New York Times Bestseller | Wall Street Journal Bestseller | Publishers Weekly Bestseller | Publishers Marketplace 2020 Buzz Book | Amazon Best Book of the Year | Longlisted for the 2022 PEN/E.O. Wilson Literary Science Writing Award Harvard's top astronomer lays out his controversial theory that our solar system was recently visited by advanced alien technology from a distant star. "Provocative and thrilling ... Loeb asks us to think big and to expect the unexpected."--Alan Lightman, New York Times bestselling author of Einstein's Dreams and Searching for Stars on an Island in Maine In late 2017, scientists at a Hawaiian observatory glimpsed an object soaring through our inner solar system, moving so quickly that it could only have come from another star. Avi Loeb, Harvard's top astronomer, showed it was not an asteroid; it was moving too fast along a strange orbit, and left no trail of gas or debris in its wake. There was only one conceivable explanation: the object was a piece of advanced technology created by a distant alien civilization. In Extraterrestrial, Loeb takes readers inside the thrilling story of the first interstellar visitor to be spotted in our solar system. He outlines his controversial theory and its profound implications: for science, for religion, and for the future of our species and our planet. A mind-bending journey through the furthest reaches of science, space-time, and the human imagination, Extraterrestrial challenges readers to aim for the stars--and to think critically about what's out there, no matter how strange it seems.

With this first of eight volumes, the eminent economist Fritz Machlup launches his monumental inquiry into the production of knowledge as an economic activity. Volume I presents the conceptual framework for this inquiry and falls into three parts: Types of Knowledge, Qualities of Knowledge, and Knowledge as a Product. Originally published in 1981. The Princeton Legacy Library uses the latest print-on-demand technology to again make available previously out-of-print books from the distinguished backlist of Princeton University Press. These editions preserve the original texts of these important books while presenting them in durable paperback and hardcover editions. The goal of the Princeton Legacy Library is to vastly increase access to the rich scholarly heritage found in the thousands of books published by Princeton University Press since its founding in 1905.

This is the third and final volume of A System of Pragmatic Idealism, a series that will synthesize the life's work of the philosopher Nicholas Rescher. Rescher's numerous books and articles, which address almost every major philosophical topic, reflect a unified approach: the combination of pragmatism and idealism characteristic of his thinking throughout his career. The three related but independently readable books of the series present Rescher's system as a whole. In combining leading ideas of European continental idealism and American pragmatism in a new way, Rescher has created an integrated philosophical position in which the central concepts of these two traditions become a coherent totality. The initial volume in the series was dedicated to epistemology, the philosophy of science, and the philosophy of nature, while the second dealt with issues of value theory, ethics, and practical philosophy. In Volume III Rescher examines the nature of philosophical inquiry itself, seeking to affirm the classical conception of philosophy as a significant problem-solving enterprise that draws on the whole range of human experience to attempt to resolve the "big questions." Originally published in 1994. The Princeton Legacy Library uses the latest print-on-demand technology to again make available previously out-of-print books from the distinguished backlist of Princeton University Press. These editions preserve the original texts of these important books while presenting them in durable paperback and hardcover editions. The goal of the Princeton Legacy Library is to vastly increase access to the rich scholarly heritage found in the thousands of books published by Princeton University Press since its founding in 1905.