The discussion about the existence of extraterrestrial life and intelligent civilizations has always been one of the most intriguing and challenging topics in space sciences and astronomy. In recent years, numerous studies and theories have been proposed in this field. Below are some of the most important ones:

1. The Drake Equation and Estimating the Number of Intelligent Civilizations

The Drake Equation, presented by Frank Drake in 1961, is an attempt to estimate the number of communicative intelligent civilizations in the Milky Way galaxy. This equation includes variables such as the rate of star formation, the fraction of planets that can support life, and the duration of intelligent civilizations.

According to a 2020 study, scientists have estimated that there are at least 36 intelligent civilizations in our galaxy. However, detecting them remains a significant challenge.

2. The “Great Filter” Hypothesis and the Evolution of Intelligent Life

In 1983, Brandon Carter proposed the “Great Filter” model, suggesting that the evolution of intelligent life results from a series of extremely rare and exceptional events. This theory implies that the probability of other civilizations existing in the universe is very low.

However, a 2025 study from Pennsylvania State University suggests that the evolution of intelligent life may be a logical and predictable outcome of natural planetary processes, rather than a rare event.

3. The Fermi Paradox and the Lack of Contact with Extraterrestrials

The Fermi Paradox refers to the contradiction that, despite the high probability of intelligent civilizations in the galaxy, no evidence of their existence has been observed.

One explanation proposed in 2023 is that our signals and messages may not have reached them yet, or vice versa—their signals have not yet reached Earth. This delay is due to the vast cosmic distances and the limitation of the speed of light.

4. Searching for Technosignatures

Scientists, in an effort to find evidence of advanced civilizations, are focusing on “technosignatures” instead of solely biological markers. These technosignatures can include radio or laser signals, or even chemical pollutants in the atmospheres of planets, indicating industrial activities and advanced technology. This approach could increase our chances of discovering extraterrestrial civilizations.

5. The “Dark Forest” Theory and Cosmic Silence

According to the “Dark Forest” theory, intelligent civilizations, fearing detection and potential destruction by others, deliberately avoid sending identifiable signals. This behavior could explain the cosmic silence and the lack of received extraterrestrial signals.

Conclusion

Despite scientific advancements and research, we still do not have a definitive answer to the question of the existence of extraterrestrial life and intelligent civilizations. However, the development of technology and new approaches in searching for signs of life and technology in the universe have increased hopes of answering this age-old question.

Department of Metaphysical Research
International Institute for Intelligent Civilizations Studies (IIICS)

📧 Contact Email: info@iiics.ir