Press enter or click to view image in full size(Credit: anash.org)
My day started with an uplifting message from the brilliant Professor Smadar Naoz who was an Einstein Postdoctoral Fellow in my research group and currently holds the Preston Chair in Astrophysics at UCLA:
“Dear Avi,
Shanna Tova to you and your loved ones.
May this be a year of peace and prosperity — a year of discoveries and pushing boundaries.
All the best,
Smadar”
There is no better opening to the Jewish (and academic!) New Year than this message. Here’s hoping that 2025/26 will be a year rich in discoveries of anomalous interstellar objects by the NSF-DOE Rubin Observatory in Chile or Unidentified Anomalous Phenomena by the three Galileo Project Observatories. Such discoveries might facilitate the second part of Smadar’s wish, by inspiring peace and prosperity.
An encounter with alien technology will not only endow humanity with the practical benefits associated with new technologies, but might also promote world peace. Psychological studies show that humans cooperate when facing an external common threat. Such a threat strengthens group identity and increases the motivation to protect its well-being. The resulting “threat-dependent cooperation” offers a meaningful strategy for survival, as collective action is often more effective against shared dangers than individual efforts. Facing danger leads to group bonding and increased willingness to contribute to the collective good.
This may explains the viral interest of the public in the five anomalies of 3I/ATLAS as a potential threat from alien technology, including: (i) its alignment with the plane of the planets around the Sun (as discussed here); (ii) its large diameter of up to 46 kilometers (as derived here); (iii) its cigar-shaped anti-tail of scattered light towards the Sun with a length that is ten times longer than its width (as analyzed here); (iv) its surrounding nickel without iron, as found in industrially-produced nickel alloys (as reported here); and (v) its extreme negative polarization and low inversion angle (as reported here).
When will we know whether 3I/ATLAS is a natural rock or a technological messenger on the Loeb Scale?
As I explained in a new episode of the podcast “Event Horizon” (available here), the verdict will be decided by data obtained in the coming months. Conclusive evidence may arrive as early as October 3, 2025 when 3I/ATLAS arrives within 29 million kilometers from Mars orbiters or as late as March 16, 2026 after 3I/ATLAS arrives within 54 million kilometers from Jupiter’s Juno spacecraft. These forecasts assume that 3I/ATLAS will not deviate from a path dictated by the Sun’s gravity. Any significant non-gravitational acceleration would change these expectations.
A velocity shift by 30–40 kilometers per second during the month of October 2025, could bring 3I/ATLAS or any component of it to Earth between December 26, 2025 and January 9, 2026. This was derived in the second panel from the top of Figure 4 of the paper I co-authored with Adam Hibberd and Adma Crowl (available here). Such a velocity kick is possible with our own rocket technology.
If 3I/ATLAS maneuvers or displays artificial electromagnetic signals beyond the reflection of sunlight by a plume of gas and dust around a kilometer-scale cometary nucleus (as discussed in my first paper about it, available here), then a technological origin will offer a reasonable interpretation. The signals may be beamed and not visible from Earth, but it could be detected by the Mars orbiters. However, if the high-resolution images from cameras on Mars orbiters indicate in October 2025 that the nucleus is smaller than a kilometer in diameter and sheds mass like familiar comets as it approaches the Sun, then a natural interpretation would be most reasonable.
Among the dozens of letters and emails I received today from all over the world, there were three questions from David O’Neill, a retired technology executive, to which I replied as follows:
Statistics with tiny samples — Some of the odds quoted about 3I/ATLAS — such as its retrograde orbit aligning within 5 degrees of the ecliptic plane or its coincidental timing near Mars, Venus, and Jupiter — sound extraordinary. But given that we’ve only observed three interstellar objects, how should we treat these probabilities? Do they provide meaningful insight, or do they risk overstating coincidences? Are they even valid in the context of such a small event sample?
The alignment of 3I/ATLAS with the ecliptic plane can be framed in terms of the alignment of its vector of orbital angular momentum relative to the Sun. The vectors of 3I/ATLAS and solar system planets are tightly aligned. Such an alignment would be statistically plausible for a random coincidence only after observing a sample of hundreds of interstellar objects. If you choose 3 random arrival directions, you would find that the chance of one of them being retrograde and aligned with the ecliptic to within 5 degrees is below a percent. On top of that, if you adopt the actual trajectory of 3I/ATLAS and choose the arrival time at random, you would find a tiny probability of getting as close to Mars and Jupiter as 3I/ATLAS does.
Physical anomalies — 3I/ATLAS shows unusual traits: a CO₂-rich coma, nickel-rich but iron-poor composition, and extreme negative polarization and low inversion angle. Which of these might point to natural explanations? At what point should we allow room for more exotic interpretations?
Anomalies should trigger exotic interpretations in the mind of imaginative scientists. However, dogmatists act as “thought police” and use all the tools at their disposal to suppress imaginative thinking. While serving as referees or editors, they deny publications who offer alternatives, and by writing blogs or posting YouTube videos, they launch personal attacks to discredit imaginative scientists. Their attitude is anti-scientific in the global scheme of science. Other branches of physics involve attempts to unify quantum mechanics and gravity or to identify the nature of dark matter and dark energy, and were guided by speculative ideas for nearly a century. The “thought police” fails to discipline followers of these frontiers because they already represent large communities of scientists.
Scientific importance — Why does 3I/ATLAS matter scientifically, even if it turns out to be a completely natural comet? What can it tell us about planetary system formation beyond our own?
In the future, we could design interceptors that would collect materials from interstellar objects like 3I/ATLAS and return the samples to Earth for laboratory studies. This feat was accomplished by the OSIRIS-REx mission which revealed that the building blocks of life — in the form of most amino acids — exist on the asteroid Bennu. Finding whether interstellar rocks contain the same building blocks for life would open a new frontier in astrobiology, very different from the current popular approach of searching for the chemical fingerprints of extraterrestrial life in exoplanet atmospheres.
As Galileo Galilei noted: “In questions of science, the authority of a thousand is not worth the humble reasoning of a single individual.” Dogmatists did not like this statement back then and they do not like it today. If social media existed 400 years ago, , Galileo would have been cancelled by influencers who side with the popular view advocated by the church.
How can we figure out the truth on 3I/ATLAS? By challenging dogmatists to explain the specific anomalies in its data. If they fail to do so, then “truth in advertising” requires that we all remain curious about alternative interpretations. 3I/ATLAS tests our collective intelligence. If we insist on prejudice, we might fail the test.
ABOUT THE AUTHOR
Press enter or click to view image in full size(Image Credit: Chris Michel, National Academy of Sciences, 2023)
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.