The Most Consequential Movie of the Sky
At the annual banquet dinner of Harvard’s Black Hole Initiative a few weeks ago, a mainstream physicist with expertise on quantum gravity in the context of black holes and cosmology, was eager to join me at my table. After we settled at our seats, he promptly said: “I read your work on `Oumuamua and interstellar objects. Surely, you would agree that the chance of an extraterrestrial technological artifact near Earth is practically zero!” This struck me by surprise and so I asked: “How did you reach that conclusion without additional data on the anomalies exhibited by `Oumuamua?”
What surprised me is not only the firm tone of the question but also the professional identity of the questioner. After all, supersymmetry whose existence was assumed to be self-evident by physicists of his tribe, was ruled out in its natural parameter space by CERN’s Large Hadron Collider. Surely, his intuition did not prove out to be valid in that context of mathematical physics. Why should we trust that same intuition in the context of `Oumuamua being a rock of a type never seen before? In both cases, experimental evidence rather than theoretical intuition should guide our scientific knowledge.
Unfortunately, `Oumuamua is now two hundred thousand times fainter than at its closest approach to Earth and we cannot study it further. However, we can discover the siblings from its family of outliers and study them in greater detail. In particular, the Webb telescope can detect the heat they emit and infer their surface area from their measured temperature, distance and flux. If `Oumuamua’s siblings rotate, we might be able to measure their projected surface area as a function of time and map their three-dimensional structure.
Today, the first images from the largest digital camera in the world, funded by the National Science Foundation (NSF) and the Department of Energy (DOE), were celebrated in Washington DC. The video of the awe-inspiring data shared with the public is available here. Michael Kratsios, who serves as director of the Office of Science and Technology Policy at the White House, gave a visionary speech in which he referred to the Rubin Observatory as “a triumph of American technological ingenuity and skill.” The Rubin Observatory director, Zeljko Ivezic, mentioned interstellar objects three times in response to questions from reporters and noted that he expects more than ten objects like `Oumuamua to be discovered by the upcoming data stream from the 3.2 gigapixel Rubin camera. The question of whether Oumuamua is natural or artificial came up at the end. But even before the questions from the reporters, Zeljko concluded his presentation with the Vulcan salute.
Zeljko’s presentation included a short video which featured the discovery of 2,104 new asteroids from just a few nights of Rubin data. Within the first two years of its Legacy Survey of Space and Time (LSST), the Rubin Observatory is expected to discover millions of new asteroids, exceeding the entire known population of asteroids detected in past centuries. Rubin will also be the most effective observatory at spotting interstellar objects like `Oumuamua, which originate outside the Solar System.
All in all, LSST promises to deliver the most exciting movie of the sky as it holds the potential to reveal that we are not alone. Follow-up observations of its harvest of interstellar objects would show whether any of them might be of technological origin, potentially space trash or functional space probes from another civilization. The question of whether such objects exist near Earth will not be up to the whimsical intuition of quantum-gravity experts but the result of rigorous data collection and analysis.
From my perspective, the more data we have on interstellar objects the better, because if they show robust evidence for anomalies — it would be difficult to brush them under the carpet of conventional thinking.
In collaboration with my Laukien-Oumuamua Postdoc Richard Cloete and Peter Veres, we developed machine learning (ML) software that would flag interstellar objects in the LSST data stream. This will trigger follow up observations of these candidates with other ground-based observatories as well as the Webb telescope, as suggested in a recent paper I wrote with my student Sriram Elango.
My experience with skeptics raises an interesting question about the future of science in the age of artificial intelligence (AI). Will it be possible for AI/ML scientists to weed out human prejudice and false intuition, and lead us faster to scientific discoveries? This would be possible as long as we will not train AI/ML scientists only on human content as that will make them inherit bad traits from human scientists. If AI/ML scientists will do better than human scientists on Rubin data in the coming year, I would prefer having digital screens at my table in the banquet dinner scheduled for next year.
ABOUT THE AUTHOR
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 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. The paperback edition of his new book, titled “Interstellar”, was published in August 2024.
