Friday, 23 October 2015 — 12:00 noon — WAG 316

Al Martinez, University of Texas

“Galileo and the Heresy of Many Worlds”

In 1610, Galileo announced his telescopic discovery that the Moon seemed to resemble the Earth. Previously, the philosopher Giordano Bruno had published similar claims. Bruno argued that the Moon was an inhabited world, with water, mountains and valleys. Historians have argued that Bruno’s belief in other worlds was of minor importance in the Roman Inquisition’s trial and execution of Bruno, and of no importance in the Inquisition’s proceedings against Galileo. However, I will show that such conjectures were mistaken. Immediately before Bruno began to publish his cosmological views, the Catholic Church had declared that belief in many worlds was heretical, following the views of ancient Church Fathers. I will show that the heresy of many worlds was the most recurring and important issue in Bruno’s trial and condemnation. Next, I will discuss how, by 1616 (when Inquisitors first met with Galileo), nine prominent individuals had linked the plurality of worlds to Galileo’s telescopic discoveries, and how their concerns affected the censorship of Copernicus’s work in 1620. Such considerations seemed entirely absent from Galileo’s trial of 1633. Yet I have found that a previously unanalyzed and unpublished Latin manuscript by the Consultor for the Inquisition who provided the most critical expert opinion against Galileo, explicitly reveals that Galileo’s works were offensive, scandalous, and temerarious partly for defending the heresy of many inhabited worlds.]


Professor Al Martinez is a member of the faculty of the UT Department of History. He first came to UT Austin ten years ago, in 2005. He earned his PhD in history of science at the University of Minnesota, in Minneapolis, in 2001, followed by postdocs at MIT, Harvard, Boston University, and Caltech. He has published four books, including most recently The Cult of Pythagoras: Math and Myths (Pittsburgh: University of Pittsburgh Press, 2012). He is now working on a book project about Galileo and Giordano Bruno.