During a lunch discussion with colleagues at Los Alamos, Italian physicist Enrico Fermi summarized what would become known as Fermi’s Paradox: if so many extraterrestrial civilizations exist, where are they? A simple and essential question, perfectly in keeping with the character: if there are so many beings more advanced than us, why haven’t we seen clear signs of their presence? A few years later, the concept would be refined by Von Neumann: if an advanced civilization systematically launched probes (later known as Von Neumann Probes) capable of self-repairing and multiplying to colonize other planetary systems, it would be able to colonize the entire galaxy in less than 3 million years. Since we don’t see any alien civilizations on Earth, that advanced civilization is us! (That is, we are necessarily the first, a sort of anthropic principle.)
