https://iopscience.iop.org/article/10.3847/2041-8213/adc1c8

They possibly detected dimethyl sulfide, which is only known to be produced by living organisms.

Secondly, my prior was always that life existed outside of earth. It just seems so unlikely that we are somehow that special. If life developed here I always felt it overwhelmingly likely that it developed elsewhere too given how incredibly unfathomably vast the universe is.

On DMS:

- DMS is a very specific configuration that’s rarely the endpoint of non-living chemical cycles.

- The simplicity of DMS doesn’t make it less indicative of life—it actually makes it a very selective molecule, which only shows up in large quantities when life is involved (at least in Earth-like chemistry).

- Until we find a compelling abiotic pathway, high DMS remains a strong biosignature, especially in the context of a planet with a potential ocean and mild temperatures

Possible origins:

We’re looking at some form of life that can:

- Thrive in a hydrogen-rich atmosphere

- Possibly live in or on top of a global ocean

- Generate large amounts of DMS—potentially thousands of times more than Earth

The closest Earth analogy is:

- Marine phytoplankton, particularly species like Emiliania huxleyi, produce DMS as a byproduct of breaking down DMSP, a molecule they use to regulate osmotic pressure and protect against oxidative stress.

- If something similar is happening on K2-18 b, we’d be talking about an ocean teeming with such microbes—perhaps far denser than Earth’s oceans.

Possibly "Giant photosynthetic mats" or sulfuric "algae"

If there’s some landmass or floating structures, maybe the DMS producers are:

- Photosynthetic, sulfur-metabolizing analogues to cyanobacteria

- Living in dense floating colonies or mats like microbial reefs

- Using dimethylated sulfur compounds in their metabolism, and leaking DMS as waste or signaling molecules

===========

Of course there have been lots of ocean planets in sci-fi literature, but I'm most reminded of the "Pattern Juggler" Planet Ararat from Alastair Reynolds' "Revelation Space" series.

This is incredibly exciting news!

That means if we develop a way to make a space ship accelerate at 1g for a long period of time, you could go there in just 10 relativistic years.

Unfortunately, whilst science allows such a rocket, our engineering skills are far from being able to build one.

> Astronomers have found the 'most promising signs yet' of alien life on a planet beyond our Solar System

I've never understood how that stuff seems to capture the imagination more than actual science like this.

"Astronomers have found signs of alien life on a planet beyond our Solar System" means something completely different. Please @dang update or this looks like the Daily Mail.

It's an example of scientists acting irresponsibly. They might have found dimethyl sulfide but it can be produced abiotically.

Dimethyl sulfide (CH3SCH3, DMS) signatures were found in comet 67P/Churyumov-Gerasimenko and that is for sure not Times Square on Saturday night...: https://astrobiology.com/2025/02/on-the-abiotic-origin-of-di...

The planet looks more like a Neptune or Uranus than Earth type. They need to find multiple examples of different types of biomarkers, before contacting the press as they obviously did.

"Evidence for Abiotic Dimethyl Sulfide in Cometary Matter" - https://arxiv.org/abs/2410.08724

"On the abiotic origin of dimethyl sulfide: discovery of DMS in the Interstellar Medium" - https://arxiv.org/abs/2501.08892

Edit: I see title is now updated.

If life, even of a very primitive sort, were found, it would stand to reason that it had done so in the past and that other civilizations, possibly even many of them, had formed in our huge galaxy long ago, giving them time to develop enough to be detectable even to us, so then, where are they?

Then again of course, there are probably many, many known unknowns and unknown unknowns lurking amidst all of the above supposition.

If that time is a few hundred years, then very few happen to be functioning _now_ (in relativistic meaning) and very far away to have meaningful contact.

[1] https://www.goodreads.com/book/show/180506.If_the_Universe_I...

Of course, the weak link here is the assumption that these bio-markers can't be produced abiotically, which is a pretty big assumption. Our understanding of planetary science is still in its infancy. This is (thought to be) a hycean planet, a type of planet unknown to us until very recently(post-JWST, I believe?). And given that the solar system has no hycean planets, it's a class of planets which is fundamentally poorly studied, with pretty limited access to data. We can make models, and we can get some spectral data on the contents of their gaseous atmospheres. But we have no way of looking at their surface oceans. Thinking about what kind of chemistry might be going on there is mostly just an act of speculative modelling.

So the interesting question is, without new sources of data, can we determine whether these bio-markers are biological in origin? Not really. Not without a much better understanding of planetary science in general and hycean worlds in particular(of course, that's what this research is trying to do, and making progress at). As well as a deeper understanding of abiogenesis. I could imagine a working understanding of abiogenesis at least being able to eliminate some candidate planets, but even that assumes only one type of abiogenesis is possible, which is more or less unfounded. That is, unless the understanding includes some deep information theoretic/evolutionary perspective on abiogenesis which would probably have to include a completely unambiguous information theoretic and physical definition of what life even is. It is conceivable that such an understanding might provide very strong restrictions on what kinds of chemical systems are capable of abiogenesis, and that those restrictions could then be used to eliminate certain planets or even entire star systems from contention. And if these hycean worlds were eliminated that way, we'd know there must be some abiotic source of these "biomarkers", and knowing that, we would likely be able to figure out what it is. But ok, that's a lot of assumptions.

Maybe we get lucky, and some chemists stumble on a non-biotic chemical system that can produce these chmicals in concentrations that can be detected by JWST at a distance of hundreds of light years. Or, conversely, maybe chemists somehow manage to prove conclusively that biotic origin is the only possible source. I'm not a chemist or a microbiologist, so I have no idea what that would look like. It's probably well beyond our current understanding.

I guess what I'm rantingly saying is, while this result changes my credence that there's life on this planet about as much as is possible with current science and technology, it still barely changes it at all. Before it was maybe 0.5 + ε(habitable zone, liquid water), and it is now 0.5 + 2ε.

I guess something which could move the needle much more significantly, is if we found a large number(say 10) of chemically unrelated potential bio-markers in the atmosphere of a planet very similar to earth, in a very similar star system. Then, the assumption of the impossibility of abiotic sources would be much more plausible. I believe doing this type of research for earth-sized exoplanets with JWST is still quite borderline(please correct me if I'm wrong).

Having said all that, this result is still extremely exciting. For the first time, the field of exobiology has any contact with observational data from outside our solar system at all(besides mere astronomical data), and things will only improve from here. Future telescopes will be better at this type of observation, and our understanding of planetary science is evolving at an accelerating pace. I'm very excited to see where this research goes in the future.

- K2-18b

- detected dimethyl sulfide and dimethyl disulfide, false positive possibility is now very low

- "produced by marine-dwelling organisms on Earth", possibility they were produced by other processes (unrelated to life as we know it) not high but maybe unknown unknowns

- other factors like distance from the star are in favor of life & water

- previous studies detected methane and carbon dioxide

I do wonder why I was stupid enough to pay for a phone with a bigger screen as it just seems to mean more and bigger ads on screen at once and the same amount of content.

Morons, I'm surrounded by morons.