As an astrophysicist, probably the most common question I ask is: "We are just in the universe and there are aliens?"
There is no doubt: people love to think and talk about foreigners. Therefore, stories about the quest for extraterrestrial intelligence are collected and well-informed in the media.
But what is really at the heart of this complicated and popular issue is the evidence: the nature of any evidence of alien life, the way we see and respect this evidence and how it is communicated to the public.
Nobody is more important than the coverage of the scientific studies of a mysterious object -Oumuamua- that was discovered recently through our solar system. For example, two publications in two respected peer-reviewed magazines suggested very different reactions.
Oumuamua, which means scout or messenger in Hawaiian, is the name given to the first interstellar object detected to visit our solar system. In the discovery of last year, "Oumuamua was classified as a comet, but later it was withdrawn when no evidence of cometary activity was detected.
Oumuamua quickly found itself with an orbit that does not belong to our solar system. It has its origin in another place in our galaxy and a trajectory that has seen crossing the internal solar system over a few months.
He passed near the Sun and the Earth, and found himself with an unusual geometry, about 200 meters long and about 35 meters wide, rotating every seven hours.
The discovery of "Oumuamua" has generated a lot of attention in the scientific community and in the media. Given its unusual geometry and its origin outside the solar system, questions were soon asked about whether Oumuamua could be a spacecraft.
The observations were made with radio telescopes to look for direct evidence of transmissions that indicate intelligent life, including a team led by me using an Australian telescope (Murchison Widefield Array). We listen to FM radio frequencies, based on the fact that any intelligent life in Oumuamua can recognize popular FM frequencies on Earth.
No direct evidence of intelligent life was found in these searches.
More information on "Oumuamua"
Extensive and impressive observations have been observed with various telescopes, including the Hubble Space Telescope, to accurately determine the trajectory of Oumuamua. The results of the study, conducted by a team of astronomers led by Marco Micheli of the European Space Agency, were published in Nature in June.
These very careful observations have shown that "Oumuamua accelerated when it left the solar system, revealing the existence of" non-gravitational forces. "This means that the trajectory of the object can not be explained by the gravity of the sun and other major objects in our solar system.
There are a number of possible explanations for acceleration. One of them is that hot gas escaping from "Oumuamua & # 39; (excess gasoline) could produce a force that triggered the acceleration observed. This is commonly seen in normal comets.
But Oumuamua still does not show evidence of cometary activity. Micheli's team went through six possible explanations and concluded that excess spending is the most likely option, although there is no direct evidence that this is the case.
They showed that the acceleration of "Oumuamua" is unusual, but within the limits of what was previously seen for solar system comets.
One of the explanations described by the study team is that "Oumuamua has been accelerated by the radiation pressure of our sun. Sun radiation can push distant objects.
But they concluded that this explanation is not preferred because it means that the density of Oumuamua should be very low. An object needs to have a large surface and low mass (low density) to be accelerated by radiation pressure.
Can they be foreigners?
Another study by the postdoctoral researcher Shmuel Bialy and distinguished astronomer Avi Loeb from Harvard University took a different approach.
The study details have just been published in The Letters of astrophysical newspapers, but they were available online before.
The authors chose assume The pressure of solar radiation was the cause of the acceleration and determined the properties of Oumuamua necessary to carry out this work. They require an object with a thickness of less than 1 mm, with a mass density of 1 to 2 grams per square centimeter and a large area.
It is unlikely that nature produces such an extreme geometry. The authors quickly mention this, before moving on to a discussion that, under the assumption that solar radiation is the cause of acceleration, "Oumuamua is artificial – that means the product of an alien civilization.
The properties that the authors derive under their assumptions are similar to those of solar candles designed and constructed by human beings as a possible way to cross interstellar distances.
Bialy and Loeb spend half of the article discussion section on the idea that "Oumuamua" could be a missing or active sun candle pertaining to an alien civilization.
The nature and the communication of the tests
Bialy and Loeb did not issue a press release about their study, but the media collected the document once it was accepted and available online before the publication of the newspaper.
(This is something that happened to me in 2012, leading to my non-detection published by foreigners running on the first page of the BBC website).
The publication of Bialy and Loeb attracted headlines like this, for example: "Harvard's astronomers claim that Oumuamua is ALIEN PROBE -" Nothing like what we've ever seen. "Most of the other reports were more balanced.
This is pretty normal. Many of the media jump to foreigners in the report on space and astronomy, even when the original relative studies never mentioned foreigners. The recent reports on Fast Radio Bursts (FRB) are an example.
What surprised me was the reaction of some of my colleagues to the role of Bialy and Loeb. In social media, there were quite personal attacks by scientists – particularly Loeb – for being in the media for this work.
Both new studies detail their assumptions, cite substantial evidences and perform rigorous calculations. Both were accepted by high quality magazines after peer review.
Both end up with lower lines than Oumuamua's studies are unfinished and we will need to examine more objects that come through the solar system in the future.
Both sets of authors also present different perspectives and motivate different questions. But Loeb ended up in the media, talking about his work, and is being examined by some colleagues for that.
Since the pre-newspaper newspaper was withdrawn, he told me he was flooded with the interests of the media. "I use discussions with the media as a platform to highlight the standard scientific methodology: there is an anomaly in the data, the standard explanation is not explained, so an alternative interpretation is proposed. Encouraged anyone with the best explanation to write an article about it and publish it. It is possible to rule out incorrect interpretations when more data will be published in "Oumuamua" or other members of its population in the future & # 39;
Regarding the negative reactions he received, he referred to an article he published recently where he paraphrased another scientist known for his theories, once controversial. "As Galileo reasoned after looking through his telescope," in the sciences, the authority of a thousand is not worth as much as the humble reasoning of a single individual. "
Let's talk about tests
Given my work on Oumuamua's observations, some journalists contacted me to comment.
These were great opportunities to discuss in depth with journalists the nature of the evidence, the difference between something consistent with observations and direct evidence for a conclusion, and the need for the evidence to be compatible with the impact of a claim.
If extraterrestrials are claimed, direct and robust evidence is needed, and not a conclusion based on some observations that are difficult to explain, as well as a series of assumptions.
But no scientist said "Oumuamua is alien in this discussion: they recently raised questions and explored the answers.
There is no point in avoiding a good discussion about the quest for extraterrestrial intelligence, or being a personal critic of your colleagues.
Scientists should take every opportunity to interact with the public and the media on the subject, given the interest of the public and the provision of the media to inform.
It is interesting, fun and scientific, and a great opportunity to talk about the scientific method and science in an attractive way. Oumuamua's press reports show that (apart from a few headlines), the content of the reports is usually very good and responsible.
Whatever "Oumuamua" (almost certainly not made by aliens, in my opinion), is a fascinating object and presents many interesting scientific questions that will trigger studies and observations.
We will never see "Oumuamua again, and maybe we never know exactly what it is." But seeing "Oumuamua in the news is likely to inspire some children to take a career in science.
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Scientists regain the theory of the alien spacecraft of Harvard