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

Nasa Space

Reporting on whether James Webb Space Telescope May Have Just Detected Alien Life at Exoplanet K2-18b. Either we found a new chemical process we've never run across before, or we found alien life.

Transcript

00:00It's always been murmured in slightly hushed tones in the scientific community that the

00:05wildly successful James Webb Space Telescope has within its capability, just barely so,

00:12the possibility to characterize exoplanet atmospheres to the level of potentially picking

00:16up a biosignature.

00:18Now burning down the media, we have a story of an increasingly solid case that JWST may

00:24have actually found one, and this detection, if validated, changes everything in regards

00:30to the question of alien life in the universe.

00:33I do not say that lightly, this may well be our first detection of alien life.

00:39This is in regards to the exoplanet K2 18b, which is a sub-Neptune world about 2.6 times

00:45the radius of earth and about 8.6 times as massive and about 124 light years distant.

00:53It's well distant enough to have never interacted with earth life, thus this would not be contamination,

00:59but a true, separate abiogenesis.

01:02This planet orbits within its star's habitable zone, and the planet receives a comparable

01:07amount to earth of solar radiation from its star.

01:11More on that in a bit, because that star is a red dwarf.

01:15The planet is on a 33 day orbit, and interestingly was another discovery of the Kepler space telescope,

01:21just like another candidate for alien life, Tabby's star.

01:25The age of the star system is about 2.4 billion years.

01:29It's worth noting that oxygen has not been detected at this exoplanet, which means that

01:34there may not be photosynthesis there.

01:37When earth was 2.4 billion, there was already photosynthesis occurring.

01:42What that means will be a matter of debate as this progresses.

01:46This exoplanet became very interesting in 2019 when water vapor was detected in its atmosphere.

01:52That could indicate that it is an oceanic world.

01:56Researchers using JWST found in 2023 that the planet also has carbon dioxide and methane

02:03in the atmosphere.

02:04Both are gases linked to life, but not solely made by life.

02:08Not by a long shot for carbon dioxide.

02:11There have been several different interpretations of the data as to the question of what this

02:16world is really like, whether it's a gas planet, like Uranus or Neptune, just smaller,

02:21or if it's an ocean planet of some sort.

02:24If a water world, this planet is a candidate for what is called a Heischen world, a hypothesized

02:30class of planet where you have a liquid water ocean existing in a hydrogen rich atmosphere.

02:36Hydrogen.

02:37Ocean.

02:38Heischen.

02:39Heischen worlds would be water worlds, with likely little or no land, and thus any life

02:45on one would be aquatic in nature.

02:48There are a number of candidates for this type of world discovered by Kepler, but K2-18b

02:53has rocketed to the top of that list.

02:56In 2023, JWST made a detection of a very interesting gas in the atmosphere of this world, dimethylsulfide,

03:04which as far as anyone knows, is only produced by life.

03:08There is a link in the description below to an Event Horizon interview I did with Dr. Niku

03:12Madhusudan on that detection.

03:16The problem is that the detection was very weak, leading to much skepticism in the scientific

03:20community as to whether this detection was actually real or just noise.

03:25The researchers at the University of Cambridge, involved, were able to get more time on JWSTs

03:31to use a different instrument to redo the measurement and if it's valid, it's staggering.

03:36The detection is now at the three sigma level, that's huge because it means that there is

03:41only a 0.3% chance that this is a random fluke detection.

03:46The detection could be one of two gases, or a combination of them both, and both are thought

03:51to be unique to biology, dimethylsulfide and dimethyl disulfide.

03:56Only further work will constrain which one it is, or if it's both.

04:01What the scientific community is going to want for this discovery, however, is a five

04:05sigma detection, because extraordinary claims require extraordinary proof.

04:10Which a five sigma detection would bring the chances of it being a fluke down to a .00006

04:17chance.

04:19That level would make this a robust detection.

04:22The team believes that they can do that, with further time on JWST, which with a three

04:28sigma detection seems very likely to happen.

04:30It's worth noting that the measurement from 2023 was done with JWST's nearest and near-spec

04:37instruments.

04:38Whereas the new detection was by the MIRI instrument, which qualifies as an independent detection.

04:44The chances are good that the observations are in fact indicating what could be a biosignature

04:49on the sexoplanet.

04:51But there is still some weirdness and reason for caution.

04:54This is not a confirmed detection of alien life, and if the observations continue to hold

04:59up, the first question scientists will ask is if the chemists can think of a way where

05:04these gases could be produced in huge concentrations without biology.

05:08Maybe this is some unknown chemical process we weren't aware of going on here.

05:14One potentially weird aspect is that this planet has on the order of 20 times higher concentrations

05:19of these gases than Earth has.

05:22Interestingly, other theoretical work indicated that Heishin worlds with life would actually

05:27have these high concentrations of these two gases.

05:30It was expected.

05:32Everything so far is consistent with a Heishin world with microbial life.

05:37I want to stress caution as always, but this is the best candidate we've ever seen for

05:42a detection of a biosphere outside of Earth.

05:45If the observations hold up, then this will be difficult to knock down.

05:49It's worth noting here that these two chemicals are linked to microbial life on Earth primarily,

05:54specifically marine phytoplankton.

05:57If this is indeed an inhabited ocean world, then an analog of that seems possible.

06:03Phytoplankton are ultimately a kind of plant, which means that further observations in infrared

06:09with much larger telescopes might allow for the detection of a vegetative red edge where

06:14plant cells on Earth become highly reflective.

06:17This probably is not possible with JWST, it's simply watching the exoplanet transit its star,

06:24with the light passing through the atmosphere, and coloring it with its constituent spectra.

06:29But in the future it may be possible to directly image the planet and look for the red edge.

06:35But there are also problems.

06:36One problem is that some thinking in astrobiology is that worlds larger than two earth masses

06:41are not good candidates for life, because at some stage gravity starts getting crushing.

06:47This may not be a problem for some microbial life, extremophiles of some sort, but it does

06:52get to be a problem for anything more complex.

06:55And that high gravity would make for some very calm oceans, at least on the surface, though

07:00it's possible that there is tidal action as the planet interacts with other members

07:04of the system.

07:06This would be a very alien world indeed.

07:08If you were able to stand on it, you would feel the titanic gravity.

07:11But if you could smell these gases, the world would smell something like cooking cabbage.

07:18And oddly the analog of life there might actually taste good, as dimethyl sulfide is a food additive

07:24with a savory flavor.

07:25You taste it in things like asparagus.

07:28But you wouldn't last long in concentrations this high, because while dimethyl sulfide

07:32is normal and present in the human body, it causes medical issues, including severe bloodborne

07:38halitosis at high levels and other medical issues.

07:42And whatever is producing these gases is a massive process, because dimethyl sulfide is

07:47short lived in atmospheres.

07:50Because whatever is doing it is replenishing it actively and on a truly huge scale.

07:56That also ticks a box for life.

07:59It can do that in principle.

08:01Some other chemical process that we aren't aware of and haven't ever come across, less

08:05so.

08:06But now to the implications of this.

08:08The planet, as I mentioned, orbits a red dwarf.

08:11This would be huge news if indeed this is a biosphere detection.

08:16Because the question of red dwarf's inhabitability has been raging back and forth for years.

08:22The argument against it is that red dwarfs, when they are young, are flare stars, meaning

08:27that they would seemingly strip off the atmospheres of their habitable zone planets early on.

08:32Because the habitable zone is so close in to the star.

08:36So far, the JWST work with the TRAPPIST-1 system has borne this out.

08:41The two innermost planets appear to have no atmospheres.

08:44K2-18b does.

08:47Other work suggested that the stellar physics of red dwarfs is such that they do not flare

08:51through equators, meaning that the flares never hit their planets, which makes them

08:55completely viable for life.

08:58If this detection is valid and life remains the simplest explanation, then that changes the

09:03landscape and answers the question.

09:06The most numerous type of star by far, 73% for the Milky Way, in the universe is indeed

09:12habitable, and 80% of them are believed to have habitable zone exoplanets.

09:18And that we saw life just 124 light years away, coupled with red dwarf habitability, would strongly

09:25imply that the entire universe teems with microbial life at least.

09:30This detection probably does not hold the potential for intelligent alien life.

09:35If it holds up, then life on earth is not alone.

09:38But then comes the sad part, if all this holds.

09:41High gravity planets like this are probably not good candidates for civilizations, and that's

09:45a good thing on two counts.

09:47The first is that they would be stuck.

09:49It's unlikely that chemical rockets or any easy means could launch from this world.

09:54They very likely would have no way to perform space travel.

09:58Which means no satellites, and so on, which would greatly hamper their development.

10:03If they could develop at all in that kind of gravity.

10:06But there is a bigger problem.

10:07Heishen worlds like K2-18b might be, are thought to be exclusively oceanic worlds.

10:16If this holds for lower gravity planets, then any complex life there would be locked in a

10:20very deep ocean.

10:22And most, not all, ocean life on earth exists near the surface.

10:28Any intelligence there would be locked in their ocean with no method of smelting metal.

10:34If the majority of inhabited planets in the universe are large Heishen worlds, then there

10:39is the solution to the Fermi paradox.

10:42Intelligent life that can leave its planet is simply very, very rare.

10:46That's a sad universe to envision indeed, because if we ever spread out into the stars and start

10:51colonizing exoplanets, then we will probably be doing a lot of rescue work when we come

10:56across locked in intelligences.

10:59We will be the uplifters that rescue the Milky Way's intelligences, providing we can

11:03figure out a way to get them off their planet.

11:06Another odd effect of this would be that if this planet is fully oceanic, then that suggests

11:11that abiogenesis can indeed happen at oceanic hydrothermal vents.

11:17Yet research on earth was starting to point to hot springs in a volcanic environment on land.

11:23That might mean that abiogenesis actually has two ways to happen, again bolstering the

11:27case that microbial life is everywhere.

11:30And with a separate abiogenesis detection, it implies that abiogenesis is not complicated

11:36however it happens.

11:38So there you have it, this may, just may be it, and we are very close to the ability to

11:44confirm the first detection of alien life.

11:47If it gets shot down, we still learn something new about how these gases can form, and how

11:52it is they can end up in the atmosphere of exoplanets like this.

11:56If this is proven, it's likely this will result in Nobel Prizes and reinforce the glory of

12:02the James Webb Space Telescope.

12:04But I leave you with this, if K-1218b turns out to not be a Haitian terrestrial type world,

12:11and indeed is a sub-Neptune gas planet, the detection of these gases gets very strange indeed,

12:18because that constrains the possible non-biological chemistry option.

12:23It removes the geology from the equation, in which case,

Category

Transcript

Recommended