Final answer:
Galileo and Copernicus changed their views on the universe by refuting the ancient Greek geocentric model and advocating for a heliocentric system, which led to conflict with the Catholic Church.
Step-by-step explanation:
The work of Copernicus and Galileo Galilei challenged the geocentric model of the universe that was long upheld by the ancient Greeks and the Catholic Church. Unlike Aristotle and Ptolemy, who believed Earth was the center of the universe, Copernicus proposed a heliocentric system, which Galileo supported with empirical evidence, furthering the scientific method. Their insistence on observational data over philosophical speculation marked a significant shift in thinking, ultimately reshaping the understanding of our place in the cosmos. Galileo's public advocacy for the heliocentric model, especially his use of the Italian language for broader dissemination, and his defense of nature's authority in matters of science despite the Church's opposition, underscored this paradigm shift. Facing the Inquisition, he was forced to recant, but his ideas prevailed and continued to influence scientific thought.