it is until it isn't.
this post was submitted on 10 Oct 2025
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As a guy taking the "Great Filter" hypothesis seriously, I would definitely switch the captions in the meme.
Please explain. I’m way too stupid.
my guess: there is an exoplanet, K2-18b, that was discovered to have an abundance of detectable biosignatures in its atmosphere. at the time, there wasn't much in the way of another explanation that didn't involve life. however, astronomers recently found a failed star that is filled with biosignature molecules.. so.. ah lol. now perhaps K2-18b has another explanation after all.
edit: please read Legianus' response to this
So much Astronomy drama!
Would be funny if that failed star was actually an alien megaproject but we think it's a natural explanation that means a planet teeming with ancient life is assumed to be barren like the rest of them.
Is there a name for that, when something very interesting is mistaken for something very uninteresting? Not that a failed star full of biosignature molecules sounds uninteresting, do they have any explanation for that?
Astronomer here, the "life detection" on K2-18b was dimethyl sulfide (DMS) which may be ̶I̶s̶ ̶a̶n̶d̶ ̶r̶e̶m̶a̶i̶n̶s̶ a marker for life. What you get from the James Webb Space Telescope (JWST) is raw data that needs to be treated and calibrated to some extent to be usable in scientific study. This is called data retrieval.
However, the lead scientist on this paper claiming they found DMS basically used his own very specific way to do it and found very very weak signals in that way. Other scientist tried to both reproduce it in the way he did it and also with their ways to retrieve the data, but couldn't find anything. So it turns out, it was simply a non-detection.
Edit: It might be the case that DMS can be produced abiotically (scientific works of this year) as chosensilence pointed out correctly.
My main point is, that the DMS detection itself was a non-detection in this case
also, may i ask a question? you say "is and remains" a marker for life. i am not well read about these things, is that because DMS is only observed as a biosignature here on Earth, or are you saying it couldn't possibly have a nonbiological origin?
Sure. Generally, it is a marker for life as we see it being produced by living organisms on Earth (e.g. Algae) and it also should vanish quickly from atmospheres if it is not replenished.
However, as you correctly put it, there may always be a non-biological explanation as well for any of these markers, which we might not know as of yet. So far as I know, DMS has no non-biological explanation and is seen as a biological marker still.
Alas, the possibility of it being proven non-biological or even (as happend here) not a real detection makes it even more important to get more data and be very careful about the statements made from it than as otherwise those statements and/or connected papers have to be corrected/retracted. And if these then reach the public (and why wouldn't they with the possibility of alien life) then this could diminish the trust in science if it turns out to be wrong.
Edit: I had a look and as you stated for DMS there may indeed be abiotic ways to produce it (scientific works from this year). They found it in comets and could reproduce it in labs as well.
My main point of the original comment was to add that the detection (paper) itself was flawed. Regardless of DMS being a sign of life.
oh hey, wonderful. thank you!
John Michael Godier will be disappointed
Methane in Earth's atmosphere mostly come from cow farts.
Methane in other atmospheres, as far as we know, doesn't come from alien cow farts.
There's a bunch of stuff that's made by life, but it can also be made by not-life.
I believe the alien cow fart theory!
Burps primarily as far as the cows are concerned. Mostly just cow pies are coming out the other end.
Look for free Oxygen, the only reason it sits around is because of life. Sure, there are lots of forms of life that won't show up that way, but if you do see it, you know you found life.
Many elements up to iron and nickel can be produced from supernovae, including oxygen. And I’m pretty sure a supernova isn’t a very habitable place…
Just about every element comes out of a super nova. By the time it's around a planet, Oxygen has made friends, usually Hydrogen, so it's no longer free molecules.
Oxygen can make friends with other oxygen, no? O2. It isn’t only produced by biotic means…
Also, not every element comes out of a supernova. Elements that are heavier than iron and nickel are created when neutron stars merge! Very cool. Not to mention all the manmade elements…
o2 isn't as stable as most molecules containing oxygen. Free o2 oxidizes damn near everything, so it doesn't last in an atmosphere without a new source. Take a look at the solar system. Every planet has oxygen, none of it is o2 outside of earth.
O2 could be produced by abiotic means, the source isn’t necessarily life. It could be, but it’s probably not. Looking for life isn’t as simple as finding oxygen, otherwise it would be way too easy, there’s a bunch of other biosignatures and signs of habitability to look for.
Except o2 is only produced in volume by a nova. Which isn't happening on a planet.
A quick search shows that there’s many studies on abiotic ways to produce O2 in terrestrial planet. From good sources too, not just your random Joe. Hence, we need to look at other factors too, not just oxygen.