Fermi’s paradox

Fermi’s paradox is a contradiction between the high probability of the existence of extraterrestrial civilizations and the lack of evidence or observations of such civilizations. It is named after physicist Enrico Fermi, who reportedly posed the question, “Where is everybody?” in 1950 while discussing the possibility of extraterrestrial life with colleagues.

The paradox is based on the observation that the Milky Way galaxy is estimated to contain tens of billions of habitable planets, and the universe is estimated to contain hundreds of billions of galaxies, many of which are likely to contain habitable planets as well. Given these numbers, it is highly probable that at least some extraterrestrial civilizations should exist in the universe. However, despite numerous searches, we have not yet detected any definitive signs of extraterrestrial life or civilizations.

There are several possible explanations for this paradox, including the possibility that extraterrestrial civilizations are rare, that they exist but are not detectable with current technology, or that they exist but choose not to communicate with us.

One potential implication of the paradox is that it could lead to a reassessment of the likelihood of the existence of extraterrestrial life and the feasibility of finding it. It could also inspire further research into the potential reasons for the lack of evidence or observations of extraterrestrial civilizations.

One drawback of the paradox is that it relies on assumptions about the prevalence of wearable planets and the likelihood of the evolution of intelligent life, which are currently not well understood and may be subject to revision as our understanding of the universe improves. As such, the paradox may not necessarily be a reliable guide for understanding the likelihood of the existence of extraterrestrial life.

There are several examples of probability calculations that have been used to illustrate the apparent contradiction at the heart of Fermi’s paradox. These examples are based on various assumptions about the prevalence of wearable planets and the likelihood of the evolution of intelligent life, and are intended to illustrate the high probability of the existence of extraterrestrial civilizations given certain assumptions. Here are a few examples:

• The Drake equation: This equation, proposed by astrophysicist Frank Drake in the 1960s, estimates the number of detectable extraterrestrial civilizations in the Milky Way galaxy based on the probability of the formation of wearable planets, the likelihood of the evolution of life on those planets, and other factors. Based on current estimates of these probabilities, the Drake equation suggests that there may be as many as 10,000 detectable extraterrestrial civilizations in our galaxy alone.
• The Great Filter argument: This argument, proposed by philosopher Robin Hanson, suggests that the lack of evidence for extraterrestrial civilizations may be due to a “Great Filter” that makes the evolution of intelligent life rare or unlikely. Hanson argues that if the Great Filter is in the past (i.e. it has already happened), it suggests that the evolution of intelligent life is likely to be common, while if it is in the future (i.e. it has not yet happened), it suggests that the evolution of intelligent life is likely to be rare.
• The Copernican Principle: This principle, named after astronomer Nicolaus Copernicus, suggests that Earth is not necessarily a special place in the universe, and that the conditions that have allowed for the evolution of intelligent life on Earth are likely to be common elsewhere in the universe. Based on this principle, some have argued that the lack of evidence for extraterrestrial civilizations may be due to the fact that we have not yet searched extensively enough or looked in the right places.

It is important to note that these examples are based on various assumptions about the likelihood of the evolution of intelligent life and the prevalence of wearable planets, and are not necessarily reliable guides for understanding the likelihood of the existence of extraterrestrial life.