Intelligent life may be extremely rare in our universe, according to Princeton University Astrophysical Sciences Professor Ed Turner.
This view is not surprising, since intelligence is also rare on Earth, so extending this proposition to cosmic scales seems plausible. Turner made the case about how special we might be at a recent Galileo Project conference. I could not resist asking him, “Do these arguments make you religious?”
There are two ways to interpret our existence as sentient beings. The materialistic view considers consciousness as an emergent phenomenon out of the initial soup of chemicals that pervaded early Earth. It took 4.5 billion years for natural selection to make Homo Sapiens a few million years ago, and within a billion years from now the sun will boil off all liquid water on Earth.
With this perspective in mind, our existence may have been replicated repeatedly on other planets over the past 13.8 billion years since the Big Bang. Keep in mind that the number of times the dice was rolled in the form of an Earth-size planet in the habitable zone around a sun-like star, is at least 10 to the power of 31, the number of habitable planets in the spatial region that extends 4,000 times beyond the horizon of the observable universe, the minimum volume where such planets are expected to exist. The principle of mediocrity echoes the Copernican principle, namely that the Earth is not at the center of the universe and that we, as observers, are not privileged. Intelligence emerged in the last fifth of the lifetime of Earth as a habitable planet, but a factor of five is not necessarily making us rare given that most stars formed billions of years before the sun.
Just as with composer Wolfgang Amadeus Mozart who died prematurely just before reaching a young age of 36 years, the most advanced extraterrestrial civilizations may have died by the time we reach their technological lifespan and attempt to reproduce their astonishing accomplishments. Searching for their radio signals — echoing our own technological baby steps, would resemble an unrealistic attempt to reach Mozart over the phone after his death. Instead, we should seek the relics these civilizations left behind, like the musical notes of Mozart.
On the other side of the argument, the “Rare Earth hypothesis” lists many unlikely astrophysical events and circumstances that were needed for terrestrial life to exist. This hypothesis makes us feel special. But it also brings home a sense of responsibility. If we are cosmically rare, we must guarantee our long-term survival. Toward that goal, we may wish to spread copies of our precious existence elsewhere in the solar system or the Milky Way galaxy, so that our existence will not be vulnerable to a single-planet catastrophe.
What is the relevance of whether we are mediocre or special? It’s a scientific search for the relics of extraterrestrial technological civilizations.
As anyone in the dating business knows, finding a match requires dedicated efforts and resources. Believing that we are unique, removes the wind behind the sails of the search. But without searching, we will never know if we are truly rare. Scientific evidence is under no obligation to conform with our misconceptions, especially if those are driven by an unsubstantiated sense of privilege. Scientific inquiry stems from our willingness to accept evidence that violates our prior beliefs. It is our obligation to our self-assigned title of an “intelligent civilization,” that makes us adapt to agnostic observations of reality rather than surrender to an exaggerated sense of self-importance.
The traditional Search for extraterrestrial intelligence (SETI) approach of seeking radio signals is now complemented by the Galileo Project at Harvard, which I lead, the first privately-funded scientific research program in search for objects near Earth that may have originated from an extraterrestrial technological civilization. Finding even a single extraterrestrial artifact would be sufficient to settle the debate about our intellectual status in the cosmos. Finding no such object after an exhaustive search would set limits on the technological capabilities or motivations of anyone else out there.
The search for the unknown resonates with spirituality and not just materialism, because we never know what we might find. Currently, there is no business plan associated with the search for other civilizations, but one can imagine huge profits from importing unfamiliar technologies to Earth. Our culture could also benefit greatly from new scientific knowledge, but like with dating opportunities — we must first invest major efforts and resources in the search.
At the conference, Turner warned that the Galileo Project might find nothing.
In my view, in pursuing the search, at least we know that we have tried. Whatever we find, learning from experience provides a sense of purpose or meaning to our life.
We need a diverse group of skeptics and advocates in the search for possible extraterrestrial civilizations so that when they all agree, the evidence collected has a robust interpretation. This is the trademark of the scientific method.
Avi Loeb is the head of the Galileo Project, founding director of Harvard University’s – Black Hole Initiative, director of the Institute for Theory and Computation at the Harvard-Smithsonian Center for Astrophysics, and the former chair of the astronomy department at Harvard University (2011-2020). He chairs the advisory board for the Breakthrough Starshot project, and he is a former member of the President’s Council of Advisors on Science and Technology and a former chair of the Board on Physics and Astronomy of the National Academies. He is the bestselling author of “Extraterrestrial: The First Sign of Intelligent Life Beyond Earth” and a co-author of the textbook “Life in the Cosmos,” both published in 2021.