opposition to Aristotelian philosophy and physics.

During his tenure, which began in 1589, Galileo challenged long-held scientific beliefs, most notably by demonstrating that the speed at which an object falls is not proportional to its weight—a direct contradiction of Aristotle’s claims. By adopting an Archimedean approach to the study of motion rather than the traditional Aristotelian one, he alienated his peers. This friction ultimately led to his contract not being renewed in 1592.1