Avi Loeb is playing games with his peculiar interpretation of interstellar object 3I/ATLAS. He keeps suggesting that this interesting, carbon-rich, and very old rock is an artificial construct built by a distant civilization, that it is a probe sent to examine our solar system, and that it could be a “Trojan horse” that will do something, who knows what, when it arrives.

Reading some his justifications for that claim, I am forced to conclude that he is an idiot putting on a display to get attention.

Worse, he’s a bad scientist whoring irrational claims and calculations that he has to know are invalid. I am not an astronomer, but I do understand logic a little bit, and seeing him derive extravagant conclusions from mundane observations hurts, especially since he’s using them to obscure the really interesting (and entirely natural) interpretations of the data.

For instance, he’s on the record for inferring the probability that 3I/ATLAS is an alien space probe on the basis of “anomalies” that turn out to not be anomalous at all, just unique properties of an interstellar comet.

As of now, I assign a 30–40% likelihood that 3I/ATLAS does not have a fully natural origin, based on its seven anomalies that I listed here. This low-probability scenario includes the possibility of a black swan event akin to a Trojan Horse, where a technological object masquerades as a natural comet.

Show your work, Avi. How did you calculate that 30-40% likelihood? I think he got it by fumbling about in his rectum and pulling out a squishy number that he likes because it fits his presuppositions. There is nothing in his list of seven “anomalies” to warrant that degree of estimation. They aren’t even anomalies, he’s just looking at the brute facts of its existence and declaring that the details are improbable. Of course they are! It’s a unique object in space!

I tried looking at his list. I am unimpressed.

Anomalies that could be alleviated or explained away with upcoming data:

1. Size: The diameter of 3I/ATLAS is larger than 5 kilometers, making its minimum mass of 33 billion tons, larger by a factor of a thousand to a million than the mass of the second and first interstellar objects (as derived here).

OK, it has a size. That is not anomalous. Call me when you observe an object that is massless–that would be anomalous. I don’t see how finding that it has a mass of 33 billion tons makes it more likely to be artificial than if it had a mass of 3 billion tons or 333 billion tons.

I also don’t see how more data would explain away the mass.

It’s also a fuzzy blob far away and hard to resolve. The size is subject to revision, so how do you conclude anything from a measurement with so much variability?

Initial estimates suggested 3I/ATLAS might be up 20 kilometers (12 miles) across—very big for a comet—but most astronomers now think it is much smaller. “It’s probably somewhere in the range of one or two kilometers,” says John Noonan at Auburn University in Alabama. That would be somewhat comparable in size to our first two interstellar visitors: 1I/ʻOumuamua, which was discovered in 2017 and was up to about 400 meters (0.25 mile) long, and 2I/Borisov, which was found in 2019 and was about one kilometer (0.6 mile) wide.

It doesn’t matter — any number you attach to it will be used by Loeb to claim it is probably artificial.

2. Jet: The Hubble image of 3I/ATLAS showed a forward jet of scattered sunlight — 10 times longer than it is wide, pointing towards the Sun (as discussed here). A weak tail showed up only at the end of August (as reported here).

Yes? It’s apparently a carbon-rich object, and gasses are sublimating off of it and spewing in the direction of the heat source, the Sun, that is thawing them, making an anti-tail. How does that make it more likely that it is artificial? It has a chemical composition is what that tells me.

3. Unusual chemical composition: the plume of gas around 3I/ATLAS showed much more nickel than iron (as discussed here and here), as in industrial nickel alloys. Unlike solar system comets, the plume contained mostly carbon dioxide and not water (as reported here and here).

Note the dishonest trick he’s pulling here, comparing it to “industrial nickel alloys.” These are estimates of the composition of the comet made from the spectroscopy of the diffuse cloud of gas surrounding it, not a determination that it’s made of metal alloys.

It actually is an interesting difference — its composition differs from more familiar comets found in our solar system. That composition also seems to be changing over time, which is somewhat odd, but explainable.

To make sense of this mystery, scientists turned to chemistry — specifically, to organometallic compounds, which are molecules containing both metal atoms and carbon-based groups.

In particular, they looked at compounds called carbonyls: nickel tetracarbonyl (Ni(CO)₄) and iron pentacarbonyl (Fe(CO)₅). Both can form under cold, low-pressure conditions, like those found in the outer reaches of a protoplanetary disk — the birthplace of comets and planets alike.

These carbonyls are highly volatile, meaning they can sublimate (turn from solid to gas) at relatively low temperatures. Nickel tetracarbonyl is more volatile than its iron counterpart, meaning it will vaporize first as the comet warms up.

This neatly explained what the VLT was seeing. When 3I/ATLAS was still far from the sun, only nickel tetracarbonyl had begun to sublimate, filling the coma with nickel. As the comet drew closer, the temperature crossed the sublimation threshold for iron pentacarbonyl — and suddenly, iron began to appear. The Ni/Fe ratio plummeted, not because the amount of nickel was decreasing, but because iron was finally joining the show.

Now, though, somebody needs to explain to me how being composed of volatile organometallic compounds is a signature of artificial manufacture.

4. Polarization: the light from 3I/ATLAS showed extreme negative polarization (as reported here).

I read the paper, and I must admit, the topic is beyond me. It does say that 3I/ATLAS has distinct, unique polarization properties and that “Its polarimetric characteristics provide novel insights into the dust properties of interstellar objects, suggesting that ISOs may encompass a broader diversity than previously recognised,” but does not even come close to implying that this is a marker of artificiality.

Anomalies that will remain puzzling forever:

5. The trajectory of 3I/ATLAS is aligned with the ecliptic plane of planets around the Sun to within 5 degrees (0.2% likelihood), as discussed here.

It has a trajectory. That is not anomalous. Every object moving through space has one. Yes, this trajectory is roughly similar to the ecliptic plane, but so what? 3I/ATLAS is very old, between 3 and 14 billion years old, is Loeb suggesting that aliens aimed their space probe at a condensing protosystem before the planets existed in order to tour potential planets?

6. The arrival time of 3I/ATLAS was optimized to pass near Mars, Venus and Jupiter (0.005% likelihood), as discussed here.

“optimized”…such misleading language, implying intent behind its trajectory. Here’s what that trajectory looks like:

Ooooh. Does that look like a pre-planned course to you? It does to Avi Loeb.

7. The arrival direction of 3I/ATLAS is aligned to within 9 degrees with the “Wow! Signal” from August 15, 1977 (0.6% likelihood), as discussed here.

The “wow” signal was a brief, unexplained, unrepeated pulse of radio signal noise. It got SETI researchers very excited for a while, but there’s no reason to think it is a message from space aliens, and Loeb is making an exceptionally tenuous connection between it and 3I/ATLAS. A 9 degree difference is an immense difference in location at the astronomical distances we’re talking about.

You know, as an atheist I read far too much nonsense from religious apologists claiming to have proof of their god’s existence — bizarre non sequiturs about physical constants and numerological coincidences, collections of anecdotes that are supposed to add up to evidence, and a tiny set of permutations on the same old arguments that even in their best interpretations don’t make up a justification for their beliefs. Reading Avi Loeb’s work gave me a strong sense of deja vu. It’s the same thing! A good analysis of a phenomenon should lead one to a minimal conclusion, but everything Loeb does ends up supporting the remarkable interpretation that God Aliens exist, and they want to talk to you, and this tiny fragment of data is how they shout at you, Occam’s Razor be damned.

I’m going to say it: Loeb has gone batty, and all this noise he makes is nothing but a dedicated (and successful!) effort to get his name in the tabloids. He’s the Percival Lowell of our generation, a scientist who did good work but whose reputation was poisoned by his irrational pursuit of astronomical phantasms, the Martian canals in one case and this alien obsession in Loeb’s.