Three things are certain in this world: death, taxes and people who go to banana for strangers. Between Harvard University physicist Avi Loeb and postdoctoral student Shmuel Bialy, as well as their new pre-print document, suggesting a possibility that the interstellar asteroid known as "Oumuamua" is a spacecraft at lightweight sailing propulsion of artificial origin designed for interstellar travel. Yes, they say it could be extraterrestrials.
Do not get carried away. The paper does not present any proof of this kind. It is essentially an attempt to explain some strange behavior of the object with an unrealistic assumption. The full story on the new paper is a good example of why extreme ideas, even those from some of the most prestigious institutions in the world, must be treated with caution.
Here is the agreement: "A year ago, Oumuamua came from the interstellar space for a quick visit of the solar system, traveling 200,000 km / h for an essentially cosmic weekend. Once scientists realized that this was the first interstellar object observed in our solar system, they rushed to work to gather as much data as possible. They had barely two weeks with ground telescopes and about three months with the Hubble Space Telescope to observe 'Oumuamua before it disappeared forever.
'Oumuamua is not your garden variety' minor planet '. It is 800 meters long, 80 meters wide, is composed of rocks and ice forming a cigar. It was quite difficult to know if the object was called comet or asteroid; its shape evoked a comet, but it did not produce the kind of small comets of dust usually spread.
And the lost weekend of Oumuamua through the solar system was just as strange to start. The object exhibited small changes in direction and velocity that could not be attributed solely to gravitational forces, accelerating as it left the solar system. A good explanation for this would be outgassing: gaseous material jets are expelled from the surface through interactions between the sun's heat and the volatile iced components of the object, increasing the overall velocity of Oumuamua. It would also have been a clear sign that 'Oumuamua was a comet.
But degassing is supposed to occur when a comet gets closer to the sun and not as it moves away. Loeb and Bialy presented a counter-argument suggesting that "the movement of Oumuamua is what we would expect if the object was designed to be propelled into space using the force of sunlight. This is how a veil of light is supposed to work: the solar radiation hits the surface and induces a force that accelerates the speed of an object when it moves in space. And something like a veil of light, optimized for interstellar travel, should be done by intelligent life.
In his defense of paper, to be published next week in The letters of the astrophysical journalLoeb told NBC News Mach that his new hypothesis was "purely scientific and evidence-based … I am Sherlock Holmes' maxim: when you ruled out the impossible, all that is left, as unlikely as it is, must be the truth.
It's a wild way to come to such a radical conclusion. Michele Bannister, an astrophysicist at Queen's University in Belfast, Northern Ireland, points out that Loeb's hypothesis would only be appropriate if it existed no other good explanations the sharp increase in the acceleration of Oumuamua. "And we have a good explanation that fits the data well," says Bannister, citing an article published in Nature earlier this year, which uses data to corroborate the idea that gassing took place at the exit of the solar system object. Bannister argues that the lack of purely gaseous observations may simply be a symptom of the limited time available for astronomers to study 'Oumuamua before it is too far away. "Do the data need extreme assumptions when you have reasonable assumptions that fit the data perfectly?", She asks rhetorically.
And if 'Oumuamua is a comet, it is certainly not the first to refrain from emitting small dust. 2P / Encke is an excellent example of such a comet, producing larger particles on the scale of several millimeters in diameter compared to smaller dust particles of only a few microns in diameter.
"There is a whole range of comet behaviors," says Bannister. Billions of tiny worlds of ice and rocks litter the universe. According to her, it is likely that we expected to see one play a little unusual like 'Oumuamua.
The truth is that this last article is not even the first time scientists speculate that "Oumuamua could have a history of origin linked to intelligent extraterrestrials. And for a moment, the hype around Oumuamua as the first registered interstellar visitor means that every weird bit will be picked up – and possibly interpreted as evidence of something weird.
But there is a big difference between this speculation of a year ago and what Loeb and Bialy are launching now. A year ago, people were trying to understand the data as quickly as possible to determine if our instruments needed to search for something in particular, which is why the craziest ideas were taken more seriously. Now, "it's been more than a year since the flight over Oumuamua," says Bannister. "We are not in a hurry at this point. We have all the data that will ever be collected on this object. We are now simply trying to improve our understanding of the visitor, and it will take time for this to crystallize. A new hypothesis like that of Harvard researchers is more noise than signal.
So why does this paper exist? Astrophysicist Katie Mack raised a good point on Twitter that many scientists are happy to speculate on even the most extreme explanations of a phenomenon that can not be 100% proven false, even if they do not really take it seriously. In the space, any mysterious object could theoretically to be the work of the extraterrestrials. But it is not because something escapes the conventional explanation that it is the work of intelligent life forms coming from beyond our solar system.
Loeb and Shmuel may have tried to provoke strong reactions through their document. Why? Loeb is heavily involved in traffic light research in development on Earth, particularly as part of his work as Chairman of the Breakthrough Starshot Advisory Committee. A cynical reading of these events might be that Loeb presented a strange theory about 'Oumuamua to spark discussion about bright sails. But Loeb is a big name in his field, and it would be a strange tactic to write and submit a document for advertising purposes only. At the very least, bright tails come to his mind, so it makes sense that he tries to see if 'Oumuamua has certain characteristics.
It will take a lot of work to reach an agreement with 'Oumuamua, but those like Bannister have no trouble saying what the object is not:' it's not extraterrestrials'.