Serious question: Can some science person here give me the more realistic answer on the possibility of life on K2-18b? Because the media always assumes the coolest possibility.
The paper says it has a 3 sigma chance of life given the compounds assuming their methodology is good, scientific proof requires 5 sigma. Its a difference between 99.7% accuracy and near 100% accuracy, kind of important though when we’re talking about shit we have no clue about and can’t observe by conventional means.
It should be noted that the majority of the citations on the paper are the same guy citing himself. I’d take it with a grain of salt until other people can corroborate it. Most other papers say the planet is a hot, small mini-Neptune gas planet with rings probably, maybe a warm enough atmosphere for life. The compounds measured are basically related to farts and decaying plant matter in a hot environment, should smell like mexican food a bit. In a comparison, the planet should have about 20-1000x more plant-fart compounds than we do, some people argue this is evidence of early algal/bacterial growth like on earth’s oceans.
Basically had to do with standard deviations, for something to be very certain it needs to be beyond 99.7% on accurate equipment.
In the social sciences, a result may be considered statistically significant if its confidence level is of the order of a two-sigma effect (95%), while in particle physics and astrophysics, there is a convention of requiring statistical significance of a five-sigma effect (99.99994% confidence) to qualify as a discovery.
The whole incel thing of a sigma male is supposed to be a male that is in the top percentage of males, thats the whole joke.
It’s ultimately going to take multiple lines of evidence. Yes, there are compounds that we think are strong indicators of life; we don’t know how to explain them except for life. However, we can never rule out some other abiotic origin for that compound exists that we simply haven’t discovered yet. We don’t know what we don’t know. Abundant life however is likely to cause all sorts of these biosignature compounds to be present in an atmosphere. If we find a planet with many of these compounds, we’ll have many independent lines of evidence pointing at life being present there. That is how we are likely to finally accept that life has indeed been detected.
Another pathway that may result in the acceptance of a detection of life is us learning more about the origins of life. It’s possible as we learn more about how life started on Earth, we will discover that mechanisms to get it going make it a near inevitability where the necessary conditions exist. That would make its detection much easier to accept.
They used telescopes to infer that this planet has a specific molecule on it that is known to be made by life on earth and not en masse by any other process.
IMO this is a stretch because life on another planet probably has somewhat different chemistry. There is a massive unfounded bias in all pop exobiology that finding other life means finding stuff just like life on earth.
Which is not to say it isn’t neat but it is literally another planet light years away. We know almost nothing about it.
IMO this is a stretch because life on another planet probably has somewhat different chemistry.
Astronomers are aware of this possibility. But because chemistry as such is pretty certain to be the same everywhere in the universe (confirmed, for instance, by stellar spectroscopy), we can study chemistry in the laboratory to understand the conditions under which chemicals are made. The more we understand chemistry, the smaller the set of unknown abiological methods of producing “biosignature” chemicals and the more certain we can be that a chemical was produced by something biological in origin. I mean yeah, we can say forever that we don’t know everything (that will always be true) but there are some things that we do know pretty damn well enough.
Yes but it’s actually the opposite of what to look for, understanding evolution. Evolution is historically contingent - it only builds on what it already has. Life on earth has billions of years of a semi-random walk on which life was built. If you replayed it under slightly different conditions you would expect to see something quite different.
For example, we depict aliens as humanoid in fiction, mostly so we can tell storoes. The more imaginative writers might make them look reptilian or something. But there’s no reason to think they would even have bilateral symmetry. Or have cells. Or live on the same spatial or temporal scale. The same applies to biochemistry.
It’s understandable that people would want to look for the familiar to look for life, but our own knowledge of how life on earth operates tells us that we need to look for something fairly unfamiliar.
even so, we can’t really look for what we don’t know to look for. if we take spectra from a billion exoplanets we’d definitely recognize something very similar to ours if that happened to exist in the set.
you drop your phone at night and look for it where the streetlight illuminates because you can’t see in the dark
The problem here is that we don’t know you dropped your phone. Instead of a phone it might be a pool of jelly or an entire asteroid or a lichen thing that eats methane and only lives on the absolute best, truly primo rocks. So when you illuminate it you go, “aww man it’s just a rock!” and move on. And you already know other life isn’t going to be a phone, that’s something for humans in particular. You need to look for the rock dwellers, they are more likely than the phone-havers.
One also has to make peace with the fact that we may not know if there is life in other solar systems for a very, very long time. It probably requires making an actual visit and sending back results. And that would likely take hundreds of thousands of years in our small neighborhood of systems. We can imagine getting really good telescopes before that, I suppose, but they would probably have limits. As in, with what resolution could we make observations via a constellation of telescopes distributed around the solar system? So we can get much better spatial resolution to ask the most important question: is there metabolism?
The problem here is that we don’t know you dropped your phone.
sure maybe it’s in your pocket. the point of the analogy is that you look where you can see, i.e. with bias, not that we’re looking for evidence of silicon fabrication.
i’m not sure what you mean, biases aren’t true or false they’re a thumb on the scale. we know what we look like, we would instantly recognize something that looks like we do but that’s separate from how likely it is for something else to look like earth life or whether there’s anything to find at all.
It makes sense to me why they’d look at stuff that indicates life on earth though, because we don’t yet know what causes life to form, all we have is Earth life. We know life can form on planets like Earth because, well, it has.
Even then, evolution is historically contingent. If you rewound and replayed the tape of life on earth and changed a few early conditions, you’d end up with a very different story. Evolutionary biology teaches us that life on other planets should be different from us more than similar. This also applies at the biochemical level.
It’s understandable that people take your logic and run with it, but it rapidly clashes with evolution. In addition, we don’t actually know what conditions are necessary for abiogenesis (probably not just one kind). Even on our own planet! We know there wasn’t much atmospheric oxygen at the time. And possibly not that much water. Yet exobiologists look for oceanic planets with atmospheric oxygen because that’s what we have. Sure, oxygen is a good electron receptor and can be produced from water (in our case, chlorophyllic photosynthesis), but there is mo reason to think photosynthesis would evolve the same way independently. Exactly the opposite, actually. It should be different. No reason to think there would even be proteins. The chemistry would be very different. And it took over a billion years for chlorophyllic photosynthesis to evolve on earth!
Serious question: Can some science person here give me the more realistic answer on the possibility of life on K2-18b? Because the media always assumes the coolest possibility.
The paper says it has a 3 sigma chance of life given the compounds assuming their methodology is good, scientific proof requires 5 sigma. Its a difference between 99.7% accuracy and near 100% accuracy, kind of important though when we’re talking about shit we have no clue about and can’t observe by conventional means.
It should be noted that the majority of the citations on the paper are the same guy citing himself. I’d take it with a grain of salt until other people can corroborate it. Most other papers say the planet is a hot, small mini-Neptune gas planet with rings probably, maybe a warm enough atmosphere for life. The compounds measured are basically related to farts and decaying plant matter in a hot environment, should smell like mexican food a bit. In a comparison, the planet should have about 20-1000x more plant-fart compounds than we do, some people argue this is evidence of early algal/bacterial growth like on earth’s oceans.
If the other papers are right about the pressure of the atmosphere the water on the planet would behave quite differently than here. https://en.wikipedia.org/wiki/Supercritical_fluid
what is a sigma
https://en.wikipedia.org/wiki/68–95–99.7_rule
Basically had to do with standard deviations, for something to be very certain it needs to be beyond 99.7% on accurate equipment.
The whole incel thing of a sigma male is supposed to be a male that is in the top percentage of males, thats the whole joke.
There’s a strong clue but it will take more investigation before we know one way or the other.
It could be decades before we are fully confident in either direction (could be less than that), but it’s an exciting prospect.
It’s ultimately going to take multiple lines of evidence. Yes, there are compounds that we think are strong indicators of life; we don’t know how to explain them except for life. However, we can never rule out some other abiotic origin for that compound exists that we simply haven’t discovered yet. We don’t know what we don’t know. Abundant life however is likely to cause all sorts of these biosignature compounds to be present in an atmosphere. If we find a planet with many of these compounds, we’ll have many independent lines of evidence pointing at life being present there. That is how we are likely to finally accept that life has indeed been detected.
Another pathway that may result in the acceptance of a detection of life is us learning more about the origins of life. It’s possible as we learn more about how life started on Earth, we will discover that mechanisms to get it going make it a near inevitability where the necessary conditions exist. That would make its detection much easier to accept.
Put stronger telescope in space now I need to see it for myself
They used telescopes to infer that this planet has a specific molecule on it that is known to be made by life on earth and not en masse by any other process.
IMO this is a stretch because life on another planet probably has somewhat different chemistry. There is a massive unfounded bias in all pop exobiology that finding other life means finding stuff just like life on earth.
Which is not to say it isn’t neat but it is literally another planet light years away. We know almost nothing about it.
Astronomers are aware of this possibility. But because chemistry as such is pretty certain to be the same everywhere in the universe (confirmed, for instance, by stellar spectroscopy), we can study chemistry in the laboratory to understand the conditions under which chemicals are made. The more we understand chemistry, the smaller the set of unknown abiological methods of producing “biosignature” chemicals and the more certain we can be that a chemical was produced by something biological in origin. I mean yeah, we can say forever that we don’t know everything (that will always be true) but there are some things that we do know pretty damn well enough.
it’s a bias sure but the more similar the life is to us the easier it would be to recognize in the spectrum shit
Yes but it’s actually the opposite of what to look for, understanding evolution. Evolution is historically contingent - it only builds on what it already has. Life on earth has billions of years of a semi-random walk on which life was built. If you replayed it under slightly different conditions you would expect to see something quite different.
For example, we depict aliens as humanoid in fiction, mostly so we can tell storoes. The more imaginative writers might make them look reptilian or something. But there’s no reason to think they would even have bilateral symmetry. Or have cells. Or live on the same spatial or temporal scale. The same applies to biochemistry.
It’s understandable that people would want to look for the familiar to look for life, but our own knowledge of how life on earth operates tells us that we need to look for something fairly unfamiliar.
even so, we can’t really look for what we don’t know to look for. if we take spectra from a billion exoplanets we’d definitely recognize something very similar to ours if that happened to exist in the set.
you drop your phone at night and look for it where the streetlight illuminates because you can’t see in the dark
The problem here is that we don’t know you dropped your phone. Instead of a phone it might be a pool of jelly or an entire asteroid or a lichen thing that eats methane and only lives on the absolute best, truly primo rocks. So when you illuminate it you go, “aww man it’s just a rock!” and move on. And you already know other life isn’t going to be a phone, that’s something for humans in particular. You need to look for the rock dwellers, they are more likely than the phone-havers.
One also has to make peace with the fact that we may not know if there is life in other solar systems for a very, very long time. It probably requires making an actual visit and sending back results. And that would likely take hundreds of thousands of years in our small neighborhood of systems. We can imagine getting really good telescopes before that, I suppose, but they would probably have limits. As in, with what resolution could we make observations via a constellation of telescopes distributed around the solar system? So we can get much better spatial resolution to ask the most important question: is there metabolism?
sure maybe it’s in your pocket. the point of the analogy is that you look where you can see, i.e. with bias, not that we’re looking for evidence of silicon fabrication.
The bias is incorrect, though
i’m not sure what you mean, biases aren’t true or false they’re a thumb on the scale. we know what we look like, we would instantly recognize something that looks like we do but that’s separate from how likely it is for something else to look like earth life or whether there’s anything to find at all.
It makes sense to me why they’d look at stuff that indicates life on earth though, because we don’t yet know what causes life to form, all we have is Earth life. We know life can form on planets like Earth because, well, it has.
Even then, evolution is historically contingent. If you rewound and replayed the tape of life on earth and changed a few early conditions, you’d end up with a very different story. Evolutionary biology teaches us that life on other planets should be different from us more than similar. This also applies at the biochemical level.
It’s understandable that people take your logic and run with it, but it rapidly clashes with evolution. In addition, we don’t actually know what conditions are necessary for abiogenesis (probably not just one kind). Even on our own planet! We know there wasn’t much atmospheric oxygen at the time. And possibly not that much water. Yet exobiologists look for oceanic planets with atmospheric oxygen because that’s what we have. Sure, oxygen is a good electron receptor and can be produced from water (in our case, chlorophyllic photosynthesis), but there is mo reason to think photosynthesis would evolve the same way independently. Exactly the opposite, actually. It should be different. No reason to think there would even be proteins. The chemistry would be very different. And it took over a billion years for chlorophyllic photosynthesis to evolve on earth!
Recent takes are more sceptic. Besides its not a confirmation of life, just a 3 sigma detection of DMS.
This is one of the legit, actually promising announcements. But still only at the “follow up for more clues” stage.