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“Most promising signs yet” of alien life on a planet beyond our Solar System

skyatnightmagazine.com

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Re: “Most promising signs yet” of alien life on a planet beyond our Solar System

#251

Post by perihelions »

perihelions wrote: post #146
weberer wrote: post #5

Here's the primary source https://iopscience.iop.org/article/10.3847/2041-8213/adc1c8 They possibly detected dimethyl sulfide, which is only known to be produced by living organisms.

I'm not convinced about the methods. It looks a lot like p-hacking to me: they have a highly specific hypothesis drawn from a large universe—that dozen or so molecules (§3.1) in their infrared spectrum model they're fitting experimental data against. I don't buy the way they created that hypothesis. The put a handful of highly specific biosignature gases into it, things that were proposed by exobiology theory papers.…

I'm going to double-down on my stubborn, unpopular opinion. This is my best attempt at explaining my criticism:

- Alien metabolites are a low-prior probability hypothesis. Dimethyl sulfide is a long-postulated biosignature with no natural source, so, it's low-prior

- The paper's model fits Webb data—a handful of photons—against no more than 20 candidate molecules, combined across all of their atmospheric models. Many of those gases are drawn from that low-prior "alien metabolite" class

- There's a much larger class of strongly infrared-absorbing gases, that can naturally occur in planetary atmospheres. Beyond those included in the 20 candidates. These (should!) have higher prior probability of occurring in Webb data than alien metabolites. (This class is so large and complicated, there's major spectral features in our own solar system's gas planets we haven't characterized yet)

- If you were to fit Webb data against that expanded class, those alternative hypotheses, you'd get a large number of 3-sigma detections by pure chance.

- The Webb data is too weak to distinguish between these. With only a few bits of information, you can distinguish between only a small set of alternative hypotheses

- This paper elevates the alien-metabolite hypothesis very highly, and that is why when it has a spurious statistical detection, it happens to be an alien metabolite detection. Because that hypothesis is overrepresented in their model

- The root problem is that since there's only a trickle of real data from this exoplanet, from Webb, it's unlikely one can infer anything super interesting from those few bits

Re: “Most promising signs yet” of alien life on a planet beyond our Solar System

#253

Post by lupusreal »

energy123 wrote: post #180
lupusreal wrote: post #153

Earlier quoted context omitted.

Being intelligent doesn't necessarily lead to runaway technological development. Dolphins are smart but they're never going to invent radios to broadcast their existence to other star systems. They're stuck in the water and don't have thumbs. And even orangutans, who have thumbs and live on land, don't seem tracked for technology even if humans weren't around; their ecological niche is small even if we assumed humans…

Nevertheless, if abiogenesis is common & intelligence is easy for evolution conditional on abiogenesis, the number of explanations for the Fermi Paradox just shrunk by a great deal, increasing the probability of the remaining explanations.

I doubt there is one single grand answer for the Fermi Paradox. Probably it's lots of smaller blockers which all stack up with each other. The chance of life forming, the chance that it becomes multicellular, the chance that it develops complex nervous systems, intelligence, the physiological hardware for tool use and creation, not stagnating or getting wiped out, having the inclination to look out and broadcast their existence, the chance that they survive long enough while doing this to exist at the same time as another civilization of comparable development, etc. It's easy to come up with these and even if they all have modestly small probabilities each, together they stack up to a plausible answer to the so called paradox.

Re: “Most promising signs yet” of alien life on a planet beyond our Solar System

#254

Post by diggan »

lupusreal wrote: post #153
energy123 wrote: post #144

Earlier quoted context omitted.

This is now much less plausible. Intelligence, like eyesight, is believed to be a result of convergent evolution[0]. [0] https://www.quantamagazine.org/intelligence-evolved-at-least...

Being intelligent doesn't necessarily lead to runaway technological development. Dolphins are smart but they're never going to invent radios to broadcast their existence to other star systems. They're stuck in the water and don't have thumbs. And even orangutans, who have thumbs and live on land, don't seem tracked for technology even if humans weren't around; their ecological niche is small even if we assumed humans…

> Dolphins are smart but they're never going to invent radios to broadcast their existence to other star systems.

How could we possibly know this? The only case of "Dolphins" we know of, is on Earth, with the interference of humanity, and we're looking at Dolphins at a really small timescale.

Given N thousands of years without interference from other species, who can really confidently tell exactly how Dolphins would evolve?

Re: “Most promising signs yet” of alien life on a planet beyond our Solar System

#255

Post by Loughla »

lordnacho wrote: post #178
lupusreal wrote: post #153

Earlier quoted context omitted.

Being intelligent doesn't necessarily lead to runaway technological development. Dolphins are smart but they're never going to invent radios to broadcast their existence to other star systems. They're stuck in the water and don't have thumbs. And even orangutans, who have thumbs and live on land, don't seem tracked for technology even if humans weren't around; their ecological niche is small even if we assumed humans…

We don't even need to look at other species. Humans have been just as smart as you and me, maybe even smarter according to cranial measurements, without inventing anything that significantly changed their way of life. There could be loads of planets with prehistoric humans, having a fine time hunting with bows and picking fruit.

I don't think so, though. I think that unless there are limiting factors (no ores or some other necessary component) life would tend toward technology.

Curiosity as an evolutionary trait is quite an advantage, and I would think is necessary for intelligent omnivores. It's what helped us figure out what we could and couldn't eat, and taught us better techniques for living. Curiosity naturally leads to technological developments, I would argue.

Re: “Most promising signs yet” of alien life on a planet beyond our Solar System

#256

Post by lupusreal »

diggan wrote: post #254
lupusreal wrote: post #153

Earlier quoted context omitted.

Being intelligent doesn't necessarily lead to runaway technological development. Dolphins are smart but they're never going to invent radios to broadcast their existence to other star systems. They're stuck in the water and don't have thumbs. And even orangutans, who have thumbs and live on land, don't seem tracked for technology even if humans weren't around; their ecological niche is small even if we assumed humans…

> Dolphins are smart but they're never going to invent radios to broadcast their existence to other star systems. How could we possibly know this? The only case of "Dolphins" we know of, is on Earth, with the interference of humanity, and we're looking at Dolphins at a really small timescale. Given N thousands of years without interference from other species, who can really confidently tell exactly how Dolphins would…

We've had at least two developments of ""dolphins"" that I know of. We also have other intelligent sea life, like squids and octopuses, who've been around for a hell of a long time and are on track to never develop advanced tool creation and use. Living in the water is a massive tech nerf.

Re: “Most promising signs yet” of alien life on a planet beyond our Solar System

#257

Post by pc86 »

ta8645 wrote: post #18
seanhunter wrote: post #6

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…

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…

It's extremely likely that our demise will come before too long.

The problem is that "before too long" is on a universal timescale, not a human timescale.

Humanity could exist for a million times longer than it already has, expand to other planets in our solar system and even to another solar system or two, be wiped out completely, and on the appropriate timescale we were absolutely "short lived."

Re: “Most promising signs yet” of alien life on a planet beyond our Solar System

#258

Post by floatrock »

ta8645 wrote: post #45
Philip-J-Fry wrote: post #34

Earlier quoted context omitted.

Say another human-like civilisation existed and was more technologically advanced, what sort of tell-tale signs do you expect to see?

Scientists use the term "technosignatures", which you can google for more info. But broadly: radio signals, infrared from megastructures, optical signals like laser pulses. We haven't put a huge amount of effort in searching for such signatures, but there has been some.

Another possibility is we're looking for the wrong techno signatures, or just haven't conceived what the technosignatures for a 10,000-year technologically advanced civilization are.

We've been a techno-civ for what? Maybe only 200-ish years? Our paradigm is gobble up all the energy and grow at all costs. So extrapolate that out, and the logical conclusion is a dyson megasphere that radiates all over the infrared.

But then again, that paradigm is careening us towards an environmental and ecosystem collapse: the hunger for infinite growth is warming our climate, it's unclear whether our nuclear-armed social structures can handle the coming disruptions and migrations, and if we don't kill ourselves, unclear how big a population all the environmental degradation and pollution can support.

So we can project our cute 200-year-old patterns out to a maybe-discoverable 10,000-year civilization driven by the same motivations and flows, but those extrapolations quickly run up against some pretty existential pragmatic threats.

Maybe the answer is we aren't seeing any of the technosignatures because the techonsignatures on the other side of the Great Filter look very different from the ones we conceive of now.

Re: “Most promising signs yet” of alien life on a planet beyond our Solar System

#259

Post by diggan »

lupusreal wrote: post #256
diggan wrote: post #254

Earlier quoted context omitted.

> Dolphins are smart but they're never going to invent radios to broadcast their existence to other star systems. How could we possibly know this? The only case of "Dolphins" we know of, is on Earth, with the interference of humanity, and we're looking at Dolphins at a really small timescale. Given N thousands of years without interference from other species, who can really confidently tell exactly how Dolphins would…

We've had at least two developments of ""dolphins"" that I know of. We also have other intelligent sea life, like squids and octopuses, who've been around for a hell of a long time and are on track to never develop advanced tool creation and use. Living in the water is a massive tech nerf.

> Living in the water is a massive tech nerf.

Says land-living animal :)

Again, are you saying that you confidently can predict a hypothetical future where Dolphins, even given millions of years, would never invent the radio? I think it's unlikely too, but so are humans, so who knows what could happen.

Re: “Most promising signs yet” of alien life on a planet beyond our Solar System

#260

Post by throw4847285 »

ta8645 wrote: post #18
seanhunter wrote: post #6

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…

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…

This is where the discussion, as it always does, silently transitions from science into science fiction.

We know absolutely nothing about extraterrestrial life. We can only project our own singular experience onto the rest of the universe. We only have one data point. There is no scientifically acceptable method of induction from a single data point. The possibilities are endless, and are capacity to narrow them down becomes warped by our love of stories and the kinds of art that we have created about extraterrestial life, all of which are in one way or another metaphors for the human condition.

There is nothing wrong with saying, "Anything is possible and we have 0 evidence allowing us to narrow it down." It isn't fun, but it's true.

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