For centuries, great thinkers have wondered why, given the hundreds of billions of planets in the galaxy, we have seen no convincing signs of intelligent life beyond Earth.
Today, scientists are considering an intriguing possibility: If aliens exist, their technology might be only slightly better than ours. And after exploring their cosmic neighborhood for a while, they simply got bored and stopped caring, making it difficult to detect them.
The scenario, described in a new paper, embraces the principle of “radical worldliness”, which rejects the notion of aliens roaming the universe having exploited physics beyond our understanding. Instead, he proposes a Milky Way that is home to a modest number of civilizations whose technology is not much more impressive than ours.
“The idea is that they are more advanced, but not much more advanced. It’s like having an iPhone 42 rather than an iPhone 17,” said Dr. Robin Corbet, a senior research scientist at the University of Maryland, Baltimore County, based at NASA’s Goddard Space Flight Center. “It seems more possible, more natural, because it doesn’t propose anything very extreme.”
Corbet hypothesized after reviewing researchers’ explanations for the “great silence” or Fermi paradox, the gap between the lack of compelling evidence for the existence of extraterrestrial civilizations and the likelihood of their existence in a vast, aging universe. Most of the theories seemed exotic to Corbet. Maybe the aliens were too advanced to be detected? Maybe Earth was a cosmic zoo that the aliens agreed to leave alone? Maybe Earth was the only home of life in the galaxy?
The search for extraterrestrial intelligence (SETI) has focused on detecting “technosignatures.” Advanced civilizations could announce their existence by building powerful laser beacons that can be spotted from other planets. They can reveal themselves by sending robotic probes across the galaxy or building enormous structures in space to harness the energy of their star. They might even visit other planets or scatter artifacts across the galaxy. Everyone could make them visible.
But the radical principle of worldliness says no. He explains this great silence by proposing that extraterrestrial civilizations are reaching a technological plateau not much superior to our own capabilities. “They don’t have light faster than light, they don’t have machines based on dark energy or dark matter, or black holes. They don’t exploit the new laws of physics,” Corbet said.
If that were the case, alien civilizations would struggle to operate powerful laser tags for millions of years. They wouldn’t move from one planet to another. And after exploring the galaxy with robotic probes, they may become bored with the information sent back and abandon space exploration.
Science fiction author Arthur C Clarke is quoted as saying: “Two possibilities exist: either we are alone in the universe, or we are not. Both are equally terrifying.” Corbet, whose paper has not yet been peer-reviewed, suspects the truth might lie somewhere between “in a universe that is a little more mundane and therefore less terrifying.” Contact, he adds, “could leave us somewhat disappointed.”
Professor Michael Garrett, director of the Jodrell Bank Center for Astrophysics, welcomed this “new perspective” but expressed reservations. “It projects a very human apathy onto the rest of the cosmos. I find it hard to believe that all intelligent life is so uniformly boring,” he said. Any technological plateau could be well above our level, he added.
In an article to appear in the journal Acta Astronautica, Garrett favors another theory. “I lean towards a more adventurous explanation of the Fermi Paradox: other post-biological civilizations are advancing so rapidly that they are beyond our ability to perceive them,” he said. “I hope I’m right, but I could very well be wrong. Nature always has some sort of surprise around the corner.”
Professor Michael Bohlander, an expert in SETI policy and law at Durham University, said evidence may already have reached us in the form of unexplained aerial phenomena, or UAPs. “If it turned out that only a small percentage of these objects were not made by humans – and that their capabilities demonstrated in numerous observations suggest at least a state of advancement well beyond current publicly known human technology – then the question posed by Fermi, ‘Where is everyone?’, could be answered empirically,” he said.
