Most of the mainstream media seems to be ignoring him now. Less mainstream places are still inviting him on because he wants to talk about aliens visiting. Other scientists don't want to talk about that because it's unwarranted for 3I/ATLAS, so it's just him.

The comet has complex structure, including gas/plasma, dust, and various jets.

Loeb's gas calculation was specifically about the anti-tail, which, as has been explained, is actually made of dust.

There is also a plasma tail, but it points in a different direction and is not what Loeb referred to.

See www.facebook.com/christoph.ge... for a good image from this morning: stubby antitail to the left, classical plasma tail to right, all as expected from a neat comet and the viewing geometry right now. Why is there even a question to be answered?

Most images like B&N show both of the plasma and the dust. Loeb’s measurements are of the dust. R band images only show the dust.

I am no expert, but I think the problem is he is applying the physics of an ion tail to what is obviously a dust tail.

Don’t give him any ideas! I feel like he tries to prove he’s beyond parody by adopting posts like this as serious claims in his next blog post:

bsky.app/profile/astr...

I’m unaware of any model for an alien spacecraft that behaves and looks as much like a comet as 3I/ATLAS.

Loeb has given a handwaving explanation for why it might have some ices on its surface after a trip, but never justified why it would have just as much ice to sublimate as a comet!

Is that a thing? It might be a thing!

When Arnold Schwarzenegger became governor, a bunch of us Berkeley grad students asked for belated copies of our masters diplomas and sure enough his (not really his) signature was on them!

I still have it somewhere…

Yes, somehow he has managed to win the debate no matter what happens by framing any anomaly that cannot be perfectly explained as proof it’s aliens!

This, despite the fact that the alien spacecraft hypothesis is a terrible fit to the data!

His current hobbyhorse has to do with his claim that the active surface of the comet must be an order of magnitude larger than it could be if it were a monolith to produce the jets we see. I presume his math is characteristically naïve, but I don’t know enough comet science to refute it.

We had more than enough evidence to see it was certainly a comet weeks ago. He keeps making up new reasons to keep the spaceship hypothesis alive.

Avi has already said no amount of evidence will push his probability below 20% so you can just ignore him at this point

I focused on the -S tail in the second point because I was trying to demonstrate that Avi wasn't applying the most basic comet knowledge to his work. Overall, my point is that he's making mistakes that don't even require significant experience with cometary astronomy.

Yes, the point of tenure is to give one the freedom to go off in unpopular directions, even ones as unfortunate as these, without having to worry about one’s job.

As long as he does his teaching and service well, his job will remain very comfortable.

He is suffering bad reputational damage though.

It seems he's trying to determine the mass in the jets from their *length* and speed?! I have no idea if there is any merit to this approach.

Yes, I'm dubious about his re-invention of comet jet dynamics given his track record. There's a reddit post on this thread somewhere where someone takes apart his math but I don't know how reliable it is.

Aha! This is very neat!

So it is very common for comets to outgas at rates higher than an equilibrium model would expect at a given insolation!

Yes, that would certainly explain his error!

No, I think he's been at least internally consistent here? I think his line was "If it were comet, then there must necessarily have been a breakup to explain the amount of mass in the jets. We observe no breakup, therefore it is not a comet".

This post seems like a good takedown, but I don’t know the author and haven’t looked carefully at the math

www.reddit.com/r/3I_ATLAS/s...