An artist’s rendering of alien beings observing. Depositphotos.

What the silence from space tells us about alien civilizations

A new study in Acta Astronautica offers a statistical perspective on the quest for alien civilizations.


The buzz surrounding aliens has reached new heights, with congressional hearings on Unidentified Anomalous Phenomena (UAPs) making headlines. But beyond the thrilling idea of extraterrestrials visiting our planet, the focus remains on the possibility of life on distant worlds. Decades of exploration have yielded no evidence, leading to questions about what this absence of proof reveals. A new study in Acta Astronautica offers a statistical perspective on the quest for alien civilizations. The question scientists asked is simple; what does silence from space tell us about potential alien civilizations?

The Absence of Evidence: A Look into the Universe

It may seem perplexing, but the lack of evidence does reveal clues about the cosmos. We haven’t found concrete radio signals from an alien civilization, but after years of research, this long silence informs our understanding of the chances of discovering such beings. This very silence is the subject of recent research employing Bayesian statistics.


Bayesian Statistics and the Search for Alien Life

This particular study focuses on the odds of discovering an alien technosignal using Bayesian statistics, which emphasizes the likelihood rather than the certainty of an outcome. Two key assumptions are considered:

  • Intelligent life can evolve in the universe
  • No signals have been found in the last 60 years

Further assumptions include that intelligent civilizations appear at random times and places, and if they send signals, they are either broadcasted in all directions or aimed randomly.

Findings and Implications

With these considerations, the study determined an upper limit on alien technosignatures. The best estimate suggests a 95% chance of no more than five galaxy-wide alien signals being emitted per century. This translates to only a 50/50 chance of Earth detecting such a signal in the next 1,800 years. In other words, our chances of picking up something in the near future are slim unless an alien civilization deliberately targets us.

Despite the sobering statistics, the search for extraterrestrial life must continue. Those eager for evidence of aliens may find their attention drawn to ongoing congressional hearings on UAPs. But for the scientists and enthusiasts looking beyond our world, the quest continues, fueled by the tantalizing possibility of intelligent life elsewhere in the universe.


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Written by Ivan Petricevic

I've been writing passionately about ancient civilizations, history, alien life, and various other subjects for more than eight years. You may have seen me appear on Discovery Channel's What On Earth series, History Channel's Ancient Aliens, and Gaia's Ancient Civilizations among others.

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