The Fermi paradox raises a key question: Given the likelihood of intelligent extraterrestrial life, why is there still no compelling evidence of it? A new theory, described in a paper not yet peer-reviewed, provides a potential answer that has nothing to do with advanced invisibility gadgets: maybe extraterrestrial civilizations are only slightly ahead of us technologically—and, after a brief burst of cosmic curiosity, they simply lost interest in reaching out. This hypothesis, outlined by NASA scientist Robin Corbet, is built on what he calls the principle of "radical mundanity"—the idea that alien civilizations might hit a technological ceiling not far above ours, the Guardian reports.
"The idea is that they're more advanced, but not much more advanced. It's like having an iPhone 42 rather than an iPhone 17," Corbet tells the outlet. Under this theory, aliens would lack the means for spectacular feats like faster-than-light travel or massive energy-harvesting structures, and after some initial interstellar exploration, might've found the results underwhelming. In that case, they might have just stopped trying to make contact. This suggests the risk of aliens invading Earth or colonizing the galaxy is low, per the Independent.
Not everyone is convinced. Michael Garrett, head of the Jodrell Bank Centre for Astrophysics, says the theory assumes aliens would share our tendency toward boredom, and that it's hard to imagine every intelligent species in the galaxy being "uniformly dull." In another paper, he favors the idea that truly advanced civilizations might evolve so quickly that they slip beyond our ability to detect them at all. Meanwhile, Michael Bohlander of Durham University points out that unexplained aerial phenomena on Earth could already be evidence of alien technology, if even a fraction of those sightings turn out to be the real deal.