Free Astronomy Magazine March-April 2023

34 ASTRO PUBLISHING by Michele Ferrara revised by Damian G. Allis NASA Solar System Ambassador The Fermi paradox − many solutions, no certainty I n the summer of 1950, Nobel laureate Enrico Fermi and some of his fellow nuclear physicists had a friendly conver- sation about a recent sighting of alleged alien flying objects. To those who pointed out that, given the enormous number of stars and probably planets (still undiscovered at the time) that make up our galaxy, there could be many advanced civi- lizations capable of interstellar travel, Fermi posed a famous question, which has stimulated countless debates in the last seventy years: “If the universe is teeming with aliens, where is everybody?” This question, known today as the “Fermi paradox,” empha- sizes the discrepancy between the absence of evidence for the existence of life beyond Earth and the apparent high proba- bility of its existence. I n this section, we propose some readings focused on the existence of life beyond Earth and on the possibility of coming into contact with alien technological civilizations. Cur- rently, there are at least 150 books available on the international market that deal exclu- sively with these two topics. We have selected 30 for you that we consider most relevant and which, as a whole, both address the different aspects of these themes from different perspectives and, in the interest of your consideration, are affordably priced. If the Universe is teeming with aliens ... Where is everybody? Given the fact that there are perhaps 400 billion stars in our Galaxy alone, and perhaps 400 billion galaxies in the Universe, it stands to reason that somewhere out there, in the 14-billion- year-old cosmos, there is or once was a civilization at least as advanced as our own. The sheer enormity of the numbers almost demands that we accept the truth of this hypothesis. Why, then, have we encountered no evidence, no messages, no artifacts of these extraterrestrials? What we know about extraterrestrial intelligence: Foundations of Xenology Have you ever wondered what could happen when we dis- cover another communicating species outside the Earth? This book addresses this question in all its complexity. In addition to the physical barriers for communication, such as the enormous distances where a message can take centuries to reach its recipient, the book also examines the biological problems of communicating between species, the problems of identifying a non-Terrestrial intelligence, and the ethical, religious, legal and other problems of conducting discussions across light years.