Let's Talk About Recent Claims of Alien Life on Planet K2-18b

Okay, looks like we have to talk about K2-18b once again, and really because of the recent study and a recent press release by Cambridge University that I guess kind of annoyed a lot of scientists. Mostly because of the wording used and because of the implications for the discovery of alien life on another planet. And so today we're going to be discussing this. Strongest hints yet of And well, looks like today I'm going to have to put on my skeptics glasses and discuss this from a perspective of this not potentially being true at all. But in case this is the first time you've heard about this, let's briefly go through some of the basics and through some of the previous discoveries and previous claims. And the story starts right here. K2-18b. A somewhat intriguing planet located in the star system 124 light years away from us that's orbiting a red dwarf known as K2-18. This planet was actually discovered by the Kepler mission as far back as 2015 and almost right away became kind of exciting because of its orbit. Here this is a red dwarf system and a single orbit is approximately 33 days long, implying that this planet is in the habitable zone of the system where we can technically expect maybe liquid water. But we also know that this planet is very different from anything in the solar system. First of all it's approximately 2.6 times the radius of planet earth and at least 8.6 times the mass of earth, which makes this a much larger and much more massive planet with a density of about 2.67 gram per centimeter cube. And so this is technically what's known as a mini-Neptune. An extremely common type of a planet out there, but something that we just don't have here in the solar system. Why? Well, that's one of the mysteries. But in 2019 this planet became super exciting because of the potential discovery of water vapor in its atmosphere. And within a few years, after discoveries of similar planets, researchers actually proposed an unusual type of planets that might exist out there. These bizarre ocean worlds started to be known as Hycean planets. A lot of this is still very hypothetical, but if they do exist they would essentially be somewhere between a kind of a terrestrial world and a Neptune-like gas giant, very likely featuring an extremely thick hydrogen-rich atmosphere, which allows liquid water to exist underneath, but possibly in extremely hot conditions, and maybe even above the boiling temperature of water itself, which would actually make this supercritical water, or water existing in much hotter, much more extreme conditions, we don't really find here on earth very often. The word Hycean is actually a combination of hydrogen and ocean. And I actually figured I'm going to mention this now before I forget. This concept of Hycean planets was actually originally proposed by the University of Cambridge, and specifically the same researcher that published this recent paper we're discussing today, Niku Madhusudana. And at least two such planets have been potentially discovered, but obviously have never really been officially confirmed. You can learn more about this in one of the videos in the description. But when it comes to this particular planet, while quite a few additional investigations have been conducted, but years after years, the results were actually not very satisfactory. For example, some studies at first reported ammonia, but other studies found none. And though in 2023, observations from the Genesweb reported carbon dioxide and methane, possibly representing 1% of the atmosphere in total, in one of the recent videos we've discussed this study, the most comprehensive analysis to date that essentially questioned the detection of many of the carbon-based molecules, and especially the one you see right here, DMS. And this is essentially the entire controversy when it comes to this exoplanet and the studies about it. DMS is dimethyl sulfide, a somewhat stinky gas that on Earth is usually produced by marine algae. And because this gas breaks apart pretty quickly, if we actually find a lot of it somewhere out there, it means that something is actively creating it. And so for many years, it was assumed to be maybe a kind of a biosignature or a sign of potential extraterrestrial life. But up until the potential discovery of DMS on this planet, it was never really that thoroughly investigated. As in, we knew some of it can be produced through physical means and through non-biological reactions, it was not entirely clear how common this gas was outside of planet Earth. But as we've discussed in that previous video, turns out it might be way more common than we thought originally. And this was actually based on this study that discovered DMS in an extremely famous comet. This was completely unexpected, but here, comet 67P turned out to contain quite a lot of it, implying that there are chemical reactions we still don't know that can possibly form this gas without any presence of life. With this study basically questioning if DMS is even a biosignature at all. But let's go back to that planet again. And so in October of 2023, Nikko Modusudan and the team you see right here published this now famous study, carbon-bearing molecules in a possible hyacine atmosphere. And in a nutshell, the study was about a discovery of dimethyl sulfide in the atmosphere of the planet K2-18b. With the discovery itself, though being somewhat exciting, basically being questioned almost right away. And in this case, only because of one thing. The statistical analysis that the scientists used in this study to confirm the presence of DMS was apparently not very rigorous. In other words, the detection of DMS here was possibly just a statistical anomaly. And in this case, in terms of statistical significance, it was reported at 2.4 sigma, which basically means that there might be something here, but we're not sure. And almost right away, every single study after this, that essentially tried to reanalyze this using different techniques, actually didn't seem to discover anything. As I mentioned before, the recent reanalysis seems to have discovered absolutely nothing using a completely different technique. And so several different studies tried to explain this as maybe a very unusual gas reached mini-Neptune, and almost certainly not a habitable planet, and not a planet containing life. And here I thought that maybe this is the end of the saga, and maybe we're not going to hear about this planet for quite some time. But basically, as soon as this reanalysis was published, literally a week later, we get hit by a title like this from University of Cambridge. Yeah, this is basically as clickbaity as it gets. Hints of biological activity. And that's kind of what triggered most of the scientists and why there's a lot of discussion about this now. Mostly contradicting the results. And personally, I was just basically laughing about this because it means I have to make another video. And so let's talk about what was recently conducted, and what was recently done, and why this is maybe not correct after all. Now, as always, you can find the study and all of the links in the description below. But in essence, this is based on a follow-up observation. This was actually expected a few months back, and it was finally conducted. Here, this was based on two observations using mid-infrared instrument on the James Webb Space Telescope, which in total lasted for approximately eight hours. The data itself was collected last year, around April 2024. And well, once again, based on a somewhat similar analysis, the researchers in the study get a detection of DMS, but also maybe DMDS, dimethyl disulfide. A somewhat similar element that might be biological in nature too, or just like DMS, could be natural as well. With the researchers also claiming that this is right now one of the most promising hints for the potential life beyond planet Earth, and providing slightly more significant evidence. But here, if you actually read the paper, quite a lot of problems basically pop up right away. The first and obvious problem is the actual significance. In the previous study, as I mentioned, it was approximately 2.4 sigma. Not a lot, but also maybe something. Here, in this new, more accurate observation, it's basically 3. And 3 is obviously better than 2.4, but very far from the required 5 for this to be actually something that's definitively there. Usually in science, three levels sigma of significance just means that maybe we should take a look at it again. And so in terms of actual mathematics and statistics, and the wording used in the study, there is a huge discrepancy. In other words, the actual claims versus the actual math do not match. With some additional wording also being controversial. For example, here, there's a statement that DMS and DMDS are only produced by life and mostly microbial life, such as marine phytoplankton. But as I previously showed you in one of the studies, we've discovered a lot of sources of abiotic production of DMS, including things like comets and potentially a lot of other objects. So claiming this as a biased signature is unfortunately a little bit misleading. And though in this case, the study does mention the potential cometary influence, it's only mentioned briefly. At the same time, there's a claim that the molecules detected in the study cannot be explained by most molecules predicted for this particular planet. But that's not entirely correct because the study that reanalyzed a lot of previous data does provide additional explanations and additional models that don't require any CO2 and any DMS. As a matter of fact, our conclusion overall is that this is extremely likely to be just a typical gas dwarf, or what we call a mini-Neptune. A really hot one, very likely containing a lot of water inside, but unlikely to be a source of microbial phytoplankton. And so right now, in this new study, the actual evidence is extremely weak. Or at least that's what the exoplanetary scientists believe right now. Moreover, additional recent studies basically point at this planet extremely unlikely to be habitable at all, even based on studies involving things like albedo. For example, this extremely recent study you can find in a description discovers that the reflectivity of this planet would very likely make it extremely hot, suggesting that it's either some kind of a magma ocean planet or extremely hot gas dwarf. So basically, no ocean whatsoever. This was based on trying to figure out how much light clouds here generally reflect. And so right now there's basically this major concern. The wording in the study suggests we've found life. But a lot of exoplanetary scientists and astrobiologists have voiced their concern. They suggest the opposite, especially because we have no idea what this planet is like. And just as a reminder, it was once again this researcher that proposed the existence of Icean planets. They were never confirmed by anyone else, and we've never actually discovered any of them out there. And so here it looks like Niku Madhusudana is sort of creating a narrative. A narrative for the existence of these unusual ocean worlds that potentially create conditions for exotic life. And this planet, according to him, is the first official candidate. But not a lot of people seem to actually agree with this narrative, and many researchers disagree with the conclusions, with the results, and with the overall approach. But for me personally, even though this is an interesting study, there is another really important concern. Usually when I read studies, I also go through various references. But in this case, as you can see, there is a lot of self-referencing. Almost every single study reference here was actually written by the same researcher. And to someone that reads a lot of studies, this is not a good sign. It's once again a sign that someone is trying to create a very specific narrative. But if a lot of scientists are disagreeing with it, and a lot of counter evidence points at the opposite, in these situations, I usually become super critical. Kind of like that super critical And so what's the actual conclusion? Well, right now the conclusion is that there is no conclusion. We know this planet is exciting. We know that it's in a habitable zone. But it's also very different from anything in the solar system. And though it might have habitable conditions, right now many studies suggest otherwise. And so here, even after these eight extra hours of observations, we unfortunately don't have enough. The five sigma threshold has not been reached, and only future observations with the James Webb can maybe confirm something. At the moment though, the most likely conclusion is that this is just a really hot gas giant, or a mini gas dwarf that seems to exist in a lot of different exoplanetary systems out there, but just does not exist around the solar system. And though it is still possible that this object might contain some kind of a really exotic ocean underneath, and the water vapor has been discovered here, when it comes to life, that's a completely different story. As of April of 2025, we don't have enough evidence. And right now there's actually more evidence that DMS and DMDS are just statistical anomalies. Or even if they do exist here, claiming that it's biological in nature is very misleading. Because in the last three years, it's been definitely proven that DMS is unlikely to be a good biosignature. Several lab experiments produced it without any life. But on that note, we'll definitely come back and discuss this more once there are some clarifications or more evidence. And we'll actually come back and discuss more of these hypothetical high-seeing planets, because there is another one out there that was explored extremely recently. And so on that note, thank you for watching, subscribe, share this with someone who loves learning about science, come back tomorrow to learn something else, support the channel on Patreon by doing a channel membership, or by buying the wonderful person t-shirt you can find in the description. Stay wonderful, I'll see you tomorrow, and as always, buh-bye.