Astronomers Detect a Possible Signature of Life on a Distant Planet

The detection of dimethyl sulfide on an exoplanet is an exciting development, ok. And DMS on Earth is almost entirely biologically sourced, but that doesn’t make it an exclusive biosignature. There are plausible abiotic pathways for DMS formation, such as in geochemistry we can’t know entirely about because we live on earth.

I’m not sure a journalist for this exalted American newspaper here knows anything about this and frankly the excited language of this article is dumb af. Probably because excited people keep paying for subscriptions to this trash.

It took my amateur self nearly 10 mins to ask around to qualified friends and research some counter ideas.

The article isn't overly excited imo. It clearly states nothing has been proven for certainty, which is in alignment with what you're saying.

> Astronomers Detect a Possible Signature of Life on a Distant Planet

> Further studies are needed to determine whether K2-18b, which orbits a star 120 light-years away, is inhabited, or even habitable.

It's not fair to call it "trash"

“Remotely possible” sounds like a neat editorial compromise. A bit tongue in cheek. A pun. Fun.

Otherwise? Clickbait.

You could have just read to the end of the article and avoided wasting the time of your "qualified" friends:

> Other researchers emphasized that much research remained to be done. One question yet to be resolved is whether K2-18b is in fact a habitable, Hycean world as Dr. Madhusudhan’s team claims.

> In a paper posted online Sunday, Dr. Glein and his colleagues argued that K2-18b could instead be a massive hunk of rock with a magma ocean and a thick, scorching hydrogen atmosphere — hardly conducive to life as we know it.

> Scientists will also need to run laboratory experiments to make sense of the new study — to recreate the possible conditions on sub-Neptunes, for instance, to see whether dimethyl sulfide behaves there as it does on Earth.

> “It’s important to remember that we’re just starting to understand the nature of these exotic worlds,” said Matthew Nixon, a planetary scientist at the University of Maryland who was not involved in the new study.

The end of the article?

Thanks for making exactly my point.

It is literally in the subtitle. You are making a storm in a teacup here.

>but that doesn’t make it an exclusive biosignature. There are plausible abiotic pathways for DMS formation, such as in geochemistry we can’t know entirely about because we live on earth.

I'm sorry, but this is ridiculous. You started by acknowledging that it is indeed exciting, that it is something we only understand to be produced by living organisms. I wholeheartedly agree with that. And so the plausibility of an abiotic alternative is the big question.

You suggest that there are plausible abiotic pathways, but I think that's where this all starts to go off the rails, because I don't think there are in fact plausible abiotic pathways. We absolutely should attempt to model such possibilities and should be extremely careful about assumptions before working that out. But the state of our knowledge thus far counts for something too and it would suggest that such a process is pretty rare or unique. And then it really goes off the rails because instead of an actual example, you suggest not any specific known pathway, but a kind of bizarre philosophical musing that maybe there's "geochemistry we can't entirely know about."

We most definitely are capable of modeling chemical processes even if they don't happen on Earth. And there sure as heck is no such thing as a principle that things beyond Earth's surface are things we "can't" know about. I truly can't stress enough how ridiculous an assumption like that is.

We know, for instance, that gas giants are capable of producing phosphine, even though that doesn't happen on Earth. We know that the moon likely has a molten core. We know all kinds of things about atmospheric chemistry of planets and stars, because even if the abiotic processes can't be witnessed directly on Earth, we know enough about the principles of chemistry to model them in new contexts with reasonably high confidence.

And that's before we get to the idea that such uncertainty about off-world chemistry can be treated as tantamount to evidence of known abiotic process. It's nothing of the sort, it's more like "who knows, maybe it's possible." We do indeed have to figure out if there are such things as an aviotic process, but just the idea that, hey, who knows, something offworld might be happening is nowhere near enough to count.