Astrobiology is an unusual science in that there’s no clear, undisputed evidence that its subject of study – extraterrestrial life – even exists. It’s still an active field of research, though, with observational astronomers scouring the skies for telltale signs of life, and theoreticians tying themselves in knots trying to explain why we haven’t seen any of those signs yet. This book deals almost exclusively with the second of those topics.Before going any further, it’s worth def...
