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On DMS:
- DMS is a very specific configuration that’s rarely the endpoint of non-living chemical cycles.
- The simplicity of DMS doesn’t make it less indicative of life—it actually makes it a very selective molecule, which only shows up in large quantities when life is involved (at least in Earth-like chemistry).
- Until we find a compelling abiotic pathway, high DMS remains a strong biosignature, especially in the context of a planet with a potential ocean and mild temperatures
Possible origins:
We’re looking at some form of life that can:
- Thrive in a hydrogen-rich atmosphere
- Possibly live in or on top of a global ocean
- Generate large amounts of DMS—potentially thousands of times more than Earth
The closest Earth analogy is:
- Marine phytoplankton, particularly species like Emiliania huxleyi, produce DMS as a byproduct of breaking down DMSP, a molecule they use to regulate osmotic pressure and protect against oxidative stress.
- If something similar is happening on K2-18 b, we’d be talking about an ocean teeming with such microbes—perhaps far denser than Earth’s oceans.
Possibly "Giant photosynthetic mats" or sulfuric "algae"
If there’s some landmass or floating structures, maybe the DMS producers are:
- Photosynthetic, sulfur-metabolizing analogues to cyanobacteria
- Living in dense floating colonies or mats like microbial reefs
- Using dimethylated sulfur compounds in their metabolism, and leaking DMS as waste or signaling molecules
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Of course there have been lots of ocean planets in sci-fi literature, but I'm most reminded of the "Pattern Juggler" Planet Ararat from Alastair Reynolds' "Revelation Space" series.
This is incredibly exciting news!
Firstly that is completely badass science. The idea that you can use observations to detect the chemical composition of an exoplanet millions of kilometres away is an absolute triumph of the work of thousands of people over hundreds of years. Really amazing and deeply humbling to me. Secondly, my prior was always that life existed outside of earth. It just seems so unlikely that we are somehow that special. If life d…
Earlier quoted context omitted.
If life is very common in the universe, then that is probably bad news for us. It means that civilizations should exist that are millions of years more technologically advanced than us; and should be leaving telltale signatures across the sky that we'd likely have detected by now. And the absence of those signs would be relatively strong evidence that life, while common, isn't long-lived. Suggesting that our demise t…
You seem to be conflating life, multicellular life, and intelligent life. Life appears to have developed on Earth pretty quickly, multicellular life took a long time to appear, and we are only aware of one species that developed civilisation building capabilities. Life might be very common, but intelligent life still be incrediblY rare.
Firstly that is completely badass science. The idea that you can use observations to detect the chemical composition of an exoplanet millions of kilometres away is an absolute triumph of the work of thousands of people over hundreds of years. Really amazing and deeply humbling to me. Secondly, my prior was always that life existed outside of earth. It just seems so unlikely that we are somehow that special. If life d…
The only place we know for sure life exists on is Earth. You can't reason about the likelihood of life existing elsewhere with a sample of N=1.
Earlier discussion: https://news.ycombinator.com/item?id=43711376
How far off are we from being able to image an exoplanet?
This is happening 124 light years away from earth. That means if we develop a way to make a space ship accelerate at 1g for a long period of time, you could go there in just 10 relativistic years. Unfortunately, whilst science allows such a rocket, our engineering skills are far from being able to build one.
Calling it simply an engineering issue is not properly conveying the ridiculousness of such a journey. For a small space ship of 1000 tons, this would take ten thousand times the current yearly energy consumption of mankind. So we'd need to figure out how to generate the energy and then store it on a space ship before even thinking about the engineering. And that's ignoring the mass of the fuel. The classical rocket…
This made me think that F = G((m1m2)/rr) is good enough to go to the Moon, but not good enough to give us GPS.
Maybe some discovery could help us build antimatter drives one day.