They have a new preprint that argues that Assembly theory can explain and quantify selection and evolution in complex systems: https://arxiv.org/abs/2206.02279 (I think that it is one of the more under-appreciated papers out there).
You don't really need to detect organic molecules. If anyone detected 21% oxygen (O2, inorganic) in Earth's atmosphere, they sure knew something was going on. Lifeless planets like Venus, Mars, have atmospheres that are close to chemical equilibrium. And Earth's atmosphere is far from equilibrium, free oxygen it much too reactive and wouldn't exist without photosynthesis continuously producing it.
Our understanding of astrochemestry is still limited enough, that we cannot say with confidence that a given signature requires a biotic process to produce.
It will always be possible to find a new extreme edge case to deny far easier and more common processes that leave around biosignatures, it's the exact same rhetoric used to handwave away the methane in the martian atmosphere.
There are lots of natural objections to this statement (eg civilizations that "hide") and a lot of these has gone into these explanations for the Fermi Paradox. It can be shown that such a structure has massive benefits, the biggest of which is energy (which is our ultimate limiting factor). If there's 1 other civilization in our galaxy then we can't really guess what they'll do. If there are 1000 civilizatiions then what are the chances that none of them go this route, given if there's even one there's a reasonable chance we could detect it? It starts to stretch credulity.
That's the entire point of the headline. Scientists are forced to search for 'wunderwaffe' solutions to make these observations.
Unfortunately large objects emitting a lot of total energy in infrared don't stick out like a sore thumb. It's very difficult to distinguish a Dyson swarm from a Dyson swarm sized ball of Dyson swarm temperature gas and dust, which is a reasonably commonplace phenomenon. Indeed for one of the simpler construction methods, a dyson swarm may essentially be a big ball of dust where each mote is a solar energy collector. Further, over long time scales without active maintenance you'd expect dyson swarms to break down into literal clouds of gas and dust. While dyson swarm candidates might be good places to focus other SETI experiments like radio telescopes, it's unlikely that the thermal signature of the swarm alone would ever be unambiguously artificial.
This whole line of thinking is short sighted. For example "No magic theorized materials are required;" but we literally WILL have 'magic' materials in the future. Of course we can't predict the things we don't have yet, but assuming we'd just move in some linear line from where we are is probably unlikely.
Why build and pay for a complex life support system in space when… I’m living on a really big and really good one for free? It doesn’t seem like we’re going to run out of space for people, so why expend resources making mediocre space environments for people to live on, except for certain narrow purposes?
[edit] I think the problem becomes obvious if one considers colonizing the oceans with big ships and floating platforms. We haven’t really done it, and it’s hard to imagine why we would—it’s just so much more expensive and less convenient than living on land. Space is like that, except all the bad parts are even worse. What do we have on the oceans? Resource-gathering operations, shipping, exploration ships. I don’t see why space would see more colonization than the oceans have (which is nearly zero, mostly temporary purpose-specific habitation and movement across it to land)
I’d include Mars and such as places much worse and more expensive to colonize than the oceans. I don’t see it happening any time soon—why would it?
Dinosaurs lived for 100+ million years on Earth, then boom, extraterrestrial events extincted them. As an intelligent species (somewhere above dinosaur/ape intelligence) eventually you discover that planets and stars are unstable. You are not living in harmony with nature. Nature is just temporarily not killing you. Now you've further pushed the question to "Does an intelligent species accept its eventual planetary extinction".
It doesn't matter what many do. For example with bacteria it only takes a single cell to make a single change to become the dominant form of that species in some number of generations if it gives them a evolutionary advantage.
Our current rate of energy consumption is unsustainable. This is a problem no matter how you want to live (unless you want the entire civilization to go primitive). This is a problem.
> This whole line of thinking is short sighted.
That's a strange assertion. It's a really long term solution, like billions of years long.
As for your magic materials, I hate this kind of argument. It's really just hand-waving "we don't know what we don't know". But we do know physics and we know we need energy. That energy has to come from somewhere. We can't just make it up from nothing. So far the only viable long-term energy options we have are solar power and nuclear power (particularly fusion). There are some far future options like antimatter and using black holes but these don't actually solve the energy problem. They just make really great batteries (eg to have antimatter you have to make it and that takes energy).
This is presently true. My point is that it's a conservative estimate to say we'll be capable of it within the next 1000 years. Our biggest issue currently is the high cost of getting payloads into LEO. For Apollo and the Space Shuttle that cost was ~$50,000/kg. Factoring in reusability it's now estimated to be $1000/kg or less. There are paths to get this much lower (eg <$10/kg).
Mercury has specific issues and advantages. The biggest advantages are access to energy, high orbital velocity and no atmosphere. A thin atmosphere like on Mars is the worst of both worlds. It really just makes landing difficult and creates dust storms to cover your equipment in dust.
The high orbital velocity of Mercury is both an advantage and a disadvantage. It makes it really difficult to get there, which is why there have been relatively few missions there, but once you are there, it means the delta-V of getting anywhere else in the Solar System is quite low, whether that be finished products or just raw materials.
Mercury is metal rich but probably lacks elements like oxygen for, say, smelting steel (and, of course, living). The long day/night cycle is an issue too.
My point in relating the mass requirement to Mercury is because, even though 1% of Mercury is still a lot of mass, it would still leave Mercury relatively intact. It's also metal-rich.
I had another vision, informed from science fiction. It was that we could send relatively small machines (self replicating using local materials on the asteroid) and they could do everything we want after we figure out the replicating w local materials part. And because we only need to send a small starter robot it doesn't use that much energy.
What do you think of that? I mean we could do the same with materials to process them on Mercury.
There's no resources up there. Where do you get the water from? Where do you get the materials from?
Unless you have a close, cheap source to replace and replenish, this is a pipe dream.
The future of humanity is likely to be in orbitals. With existing materials these are likely to be 2-3 miles in diameter and 10-20 miles in length, producing EArth-like gravity by simply spinning. You then cover the surface with solar panels. If graphene ever becomes viable as a mega-engineering material, you can scale these up 100x+ larger. Why? Lots of advantages:
1. You can produce this with existing materials. No magic theorized materials are required;
2. No magical new technology is required. Even something like nuclear fusion power generation, which I'm not yet convinced will ever be commercially viable, isn't required;
3. Spin gravity is identical to normal gravity. Earthlike gravity means we don't have to worry about our ability to live in microgravity or even low-G (eg Moon, Mars);
4. You can largely be shielded from cosmic radiation with water tanks beneath your feet;
5. You get to harness the full output of the Sun for energy. For reference, only about one billionth of the energy of the Sun hits Earth. This is a Dyson Swarm;
6. This is incredibly efficient in creating living space per unit mass. Roughly 1% of Mercury's mass is enough to create a Dyson Swarm with billions of times of the living area of Earth.
So, by looking for technological signatures from exoplanet atmospheres we're essentially hoping to find the ~1000 year window where there are detectable signals and we're not looking for a Dyson Swarm instead. SETI has the same problem with a much smaller window.
So why is this much easier to detect? Because of thermodynamics. You absorb a star's light output and you heat up in anything less than perfect energy efficiency (which is impossible). The only way to dispose of heat in space is to radiate it away. Technically you could eject mass but then you have to replace that mass. And the frequency of the radiated heat is determined by the temperature of the radiating object. For any reasonable temperature, that's in the IR range.
The Sun is less than a million miles in diameter. If we were looking for a Dyson Swarm around a star like our Sun, we'd see an object that was more than 200 million miles across (ie the cloud of orbitals) that is producing much of that energy as infrared. It would stick out like a sore thumb.