“Where are they?” is the question reportedly asked by the famous Italian-American physicist Enrico Fermi during a conversation with fellow scientists in the early 1950s. The other scientists understood that Fermi was referring to aliens. Over the rest of the conversation, Fermi went through a series of calculations showing not only that extraterrestrials should exist, but that they should have come to Earth eons ago, multiple times. He essentially argued that it is strange that Earth isn’t already an alien outpost, and that this could have implications for civilization itself.
In the ensuing decades, astronomers and scientists used this legendary conversation to formulate the Fermi Paradox, which asks if other alien civilizations exist throughout the Galaxy and we can theoretically detect signs of their existence, then why don’t we see them? Scientists have hypothesized many solutions to the Fermi Paradox. One is the Great Filter, which holds that some event or events prevent civilizations from reaching the technological sophistication to find each other. Another, known as the Zoo Hypothesis, claims that aliens are aware of human civilization and choose not to make contact to avoid disrupting us. There’s also the possibility that they’re already here, living among us, and we don’t know it, or that everything from Unidentified Aerial-Undersea/Anomalous Phenomena (UAPs) to the interstellar object ‘Oumuamua could be signs of aliens.
Some solutions to the Fermi Paradox rely on assumptions about technological development, evolution, or the nature of intelligence itself. By contrast, researcher Robin H.D. Corbet recently proposed that the solution to this paradox could be mundanity. Corbet’s argument stems in part from the assumption that there’s nothing fundamentally special about the Sun, the Earth, or even humans, a concept known as the Copernican Mediocrity Principle. From this principle, Corbet developed a logical chain of reasoning, arguing that if alien civilizations are like humans, it shouldn’t be surprising that we haven’t met any.
Corbet proposed 2 main assertions of the “radical mundanity” solution to the Fermi Paradox. First, that technology can only advance so far — even if alien civilizations are more technologically advanced than humans, none of them will have faster-than-light travel or other physics-defying tools. And, second, that a modest number of alien civilizations inhabit the Galaxy, meaning humans are not alone, but civilizations are not everywhere.
Regarding technology, he argued that the immutable laws of physics would prevent alien civilizations from developing warp drives that could travel across the galaxy in hours. On the more realistic side, engineering and ecological limits would push civilizations to adopt sustainable practices rather than maximize energy consumption. In principle, this means that no civilization is ever likely to build megaprojects that we could detect, such as artificial rings around their stars or enormous radio beacons broadcasting for millennia.
The presence of several civilizations like ours in the Galaxy has its own implications. If they follow similar rational logic and balance curiosity with caution, then their space exploration must be subject to cost-benefit analysis. Searching for other alien civilizations would satisfy scientific curiosity. However, gathering resources from distant star systems could take too long, and exchanging information would bring only marginal benefits unless some civilization developed paradigm-shifting technologies. This ultimately means diminishing returns for each new alien civilization discovered.
Corbet then argued that any space exploration would likely be done by self-guided and perhaps self-replicating machines, sometimes referred to as Von Neumann probes. These probes would have some form of advanced artificial intelligence and could reasonably travel between stars at 1 thousandth the speed of light, roughly 700,000 miles per hour or 1,000,000 kilometers per hour. Fears about out-of-control artificial intelligence add costs beyond the probes’ materials. This means that any given alien civilization could encounter only a fraction of the Galaxy’s civilizations before deciding that the risks of continued exploration outweigh the benefits.
Corbet concluded that if alien civilizations are living far from Earth, they could have reasonably abandoned the search for others millions of years ago, meaning we will continue to receive silence. Scientists could potentially detect nearby alien civilizations from their radio signals, especially with the newer radio arrays. However, we should expect them to be more like Earthlings than Star Trek Vulcans, implying no replicators or antimatter engines for us anytime soon. Corbet also suggests that UAPs found on Earth are almost certainly not aliens. Extraterrestrial life might not be that technologically interesting for us to find, but we are almost certainly too mundane for them to bother spying on us.
