Free Astronomy Magazine March-April 2023

MARCH-APRIL 2023 ASTRO PUBLISHING ining only about a millionth of the stars contained in our gal- axy, it goes without saying that there are very probably billions of planets in the Milky Way, a non-negligible part of which are likely placed in the habit- able zone of their stars. It is not unreasonable to assume that millions of biospheres may exist in the Milky Way alone. In this case, an alien technological civ- ilization that had already dis- covered many of them and was located more than 200 light- years from the Earth (the limit beyond which the traces of in- dustrialization are not evident) would have, for our planet, only a statistical interest. At this point, it is evident that the solutions to the Fermi para- dox can be most disparate, from the non-existence of life beyond the Earth, up to a multitude of biospheres and technological civilizations in our own galaxy. Whichever scenario is closest to reality, the bleak silence that surrounds us, however, seems destined to last much longer. But the truth could be even gloomier than it appears if the hypothesis of the “Great Filter” were valid, a sort of barrier that prevents the development of civilizations lasting over time. This hypothesis, formulated a quarter of a century ago by Robin Hanson, essentially states that the scientific theories that consider the development of advanced intelligent life highly probable are excessively opti- mistic, and already reaching our level of development would be something exceptional and ephemeral. In other words, hu- manity could become extinct before being able to get in touch with another technologi- cal civilization. Five billion years of solitude — The search for life among the stars Since its formation nearly five billion years ago, our planet has been the sole living world in a vast and silent universe. But over the past two decades, astronomers have discovered thou- sands of “exoplanets,” including some that could be similar to our own world, and the pace of discovery is accelerating. In a fascinating account of this unfolding revolution, Lee Billings draws on interviews with the world’s top experts in the search for life beyond earth. He reveals how the search for exoplanets is not only a scientific challenge, but also a reflection of our culture’s timeless hopes, dreams, and fears. Extraterrestrial Languages (The MIT Press) If we send a message into space, will extraterrestrial beings re- ceive it? Will they understand? The endlessly fascinating ques- tion of whether we are alone in the universe has always been accompanied by another, more complicated one: if there is ex- traterrestrial life, how would we communicate with it? In this book, Daniel Oberhaus leads readers on a quest for extraterres- trial communication. Exploring Earthlings' various attempts to reach out to non-Earthlings over the centuries, he poses some not entirely answerable questions: If we send a message into space, will extraterrestrial beings receive it? Will they under- stand? What languages will they speak? Is there not only a uni- versal grammar, but also a grammar of the universe? Out there — A scientific guide to alien life ... Out There is arranged in a simple question-and-answer format. The answers are delivered in Dr. Wall's informal but informative style, which mixes in a healthy dose of humor and pop culture to make big ideas easier to swallow. Dr. Wall covers questions far beyond alien life, venturing into astronomy, physics, and the practical realities of what long-term life might be like for we mere humans in outer space, such as the idea of lunar colonies, and even economic implications. Dr. Wall also shares the in- sights of some of the leading lights in space exploration today, and shows how the next space age might be brighter than ever. Solving Fermi's paradox The search for extra-terrestrial intelligence (SETI) has for sixty years attempted to solve Fermi's paradox: if intelligent life is rel- atively common in the universe, where is everybody? Examining SETI through this lens, this volume summarizes current think- ing on the prevalence of intelligent life in the universe, and dis- cusses sixty-six distinct solutions to the so-called paradox. It de- scribes the methodology of SETI, and how many disciplines feed into the debate, from physics and biology, to philosophy and an- thropology. This comprehensive introduction to SETI concludes by looking at the future of the field and speculating on human- ity's potential fate. !