Into the Impossible With Brian Keating - The Hype and Skepticism of Finding Life on Exoplanet K2-18b

Episode Date: April 18, 2025

Brian Keating explores the buzz around a possible sign of alien life on exoplanet K2-18 b, discussing the detection of dimethyl sulfide—a molecule that on Earth is linked only to biology. He urges caution, explaining that while the findings are exciting and headline-grabbing, the evidence is not yet conclusive and scientific skepticism is essential. Learn more about your ad choices. Visit megaphone.fm/adchoices

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And that's based on a discovery around the star known as K218B, the exoplanet actually. And it's perhaps a discovery for all time, or perhaps it could be sort of another twisting turn in the long road to finding extraterrestrial life. So we may have heard a whisper, we may have heard a war, we may have heard nothing. And that's why I want to present this short video, and my friends and family are asking me, about it, so I figured I'd make a short video about it. So what is the signal? The signal is sort of a hint, a molecular

signal. It's not from extraterrestrial intelligence or technology. But it is a whisper, perhaps of life. A signal faint and suggestive from a planet over 124 light years away. The name of the planet is the

Winsome K2-18B and according to a new paper by Dr. Niku Matt Housudon, and his team using the James Webb Space Telescope, they may have detected a chemical called dimethyl sulfide. Now, dimethyl sulfide, DMS, so slide into my DMS, in this alien world's atmosphere could be a harbinger of life.

Not like us, but life nonetheless, and that would be one of the greatest discoveries of all time. On Earth, DMS has just one source, life. Predominantly, some argue about that. Specifically, microbes in the ocean produce it. So naturally, headlines exploded, possible signs of life, undiscovered on a habitable planet, revolutionary moment in the search for aliens.

Disclosure is here. Even Dr. Madhusadan himself told the New York Times, this is a revolutionary moment. The first time humanity has seen potential biosignatures on a habitable planet. Now, I don't fault them for being so excited. I'm excited about this, too. And I studied cosmology. But it's a big claim, and it requires big evidence.

So let's not just book a ride to this place. planet anytime soon, we have to talk about what real proof might mean or might look like. First, let's understand what the signal actually is. Now, this is detected in the atmosphere of the planet, and it was actually detected this type of molecule, DMS. Biomethal sulfate was detected over a year and a half ago, I think, by James Obe's Space Telescope. At that time, the significance was much lower, so called 1-Sigma versus a 3-sigma or beyond

that's required for scientists to accept it as a true hint or suggest. even a detection. Now K218B is not Earth 2.0. It's actually a planet about the size of Neptune, about 2.6 times Earth's radius and about 8.6 times its mass, with a hydrogen-rich atmosphere and temperatures hovering just above freezing. This picture behind me from the New York Times depicts what's called the Hysean world, a theoretical class of exoplanets with hydrogen ocean, hycean ocean, hydrogen ocean, under hydrogen skies. It's strange, exotic, and unfamiliar, and that's part the problem. When the web telescope looked at K2-18B,

it wasn't snapping a photo. It was actually analyzing the spectrum of light filtered through the atmosphere. That means interpreting complex absorption lines buried in infrared noise. That's really challenging to do. And only the web can really do it for us. And while the team did find hints of methane

and carbon dioxide, both previously expected, and signs of life themselves in many cases, it's the possible detection of dimethyl sulfide DMS that slid into our DMs, and causes to raise eyebrows. And caution is advised. According to their own paper,

DMS detection is at low confidence. The signal's weak. It's very challenging. And the statistical significance around 3-Sigma, which is below the usual threshold, about 5 or more, required for a claim of detection in, say, particle physics or cosmology.

Now, this is just one molecule inferred from one set of JWST transits using atmospheric models that depend on dozens of parameters. Temperature gradients, cloud layers, planetary mass, stellar activity, tiny changes in those assumptions, well, they shift the outcome completely. Also worth noting is that DMS isn't as exclusive to biology as we once thought.

A recent paper from last year, which I'll put a link to in the description below, along with a gift to you of the article from the New York Times from my friend Carl Charles shows DMS can arise from abiotic processes, non-living processes, especially in comet-like collisions, or conditions rather, or prebiotic chemistry that we don't fully understand. So no, this isn't a smoking gun yet. It's a sort of chemical nudge. And the history of astronomy,

especially these that involve chemistry on exoplanets or even planets in our own solar system like Venus. Remember, phosphine on Venus? Remember the 1976 Viking mission and its positive life detection on Mars? Remember the meteorite fragment found in Antarctica that had microbial life elements of what microbees? Curbio Life found on it, featured in the movie Contact, while those all went away to some degree

or another. So this is where I think it gets interesting to my audience of cosmologists, physicists, and philosophers, and that's how to think scientifically also balanced with sociological thinking. Because the story about life tells us something about how science is communicated, and the interpretation has ramifications both in philosophy and even in theology. And so when faced with these career-defining moments, scientists, sometimes phrase ambiguous results with a dramatic tension. This revolutionary moment, as Dr. Maddie Haaschen said, could be true or it could be an example of scientific overreach. And it's not just the scientists that are

eager to do this. The media, too, are eager to capture the public's imagination. And they lean hard into speculation, burying the caveats and glossing over the uncertainties. But here's the thing. for me when I think about this the search for alien life is not going to end in a Hollywood moment most Hollywood moments aren't real Hollywood moments they're often terrifying there won't be a clear voice ringing out take me to your leader no it's going to be slow messy frustrating

and filled with false starts and often twist and turns and full stops and that's not a flaw that's the way good real true science works discovery in the scientific process isn't a race, it's not a sprint, it's a crawl, it's agonizing. Sometimes when readers and listeners and viewers get burned by premature excitement, they become skeptical, not in a healthy way, but in a somewhat dismissive way. So we should all, as active citizens and the media and so forth, demand better from reporters,

but from scientists too. We have an obligation, a moral obligation, as I often say, not to overstate our case. We don't want to hurt the credibility of individual scientists or the credibility of science itself. I'm not saying, are accusing anyone of that in this case. I'm just saying we should be advised to have caution not to overthrow the paradigm that we are no longer solely inhabiting this beautiful cosmos. So we live on this amazing time, amazing moment when these technology, these tools funded by taxpayer dollars in the U.S. and Europe may have found life. We may have found life. But we also have to learn how we can recognize when we haven't found it and know

we could be wrong. It's a story we're telling, and it's an incredible reminder of what Richard Feynman once said, as the first principle of science is that you must not fool yourself. And the second principle is that you are the easiest person to fool. So we didn't find aliens, not yet. We may have found some evidence of the byproducts of life. That's very clear. We need to make that very clear. So it's a reminder of something else. Science isn't about belief. I always say I don't believe in gravity. It's about having evidence and it requires doubting precisely, rigorously, and beautifully yourself, most of all. Next time we'll talk about what real evidence might look like if aliens were discovered. And in fact, this coming weekend, I'm going to have an

interview with one of the pioneers in the search for planets beyond the orbit of Neptune in our own solar system. That's Dr. Mike Brown, who's also known as a killer, not just for his amazing scientific abilities, but also for his killing of Pluto. So stay tuned for that. That's coming soon Sunday on my channel, Dr. Brian Keating on YouTube. So thanks very much for this short little update. Hope you enjoyed it. And we should have more data, evidence, and skepticism for now. Try not to be too excited for now. Okay. Ambition comes in all shapes and sizes. At First Citizens Bank, we roll with your goals. Because we're built for what you're building.

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