Scientists Uncover Limit on Lifespan of Advanced Civilisations

The question of why humanity has not encountered extraterrestrial civilisations has intrigued scientists for decades. This inquiry, known as the Fermi paradox, was famously articulated by physicist Enrico Fermi, who wondered, “Where is everybody?” Despite the universe’s vastness and the estimated 13 billion years of its existence, no evidence of other intelligent life has emerged. Now, physicists from Sharif University of Technology in Tehran, Sohrab Rahvar and Shahin Rouhani, have approached this enduring mystery with a fresh perspective, suggesting that the silence itself may indicate a limited lifespan for technologically advanced civilisations.

The researchers argue that if intelligent life is relatively common, the absence of contact with other civilisations implies that they may not exist anymore. Given the age of the Galaxy and its interconnected nature, any long-lived technological society would likely have left some trace of its existence. The absence of signals or probes leads to a troubling conclusion: technologically advanced civilisations may only survive for about 5,000 years, a strikingly short timeframe when compared to the millions of years one might expect.

To arrive at their conclusion, Rahvar and Rouhani built on the Drake Equation, which estimates the number of communicating civilisations in the Galaxy. They introduced constraints based on electromagnetic communication, noting that radio telescopes have been listening for signals long enough that our “light cone” encompasses the entire history of the Galaxy for roughly the past 100,000 years. Any civilisation broadcasting detectable signals within this timeframe should, in theory, have been heard by now.

This silence is not merely a reflection of humanity’s technological limitations. The authors assert that it is indicative of a genuine absence of detectable civilisations. Their calculations suggest that if intelligent life is prevalent, technological societies must typically perish within 5,000 years. This figure starkly highlights humanity’s vulnerability; having only been a technological civilisation for approximately 200 years, we find ourselves at the beginning of a precarious period in our history.

The paper outlines several existential threats that could contribute to the downfall of civilisations, including asteroid impacts, supervolcano eruptions, climate change, pandemics, nuclear war, artificial intelligence, and rogue biotechnology. The authors reference historical examples of collapsed civilisations, such as the Romans and the Maya, which never fully recovered. In an increasingly interconnected world, the potential for a global catastrophe is unprecedented.

While the mathematics suggests a limit on the lifespan of civilisations, it does not imply that they must all end within this timeframe. Alternative explanations remain viable, including the possibility that civilisations choose not to communicate or that humanity is among the first intelligent species to emerge. The distances between stars may also hinder contact.

Despite these alternatives, the implications of this research are hard to ignore. The Galaxy may have once been teeming with civilisations that achieved remarkable feats, only to fall silent before making contact with others. Whether through war, environmental collapse, or the misuse of technology, the universe appears to impose a strict limit on the duration of intelligence.

As humanity continues to navigate its future, understanding our place in the cosmos becomes increasingly crucial. The study highlights the urgent need for awareness of the threats we face and the potential outcomes of our technological pursuits. The question of whether we will endure or follow the same fate as those before us remains open, but the research serves as a sobering reminder of our fragile existence in an expansive universe.