“Most promising signs yet” of alien life on a planet beyond our Solar System
358 comments
·April 17, 2025weberer
teamonkey
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.
x-yl
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.
teamonkey
Yes you’re right, thanks.
netsharc
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.
teamonkey
I don’t think it’s an unreasonable title, but it’s also not accurate. The paper states quite clearly that they’ve found reasonable evidence of a known biomarker. They don’t know enough to say whether it’s from a biological or some abiotic process (but speculate a little about what that might mean and what evidence they would need to take that further).
That’s quite a different tone from the article, and I think the comments here and elsewhere online reflect that.
rkagerer
More like big green algae?
weard_beard
I'm imagining some new kind of volcanism and one less way to detect life. Or, as my wife put it, "Ah, rock babies again."
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scrivna
The scientists are also saying ALIENS! but they're covering their backs, they want their research to make headlines too
perihelions
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?
perihelions
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
fc417fc802
False positives are acceptable if the goal is to generate leads to follow up on. If the detection was due to chance then it won't hold up to further measurement. There's few enough hits that we don't need to worry about being more rigorous (and potentially introducing false negatives) at an earlier stage.
Given the context, a publication seems appropriate. A high profile similar example is when neutrinos supposedly broke the light speed barrier. If the mass media misrepresents things that's hardly the fault of the scientists.
moefh
So if I understand correctly, this[1] is what they did?
spacemark
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.
null
dguest
also: https://arxiv.org/abs/2504.12267
(if you want a cleaner interface)
belter
> which is only known to be produced by living organisms.
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..."
api
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.
stogot
Thank you for posting this. Really balances out all the conjecture.
metalman
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
pinkmuffinere
Ya, it’s a bit less exciting, but I bet we’re about to learn many new ways to produce dimethyl sulfide outside of a living organism
allan_s
actually we know how to produce it without involving living organism
https://en.wikipedia.org/wiki/Dimethyl_sulfide#Industrial_pr...
poulpy123
actually a living organism is needed to produce it this way
null
HelloNurse
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.
seanhunter
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.
ta8645
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.
Andrew_nenakhov
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.
energy123
This is now much less plausible. Intelligence, like eyesight, is believed to be a result of convergent evolution[0].
[0] https://www.quantamagazine.org/intelligence-evolved-at-least...
dtech
The sun has about 5B years more to go before it turns into a red giant, not 0.5B years...
ninjagoo
You may want to update your view that non-human animals lack sentience. [1]
[1] https://pmc.ncbi.nlm.nih.gov/articles/PMC4494450/
If you're referring to technology/civilization-building capabilities, that is a different matter.
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antisthenes
> in just .5B years Earth would likely become uninhabitable due to Sun becoming a red giant
The Sun will not become a red giant in 500 million years.
uwagar
why isnt a crocodile sentient?
ImHereToVote
The fact that sharks have existed for 450 million years fairly unchanged fills me with hope. Our existence might be a huge fluke even if eukaryotic life can happen once and again in the Universe.
thenewem
[dead]
aardvark179
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.
martopix
It depends what you mean by "civilization building". I think we gloss over that a bit too much. We're not the largest population, not the largest total mass, not the only one that builds large structures. We're the only one that sent stuff outside of Earth, yes, and a few other things. But discussing the definition is itself interesting
falcor84
Indeed. We might finally start getting some real estimates for those factors in the Drake Equation.
goognighz
Intelligent life most like arose from the extinction level events that wiped out less intelligent super predators. This gave those who are far weaker but with higher brain capacity the chance to express their genetic variations.
trhway
>we are only aware of one species that developed civilization building capabilities.
well, the first one just doesn't leave any chance for any other one.
>Life might be very common, but intelligent life still be incrediblY rare.
the time period between big ape and nuclear bomb is extremely short - few millions years. In a hundred or a thousand - doesn't really matter - years we'll be an interstellar species or may be we destroy ourselves by Covid-2319. The point is that complexity develops exponentially and tremendous changes are happening in an extremely a short period of time - i.e. if life has 4B years to develop when it most probably has 4.01B years to develop civilization.
Ekaros
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.
throw4847285
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.
goognighz
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.
cmsj
Dark Forest depends on the presumption that interstellar travel is worth engaging in (ie it's possible to do faster than light), and that spectacularly devastating weapons are possible. So far we have no reason to believe that either of those assumptions is smart.
Intralexical
It's also largely bunk. More a story than a hypothesis, really. Game theory shows cooperation beats aggression on a long enough timescale. Politics shows alliances and MAD deters first strike. Even actual "dark forests" are full of animals that have bright colors and make loud noises.
nbadg
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.
cmsj
The thinking generally would be that while it might take political pressure to initially begin leaving the home planet, once politics has unlocked that capability, commerce will take over.
If we were to begin mining the solar system, it unlocks vast pools of resources that would really change things.
That said, interstellar travel is still a pipe dream because of the time involved. Without finding a cheat code for physics, it may well be that intelligent life is always trapped in its home system and has to live and die within the limitations of stellar evolution.
jimbokun
53 years is instantaneous on cosmological time scales.
lordnacho
I thought it might just be the rocket equation. Bigger planet = very little of the rocket is payload.
If most planets are bigger than Earth, then most civilizations will be like "muh we can do it but what's the point?" and they'll be content with just having a few science experiments in orbit, and that's all.
perlgeek
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.
volemo
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?
bufferoverflow
> millions of kilometres away
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.
hackeraccount
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.
Someone
> an exoplanet millions of kilometres away
Not millions, not even billions. 124 light years is about 10¹⁵ kilometers, or a million billion kilometers.
tgv
> given how incredibly unfathomably vast the universe is ... we ...
But the probability of developing a highly developed civilization can be much, much smaller than 1 / number of planets in the universe.
layer8
Even the probability of developing any life at all might be. We simply have no idea how rare it could be.
red75prime
> 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).
_joel
Trillions of kilometres away!
qudat
The universe is so big that even very rare anomalies are common. There is life outside of earth, that is all but confirmed.
davedx
Some speculation
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!
rsynnott
> 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? :)
mr_toad
The idea of floating mats of life reminded me more of Wang’s Carpets.
nonethewiser
Or, megafauna. Some Leviathan in the deep.
belter
Not that exciting until they find other different biomarkers.
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..."
davedx
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
[1] https://iopscience.iop.org/article/10.3847/2041-8213/adc1c8/...
sph
A bit clickbaity of OP to skip the operative word ‘promising’ signs of life.
isolli
To be fair, the original title goes above HN's character limit, but the omission is almost worthy of a flag, in my opinion...
shrx
Better alternatives:
- 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
bathtub365
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.
quaintdev
This should be higher up
londons_explore
This is happening 124 light years away from earth.
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.
mr_mitm
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.
Imustaskforhelp
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.
londons_explore
I don't think there will ever be a time when energy is a 'solved' problem.
The more energy you have access to, the more uses you'll find for energy, and therefore the more energy you'll want to have access to.
hidroto
It does not have to be a chemical rocket. https://en.wikipedia.org/wiki/Breakthrough_Starshot
mr_mitm
I wasn't talking about chemicals.
My computation assumed an antimatter engine. Any drive is bound by conservation of energy and momentum.
I guess you wanted to object to an propulsion drive. Sure, you can do some fly by maneuvers or use earth bound laser propulsion, but I'm not convinced that it will put a dent in it for a regular space ship.
Also, the starshot concept won't help you with slowing down. I was assuming you actually wanted to exit the spaceship upon arrival.
rsynnott
While still ludicrously optimistic, there's a vast gulf between "20% the speed of light" and "constant 1g acceleration for 10 years", energy-wise.
tiborsaas
> The classical rocket equation has the mass going exponentially with the velocity
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.
mr_toad
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.
mr_mitm
That's mainly because our population roughly grew exponentially lately. That won't continue.
Energy production is not something self-amplifying like a population of rabbits, so there is no fundamental reason why energy production per capita should grow indefinitely.
But sure, how you would turn sunshine into antimatter at astronomical rates might be an interesting problem to think about. But my original point that basically dismissing this as an engineering issue is a bit dishonest still stands.
ta1243
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.
That's how crazy relativity and torchships are
hackeraccount
That is the most believable but bizarre thing I've read today. Maybe this week. It's probably tied for the month.
lucb1e
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)
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DiogenesKynikos
It would still be >124 years from the perspective of people on Earth, though.
eecc
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
yk
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.
Xiol32
Editorialized headline. Article is:
> Astronomers have found the 'most promising signs yet' of alien life on a planet beyond our Solar System
skc
Every once in a while for a good chuckle I visit r/UFOs or r/aliens where people go gaga over blurry videos of balloons in the sky.
I've never understood how that stuff seems to capture the imagination more than actual science like this.
throwaway743
User5 on youtube.
tsoukase
Unfortunately we cannot answer fundamental questions about ET life. Like, how long an advanced civilization lasts, which is capable of manipulating radio signals. Because we can since the last 100 years and we don't know how long we will be able.
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.
southernplaces7
It would be somewhat worrisome to actually find signs of primitive extraterrestrial life because of the Fermi Paradox. Given the age of the universe, and how long it took both complex life to develop on earth and for a creature such as us to emerge from that, finding life elsewhere would beg a return to Fermi's question of "Where is everyone?" implying that something comes along and causes evolving civilizations to be exterminated before they ever show signs to their presence to the wider galaxy.
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.
rossant
Maybe sufficiently advanced civilizations just stay under the radar to avoid being exterminated by others.
cdplayer96
Here's to hoping we can learn more about this. But I feel like this could be caused by us simply not understanding how dimethyl sulfide can be formed on other planets, especially ones over 100 lightyears away..
Here's the primary source
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.