clearspira wrote: ↑Thu Apr 17, 2025 2:57 pm
https://www.bbc.co.uk/news/articles/c39jj9vkr34o
This is definitely exciting news for those of us on forums such as these. The James Webb telescope has discovered molecules being produced on a nearby planet (only 124 light years which is a skip away by galactic standards) that on Earth are only produced by living organisms.
There is a big BUT here i'm afraid. This is one of those ''scientists say something, journalists say another situations''. The problem is, we only have one sample size for life and that is the Earth. There COULD be other naturally occurring sources of these molecules out there. I want to keep an open mind as much as anyone but this isn't the smoking gun that news outlets are suggesting it is.
We have also been here before and it turned out to be nothing. Excited but we haven't discovered Spock just yet.
It is another case of journalists not knowing what the fuck they are talking about and pumping a minor possibility up to a certainty for the sake of clicks and ad revenue.
First and foremost, we aren't yet certain of the detection of the molecule in question. Yes, we're 99.7% sure it's there, but from a scientist's point of view, the probability needs to be at 99.99999% before it becomes a certainty.
Second the planet in question is about 2.5 times the size of Terra, has a thick hydrogen atmosphere and orbits a red dwarf just barely inside it's "habitable zone". That means, no oxygen and a constant bombardment by heavy radiation, while constantly being on the threshold of a runaway greenhouse effect. We also suspect, that the planet is covered by a liquid water ocean, so there is the distinct possibility of anaerobic life existing safely shielded from radiation by the water layer, akin to the colonies of life existing around Black Smokers here on Earth. However, the production of the bio-marker molecule that was detected, does specifically
not coincide with hydrogen-rich environments here on Terra.
And third, the amounts of the molecule found in this study is thousands of times higher than you'd expect to find here on Terra, if it were produced by life.
To sum up: We aren't certain we found it and even if it is there, it's there in amounts that are atypically high for bio-production and if there is life on K2-18b, it very likely wouldn't be of the kind that produces dimethyl-sulfide here on Terra.
And to drive that point home: The primary organisms which produce dimethyl-sulfide here on Earth, is (phyto)plankton, the very kind of life that likely produces more oxygen than forests and is primarilly responsible for the "Oxygen Catastrophe" or the "Great Oxidation Event" or the "Oxygen Holocaust" (called so for good reason). This was the mass extinction event about 2.4 billion years ago that killed off over 80% of the then-current biosphere, which almost solely consisted of anaerobic life. It is easy to forget, how agressively reactive and corrosive free oxygen molecules are, because it's so mundane to us, even being the basis of our very existence, but this free oxygen is antithetical to a biosphere like the one you would expect to exist on K2-18b (yes, we live on a Death World). To produce the amounts of dimethyl-sulfide presumably observed on K2-18b (compared to Terra's production), you'd have to postulate a biosphere that is heavy and I mean HEAVY on oxygen production to a degree, that is several magnitudes beyond what happened during the Oxygen Catastrophe and you'd see that reflected in the atmosphere of the planet, because you could expect oxygen-concentrations beyond 30-40% within the atmosphere, something which isn't exactly congruent with an atmosphere that consists almost solely of hydrogen for obvious reasons (H2 + O = H2O = loads of rain = no H2 in the atmosphere in appreciable amounts...). So, if there's life on K2-18b, it's nothing like we know it from here, but we're using a molecule as a marker that is only typical for life as we know it from here. There's an obvious breaking point in that logic. Not impossible, but rather unlikely.