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.
I understand why this is the case but I think it can lead to a loss in trust in science when the reporting jumps to conclusions that aren’t supported by the research itself.
In this case the abstract is far more grounded. In particular,
> The observations also provided a tentative hint of dimethyl sulfide (DMS), a possible biosignature gas, but the inference was of low statistical significance.
> We find that the spectrum cannot be explained by most molecules predicted for K2-18 b, with the exception of DMS and dimethyl disulfide (DMDS), also a potential biosignature gas.
> More observations are needed to increase the robustness of the findings and resolve the degeneracy between DMS and DMDS. The results also highlight the need for additional experimental and theoretical work to determine accurate cross sections of important biosignature gases and identify potential abiotic sources.
Comets with DMS: https://arxiv.org/abs/2410.08724
And the interstellar medium.
"On the abiotic origin of dimethyl sulfide: discovery of DMS in the Interstellar Medium" - https://arxiv.org/abs/2501.08892
"...Although the chemistry of DMS beyond Earth is yet to be fully disclosed, this discovery provides conclusive observational evidence on its efficient abiotic production in the interstellar medium, casting doubts about using DMS as a reliable biomarker in exoplanet science..."
It's not definitive but it is suggestive. A detection would require multiple pieces of evidence. We should be building specialized space telescopes designed specifically for the characterization of extrasolar planet atmospheres, since that's the best way we have to potentially detect something.
edit: Any chance someone might have the charity to explain why my criticism is so far off-base, according to the HN consensus?
- Alien metabolites are a low-prior probability hypothesis. Dimethyl sulfide is a long-postulated biosignature with no natural source, so, it's low-prior
- The paper's model fits Webb data—a handful of photons—against no more than 20 candidate molecules, combined across all of their atmospheric models. Many of those gases are drawn from that low-prior "alien metabolite" class
- There's a much larger class of strongly infrared-absorbing gases, that can naturally occur in planetary atmospheres. Beyond those included in the 20 candidates. These (should!) have higher prior probability of occurring in Webb data than alien metabolites. (This class is so large and complicated, there's major spectral features in our own solar system's gas planets we haven't characterized yet)
- If you were to fit Webb data against that expanded class, those alternative hypotheses, you'd get a large number of 3-sigma detections by pure chance.
- The Webb data is too weak to distinguish between these. With only a few bits of information, you can distinguish between only a small set of alternative hypotheses
- This paper elevates the alien-metabolite hypothesis very highly, and that is why when it has a spurious statistical detection, it happens to be an alien metabolite detection. Because that hypothesis is overrepresented in their model
- The root problem is that since there's only a trickle of real data from this exoplanet, from Webb, it's unlikely one can infer anything super interesting from those few bits
In any case this study will likely go on the pile of papers judged by time to be an overreach of conclusions and a dead end.
(if you want a cleaner interface)
https://en.wikipedia.org/wiki/Dimethyl_sulfide#Industrial_pr...
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.
If, on the other hand, life is relatively rare, or we're the sole example, our future can't be statistically estimated that way.
Now, in just .5B years Earth would likely become uninhabitable due to Sun becoming a red giant. In other words, on Earth life spent 90% of its total available time before sentience emerged. So on one side life is constrained simply by time, and on the other, sentience might not be necessary for organisms to thrive: crocodiles are doing just fine without one for hundreds of millions of years. To think of it, it is only needed for those who can't adapt to the environment without it, so humans really might be very special, indeed.
Life might be very common, but intelligent life still be incrediblY rare.
Organisms developed on different planets could absolutely have a different view on life and society in general. Even on earth we have highly intelligent and physically capable organisms that care naught for your conceptions of how groups should function together. There are even organisms that seem to have no intersection with our set of interests that are way more successful in terms of populating earth and invading space. Putting our understanding and interests at some panacea is just hubris.
We know absolutely nothing about extraterrestrial life. We can only project our own singular experience onto the rest of the universe. We only have one data point. There is no scientifically acceptable method of induction from a single data point. The possibilities are endless, and are capacity to narrow them down becomes warped by our love of stories and the kinds of art that we have created about extraterrestial life, all of which are in one way or another metaphors for the human condition.
There is nothing wrong with saying, "Anything is possible and we have 0 evidence allowing us to narrow it down." It isn't fun, but it's true.
Besides, lack of comical presence doesn’t necessarily mean demise: maybe all face the problematic consequences of uncontrolled industrialisation and go solar punk?
I mean, think about how many stars had to align to catalyze our first steps on the moon. Now, 53 years later, we're just starting to put serious effort into going back -- not because there's any market reason to do so, but because (once again) there's political pressure for it. Which would suggest that the best case scenario for the current exploration efforts are something along the lines of what we already see in Antarctica: a well-staffed scientific presence that does really cool/valuable work, but nothing remotely approaching even a single major city in terms of human presense.
It seems to me that one of the unwritten priors to the Fermi paradox (at least in popular discourse) is that technology is the only prerequisite to expanding a civilization; in other words, if you have the technology, then interstellar expansion is only a matter of time, and that all civilizations will inevitably eventually develop the technology. And that... seems like a pretty big assumption, if human history is any indication.
> And the absence of those signs would be relatively strong evidence that life, while common, isn't long-lived.
Now look at the night sky. The chance that you eye will detect a star at any given patch of sky that is roughly the size of a star, is nearly nill. That is not bad news for those who wish to see that stars continue to exist - it is a feature of the size, vastness, and expansion of the universe. Same for life, presumably.
We have some ideas for crossing huge distances, but none of them are really practical. There are ideas for accelerating tiny probes with light sails, but when we manage to send them somewhere with 90% of the speed of light, we have no way to decelerate them again in a controlled fashion.
What I want to say is: there's good reason to think that doing anything over 200 light years or so is just infeasible.
For the overwhelming majority of time life has existed on earth only a minuscule part of it involved civilization. And an even more minuscule part of it involved technology that has a small chance to send a coherent signal to another star.
Our future is easily estimated by the hardness of traveling through space and the demise of our sun. Probability points to the end humanity by way of the death of our star. We are statistically most likely to end.
Our own technological signature is coming to form a very thin shell. Once we switch fully to fiber optics, lasers, and beamformers, there won't be any aliens learning English from listening in on our TV transmissions anymore. Radio broadcasting was cool, but also horribly wasteful.
It's probably incorrect to assume that more technologically advanced civilizations would be louder.
The problem is that "before too long" is on a universal timescale, not a human timescale.
Humanity could exist for a million times longer than it already has, expand to other planets in our solar system and even to another solar system or two, be wiped out completely, and on the appropriate timescale we were absolutely "short lived."
That is, if there is supposedly one civilisation with clear advance in technology, it could just as well be humanity.
> should be leaving telltale signatures across the sky that we'd likely have detected by now
I'm not sure the second follows from the first. What if they're hiding?
But in the grand scheme of things, even its "bad news" just ONE datapoint of life elsewhere is at least something to start working with.
Apart from the Sun, the nearest star to us is four light-years away. I'm not loosing my sleep on the thought of being "discovered" by anyone over there.
> Far out in the uncharted backwaters of the unfashionable end of the western spiral arm of the Galaxy lies a small unregarded yellow sun. Orbiting this at a distance of roughly ninety-two million miles is an utterly insignificant little blue green planet whose ape-descended life forms are so amazingly primitive that they still think digital watches are a pretty neat idea.
If dark forest theory is right, alien civilizations may stay undetectable by hiding biological signatures of their worlds.
You think the people that are having these types of atrocities committed against them would think twice about ending civilization as revenge if given the power? What do you think is going to happen with AI?
If we can’t stop a genocide, why would you think we can stop civilization ending?
Or they've reached their technological plateau millions of years ago. Like we did 50 years ago.
>And the absence of those signs would be relatively strong evidence that life, while common, isn't long-lived.
We know for a fact that life have existed on Earth for >2 billion years.
War-mongering, and otherwise zero-sum mentality shouldn't make all sense if they have the technology to actually reach us. [3-body spoiler warning] Kinda like in the Three Body Problem. It was kinda silly how advanced the Trisolarian were, while still bothering traveling to earth, rather than approach the problem in any number of more obvious ways
Yes, millions, but that's a major understatement.
It's 124 light years away. Which is around a million billion km away. (a.k.a quadrillion)
It's just so damn far.
If the closest prokaryotic type life is 100 light year away then the the closest intelligent life might is pretty far away.
I base this on almost nothing - other then the time it took for prokaryotic and eukaryotic life to emerge on Earth; which to my mind is surprisingly quick for the former an weirdly long for the later.
Not millions, not even billions. 124 light years is about 10¹⁵ kilometers, or a million billion kilometers.
But the probability of developing a highly developed civilization can be much, much smaller than 1 / number of planets in the universe.
Our ability to think about those matters is conditional on emergence of intelligent life. That is our observation of ourselves is compatible with any probability of emergence of intelligent life (including almost never that is p=0).
That prior is formed by sci-fi media, not science.
> I always felt it overwhelmingly likely that it developed elsewhere too
"Life" is an information complexity characteristic. We know that information complexity is not uniformly distributed in the universe, and in fact the vast majority of the universe is extremely information-poor. Logically from the scientific data you'd assume that "life" in the universe also has a very lopsided distribution.
And frankly we don’t know how probable or improbable it is for life to form because we aren’t actually clear how it formed in the first place. The fact that the event has not and can’t (so far) be reproduced by us means that it is already highly likely to an extremely low probability event.
The question is how low? Low enough such that there is another planet that has it within 124 light years. I actually don’t think so.
I think the probability of finding a planet that has biosignatures of life but doesn’t have any life at all is a higher probability then actually finding planets that actually have life. No matter what you think the likelihood of finding life is, I think most people agree that the above should be true.
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!
Erk. Couldn't you pick something from a less... apocalyptic universe? :)
Dead Comets have DMS: https://arxiv.org/abs/2410.08724
And the interstellar medium.... "On the abiotic origin of dimethyl sulfide: discovery of DMS in the Interstellar Medium" - https://arxiv.org/abs/2501.08892
"...Although the chemistry of DMS beyond Earth is yet to be fully disclosed, this discovery provides conclusive observational evidence on its efficient abiotic production in the interstellar medium, casting doubts about using DMS as a reliable biomarker in exoplanet science..."
It would take a lot of cometary impacts to seed the entire ocean with that much.
From the paper [1]:
> Therefore, sustaining DMS and/or DMDS at over 10–1000 ppm concentrations in a steady state in the atmosphere of K2-18 b would be implausible without a significant biogenic flux. Moreover, the abiotic photochemical production of DMS in the above experiments requires an even greater abundance of H2S as the ultimate source of sulfur—a molecule that we do not detect
[1] https://iopscience.iop.org/article/10.3847/2041-8213/adc1c8/...
- Promising signs of alien life found on a planet beyond our Solar System
- Astronomers have found promising signs of alien life on an extrasolar planet
> Astronomers say they've found "the most promising signs yet" of chemicals on a planet beyond our Solar System that could indicate the presence of life on its surface.
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.
And that's ignoring the mass of the fuel. The classical rocket equation has the mass going exponentially with the velocity, which makes this endeavor even more mind bogglingly ridiculous. We'd actually need 2 million years worth of our current yearly energy consumption.
It's fun to think about, but being clear about the challenges puts quite the damper on it.
I truly wish energy could be a solved issue. I think clean energy can be great of two types, solar and nuclear, though nuclear can require a lot of expertise to build it once and operation costs, (I am not talking about the risk of nuclear reactor exploding since its just a fraction of current risks)
I personally prefer solar as its way more flexible though I am okay with nuclear as well
Mainly the issue in solar is of battery, if I understand it correctly. So We just need to really focus as a civilization to the humble battery.
This made me think that F = G((m1m2)/rr) is good enough to go to the Moon, but not good enough to give us GPS.
Maybe some discovery could help us build antimatter drives one day.
If you just keep accelerating and left as a 20 year old, you'd be in your 50s when you saw the final stars born and die in 100 trillion (earth) years time.
That's how crazy relativity and torchships are
> 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.
A few years ago some researchers at the Future of Humanity institute explored what happens if you take distributions into account. It turns out that this makes a surprising difference and results in a substantial probability of no other intelligent life. No need for speculation about great filters, predatory civilisations, etc... . The paper is freely available on ArXiv: https://arxiv.org/pdf/1806.02404
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.
That being said, I agree. I read in a similar thread yesterday someone confused how this would be bad news rather than good news—that there are many other intelligent species indicates that such a filter either doesn't exist or is very easy to pass. But, like your point does, I think it's important to recognize that such a "good news" position is predicated on the notion that we as a species are already past the Great Filter, rather than that we're still behind it and the others are ahead.
The older I get and the more I appreciate Just How Lucky we are to exist at all on our planet here, the more I favour the above thinking.
Failing that, you’d need thousands of optical interferometers larger than the Hubble spread across a distance wider than the Earth.
My math is below.
Note: I'm not an astronomer.
----
The angular resolution limit for a telescope is roughly the wavelength of the light it's sensitive to over the diameter.
If we want to sense things 10m across, with light at the shorter end of the visible spectrum (400 nm), we'd need a telescope with a diameter of about 1/4th of an AU (i.e. the distance from the earth to the sun), around 40 million kilometers.
More practically we could use a telescope array with this diameter, which could conveniently be in lot of orbits about 1 AU out. But the area is still a problem: assuming this 100m^2 object is as bright as it would be on earth under midday sun, it's going to be reflecting around 100 kw of energy. One of these photons has an energy of around 3 eV, so we're getting 2e23 of them a second. Unfortunately these spread out over a sphere with a surface area of 1e31 km^2 by the time they reach earth, meaning we see one every second if we have a telescope array with an area of 50 million square km.
Ok, so let's go kind of sci-fi and say we can build a 30 km diameter space telescope. It would be impressive (and unprecedented) but since it's floating in space and could be made of thin material you might be able to imagine it with today's technology and a lot of coordination. That gets us around 1000 square km! Now we just do it 50,000 more times.
Great, now we have 1 Hz of photons coming from each 100 m^2 patch of Alien Manhattan! I'm sure in the process of building 50k mega-projects we'll figure out a way to filter out the noise, and with a few years of integration we'll have a nice snapshot!
[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.
Headline writing is the art of taking something that a journalist has thought about in detail and carefully crafted and making it into something that someone with low to zero interest in the topic might want to read.
Having done both, I got annoyed when headlines misrepresented what I’d written, and journalists got annoyed when I took their perfectly crafted but pedestrian articles and gave them punchy headlines in a desperate attempt to get people to read them...
- 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
It's not that low, unfortunately. From the article:
> They say their observations have reached the ‘three-sigma’ level of statistical significance. This means there's a 0.3% probability the detection occurred by chance. And to reach the accepted level that would mean scientific discovery, observations would have to meet the five-sigma threshold. In other words, there would need to be below a 0.00006% probability they occurred by chance.
No, it means we will soon discover how these compounds form naturally. Would love to be wrong, of course.
From the source paper. It is a very important result but not definitive, false positive is still possible as well as us finding a new way in which DMS can form without a biological process.
Still freaking exciting and fantastic scientific achievement. JWST is already bearing incredible fruits.
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.
That would upend a lot of religious teachings which say we're unique and that the world was given to us, as the unique creations of a creator, to consume for our own benefit.
It seems like there could be many practical benefits to showing that's not true. Hey, maybe the concept of infinite exponential growth is a bad idea. Maybe we shouldn't burn the skies and boil the seas. Maybe we should be nice to other intelligent animals, at the very least.