JWST May Have Just Detected Alien Life at Exoplanet K2-18b

It's always been murmured in slightly hushed tones in the scientific community that the wildly successful James Webb Space Telescope has within its capability, just barely so, the possibility to characterize exoplanet atmospheres to the level of potentially picking up a biosignature. Now burning down the media, we have a story of an increasingly solid case that JWST may have actually found one, and this detection, if validated, changes everything in regards to the question of alien life in the universe. I do not say that lightly. This may well be our first detection of alien life. This is in regards to the exoplanet K2-18b, which is a sub-Neptune world about 2.6 times the radius of earth, and about 8.6 times as massive, and about 124 light years distant. That's well distant enough to have never interacted with earth life, thus this would not be contamination, but a true, separate abiogenesis. This planet orbits within its star's habitable zone, and the planet receives a comparable amount to earth of solar radiation from its star. More on that in a bit, because that star is a red dwarf. The planet is on a 33 day orbit, and interestingly was another discovery of the Kepler Space Telescope, just like another candidate for alien life, Tabby's star. The age of the star system is about 2.4 billion years. It's worth noting that oxygen has not been detected at this exoplanet, which means that there may not be photosynthesis there. When earth was 2.4 billion, there was already photosynthesis occurring. What that means will be a matter of debate as this progresses. This exoplanet became very interesting in 2019 when water vapor was detected in its atmosphere. That could indicate that it is an oceanic world. Researchers using JWST found in 2023 that the planet also has carbon dioxide and methane in the atmosphere. Both are gases linked to life, but not solely made by life, not by a long shot for carbon dioxide. There have been several different interpretations of the data as to the question of what this world is really like, whether it's a gas planet, like Uranus or Neptune, just smaller, or if it's an ocean planet of some sort. If a water world, this planet is a candidate for what is called a Hyacinth world, a hypothesized class of planet where you have a liquid water ocean existing in a hydrogen-rich atmosphere. Hydrogen, ocean, hyacinth. Hyacinth worlds would be water worlds, with likely little or no land, and thus any life on one would be aquatic in nature. There are a number of candidates for this type of world discovered by Kepler, but K2-18b has rocketed to the top of that list. In 2023, JWST made a detection of a very interesting gas in the atmosphere of this world, dimethyl sulfide, which as far as anyone knows is only produced by life. There is a link in the description below to an event horizon interview I did with Dr. Neku Madhusudan on that detection. The problem is that the detection was very weak, leading to much skepticism in the scientific community as to whether this detection was actually real or just noise. The researchers at the University of Cambridge involved were able to get more time on JWST to use a different instrument to redo the measurement, and if it's valid, it's staggering. The detection is now at the three sigma level, that's huge because it means that there is only a 0.3 percent chance that this is a random fluke detection. The detection could be one of two gases, or a combination of them both, and both are thought to be unique to biology, dimethyl sulfide and dimethyl disulfide. Only further work will constrain which one it is, or if it's both. What the scientific community is going to want for this discovery however is a five sigma detection, because extraordinary claims require extraordinary proof. Which a five sigma detection would bring the chances of it being a fluke down to a 0.00006 chance. That level would make this a robust detection. The team believes that they can do that, with further time on JWST, which with a three sigma detection seems very likely to happen. It's worth noting that the measurement from 2023 was done with JWST's nearest and near spec instruments, whereas the new detection was by the MERI instrument, which qualifies as an independent detection. The chances are good that the observations are in fact indicating what could be a biosignature on this exoplanet, but there is still some weirdness and reason for caution. This is not a confirmed detection of alien life, and if the observations continue to hold up, the first question scientists will ask is if the chemists can think of a way where these gases could be produced in huge concentrations without biology. Maybe this is some unknown chemical process we weren't aware of going on here. One potentially weird aspect is that this planet has on the order of 20 times higher concentrations of these gases than earth has. Interestingly, other theoretical work indicated that Heysen worlds with life would actually have these high concentrations of these two gases. It was expected. Everything so far is consistent with a Heysen world with microbial life. I won't distress caution, as always, but this is the best candidate we've ever seen for a detection of a biosphere outside of earth. If the observations hold up, then this will be difficult to knock down. It's worth noting here that these two chemicals are linked to microbial life on earth primarily, specifically marine phytoplankton. If this is indeed an inhabited ocean world, then an analog of that seems possible. Phytoplankton are ultimately a kind of plant, which means that further observations in infrared with much larger telescopes might allow for the detection of a vegetative red edge where plant cells on earth become highly reflective. This probably is not possible with JWST, it's simply watching the exoplanet transit its star, with the light passing through the atmosphere and coloring it with its constituent spectra. But in the future it may be possible to directly image the planet and look for the red edge. But there are also problems. One problem is that some thinking in astrobiology is that worlds larger than two earth masses are not good candidates for life, because at some stage gravity starts getting crushing. This may not be a problem for some microbial life, extremophiles of some sort, but it does get to be a problem for anything more complex, and that high gravity would make for some very calm oceans, at least on the surface, though it's possible that there is tidal action as the planet interacts with other members of the system. This would be a very alien world indeed. If you were able to stand on it, you would feel the titanic gravity, but if you could smell these gases, the world would smell something like cooking cabbage. And oddly, the analog of life there might actually taste good, as dimethyl sulfide is a food additive with a savory flavor. You taste it in things like asparagus. But you wouldn't last long in concentrations this high because while dimethyl sulfide is normal and present in the human body, it causes medical issues, including severe bloodborne halitosis at high levels and other medical issues. And whatever is producing these gases is a massive process because dimethyl sulfide is short-lived in atmospheres, thus whatever is doing it is replenishing it actively and on a truly huge scale. That also ticks a box for life. It can do that in principle. Some other chemical process that we aren't aware of and haven't ever come across less so. But now to the implications of this. The planet, as I mentioned, orbits a red dwarf. This would be huge news if indeed this is a biosphere detection, because the question of red dwarfs' inhabitability has been raging back and forth for years. The argument against it is that red dwarfs, when they are young, are flare stars, meaning that they would seemingly strip off the atmospheres of their habitable zone planets early on, because the habitable zone is so close in to the star. So far, the JWST work with the TRAPPIST-1 system has borne this out. The two innermost planets appear to have no atmospheres. K2-18b does. Other work suggested that the stellar physics of red dwarfs is such that they do not flare their equators, meaning that the flares never hit their planets, which makes them completely viable for life. If this detection is valid, and life remains the simplest explanation, then that changes the landscape and answers the question. The most numerous type of star, by far, 73% for the Milky Way, in the universe, is indeed habitable, and 80% of them are believed to have habitable zone exoplanets. And that we saw life just 124 light years away, coupled with red dwarf habitability, would strongly imply that the entire universe teems with microbial life at least. This detection probably does not hold the potential for intelligent alien life. If it holds up, then life on earth is not alone. But then comes the sad part, if all this holds. High gravity planets like this are probably not good candidates for civilizations, and that's a good thing on two counts. The first is that they would be stuck, it's unlikely that chemical rockets or any easy means could launch from this world. They very likely would have no way to perform space travel, which means no satellites and so on, which would greatly hamper their development. If they could develop at all in that kind of gravity. But there is a bigger problem. Martian worlds like K2-18b might be, are thought to be exclusively oceanic worlds. If this holds for lower gravity planets, then any complex life there would be locked in a very deep ocean. And most, not all, ocean life on earth exists near the surface, especially the phytoplankton which need the sunlight. Any intelligence there would be locked in their ocean with no method of smelting metal. If the majority of inhabited planets in the universe are large hyacinth worlds, then there is the solution to the Fermi Paradox. Intelligent life that can leave its planet is simply very, very rare. That's a sad universe to envision indeed, because if we ever spread out into the stars and start colonizing exoplanets, then we will probably be doing a lot of rescue work when we come across locked in intelligences. We will be the uplifters that rescue the Milky Way's intelligences, providing we can figure out a way to get them off their planet. Another odd effect of this would be that if this planet is fully oceanic, then that suggests that abiogenesis can indeed happen at oceanic hydrothermal vents. Yet research on earth was starting to point to hot springs, in a volcanic environment on land. That might mean that abiogenesis actually has two ways to happen, again bolstering the case that microbial life is everywhere. And with a separate abiogenesis detection, it implies that abiogenesis is not complicated, however it happens. So there you have it, this may, just may be it, and we are very close to the ability to confirm the first detection of alien life. If it gets shot down, we still learn something new about how these gases can form, and how it is they can end up in the atmosphere of exoplanets like this. If this is proven, it's likely this will result in Nobel Prizes and reinforce the glory of the James Webb Space Telescope. But I leave you with this, if K12-18b turns out to not be a Haitian terrestrial type world, and indeed is a sub-Neptune gas planet, the detection of these gases gets very strange indeed, because that constrains the possible non-biological chemistry option. It removes the geology from the equation. In which case gas planets might be habitable, or this moves from strictly a biosignature candidate to a technosignature. Thanks for listening! I'm futurist and science fiction author John Michael Godier currently addressing those that are saying JMG it's 3 am for you, why are you still up? I was so intrigued by this story for obvious reasons I couldn't help but make a video. And be sure to check out my books at your favorite online book retailer and subscribe to my channels for regular, in-depth explorations into the interesting, weird and unknown aspects of this amazing universe in which we live.