A lot of science papers are like “we found a hint of this thing, we need to do more research” and it’s reported as “ALIENS??!?”
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.
I think you have misread the abstract. The 'low statistical significance' was a [prior work](https://iopscience.iop.org/article/10.3847/2041-8213/acf577). This paper has increased the significance to 3-sigmas which is on the lower end but still quite significant.
Ugh, "alien life" is a reasonable title, IMO. I think the sensationalism is happening in your head, that you're imagining the Borg or little green men.
"...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..."
But in a concentration sufficient to be visible from this far away with spectroscopy?
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.
I'm not convinced about the methods. It looks a lot like p-hacking to me: they have a highly specific hypothesis drawn from a large universe—that dozen or so molecules (§3.1) in their infrared spectrum model they're fitting experimental data against. I don't buy the way they created that hypothesis. The put a handful of highly specific biosignature gases into it, things that were proposed by exobiology theory papers. One very specific hypothesis out of many, and a low likelihood one. And that's the hypothesis they get some borderline ~3σ signals for? Really?
edit: Any chance someone might have the charity to explain why my criticism is so far off-base, according to the HN consensus?
I'm going to double-down on my stubborn, unpopular opinion. This is my best attempt at explaining my criticism:
- 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
Don't be bothered by the down votes. HN consensus is not something worth pursuing. Your criticism is valid, it's just that it runs against what HN readers want to believe in this instance. Readers here like to think they're motivated by reason and intelligence and whatnot, but that is laughable - examples of logical fallacies and assertions of fact rocketing to the top comments abound. Overconfidence and readiness to accept bold claims is a more dangerous cultural dysfunction than the lack of seriousness and ubiquitous monetization that plagues other platforms.
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.
only know to be produced.....is a whoa bessy phrase,?¿ as in 70 years ago an undergraduate figured out that dimethyl sulfide was produced by living organisms and he asked his professor what else made it, and got shrug and "nothing else I know of" and everybody has been cutting and pasting since, OR, an international team spent years and millions working on the chemistry behind
dimethyl sufide in an epic known to all quest to determine it's origins.
Science does have an issue with cutting and pasting ancient mistakes, and then bieng exceptionaly reluctant to change and move forward,
not to mention that SETI, and the rest of "alien" research is most definitly tainted with public fantasy and entertainment industry influence, so
even with one of the notoriously oderiferous sulfide compounds present, I wont hold my breath
And the question is even more complex: not whether producing dimethyl sulfide "from scratch" without involving living organisms of the familiar sort is possible (of course it is), but what the hypothesis that each of the numerous possible ways to produce dimethyl sulfide happens naturally (or that alien lifeforms want a lot of it) implies about the environment of the exoplanet.
Firstly that is completely badass science. The idea that you can use observations to detect the chemical composition of an exoplanet millions of kilometres away is an absolute triumph of the work of thousands of people over hundreds of years. Really amazing and deeply humbling to me.
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 life is very common in the universe, then that is probably bad news for us. It means that civilizations should exist that are millions of years more technologically advanced than us; and should be leaving telltale signatures across the sky that we'd likely have detected by now. And the absence of those signs would be relatively strong evidence that life, while common, isn't long-lived. Suggesting that our demise too, will come before too long.
If, on the other hand, life is relatively rare, or we're the sole example, our future can't be statistically estimated that way.
It is quite plausible that life is abundant, but sentience is not. If we take Earth, it formed 4.5 billions years ago, conditions became suitable to support life like 4B years ago and first known signs of life are dated 3.7B years ago.
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.
You seem to be conflating life, multicellular life, and intelligent life. Life appears to have developed on Earth pretty quickly, multicellular life took a long time to appear, and we are only aware of one species that developed civilisation building capabilities.
Life might be very common, but intelligent life still be incrediblY rare.
Not to take away from you personally, but civilization as we understand it is our own cliche.
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.
Maybe technology development is not exponential but s-curve. And anything large scale is impossible. So outside some radio signals there would not be any grand things that could be observed.
This is where the discussion, as it always does, silently transitions from science into science fiction.
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.
Dark forest hypothesis explains this in a “dark” way. They exist but are smart enough to hide from hostile hunter/predator life forms. Meanwhile our dumbasses are blasting radio signals into space like a little kid trying to talk to every stranger they see.
If life is quite common, that still leaves an option that we are among the oldest of civilisations.
Besides, lack of comical presence doesn’t necessarily mean demise: maybe all face the problematic consequences of uncontrolled industrialisation and go solar punk?
I often wonder if the answer to the Fermi paradox isn't just as extremely banal as "turns out that interstellar exploration just isn't economically viable". I think it's entirely plausible that advanced economies are circular, and that within a circular economy, it's just extremely difficult to justify the massive expenditure of resources that it would take to become interstellar.
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.
Stars are abundant, long-lived, and go through cycles of life and death.
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.
no matter how advanced the civilization is, proxima centauri will always be 42 trillion kms away. Our civilization in current stage is not even close to 0.1% the speed of light but lets say your advanced civilization goes at 99% the speed of light, still doesnt change the fact they need 4.25 years approx to reach earth. Still doesnt change the fact that unless they have a 1 billion km wide telscope, they cannot reliably tell if earth has life or not. So basically you are asking them to take a shot at coming to the solar system on a 5 yr trip when they have no idea what is found here. Now extrapolate the numbers for the average 100 light year trip between 2 points on our galaxy and you ll quickly realize why we dont have aliens
Even if civilizations are relatively common (which, as others have pointed out, doesn't necessarily follow from life being common), the distances involved are really huge.
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.
I always thought that how far things are in the universe and the impossibility of faster than light travel were enough to explain why life might be abundant in the universe yet we never observed it.
The probability of advanced civilization is given the probability of life is quite low itself.
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.
We don't have to look to the stars to tell that humans have a horrible tendency to make the majority's life a struggle and constantly balancing on the verge of demise.
Maybe they just don't feel the need to blast their emissions all over the sky like some sort of a caveman.
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.
It's extremely likely that our demise will come before too long.
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."
The thing is we've only been around a tiny period of time, and given the size of the universe, it would have to be an amazingly tiny Goldilocks zone in time to actually notice us, let alone do anything about it.
Conversely, it should mean there would also be lots of civilisations millions of years technologically behind us. We're more likely to be an average civilisation than the least-developed
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.
Maybe there's some truth to Douglas Adams' writing - we are just insignificant enough that nobody cares. In the Star Trek series it's similar, they are interested to see how pre-warp civilisations develop, seeing them as quaint, but that's it.
> 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.
Possibly a more advanced civilization than us has long understood that it should not try to contact and bother other ones, but rather focus on their happiness where they are
There is no way civilizations make it past a certain point. It’s so completely obvious, just look at our world. In 2025 we are enabling a genocide while the masses don’t seem to care or even know about it.
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?
>It means that civilizations should exist that are millions of years more technologically advanced than us; and should be leaving telltale signatures across the sky that we'd likely have detected by now.
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.
Not sure how bad it could be given the hypothetical "millions of years more technologically advanced". They'd need to have a pretty good reason to care about us. Otherwise, we'd be so insignificant that it seems much more likely that whatever natural resources they'd want, would also be likely nearer and easier to obtain.
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
My prior is that life is not uncommon in the universe, multicellular eukaryotic type life less common and intelligent (whatever that means) life less common still.
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.
> It just seems so unlikely that we are somehow that special.
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).
> It just seems so unlikely that we are somehow that special.
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.
I never got this. Someone eventually wins the lottery. Someone eventually gets struck by lightning. How lucky a lucky person feels doesn’t influence the cold hard probabilities. So this feeling is mostly a delusion.
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.
Interestingly we can’t actually know that we are correct in our calculations of what a planet lightyears away has as its atmosphere because we will never be able to go there and make sure we are correct. It’s a calculation and nothing more. For all we know that planet may not even exist. That’s what’s mind blowing about astronomy. We really don’t have any way of proving anything about what we are observing. All we can say is we are observing. That’s the only thing science can offer us.
- 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.
> 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.
Erk. Couldn't you pick something from a less... apocalyptic universe? :)
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..."
This planet is 2.6x larger than Earth and has concentrations of DMS "thousands of times stronger than the levels on Earth".
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
And it isn’t actually signs of life. The first paragraph:
> 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.
Calling it simply an engineering issue is not properly conveying the ridiculousness of such a journey. For a small space ship of 1000 tons, this would take ten thousand times the current yearly energy consumption of mankind. So we'd need to figure out how to generate the energy and then store it on a space ship before even thinking about the engineering.
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.
Seriously, most if not all of humanity's issue is our current energy wall. I truly wish we can invest more in energy as compared to AI because I truly believe that most AI agents are roughly the same and now are benchmark maxxing and even google's gemini is really really cool. Maybe now training it even further has less reward for the cost?
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.
Our energy production grows exponentially. For a type I civilisation, producing that kind of energy would be possible. For a type II it would be trivial. In any case the timescales involved are measured in centuries.
If you can somehow make a ship capable of constant acceleration at 1G, and had enough shielding on it to protect it against the radiation, you can travel to any point in the observable universe, in a human lifetime.
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.
If you find that sort of thing interesting... I don't always know how seriously to take the things on this channel, but I discovered Fraser Cain not so long ago and find the ideas mentioned in the interviews to be fascinating, for example "Interstellar Travel Without Breaking Physics with Andrew Higgins" https://www.youtube.com/watch?v=SkGRVvA23qI (warning: it's over an hour)
JSWT... again the most formidable piece of equipment ever shot into outer space. That think is going to shake our understanding of the Universe to its foundations a couple times around
Last time bio signatures where found (I believe on Venus), there was a flurry of papers on arXiv a week later, which all explained the signature by abiotic processes. Of course, if you have more than one explanation, then you really don't have one explanation. So I fully expect the same thing to happen here, and perhaps sometime in a decade or so follow up observations will have ruled out all but one explanation, until then exciting but ultimately it's not over before the fat lady sings.
Readit News
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
[1] https://xkcd.com/882/
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.
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.
https://en.wikipedia.org/wiki/Great_Filter
> 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.
Dead Comment
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? :)
https://en.wikipedia.org/wiki/Wang's_Carpets
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
Deleted Comment
> Astronomers have found the 'most promising signs yet' of alien life on a planet beyond our Solar System