BREAKING: Astronomer Avi Loeb is still a crackpot.
Just when you think he has divested all semblance of scientific credibility, he somehow manages to shed another layer.
Tenured Harvard professor (and formerly respected astrophysicist) Avi Loeb gave up science when he learned how much more lucrative it was to extract money from Silicon Valley tech bros for saying whatever’s needed to confirm their preferred belief that aliens actively visit the Earth.
One of the more visible times he has made himself the laughingstock of the astronomy community was last year when comet 3I/ATLAS entered our solar system — it’s one of only three confirmed interstellar objects to visit here. He quickly claimed that it was probably not a comet at all, but an alien “mothership”. When widely criticized, he did what he always does — falls back to JAQing off (Just Asking Questions) and has since retreated to “Well yeah, it’s probably a comet, but it’s good science to ‘open our minds to other possibilities’ and not be ‘slaves to the mainstream narrative.’” Go back to sleep, Avi.
The latest news is that some papers appeared on preprint servers this month, “Water D/H in 3I/ATLAS”1 and “JWST Spectroscopy of 3I/ATLAS: Isotopic Evidence for a Cold and Distant Origin of the Interstellar Comet 3I/ATLAS”2 which reported our measurements of the isotopic ratios of the comet’s water. This was an interested thing that everyone wanted to study. We have a pretty good map of the solar system incorporating isotope ratios, it’s one way we can tell where in the solar system an asteroid or comet originated from. Now we had an opportunity to see what that ratio looks like in whatever solar system 3I/ATLAS came from. We knew it would be wild and crazy and different from ours, and here we’ve had an actual chance to find out!
Comets are mostly water, so that’s what we look at. There are two common, naturally occurring isotopes of hydrogen, 1H and 2H which you might know as deuterium. It’s hydrogen with an extra neutron in the nucleus. On Earth, the naturally occurring deuterium-to-hydrogen ratio is roughly 1:6,500 — one atom of deuterium for every 6,500 atoms of regular hydrogen. Who knows what it would turn out to be in 3I/ATLAS’s system?
The papers found — drum roll please — deuterium is a lot more common in 3I/ATLAS than on Earth! About 43 times as common, with a deuterium-to-hydrogen ratio closer to 1:152. Why? Well, mainly because it’s a different solar system, with a different star, and so of course its elemental ratios and isotopic ratios are going to be different than ours! It was neat, but it was not a surprising result. In fact it was much in line with expectations. Since 3I/ATLAS came from an older and colder part of the Milky Way with metal-poor star forming regions, such a ratio was much in line with our models.3
But Loeb saw dollar signs. He denied the natural tendency of such an environment to result in high deuterium levels (which is crazytown, because it’s not like that’s controversial or anything), and asserted that 3I/ATLAS is carrying NUCLEAR FUEL (deuterium and tritium can indeed be used as fuel in modern fusion reactors4) — thus betraying the unmistakable hand of alien fusion engineers.
To restate the basics:
3I/ATLAS would have deuterium no matter what, because deuterium is naturally occurring in water, and 3I/ATLAS is mostly water;
3I/ATLAS comes from a region where everything we know about physics tells us higher ratios of deuterium — exactly like what was found — are to be expected.
For more on this, I recommend the following: Jason Wright’s articles here and here, and a more consumer-friendly description of the hubbub (albeit more equivocal) here.
So, yeah. He’s a crackpot. And if he has captured your attention, it’s because that’s exactly what he’s trying to do.
https://arxiv.org/html/2603.07026v1
https://sciety.org/articles/activity/10.21203/rs.3.rs-8930056/v1
https://astrobiology.com/2026/03/a-direct-view-of-the-chemical-properties-of-water-from-another-planetary-system-water-d-h-in-3i-atlas.html
http://hyperphysics.phy-astr.gsu.edu/hbase/NucEne/fusion.html
Notice if you zoom in on the picture, Avi Loeb has lots of pictures of himself. Methinks he takes himself too seriously--among many other problems.
If this comet is the third confirmed interstellar object to visit our solar system in roughly a decade... makes me wonder if such objects drift by every few years and we are only now able to observe them... figuring out how to observe them... Maybe some billionaire could have a probe ready to launch to study the next one.
As for Dr Loeb... tenured professor at Harvard sounds like a fine job. Does he need the money that badly? What happened to him? (What ever it is, could it happen to any of us?)