Mainstreaming SETI: ‘Oumuamua and Light-sails


Recently, an interstellar object named ‘Oumuamua entered our solar system. It was the first such observed object in recorded history. Scientists were thus already watching ‘Oumuamua when, as it came closer, it did something surprising: it sped up. Notably, it did this without outgassing, which happens with comets and explains their changing speeds.

                            Artist Depiction of ‘Oumuamua. Credit: ESA

What, in the absence of outgassing, accounts for ‘Oumuamua’s unexpected acceleration? Avi Loeb, the chairman of Harvard’s astronomy department, floated a potential explanation: alien technology. As one might guess, this led to controversy. Filling Space spoke with Dr. Loeb to learn about his thoughts on ‘Oumuamua and the search for extraterrestrial intelligence (SETI).


Have you been surprised by reactions to your comments on ‘Oumuamua?

Yes, I did not anticipate this much reaction. We wrote a regular scientific paper aimed at explaining an anomaly in the data, namely the extra force exhibited by ‘Oumuamua’s trajectory in addition to the Sun’s gravity, in the absence of visible cometary outgassing. We suggested ‘Oumuamua may be pushed by sunlight, like the light-sails we are currently developing in the Breakthrough Starshot initiative that I am involved in.

For comparison, last year I published another paper that explained an anomaly of an unusually cold gas in the early universe, as reported by the EDGES experiment. In that paper, we conjectured that dark matter has some small electric charge to explain away the anomaly. The dark matter paper was accepted for publication within a few weeks and received little attention from the media.

The reaction to the light-sail paper was different. I did not plan to have a press release about it, but the editor of The Astrophysical Journal Letters wrote to me in an e-mail: “You should consider a press release on this one”. Before I had time to act, though, two bloggers reported on our posting on arXiv (where I regularly post papers before they get accepted for publication, in order to get comments from the community before the paper is finalized). Within days, the item went viral on social media.

Since then I have received dozens of requests on a daily basis from TV, radio, and newspaper outlets. Over the past few days, I had five film producers request to make documentaries about my work and life, and so on. So, yes… this was totally unexpected. But I do my best to use this public attention for a good purpose: to explain that most of the time frontier science involves uncertainty due to lack of data, that innovation and risk-taking is essential for making discoveries, that prejudice should be banned from the scientific discourse, and that mistakes should be tolerated in order for innovation to prevail.

During your career, have you witnessed any changes in the scientific community’s opinions on the possibility of extraterrestrial life?

History teaches us an important lesson. The search for extrasolar planets encountered similar resistance in its early days. Observing proposals to search for low-hanging fruits such as hot jupiters were rejected by conservative time allocation committees who argued that such easy-to-detect planets should not exist based on what we know about the Solar System. All progress broke loose as soon as some observers dared to challenge this prejudice, demonstrating that hot jupiters are abundant. The Kepler satellite revealed that about a quarter of all the stars have a habitable Earth-size planet, where liquid water may exist and the chemistry of life may flourish on its surface. This shifted public opinion in the direction that the search for primitive life should be part of the mainstream in astronomy.

But the search for intelligent life remains outside the mainstream. I am trying to change that in two ways. First, by speaking out in the way that I did on ‘Oumuamua. And second, by writing a textbook with my postdoc, Manasvi Lingam, on the search for both biological and technological signatures of extraterrestrial life. The book should be completed by summer 2019.

How did you become interested in the search for extraterrestrial life, and what would you recommend to individuals trying to enter that field?

I was intrigued by the question: “Are we alone?”. If the answer is “no”, I will continue to be intrigued by the follow-up question: “Are we as smart as they are?”. My advice to any young scientist is: “Follow your childhood curiosity rather than your ego, and you will have a fulfilling life”.