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Astronomers Detect a Possible Signature of Life on a Distant Planet

168 points by julienchastang 2y ago

pizza 2y ago
https://archive.is/uvKw9 https://archive.is/uvKw9
- dguest 2y ago
  original source: https://arxiv.org/abs/2504.12267 https://arxiv.org/abs/2504.12267
John7878781 2y ago
This is unsettling. If we are not the only intelligent beings in the universe, it adds credence to the idea of a "great filter." https://en.wikipedia.org/wiki/Great_Filter https://en.wikipedia.org/wiki/Great_Filter
- Teever 2y ago
  I think it would be cool if the conversation on this post could go more into detail about hycean planets instead of the pretty standard and played out one about the Fermi Paradox and Great Filters. That stuff is interesting but I'd rather hear experts talk about less talked about stuff like hycean planets and detection methods of them and other bodies that are that size.
  - adriand 2y ago
    Well, it’s better than what I came here to do, which was to leave a snarky joke along the lines of, “Sounds like we just found another place we need to tariff.” But in the interest of keeping the discussion productive, I’ll refrain from doing that.
  - tagami 2y ago
    what happens if you have lightning on a hycean planet?
    - DrFalkyn 2y ago
      Unless there’s enough oxygen, it shouldn’t be a problem
- kulahan 2y ago
  My greatest desire is to know why we don’t see any galaxy-sized colonies. A great filter would certainly be a fascinating response!
  - taberiand 2y ago
    My guess is any civilisation advanced enough to populate their galaxy knows that it's inherently pointless. Unchecked growth is the impetus of lesser lifeforms
  - Shekelphile 2y ago
    Life is probably extinguished by machine intelligence before it gets the chance to.
    - kulahan 2y ago
      ALL of it? EVERY time? There should be some signs somewhere.
  - vikramkr 2y ago
    I mean, communication is insanely hard. If there's no way around the speed of light, life would still likely (slowly) expand across the stars, but it would be functionally impossible to continue to act as a unified civilization or colony across even a couple solar systems much less a whole galaxy
  - frogeyedpeas 2y ago
    I find myself believing less in the great filter. My comment here: https://news.ycombinator.com/item?id=43712645 https://news.ycombinator.com/item?id=43712645 explains why.
  - awb 2y ago
    One thing that I haven’t seen discussed much in terms of galactic colonization is genetic drift, speciation and communication. I believe there are simulations theorizing that galaxies can be thoroughly explored in 10M - 100M years. But how would those species even communicate their discoveries across a 100k LY galaxy? The delay would render data inaccurate by the time it arrives. It seems challenging to persist in a common purpose for millions of years across vast distances. And would they even be the same species on those timescales and distances? On Earth isolation leads to some unique physical and cultural evolutions.
- credit_guy 2y ago
  The Great Filter hypothesis is based on an analogy with the European conquest of the globe in the 19th century. Little by little all the white spots on the map were first explored, then annexed. The (unspoken) parallel is that an advanced civilization would explore and conquer the entire galaxy. But even if a civilization could achieve interstellar travel capabilities, it is entirely possible that they colonize, let's say, only 80% of the galaxy, not 100%. Or maybe only 50% or 10%. If our solar system is in the complement of their zone, how would we know they are out there. How would we know there are aliens around Alpha Centauri, let's say. They could be busy living their lives, broadcasting in all the regions of the radio spectrum with abandon, maybe even nuking each other from time to time. And we would just hear absolute silence. The distances between stars are just so mind-bogglingly huge.
  - api 2y ago
    Infinite expansionism is just one of a whole tower of assumptions that underlie the Fermi paradox. It’s a good thought experiment and does rule out certain scenarios with ET life but beyond that it’s a speculation. The main scenario it rules out is one where intelligent ET life is common and we are late to the party. I feel like both those things can’t be true or we would see evidence. I do find it fun to think about because it unfolds under scrutiny into such a vast tree of possibilities. But that same huge tree of possibilities makes it hard to say much. One of my favorite wild speculations is that there is somewhere more interesting to go than space, and more accessible, and eventually whatever that is gets found before starships get built. What could that be? A traversable multiverse maybe? That belongs to a subset of scenarios I call “positive great filters.” That’s where the great filter is a big success that renders space flight unimportant or uninteresting but does not result in extinction. What about hyper-miniaturization. Maybe you can have something the size and scope of a galactic civilization without leaving home by folding your minds and everything else up into quantum states or hidden extra dimensions. Think a civilization of “sophons” (three body problem reference) with trillions upon trillions of minds occupying a few square meters of space and consuming a few hundred watts. Yet another is some kind of remote sensing that lets you explore without physically moving, like a real equivalent to remote viewing. There’s a sci-fi novel called Blind Lake about this. Combine with miniaturized super efficient information processing and you could have superintelligences that explore everywhere and learn everything without going anywhere. Lots of speculations and possibilities if you allow for the fact that we’ve only been doing science seriously for about 150 years and surely do not know everything.
- fsckboy 2y ago
  i don't see the connection. being the only intelligent beings in the universe (at the moment) lends credence to the great filter, and finding large numbers of other inhabited planets eliminates it, and in between why wouldn't it monotonically decrease?
  - John7878781 2y ago
    the idea is: if we do find life elsewhere, especially basic life, it suggests that getting to that stage isn't super rare. which means the great filter probably isn't behind us (like abiogenesis or single-cell to multi-cell jump), but possibly ahead of us - maybe in surviving long-term, avoiding self-destruction, spreading beyond one planet, etc. finding life doesn't eliminate the great filter - it raises the unsettling possibility that we haven't hit it yet.
    - chatmasta 2y ago
      The argument you're referencing is usually about finding life on a nearby planet, e.g. on Mars. Nick Bostrom has articulated [0] this argument. But finding life on a distant planet lacks the same statistical power for instilling this existential fear. [0] https://nickbostrom.com/papers/where-are-they/ https://nickbostrom.com/papers/where-are-they/
      - John7878781 2y ago
        Of course. It'd be much worse if we found life on Mars than on a distant planet. In either case, the chances of humanity being ahead of the "great filter" are greatly reduced.
        deleted 2y ago
        [deleted]
        OhioMan2943 2y ago
        That's not taking into account that each solar system has its own set of circumstances, it could just be panspermia between earth and mars.
smitty1e 2y ago
> While inspecting K2-18b, Dr. Madhusudhan and his colleagues discovered it had many of the molecules they had predicted a Hycean planet would possess. In 2023, they reported they had also detected faint hints of another molecule, and one of huge potential importance: dimethyl sulfide, which is made of sulfur, carbon, and hydrogen. On Earth, the only known source of dimethyl sulfide is life. --- Intriguing.
- Loughla 2y ago
  It's absolutely amazing that we can even figure out molecules at that distance. I'm sure it's accurate but it's so sciency to me that it might as well be made up entirely. I can't begin to fathom that process.
  - jf 2y ago
    If you haven't already, I recommend learning about Astronomical spectroscopy, which helped me get a toehold on how this stuff works: https://en.wikipedia.org/wiki/Astronomical_spectroscopy https://en.wikipedia.org/wiki/Astronomical_spectroscopy
  - croemer 2y ago
    I haven't read the paper but it's likely just some fancy spectroscopy: looking at the wavelengths that are absorbed. Each molecule has a characteristic pattern.
  - hnuser123456 2y ago
    It's only possible if the planet passes directly between its star and Earth, so we can see sunlight passing through its atmosphere, and detect which specific frequencies of light got absorbed.
  - jcranmer 2y ago
    > I can't begin to fathom that process. It's basically "look at far away object with a fancy pair of sunglasses." Because of quantum mechanical reasons, molecules can only absorb and emit light with very particular energy levels (which correspond to frequency/wavelength). So point your camera at an exoplanet and carefully record the amount of the light you see at different wavelengths. My guess is that it's based on IR spectroscopy, since there's a nice region of that spectra where you can "fingerprint" a molecule based on the peaks in absorption in that region (it's literally called the "fingerprint region").
philipkglass 2y ago
This is about dimethyl sulfide in the atmosphere of exoplanet K2-18b: https://en.wikipedia.org/wiki/K2-18b https://en.wikipedia.org/wiki/K2-18b The NYT article reports a new study in The Astrophysical Journal and links to it, but the DOI is currently not found: https://dx.doi.org/10.3847/2041-8213/adc1c8 https://dx.doi.org/10.3847/2041-8213/adc1c8 I also don't see the article yet under their Latest Articles: https://iopscience.iop.org/journal/0004-637X https://iopscience.iop.org/journal/0004-637X Here are recent articles about K2-18b from Google Scholar: https://scholar.google.com/scholar?hl=en&as_sdt=0,48&q=%22K2-18b%22&scisbd=1 https://scholar.google.com/scholar?hl=en&as_sdt=0,48&q=%22K2...
- IanCal 2y ago
  Those DOIs have a different prefix, I think it might be in Letters https://iopscience.iop.org/journal/2041-8205 https://iopscience.iop.org/journal/2041-8205 It's still not out yet though. Also journals are often rather tardy or just straight up don't register the doi at all and still put it on their site, but maybe this is an embargo thing. edit - is it possibly this after publishing? https://arxiv.org/abs/2501.18477 https://arxiv.org/abs/2501.18477
  - philipkglass 2y ago
    Good point about the DOI prefix. I don't think it's that arXiv article, though, since it says there is no statistically significant evidence for carbon dioxide or dimethyl sulfide. This NYT article (and presumably whatever journal article it's based upon) reports high levels of dimethyl sulfide.
    - IanCal 2y ago
      You're right, different authors too. https://www.eurekalert.org/multimedia/1069012 https://www.eurekalert.org/multimedia/1069012 uses the DOI in the article and says it's from > A. Smith, N. Madhusudhan (University of Cambridge) Here's another article on it https://www.bbc.co.uk/news/articles/c39jj9vkr34o https://www.bbc.co.uk/news/articles/c39jj9vkr34o I think this is still under embargo, or hasn't quite been released. There's going to be some time required for visuals like on the bbc site.
belinder 2y ago
If life evolves on a planet with only oceans, no surface, imagine how much longer it would take to discover rockets that can leave the planet. Like if there was no surface on earth, and only fish, there must be some very significant reason for advanced fish to even want to leave the water, let alone the atmosphere
- gtirloni 2y ago
  How high are you? :D
- slg 2y ago
  That seems like a very landbased mindset. From a high level, what is an ocean but a thick atmosphere? I could even imagine an underwater culture would be quicker to explore because they would surely discover the surface of the ocean quicker than we discovered the concept of the atmosphere and that innately leads to the questions of whether the atmosphere has a "surface" and what is above it.
  - Jedd 2y ago
    > From a high level, what is an ocean but a thick atmosphere? "Now you have two atmospheres."
    - upghost 2y ago
      Ha. Ha ha. Nice.
  - fhdkweig 2y ago
    There is also the issue that they will likely never discover fire and thus chemistry and metallurgy.
    - johntitorjr 2y ago
      [dead]
    - slg 2y ago
JoeAltmaier 2y ago
Maybe look for signs of chemistry that indicates industry? Teflon, by-products of steel-making, plastics, something like that? Signs of intelligent(?) life.
- viraptor 2y ago
  Chemistry that indicates industry is signs of industry. In earth timescales, industry existed for effectively 0% of the time. Life existed for significantly longer though. Even if there's life in lots of places, there may be no industry as we understand it anywhere else in the universe.
  - OhioMan2943 2y ago
    The thing we keep on neglecting to mention is that life on earth actually happened pretty quickly in the time scale of the universe. I can't remember but I think we're one of the earliest points for life in the "broad" time scale. I wouldn't be surprised if stastically we're some of the first intelligent life, or the first wave.
    - kjkjadksj 2y ago
      Our generation time is probably too slow for us to be the first wave. I’d expect that title to belong to something that looks like a pile of snot on a table but under a microscope looks like a neural network.
      - AIPedant 2y ago
        A key limitation is that the early universe had virtually no heavy elements whatsoever, and it is far too fantastical to suppose there might have been life in the form of hydrogen-positron crystals or whatever. It took billions of years of supernovas for protoplanetary disks to include metals, complex organic molecules, etc, and perhaps even longer to make planets with enough chemical entropy to support life.
        2y ago
damnitbuilds 2y ago
What now? How do we confirm or disprove life there? Existing telescopes? Or do we need to design one quick, for Starship to take up next year?
- sbarre 2y ago
  I wouldn't trust Starship with a pair of cheap binoculars at this point.
  - damnitbuilds 2y ago
    The last one did seem unreasonably rushed, for some reason. Let's just hope debugging the next one distracts you-know-who from slashing any more climate science funding.
    - ralfd 2y ago
      Starship test flights have to be rushed, because they can only test it in flight. Before the last flight they static fired Ship 34 (the upper stage) for an unprecedented 60 seconds. https://www.youtube.com/watch?v=x6Z7fnikKB8 https://www.youtube.com/watch?v=x6Z7fnikKB8 But the new theory is flight 7 and flight 8 failed because of harmonic resonance developing after tanks (which big mass dampens resonance) emptying to a certain percentage. And you can’t replicate that on ground with full thrust and clamped down, or else the ship would take off, you can only test it during flight. The test flights are relatively unimportant though compared to building up infrastructure like the launch towers in Texas and Florida. The goal is supporting +50 launches per year, so while at the moment launches are multiple months apart this will change rapidly when the second (third, fourth..) launch tower is operational.
      - AIPedant 2y ago
        I think the point is that they still seem too rushed (perhaps reckless is a better term), since these are causing serious problems for planes in the area and generating very nasty pollution - what if debris hits an airliner? Nobody's saying they have to get Starship 100% right the next time, they are human. But I am very concerned that SpaceX simply has bad internal testing and design, maybe inadequate computer simulation or telemetry, who knows. But the concern is they'll improperly judge Starship as good-to-go once it launches successfully, having somewhat blindly applied a bunch of duct tape without properly understanding the cause of the failures.
jmyeet 2y ago
This is your daily reminder that if we do indeed discover life so close (~120 LY) to Earth, it's an incredibly bad sign for us. This is an exercise in Bayesian reasoning. Imagine there are 2 planets in the Milky Way where life has developed. The odds are incredibly low they're next to each other, assuming a random distribution. So it's way more likely that there are more than 2. Imagine a sphere of radius 60 LY (120/2). Our Earth is the center of one. This planet is another. That's a volume of 10^6 LY^3. The Milky Way volume (from Google) is ~17T LY^3 so there'd be roughly 170M such spheres in our galaxy. Now imagine if the odds of simple life becoming intelligent life that we could detect and could become spacefaring is 1 in 1 million. There'd be ~170 such civilization in the Milk Way. We have absolutely no evidence of this So simple life is a lot less common, intelligent life is a lot less likely or, and this is the scary part, something tends to wipe out sentient civilizations and that's likely in our future. In Fermi Paradox terms, we call this a Great Filter.
- thangalin 2y ago
  On a related note, Birth-Death Formalism connects Jaynes' Prior Probabilities in a paper, "Do SETI Optimists Have a Fine-Tuning Problem?" https://arxiv.org/abs/2407.07097 https://arxiv.org/abs/2407.07097 One of the authors posted an approachable video explaining how the ideas connect: https://www.youtube.com/watch?v=b6-9Hq8dV_4 https://www.youtube.com/watch?v=b6-9Hq8dV_4
- awb 2y ago
  There’s no evidence yet, but we also haven’t looked very carefully or in very many places. And we only know to look for planetary life as we know it. The middle of the galaxy could have a wildly different composition and habitat for life than the outer reaches where we are. Time is also another factor. Maybe the galaxy is perfect for complex life, we just happen to be early on the timescale and in another billion years or two life will be clearly abundant everywhere. For some perspective, if you take the size of the Milky Way (100k light years) and relate it to the size of NYC (~30 miles), then 120 light years ends up being ~190 feet in NYC, or less than a city block.
  - jmyeet 2y ago
cheshire137 2y ago
Looking forward to the John Michael Godier video that he'll inevitably put out about this.
- cheshire137 2y ago
  Lol, that didn't take long: https://youtu.be/82cLukqLgME?si=7PJMoGsxf6Qtaz87 https://youtu.be/82cLukqLgME?si=7PJMoGsxf6Qtaz87
  - tessellated 2y ago
    or: John Michael Godier's Event Horizon: JWST May Have Just Detected Alien Life at Exoplanet K2-18b Episode webpage: https://podcasters.spotify.com/pod/show/john-michael-godier/episodes/JWST-May-Have-Just-Detected-Alien-Life-at-Exoplanet-K2-18b-e31m41m https://podcasters.spotify.com/pod/show/john-michael-godier/... Media file: https://traffic.megaphone.fm/APO8659624232.mp3 https://traffic.megaphone.fm/APO8659624232.mp3
wewewedxfgdf 2y ago
It's never aliens.
- sandspar 2y ago
  There will probably be a first, perhaps it's this one.
ianpenney 2y ago
The detection of dimethyl sulfide on an exoplanet is an exciting development, ok. And DMS on Earth is almost entirely biologically sourced, but that doesn’t make it an exclusive biosignature. There are plausible abiotic pathways for DMS formation, such as in geochemistry we can’t know entirely about because we live on earth. I’m not sure a journalist for this exalted American newspaper here knows anything about this and frankly the excited language of this article is dumb af. Probably because excited people keep paying for subscriptions to this trash. It took my amateur self nearly 10 mins to ask around to qualified friends and research some counter ideas.
- John7878781 2y ago
  The article isn't overly excited imo. It clearly states nothing has been proven for certainty, which is in alignment with what you're saying. > Astronomers Detect a Possible Signature of Life on a Distant Planet > Further studies are needed to determine whether K2-18b, which orbits a star 120 light-years away, is inhabited, or even habitable. It's not fair to call it "trash"
  - ianpenney 2y ago
    “Remotely possible” sounds like a neat editorial compromise. A bit tongue in cheek. A pun. Fun. Otherwise? Clickbait.
- verzali 2y ago
  You could have just read to the end of the article and avoided wasting the time of your "qualified" friends: > Other researchers emphasized that much research remained to be done. One question yet to be resolved is whether K2-18b is in fact a habitable, Hycean world as Dr. Madhusudhan’s team claims. > In a paper posted online Sunday, Dr. Glein and his colleagues argued that K2-18b could instead be a massive hunk of rock with a magma ocean and a thick, scorching hydrogen atmosphere — hardly conducive to life as we know it. > Scientists will also need to run laboratory experiments to make sense of the new study — to recreate the possible conditions on sub-Neptunes, for instance, to see whether dimethyl sulfide behaves there as it does on Earth. > “It’s important to remember that we’re just starting to understand the nature of these exotic worlds,” said Matthew Nixon, a planetary scientist at the University of Maryland who was not involved in the new study.
deleted 2y ago
[deleted]

https://archive.is/uvKw9 https://archive.is/uvKw9

dguest 2y ago
original source: https://arxiv.org/abs/2504.12267 https://arxiv.org/abs/2504.12267

This is unsettling. If we are not the only intelligent beings in the universe, it adds credence to the idea of a "great filter." https://en.wikipedia.org/wiki/Great_Filter https://en.wikipedia.org/wiki/Great_Filter

Teever 2y ago
I think it would be cool if the conversation on this post could go more into detail about hycean planets instead of the pretty standard and played out one about the Fermi Paradox and Great Filters. That stuff is interesting but I'd rather hear experts talk about less talked about stuff like hycean planets and detection methods of them and other bodies that are that size.
- adriand 2y ago
  Well, it’s better than what I came here to do, which was to leave a snarky joke along the lines of, “Sounds like we just found another place we need to tariff.” But in the interest of keeping the discussion productive, I’ll refrain from doing that.
- tagami 2y ago
  what happens if you have lightning on a hycean planet?
  - DrFalkyn 2y ago
    Unless there’s enough oxygen, it shouldn’t be a problem
kulahan 2y ago
My greatest desire is to know why we don’t see any galaxy-sized colonies. A great filter would certainly be a fascinating response!
- taberiand 2y ago
  My guess is any civilisation advanced enough to populate their galaxy knows that it's inherently pointless. Unchecked growth is the impetus of lesser lifeforms
- Shekelphile 2y ago
  Life is probably extinguished by machine intelligence before it gets the chance to.
  - kulahan 2y ago
    ALL of it? EVERY time? There should be some signs somewhere.
- vikramkr 2y ago
  I mean, communication is insanely hard. If there's no way around the speed of light, life would still likely (slowly) expand across the stars, but it would be functionally impossible to continue to act as a unified civilization or colony across even a couple solar systems much less a whole galaxy
- frogeyedpeas 2y ago
  I find myself believing less in the great filter. My comment here: https://news.ycombinator.com/item?id=43712645 https://news.ycombinator.com/item?id=43712645 explains why.
- awb 2y ago
  One thing that I haven’t seen discussed much in terms of galactic colonization is genetic drift, speciation and communication. I believe there are simulations theorizing that galaxies can be thoroughly explored in 10M - 100M years. But how would those species even communicate their discoveries across a 100k LY galaxy? The delay would render data inaccurate by the time it arrives. It seems challenging to persist in a common purpose for millions of years across vast distances. And would they even be the same species on those timescales and distances? On Earth isolation leads to some unique physical and cultural evolutions.
credit_guy 2y ago
The Great Filter hypothesis is based on an analogy with the European conquest of the globe in the 19th century. Little by little all the white spots on the map were first explored, then annexed. The (unspoken) parallel is that an advanced civilization would explore and conquer the entire galaxy. But even if a civilization could achieve interstellar travel capabilities, it is entirely possible that they colonize, let's say, only 80% of the galaxy, not 100%. Or maybe only 50% or 10%. If our solar system is in the complement of their zone, how would we know they are out there. How would we know there are aliens around Alpha Centauri, let's say. They could be busy living their lives, broadcasting in all the regions of the radio spectrum with abandon, maybe even nuking each other from time to time. And we would just hear absolute silence. The distances between stars are just so mind-bogglingly huge.
- api 2y ago
  Infinite expansionism is just one of a whole tower of assumptions that underlie the Fermi paradox. It’s a good thought experiment and does rule out certain scenarios with ET life but beyond that it’s a speculation. The main scenario it rules out is one where intelligent ET life is common and we are late to the party. I feel like both those things can’t be true or we would see evidence. I do find it fun to think about because it unfolds under scrutiny into such a vast tree of possibilities. But that same huge tree of possibilities makes it hard to say much. One of my favorite wild speculations is that there is somewhere more interesting to go than space, and more accessible, and eventually whatever that is gets found before starships get built. What could that be? A traversable multiverse maybe? That belongs to a subset of scenarios I call “positive great filters.” That’s where the great filter is a big success that renders space flight unimportant or uninteresting but does not result in extinction. What about hyper-miniaturization. Maybe you can have something the size and scope of a galactic civilization without leaving home by folding your minds and everything else up into quantum states or hidden extra dimensions. Think a civilization of “sophons” (three body problem reference) with trillions upon trillions of minds occupying a few square meters of space and consuming a few hundred watts. Yet another is some kind of remote sensing that lets you explore without physically moving, like a real equivalent to remote viewing. There’s a sci-fi novel called Blind Lake about this. Combine with miniaturized super efficient information processing and you could have superintelligences that explore everywhere and learn everything without going anywhere. Lots of speculations and possibilities if you allow for the fact that we’ve only been doing science seriously for about 150 years and surely do not know everything.
fsckboy 2y ago
i don't see the connection. being the only intelligent beings in the universe (at the moment) lends credence to the great filter, and finding large numbers of other inhabited planets eliminates it, and in between why wouldn't it monotonically decrease?
- John7878781 2y ago
  the idea is: if we do find life elsewhere, especially basic life, it suggests that getting to that stage isn't super rare. which means the great filter probably isn't behind us (like abiogenesis or single-cell to multi-cell jump), but possibly ahead of us - maybe in surviving long-term, avoiding self-destruction, spreading beyond one planet, etc. finding life doesn't eliminate the great filter - it raises the unsettling possibility that we haven't hit it yet.
  - chatmasta 2y ago
    The argument you're referencing is usually about finding life on a nearby planet, e.g. on Mars. Nick Bostrom has articulated [0] this argument. But finding life on a distant planet lacks the same statistical power for instilling this existential fear. [0] https://nickbostrom.com/papers/where-are-they/ https://nickbostrom.com/papers/where-are-they/
    - John7878781 2y ago
      Of course. It'd be much worse if we found life on Mars than on a distant planet. In either case, the chances of humanity being ahead of the "great filter" are greatly reduced.
      - deleted 2y ago
        [deleted]
      - OhioMan2943 2y ago
        That's not taking into account that each solar system has its own set of circumstances, it could just be panspermia between earth and mars.

smitty1e 2y ago

> While inspecting K2-18b, Dr. Madhusudhan and his colleagues discovered it had many of the molecules they had predicted a Hycean planet would possess. In 2023, they reported they had also detected faint hints of another molecule, and one of huge potential importance: dimethyl sulfide, which is made of sulfur, carbon, and hydrogen. On Earth, the only known source of dimethyl sulfide is life. --- Intriguing.

Loughla 2y ago
It's absolutely amazing that we can even figure out molecules at that distance. I'm sure it's accurate but it's so sciency to me that it might as well be made up entirely. I can't begin to fathom that process.
- jf 2y ago
  If you haven't already, I recommend learning about Astronomical spectroscopy, which helped me get a toehold on how this stuff works: https://en.wikipedia.org/wiki/Astronomical_spectroscopy https://en.wikipedia.org/wiki/Astronomical_spectroscopy
- croemer 2y ago
  I haven't read the paper but it's likely just some fancy spectroscopy: looking at the wavelengths that are absorbed. Each molecule has a characteristic pattern.
- hnuser123456 2y ago
  It's only possible if the planet passes directly between its star and Earth, so we can see sunlight passing through its atmosphere, and detect which specific frequencies of light got absorbed.
- jcranmer 2y ago
  > I can't begin to fathom that process. It's basically "look at far away object with a fancy pair of sunglasses." Because of quantum mechanical reasons, molecules can only absorb and emit light with very particular energy levels (which correspond to frequency/wavelength). So point your camera at an exoplanet and carefully record the amount of the light you see at different wavelengths. My guess is that it's based on IR spectroscopy, since there's a nice region of that spectra where you can "fingerprint" a molecule based on the peaks in absorption in that region (it's literally called the "fingerprint region").

philipkglass 2y ago

This is about dimethyl sulfide in the atmosphere of exoplanet K2-18b: https://en.wikipedia.org/wiki/K2-18b https://en.wikipedia.org/wiki/K2-18b The NYT article reports a new study in The Astrophysical Journal and links to it, but the DOI is currently not found: https://dx.doi.org/10.3847/2041-8213/adc1c8 https://dx.doi.org/10.3847/2041-8213/adc1c8 I also don't see the article yet under their Latest Articles: https://iopscience.iop.org/journal/0004-637X https://iopscience.iop.org/journal/0004-637X Here are recent articles about K2-18b from Google Scholar: https://scholar.google.com/scholar?hl=en&as_sdt=0,48&q=%22K2-18b%22&scisbd=1 https://scholar.google.com/scholar?hl=en&as_sdt=0,48&q=%22K2...

IanCal 2y ago
Those DOIs have a different prefix, I think it might be in Letters https://iopscience.iop.org/journal/2041-8205 https://iopscience.iop.org/journal/2041-8205 It's still not out yet though. Also journals are often rather tardy or just straight up don't register the doi at all and still put it on their site, but maybe this is an embargo thing. edit - is it possibly this after publishing? https://arxiv.org/abs/2501.18477 https://arxiv.org/abs/2501.18477
- philipkglass 2y ago
  Good point about the DOI prefix. I don't think it's that arXiv article, though, since it says there is no statistically significant evidence for carbon dioxide or dimethyl sulfide. This NYT article (and presumably whatever journal article it's based upon) reports high levels of dimethyl sulfide.
  - IanCal 2y ago
    You're right, different authors too. https://www.eurekalert.org/multimedia/1069012 https://www.eurekalert.org/multimedia/1069012 uses the DOI in the article and says it's from > A. Smith, N. Madhusudhan (University of Cambridge) Here's another article on it https://www.bbc.co.uk/news/articles/c39jj9vkr34o https://www.bbc.co.uk/news/articles/c39jj9vkr34o I think this is still under embargo, or hasn't quite been released. There's going to be some time required for visuals like on the bbc site.

belinder 2y ago

If life evolves on a planet with only oceans, no surface, imagine how much longer it would take to discover rockets that can leave the planet. Like if there was no surface on earth, and only fish, there must be some very significant reason for advanced fish to even want to leave the water, let alone the atmosphere

gtirloni 2y ago
How high are you? :D
slg 2y ago
That seems like a very landbased mindset. From a high level, what is an ocean but a thick atmosphere? I could even imagine an underwater culture would be quicker to explore because they would surely discover the surface of the ocean quicker than we discovered the concept of the atmosphere and that innately leads to the questions of whether the atmosphere has a "surface" and what is above it.
- Jedd 2y ago
  > From a high level, what is an ocean but a thick atmosphere? "Now you have two atmospheres."
  - upghost 2y ago
    Ha. Ha ha. Nice.
- fhdkweig 2y ago
  There is also the issue that they will likely never discover fire and thus chemistry and metallurgy.
  - johntitorjr 2y ago
    [dead]
  - slg 2y ago

JoeAltmaier 2y ago

Maybe look for signs of chemistry that indicates industry? Teflon, by-products of steel-making, plastics, something like that? Signs of intelligent(?) life.

viraptor 2y ago
Chemistry that indicates industry is signs of industry. In earth timescales, industry existed for effectively 0% of the time. Life existed for significantly longer though. Even if there's life in lots of places, there may be no industry as we understand it anywhere else in the universe.
- OhioMan2943 2y ago
  The thing we keep on neglecting to mention is that life on earth actually happened pretty quickly in the time scale of the universe. I can't remember but I think we're one of the earliest points for life in the "broad" time scale. I wouldn't be surprised if stastically we're some of the first intelligent life, or the first wave.
  - kjkjadksj 2y ago
    Our generation time is probably too slow for us to be the first wave. I’d expect that title to belong to something that looks like a pile of snot on a table but under a microscope looks like a neural network.
    - AIPedant 2y ago
      A key limitation is that the early universe had virtually no heavy elements whatsoever, and it is far too fantastical to suppose there might have been life in the form of hydrogen-positron crystals or whatever. It took billions of years of supernovas for protoplanetary disks to include metals, complex organic molecules, etc, and perhaps even longer to make planets with enough chemical entropy to support life.
      - 2y ago

damnitbuilds 2y ago

What now? How do we confirm or disprove life there? Existing telescopes? Or do we need to design one quick, for Starship to take up next year?

sbarre 2y ago
I wouldn't trust Starship with a pair of cheap binoculars at this point.
- damnitbuilds 2y ago
  The last one did seem unreasonably rushed, for some reason. Let's just hope debugging the next one distracts you-know-who from slashing any more climate science funding.
  - ralfd 2y ago
    Starship test flights have to be rushed, because they can only test it in flight. Before the last flight they static fired Ship 34 (the upper stage) for an unprecedented 60 seconds. https://www.youtube.com/watch?v=x6Z7fnikKB8 https://www.youtube.com/watch?v=x6Z7fnikKB8 But the new theory is flight 7 and flight 8 failed because of harmonic resonance developing after tanks (which big mass dampens resonance) emptying to a certain percentage. And you can’t replicate that on ground with full thrust and clamped down, or else the ship would take off, you can only test it during flight. The test flights are relatively unimportant though compared to building up infrastructure like the launch towers in Texas and Florida. The goal is supporting +50 launches per year, so while at the moment launches are multiple months apart this will change rapidly when the second (third, fourth..) launch tower is operational.
    - AIPedant 2y ago
      I think the point is that they still seem too rushed (perhaps reckless is a better term), since these are causing serious problems for planes in the area and generating very nasty pollution - what if debris hits an airliner? Nobody's saying they have to get Starship 100% right the next time, they are human. But I am very concerned that SpaceX simply has bad internal testing and design, maybe inadequate computer simulation or telemetry, who knows. But the concern is they'll improperly judge Starship as good-to-go once it launches successfully, having somewhat blindly applied a bunch of duct tape without properly understanding the cause of the failures.

jmyeet 2y ago

This is your daily reminder that if we do indeed discover life so close (~120 LY) to Earth, it's an incredibly bad sign for us. This is an exercise in Bayesian reasoning. Imagine there are 2 planets in the Milky Way where life has developed. The odds are incredibly low they're next to each other, assuming a random distribution. So it's way more likely that there are more than 2. Imagine a sphere of radius 60 LY (120/2). Our Earth is the center of one. This planet is another. That's a volume of 10^6 LY^3. The Milky Way volume (from Google) is ~17T LY^3 so there'd be roughly 170M such spheres in our galaxy. Now imagine if the odds of simple life becoming intelligent life that we could detect and could become spacefaring is 1 in 1 million. There'd be ~170 such civilization in the Milk Way. We have absolutely no evidence of this So simple life is a lot less common, intelligent life is a lot less likely or, and this is the scary part, something tends to wipe out sentient civilizations and that's likely in our future. In Fermi Paradox terms, we call this a Great Filter.

thangalin 2y ago
On a related note, Birth-Death Formalism connects Jaynes' Prior Probabilities in a paper, "Do SETI Optimists Have a Fine-Tuning Problem?" https://arxiv.org/abs/2407.07097 https://arxiv.org/abs/2407.07097 One of the authors posted an approachable video explaining how the ideas connect: https://www.youtube.com/watch?v=b6-9Hq8dV_4 https://www.youtube.com/watch?v=b6-9Hq8dV_4
awb 2y ago
There’s no evidence yet, but we also haven’t looked very carefully or in very many places. And we only know to look for planetary life as we know it. The middle of the galaxy could have a wildly different composition and habitat for life than the outer reaches where we are. Time is also another factor. Maybe the galaxy is perfect for complex life, we just happen to be early on the timescale and in another billion years or two life will be clearly abundant everywhere. For some perspective, if you take the size of the Milky Way (100k light years) and relate it to the size of NYC (~30 miles), then 120 light years ends up being ~190 feet in NYC, or less than a city block.
- jmyeet 2y ago

cheshire137 2y ago

Looking forward to the John Michael Godier video that he'll inevitably put out about this.

cheshire137 2y ago
Lol, that didn't take long: https://youtu.be/82cLukqLgME?si=7PJMoGsxf6Qtaz87 https://youtu.be/82cLukqLgME?si=7PJMoGsxf6Qtaz87
- tessellated 2y ago
  or: John Michael Godier's Event Horizon: JWST May Have Just Detected Alien Life at Exoplanet K2-18b Episode webpage: https://podcasters.spotify.com/pod/show/john-michael-godier/episodes/JWST-May-Have-Just-Detected-Alien-Life-at-Exoplanet-K2-18b-e31m41m https://podcasters.spotify.com/pod/show/john-michael-godier/... Media file: https://traffic.megaphone.fm/APO8659624232.mp3 https://traffic.megaphone.fm/APO8659624232.mp3

wewewedxfgdf 2y ago

It's never aliens.

sandspar 2y ago
There will probably be a first, perhaps it's this one.

ianpenney 2y ago

The detection of dimethyl sulfide on an exoplanet is an exciting development, ok. And DMS on Earth is almost entirely biologically sourced, but that doesn’t make it an exclusive biosignature. There are plausible abiotic pathways for DMS formation, such as in geochemistry we can’t know entirely about because we live on earth. I’m not sure a journalist for this exalted American newspaper here knows anything about this and frankly the excited language of this article is dumb af. Probably because excited people keep paying for subscriptions to this trash. It took my amateur self nearly 10 mins to ask around to qualified friends and research some counter ideas.

John7878781 2y ago
The article isn't overly excited imo. It clearly states nothing has been proven for certainty, which is in alignment with what you're saying. > Astronomers Detect a Possible Signature of Life on a Distant Planet > Further studies are needed to determine whether K2-18b, which orbits a star 120 light-years away, is inhabited, or even habitable. It's not fair to call it "trash"
- ianpenney 2y ago
  “Remotely possible” sounds like a neat editorial compromise. A bit tongue in cheek. A pun. Fun. Otherwise? Clickbait.
verzali 2y ago
You could have just read to the end of the article and avoided wasting the time of your "qualified" friends: > Other researchers emphasized that much research remained to be done. One question yet to be resolved is whether K2-18b is in fact a habitable, Hycean world as Dr. Madhusudhan’s team claims. > In a paper posted online Sunday, Dr. Glein and his colleagues argued that K2-18b could instead be a massive hunk of rock with a magma ocean and a thick, scorching hydrogen atmosphere — hardly conducive to life as we know it. > Scientists will also need to run laboratory experiments to make sense of the new study — to recreate the possible conditions on sub-Neptunes, for instance, to see whether dimethyl sulfide behaves there as it does on Earth. > “It’s important to remember that we’re just starting to understand the nature of these exotic worlds,” said Matthew Nixon, a planetary scientist at the University of Maryland who was not involved in the new study.

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