We remember the worldwide enthusiasm that accompanied a publication a few years ago by the American-Israeli astrophysicist Abraham Loeb, usually called Avi Loeb.
President of the Astronomy Department at Harvard University (USA) from 2011 to 2020 and a key participant in the Breakthrough Starshot project – a photonic nanosail powered by laser beams and aimed at the stars closest to the Sun in the Alpha Centauri system – Loeb had a thesis about aliens defended in a book translated by Charles Frankel and published by Editions du Seuil under the title “The first sign of extraterrestrial intelligent life”.
On the blog provided by Futura, astrophysicist and cosmologist Jean-Pierre Luminet commented on the book’s publication with the following words:
“From the outset it is a sensational book that would have annoyed me at first glance. However, I know the author.
Far from being one of those fanciful popularizers who occasionally grab headlines with catchy headlines, Loeb is a real scientist who has published very serious articles on a wide range of topics, from cosmology to black holes. .
Therefore, I am well placed to recognize his contributions. He also personally received me in June 2019 at Harvard, during the gala dinner of the conference organized to celebrate the first telescopic image of a black hole, taken by his team two months earlier, which confirmed my calculations made 40 years ago (hence the invitation). »
Another ‘Oumuamua?
In particular, the work was based on the now-mythical passage through the solar system of a small body called ʻOumuamua, whose trajectory and speed, greater than that which allowed it to escape the Sun’s gravitational pull, suggested that it came from the middle interstellar .
For science fiction fans, the event was irresistibly reminiscent of the scenario from Rendezvous with Rama, the famous 1973 novel by Arthur C. Clarke.
Therefore, speculation was not long in coming as to whether ʻOumuamua was a simple asteroid ejected from another planetary system by natural processes, or an interstellar probe launched by an advanced extraterrestrial civilization that interacted with a fraction of the planet could travel at speed, light was sent from near our noosphere as a super AI in the Milky Way.
Because of ‘Oumuamua’s unusual properties, Avi Loeb leaned towards the second hypothesis, which seemed to him the most likely.
Better yet, if numerous advanced alien civilizations had emerged in our galaxy billions of years ago, there might have been frequent interstellar probes entering the solar system after journeys lasting perhaps millions of years, which would have resulted in some of them becoming inoperable were. Because even at a fraction of the speed of light between sunrises, a collision with just a tiny pebble can seriously damage even an object designed to last billions of years.
An interstellar probe that melted upon entering the atmosphere?
Loeb went even further, relying on the case of another object considered clearly interstellar, named Cneos 20140108 due to its presence in the Center for Near-Earth Object Studies (CNEOS) online meteor catalog.
Its trajectory has been somewhat reconstructed and in recent years it appeared that it collided with Earth somewhere off the coast of Papua New Guinea on January 8, 2014. We could therefore consider it at least the first interstellar meteor, or Interstellar Meteor 1 (IM1) in English.
Loeb and a few colleagues had managed to secure funding, including from cryptocurrency mogul Charles Hoskinson, with the idea that debris from the object could be found by using a powerful magnet to cover an area the size of a stone with a diameter of Ten kilometers combed and a few kilometers deep. We might be able to figure out whether it’s an interstellar asteroid or an ET probe by analyzing this debris.
In fact, Loeb announced some time ago that his team had found a type of metallic sphere with a diameter of half a millimeter in the area examined.
Analysis of the spherules found shows that some are composed primarily of iron, but also some titanium and magnesium, although according to Loeb’s own words in the expedition’s online logbook (for more details on this expedition, see the Times of Israel has one online published a remarkable article) whose “composition is abnormal. It bears no resemblance to man-made alloys, known asteroids, or other known astrophysical sources.”
Such a statement, which accompanies a long article on arXiv, is obviously disturbing and raises the question of whether it has any real merit or not.
Let us remember that a few years ago Futura had already interviewed two French astrophysicists whose expertise is known both in the formation of planetary celestial bodies and in exobiology and who were therefore able to offer particularly informed opinions, a reflection in addition to what science says Community in general about Loeb’s theses. These were Sean Raymond and Franck Selsis, for whom Loeb’s claims regarding ‘Oumuamua clearly did not apply.
Most recently, Sean Raymond suggested on his Twitter account that Loeb’s other claims, this time about Cneos 20140108, had been verified by his colleague Steven Desch.
The least we can say is that the criticism of this astrophysicist is damning.
The researcher is a professor at Arizona State University (ASU). His research focuses on the development of models for the formation of stars and planets, in particular using data from meteorites and those about their origin and the chondrules they contain. It also models small icy bodies to study the likelihood of the presence of groundwater on Pluto and its moon Charon or the asteroid Ceres.
Steven Desch generously allowed Futura to record and translate his comments. Here you are !
Since so many people have asked, here is my take on the beads Loeb found and the earth-shattering written statements he published. These are fairly typical cosmic globules. If he had conducted the essential and obvious test of a control sample 100 kilometers from the meteor, he would have found the same thing.
In order to confirm that these spherules are interstellar, the following had to be demonstrated:
- the 2014 meteor was interstellar;
- it didn’t burn completely;
- the debris was concentrated where we had looked for it;
- the beads came from THIS meteor;
- a source from the solar system is ruled out;
This did not happen. Most likely, these spherules are authentic micrometeorites from solar system asteroids that reacted with seawater over tens of thousands of years. I explain the facts and express my opinion below.
The 2014 meteor likely came from our solar system. It would be interstellar if its speed were at least 45 km/s, and the Space Force’s pinky swears that it is; but for meteors that can be checked from the ground, these numbers are wrong a third of the time (Devillepoix et al. 2019).
For high-velocity measurements, the error bars are ±20 km/s, and everything about this meteor appears to be more consistent with a speed of 25 km/s (Brown & Borovicka 2023), meaning it is just another meteor our asteroid belt.
A meteor moving through the atmosphere at 45 km/s would be 99.9999% burned (Desch et al. 2023, ACM2023). These are standard formulas in meteor physics that tell us this.
In their article on arXiv, Tillinghast-Raby, Loeb and Siraj make glaring physics errors in estimating that 10% of meteors would survive at this speed.
The location of the meteor is not known within tens of kilometers. CNEOS reports locations within a radius of ±11 kilometers. Siraj & Loeb (arXiv, unreviewed) are trying to use the Manus Island seismometer’s detection of the air burst to refine this. If the sound of the explosion arrived after 271.0 ± 0.5 s, the distance was 83.9 ± 0.7 km.
But look at their Figure 3. Can you say that the first signal arrived exactly at 271 s and not at 280 s? Otherwise the distance is uncertain to the nearest 10 kilometers. They don’t know where to look! Your Figure 4 even shows that the meteor is traveling in exactly the opposite direction!
All the material would be spread over several dozen km2. This meteor disintegrated in 0.3 s and moved several dozen kilometers to the east. Scattered debris fields are typically several dozen kilometers long. The equatorial ocean current would have distributed spherules that flowed several dozen kilometers below the surface of the Pacific Ocean.
The ocean floor is littered with cosmic spheres from the last tens of thousands of years, “tens of millions” in their search area alone, thousands of times more numerous than those from the 2014 meteor. Loeb spheres do not carry a corresponding label that they come from the 2014 meteor.
Loeb claims that the five unusual spheres came from the meteor’s trajectory as he imagines them, but they were not actually sampled outside the trajectory, and these are just small circumstantial statistics. Here, too, none of these spheres are likely to have come from the 2014 meteor.
Loeb claims that the chemistry of the five beads is unprecedented and even gives them the name “BeLaU”. Their Figure 10a shows that they have enormous excesses of Th, U, La, Nb, Ce, Ba and deficiencies of Co, Zn compared to the suspected asteroid material.
It took me 20 minutes to find a similar example in the literature. Figure 2 from Rudraswami et al. (2016; MaPS 51, 718) shows S-type scoria globules in the Indian Ocean with large excesses of Th, U, La, Nb, Ce, Ba and depletions of Co, Zn.
Why this chemistry? The spherules react with seawater and sediments containing these elements over tens of thousands of years (Prasad et al. 2015; MaPS 50, 1013). Loeb spheres have simply sat on the ocean floor for tens of thousands of years.
As for the Fe isotopes, the values measured at the top right of Figure 17 indicate that these globules come in part from materials vaporized in our atmosphere and from CERTAIN meteors. But they all lie on the Earth Splitting Line (TFL), like everything else in our solar system.
We expect that spherules from another solar system have very different Fe isotope ratios and are arranged along a parallel line well above or below the TFL. This strongly suggests that all of these spheres come from materials from the solar system. (Hat tip to @sethajacobson !)
Loeb’s strategy was to find spheres that were unlike anything else on Earth. This strategy only works if you know what everything else on Earth looks like. And to do that, you need to learn from experts who have been doing these things for decades.
But before he takes the time to learn what’s usually at the bottom of the ocean, Loeb winks at the press by saying he hopes to find an alien iPhone and press the buttons on it, ending the article with ” Another possibility is… an extraterrestrial technological phenomenon. “Origin.”
It’s “putaclic” and that’s not how science works. I too would be very happy about the discovery of extraterrestrial technology. But every claim must withstand peer review, and competent and responsible scientists rule out banal explanations until they are forced to speculate.
Loeb’s rule is instead: If he doesn’t get it, then “aliens” are a possibility, and we are petty and mediocre scientists for not giving up what we’re doing and checking it out. Sorry, but I don’t have time to continue working on something Loeb doesn’t understand.
Before Loeb publishes drafts on arXiv, draws speculative conclusions and makes “putaclics,” issues press releases, writes books, and makes fools of himself and the public, he should read the literature and get to know (and not reject) experts who are deeply in favor Asteroids and meteorites inspire.