When you walk through the wilderness, you’d better be quiet and listen, because you never know whether there are predators out there. Unfortunately, we did not follow this cautionary measure so far in outer space, as we had been broadcasting radio waves from Earth for more than a century. And if there are technological civilizations within a hundred light-years that monitor their sky with radio telescopes similar to ours, then they may already know about us and we might hear from them. Our saving grace is that chemical rockets, similar to those used in the Voyager or New Horizons missions, will take a million years to traverse a hundred light years. And so, we might be out for a prolonged suspense before encountering our cosmic neighbors.
If extraterrestrials (ETs) arrive at our doorstep, the question is how to respond? Clearly, interstellar affairs are not an imminent policy concern for any nation at this moment, and there is no international protocol issued by the United Nations for a response.
How much advance warning will we have? That depends on the size of the vehicle used by the ETs. Even without generating artificial light, any alien spacecraft would reflect sunlight. The Pan-STARRS observatory in Hawaii can detect reflected sunlight from objects bigger than a football field, that pass within the orbit of the Earth around the Sun. The first interstellar visitor of such size was discovered by this telescope on Oct. 19, 2017 and named `Oumuamua — a “scout” in the Hawaiian language. The object showed many anomalous properties that made it different from any natural comet or asteroid that we had witnessed before in the solar system, allowing for the possibility that was manufactured artificially by an alien technology.
Even if `Oumuamua is artificially made and distinct from all natural rocks in the solar system, it is most likely equipment that is billions of years old and out of commission. Most stars formed billions of years before the Sun, and the technological relics that their civilizations launched to space are probably too old to be functional.
We can retrieve more information about technological relics by taking close-up photographs or by searching on the surface of the Moon (or Mars) for unusual objects that were collected there over the past billions of years. The lack of an atmosphere or geological activity makes the Moon’s surface a museum wall that exhibits any extraterrestrial equipment that landed on it.
Are we the smartest kid on our cosmic block? To find out, we should keep our eyes open.
The Laser Interferometer Gravitational-Wave Observatory discovered gravitational waves only after the National Science Foundation invested $1.1 billion dollars in its most advanced phase. Similarly, we should expect to find extraordinary evidence for ETs only after we invested major funds in the search for it. It would be most appropriate to allocate taxpayer funds to the search for our cosmic neighbors, given the major impact that such a discovery would have on society — far exceeding the implication of discovering gravitational waves. Putting our hands on a piece of alien technology would change the way we perceive our place in the universe, our aspirations for space and our philosophical and theological beliefs.
Our psychological shock would resemble the one encountered by my daughters when they met smarter kids on their first day in kindergarten. Until that day, my daughters thought that they were unique and there was nobody smarter than them.
Instead of searching, we could choose to stay ignorant about our neighbors. This would be equivalent to my daughters choosing to stay at home. The possible existence of ETs will not go away if we ignore them, just like the Earth continued to move around the Sun after the philosophers refused to look through Galileo’s telescope.
Science relies on reproducibility of results. In order to believe evidence, it must be possible to reproduce it as an outcome of similar circumstances. The situation, therefore, gets complicated with eyewitness testimonies of one-time events related to ETs.
Recently, the Pentagon was asked by lawmakers to disclose all it knows about Unidentified Aerial Phenomena by June 2021. But this focus on past eyewitness reports is misguided. It would be prudent to progress forward with our finest instruments, rather than examine past reports.
Instead of declassifying documents that reflect decades-old technologies used by witnesses with no scientific expertise, it would be far better to deploy state-of-the-art recording devices, such as camera or audio sensors, at the sites where the reports came from, and search for unusual signals. A scientific expedition focused on reproducing old reports would be more valuable to unraveling the mysteries behind them.
Avi Loeb is a member of the American Academy of Arts and Sciences and was the longest-serving chair in the history of the astronomy department at Harvard University (2011-2020). He serves as the founding director of Harvard's Black Hole Initiative, the director of the Institute for Theory and Computation at the Harvard-Smithsonian Center for Astrophysics, and chairs and the advisory board for the Breakthrough Starshot project. Loeb is the former chair of the Board on Physics and Astronomy of the National Academies and a former member of the President’s Council of Advisors on Science and Technology at the White House. He is the bestselling author of “Extraterrestrial: The First Sign of Intelligent Life Beyond Earth,” recently published by Houghton Mifflin Harcourt.