The Fermi Paradox in 2021 -- Are We It?

Physics Dept./GI UAF

Scientists pondering humanity's role in the universe are often guided by the "modesty principle," which effectively says that there is nothing special about us, or about our home solar system. The Milky Way galaxy is roughly three times as old as our Sun, and it contains about 100 billion stars. Applying even an extremely weak version of the modesty principle to our galaxy thus suggests it could potentially host a very large number of extraterrestrial civilizations that are at least as advanced us, and often more so. Yet, despite decades of extensive searching, no evidence for these civilizations exists to date. This problem is now widely known as "the Fermi paradox," as a result of Enrico Fermi's pithy and famous (but possibly apocryphal) statement "Where is Everybody?" The problem has long fascinated everyone from astrophysicists to amateur philosophers, and I do not plan to add any new thoughts to the accumulated "extelligence" on the topic. Rather, I will simply highlight some important (and mostly recent) work on the nature of the problem, and the importance of understanding which of its many potential resolutions is most likely.