Did We Detect Life on an Alien Planet? With David Kipping

Signs of life on an exoplanet. What's up with that? I got with me David Kipping. David, welcome back to StarTalk. Hey, it's a pleasure to be back. So this is not the first time we've seen an announcement of biomarkers indicating the possible existence of life. So it's not the detection of life, it's the detection of gases involved in life as we know it. Yeah, I mean, how do you detect life directly? We can't even decide what life even is. So coming up with a way to detect it directly is very difficult. These are just the contaminants that they would release essentially into the atmosphere that we can then detect and say, hey, maybe this will... Wait a minute, is the oxygen from a tree a contaminant? I mean, in a way, it's a waste product in a way, right? Photosynthesis produces that. If you're a tree. I would think of it that way, but the tree might. So just remind me, this is 120 light years away. It's a planet discovered from the Kepler mission. Yeah, Kepler-2. It had a failure after four years. It couldn't stare at the same stars anymore, but it could do a second phase of the mission where it looks at the ecliptic plane only. So during that phase, it detected K-218. Just to get the physics of the detection straight, so you've got a star, you've got the exoplanet orbiting the star, light from the star goes through the atmosphere and comes to you after it's been touched by the gaseous signatures in the atmosphere of the planet. Contaminated, even. You need the Webb telescope to make this measurement. Yeah, you can do it with other telescopes. I mean, Hubble has looked at this before with wide field chemistry. That's an instrument on there. In that case, they weren't able to detect anything conclusively, and so once JWST came around, everyone was very excited because this is one of the best targets. It's a nice, puffy atmosphere around a bright star that's nearby. So everyone knew this would always be a good planet to look at. So what does it mean for a planet to have a puffy atmosphere? Puffy atmosphere, the three ingredients are low surface gravity, ideally. This doesn't really have that, but it's not too bad. You want a hot, warm planet. That's useful because it puffs up the gas. It heats up the gas, right. And you want a light molecular gas because that can go higher in the gravitational well and create a larger atmosphere. And when you have a puffy atmosphere as it passes in front of the host star, there's more for us to see. More for you to see. And the list of biomarkers last I checked is pretty large, even methane. Yet we have lakes of methane on Saturn's moon Titan. But no one's saying it's a place thriving with life. So it's not just the existence of the chemical, it's the conditions under which you expect to find the chemical. Yes, the context is extremely important. So for instance, with this planet, there is some debate about what the planet really is. One idea is that it's an ocean world called a hessian world. So this is a thin hydrogen atmosphere and beneath it you have oceans. So there is a surface. Hessian? Hessian. Your guess is as good as mine. I think it's hessian. An important detail here is that if it really was a hessian world, even having methane alone would basically kind of prove there was life. Actually, just the methane. Because there's no way it should be able to sustain methane in its atmosphere if it really was a hessian world with this thin atmosphere. It would require a biosphere to make it that way. I don't know the numbers but I know from reading my colleagues' papers on this that you would expect it to be parts per million level of methane if there was no life. But this thing has percent level of methane. So it has way more than it should do when you do the photochemical calculations. What's the best way to get methane from life? I guess bacteria probably, I would guess. So I've always seen methane connected to life that's anaerobic. So like deep in our gut, the microbes there are all anaerobic and so methane is one of the byproducts. That's why cows fart methane. So if we already know the methane's there but we're not sure of the environment, then what else did they find? So here they're reporting stronger evidence, not only dimethyl sulfide, but also dimethyl disulfide. So these two molecules which are on Earth, only really produced by phytoplankton in the oceans. Why do you even care about the dimethyl sulfide if you have the methane as evidence? Because it isn't necessarily a hyacine well. Not everybody believes that. So if it's just simply a shrunken down Neptune, take Neptune, shrink it down by about a factor of one and a half to two and that is maybe what this planet is. In that case, there would be this deep, there's no real surface. You can just fall all the way down. There's no real land. Because it's gaseous. It's still gaseous. And so there would be methane, ammonium, these other gases being produced in the inside of the planet, the interior, and then they'd swell up through convection currents and come up to the upper atmosphere where we could see them. So the fact we see methane is consistent with that picture. We would expect also to see these other things like ammonia. Presently the current data isn't actually good enough to distinguish that. It is possible it could be one of these worlds and the amount of ammonia is just below our detection sensitivity. So it's not a super-Earth? Well, that's a good question. We don't really know what it is. I mean, an open question is it's about two and a half times the radius of the Earth. Neptune's four times the radius of the Earth. And obviously Earth's one. So it's somewhere in between. And we don't really know what that is. We don't have anything in the solar system that looks like that. We don't have a counterpart. No. So we are guessing here what it really is. So this chemical, which is new to me, I didn't know, dimethyl sulfide? Yes. I mean, it's actually a molecule you may have experienced because it's in truffles. It's actually the truffle smell is associated with dimethyl sulfide. I like this molecule now. Okay. So that is produced on Earth how? Typically on Earth it's phytoplankton. So these are tiny microorganisms living in the ocean. Photosynthesizing plankton in the ocean. Correct. How much of that do they make? On the Earth it's hardly anything. It's like parts per billion levels concentration. And we don't know any other way that could be made naturally? Yet. I mean, it's always the unknown unknowns. Yeah. Okay. Yeah. Very good. Very important. So on the Earth, we don't know of any other way. Okay. So they've discovered these molecules on this planet. Yeah. So we're thinking phytoplankton in an ocean. It could be. It could be. And they found much more of it at a higher concentration on that planet than we have those chemicals on our planet. Much more. I mean, 10,000 to 100,000 times higher concentration. So we're talking about a thriving biota with these microorganisms. If you believe the detection and if you believe the only way to make it is via something like phytoplankton. So, if you're a skeptic you'd have to say, let me think hard about how else you'd make it that didn't involve life, which no one has come forward yet. Well, we know of, we certainly don't have a good idea for mechanisms, but we do see DMS on comets. So the comet 67P that we landed the Rosetta mission, on that comet, which is a dead comet, you see this molecule. We certainly know it can occur in the absence of life. Whether you could ever get as much as is seen here is another question. Got it. Are the data contested and is the interpretation of the data contested? Yes and yes. I mean, this is all kind of X and Twitter reactions at this point. So there's no published article that has called out these as incorrect, but the discussion I'm seeing amongst my colleagues is, A, the significance level claimed of 3 Sigma. There is skepticism about the reality that it is as high as that. It could be that the signal within the spectrum of this molecule is not as strong as claimed. Yeah, I mean, to give you the zoom-out picture here, there's a spectrum and there's these two little bumps that look like this molecule. But when you do these searches, you have a catalogue of possible molecules you could check for. And there's boatloads of them. There's trillions of molecules you could check for, really. So they guessed initially, here's 20 molecules we think are plausible in this atmosphere, and they fit it to the data, they get a good fit. And that's actually only 2 Sigma significance for DMS, when you do it that way. Then they say, hold on, we don't think all these other molecules are there, so they strip it down to just 4 that they think are most likely. So that would boost the significance. If you do that, yes. Then they get their 3, 3 plus Sigma number. So that's where there's some skepticism. Is this kind of engineering of the number, or is this a reasonable thing to do, given the data? So let's start out with just wrapping our head around what a 2 Sigma result would be. So what's your best explanation of a 2 Sigma result? It quantifies a probability, so in that case it's 5%. So 1 in 20? 1 in 20, correct. If you did the same experiment 20 times, one of those 20 times you'd expect to get a detection, even though there's nothing there to detect. It's just a spurious result. So that's your confidence level, 95%, 5% chance of being wrong. And so you get 3 Sigma, that's 1 in 1,000 times, and 5 Sigma would be like the gold standard, and that's like 1 in 10 million. So that's the Higgs boson level of confidence that we had when that was announced, you know, with the Nobel Prize for discovery. So this is not yet 5 Sigma, it is claimed to be 3 Sigma, 1 in 1,000. It may in fact be less than that, depending on who you believe. And so that's why, you know, it's still exciting. I still think, you know, 2 Sigma is still exciting, but historically there are a lot of 2 Sigma detections that disappear under subsequent scrutiny. There's then the question of, let's assume it's true, let's assume this molecule is there, does that prove life? Which is another very challenging question to unpack. That would be the interpretation of the result being correct. Yes, correct. I mean, there are many skeptics who say even no one single molecule will ever be convincing proof of life. You can't just look at a silver bullet like this, it doesn't exist. In fact, Sarah Seager, who was the PhD advisor to Nicky Medusan, who published this paper, published a paper the next day saying exactly that. There's no such thing as a silver bullet biomarker. So it's kind of funny, the timing of these two papers came out. She's coming after a student, slapping on the wrist. I think it was coincidence these papers came out, but it was amusing to see that timing, yeah. So I think the community is skeptical, because one molecule, who knows, maybe there's some weird geology on these planets we've never seen before that's making it. One molecule by itself just isn't enough to convince us. So, what I've tried to convey, every time I'm able, is that any time scientists disagree, they're only really one of three outcomes. One is wrong and the other is right. Or that person is wrong and they're right, or they're both wrong. Usually the case. But they don't fight, they say we need more or better data. And it's the start of a continuing conversation. So, is this high on the list of JWST to make another round? I should think it will be. I mean, this is, I'm sure, going to be proposed in the next cycle, and even if you're a skeptic, I think you would want James Webb to go back and get more data and remove the ambiguity. Because, look, scientists are like everyone else, we don't like uncertainty, we don't like something being 50-50, there's life there and not there. We want to know the answers for sure. So does everybody else. We have to go back. We have to get the data and figure it out. What's the period of this planet? It's once every 33 days. That's how long it takes it to go around. It's a year around the star. Oh, okay. So, and you can only get data when it's in front of the star. Correct. So that's sort of convenient that it doesn't take a whole year. Right. And it's actually convenient that the star is, I mean, if you're in the solar system, the sun, if you're at 33-day orbit, which is closer than Mercury's orbit, you'd be scorching hot. So the fact this star is cooler means that this is actually still in the temperate zone, the habitable zone of its star, despite having a 33-day orbit. So this place counts as a cool world to you? I'd say so. I mean, it is, it's at the right distance, right, where you'd call it a cool world, far enough from its star. Cool, I mean, like... A dope world? Dope world! Yeah. Down with the kid's world. Yeah. So, this is just an overview. You're gonna, on your own platform, you're gonna do a deep dive into this and bring in warring factions. Yeah, we're gonna get some of the experts. That'll be fun to watch. We're gonna get the lead author to come in and tell me why he believes this is real. I'm gonna get a critic to come on and tell me his opinion, and then I'm gonna try and break it down for the audience. So if you want a bit more depth, that's the place to go. We will look for that. And it's coming out soon. We'll look for it. Yeah, next week. Yeah, yeah. And you can find more of David Kipping in our archives. He's visited us twice to talk about his cool world. Always a pleasure. This has been yet another What's Up With That? Life on Exoplanet. It's just the beginning. Keep looking up. Every few months, a new headline warns of an asteroid on a collision course with Earth. But how real is the risk? You'll find somewhat reliable sources emphasising the asteroid's magnitude and which countries might be spared. While other, highly credible sources reassure us there's a 98% chance we'll be fine. Exaggerated language, selective framing and misleading urgency make it easy for science reporting to veer into sensationalism. The result? More clicks, more panic and less actual understanding. And that's what makes our partners at GroundNews so different. 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