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Saturn moon 'able to support life'

bbc.com

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Re: Saturn moon 'able to support life'

#111

Post by rnet85 »

Grue3 wrote: post #106
charles-salvia wrote: post #12

Earlier quoted context omitted.

Based on the developments in exo-planet research along with discoveries like this over the past couple of years, I would conjecture that life is ridiculously common. But by life, I mean microbial life. I would imagine that multi-cellular life is much rarer, and life capable of reaching human-level intelligence and beyond is probably absurdly rare, on the level of something like one species per galaxy. It's all worthl…

Why would life be ridiculously common? It cannot appear by itself, that would be "spontaneous generation" [1], a long rejected theory. The Earth is extremely suitable for life. It could've easily supported independently evolved life-forms. Yet every living thing we know has a common ancestor, including extinct organisms. Just based on that fact, the odds are firmly stacked against other life anywhere near us. The fac…

Spontaneous generation was never a valid scientific theory. For a more accurate one look at https://en.wikipedia.org/wiki/Abiogenesis Also, the probablity of generation of organic compounds which are precursors to life is pretty high given right environment, https://en.wikipedia.org/wiki/Miller%E2%80%93Urey_experiment

Re: Saturn moon 'able to support life'

#112

Post by gonvaled »

“able to support life“ ... as we know it.

The universe being so vast and so diverse, most life forms will probably escape our comprehension: completely different chemistry, environments (pressures, temperatures), time scales, state of matter (plasma based life forms?), or even energy based ones.

We are not even looking for such different life forms, since we have already concluded that:

- life must be water based

- life must be carbon based

- life must be based on dna (or simillar)

Which leads (given our limited knowledge of the chemistry of these substances) to the conclussion that life must be extremely similar to Earth's.

I see a lack of imagination here.

Re: Saturn moon 'able to support life'

#113

Post by matthewmacleod »

gonvaled wrote: post #112

“able to support life“ ... as we know it. The universe being so vast and so diverse, most life forms will probably escape our comprehension: completely different chemistry, environments (pressures, temperatures), time scales, state of matter (plasma based life forms?), or even energy based ones. We are not even looking for such different life forms, since we have already concluded that: - life must be water based - l…

I'm not sure that's fair.

Researchers would be absolutely captivated to discover life forms that were drastically different from anything we've encountered. At the moment though, there's no clear understanding of how such life might form or what it could look like – and there are reasons to think that new life forms might be quite similar to known life forms. After all, we know at a high level what makes matter-based-carbon-water-life-forms work!

It's a bit silly to try looking for something when we don't know what it looks like. Instead we can say with reasonable certainty that "life can evolve in this way, and we have evidence" – and look for life like that.

Re: Saturn moon 'able to support life'

#114

Post by alphydan »

crooked-v wrote: post #71
flubert wrote: post #23

Earlier quoted context omitted.

I wonder about satellites. How far above the earth's surface would a satellite have to be to keep atmospheric drag low enough to keep an artificial satellite in orbit for a long long time. And how big would it need to be for it to be naked eye visible at that distance. And what could be done to make it unlikely to be mistaken for a natural phenomena? Have clusters of satellites in geometric patterns? 65 Million years…

For something to last a really long time, you'd want to have it at one of the Lagrangian points. Have it be big and reflective - say, a tremendous expanse of reflective cloth behind a relatively small probe - and anybody with a telescope and patience will eventually spot it as a weird "star". Something shiny at a Lagrangian point will suggest something weird (compared to the non-shinyness of objects collected at the…

Not any Lagrangian point will do. L1, L2, L3 are unstable so a small perturbation will send your satellite away. Only L4, L5 will do under certain conditions for the mass of the satellite [0]

[0] https://map.gsfc.nasa.gov/ContentMedia/lagrange.pdf

Re: Saturn moon 'able to support life'

#117

Post by hyperpallium »

Swizec wrote: post #94
hyperpallium wrote: post #74

Earlier quoted context omitted.

I thought corvids a strong candidate, but if they've been around for 25 million years without getting human-level intelligence, they mightn't ever get it, like the dinosaurs. General commemt: we can have increasing complexity, without a specific trend towards it, by positing evolution in all directions. We'd get mostly simple life, and fewer instances as complexity increases - which is what we do see. Most life is un…

Well, birds are dinosaurs. Avian theropods to be precise. So maybe dinosaurs are still working towards their limit. We know that their brains produce more pound per pound intelligence than mammalian brains. It's like they're more efficient. But maybe something about that efficiency is Good Enough so they don't progress further. Although watching my parrot at home is quite something. He's definitely on par with a youn…

Spiders also produce more pound per pound intelligence. They are solitary. What if they became social? Brain-body ratio is provocative, but not the whole story.

Seeing galahs (Australian corvid https://wikipedia.org/wiki/Galah) socialize in trees in monkey troop-like fashion, dextrous in tooth and claw, makes me believe they are on the way. Though maybe raccons are next.

> efficiency is Good Enough

I was thinking that, now I think it may be the niche environment, which we somehow happened to stumble into, giving a more rewarding gradient for intelligence. OTOH, it could have been some neuroanatomy trick, eg faciliating abstraction/hypothesis. IDK. I think it's one of the more fascinating questions of our intelligence, and will be telling.

I don't want to harp on this point, but the birds-are-dinosaurs seems a meaningless semantic classification to me, more about our definitions than reality. Like "Pluto, planet?" I mean, why not call mammals a subgroup of reptiles, since we evolved from them? Anyway, I'm sure this debate has raged hotly across the centuries amoungst taxonomic philosophers, and carefully taking into account all the perspectives, they've collectively come up with... something.

Re: Saturn moon 'able to support life'

#118

Post by gonvaled »

matthewmacleod wrote: post #113
gonvaled wrote: post #112

“able to support life“ ... as we know it. The universe being so vast and so diverse, most life forms will probably escape our comprehension: completely different chemistry, environments (pressures, temperatures), time scales, state of matter (plasma based life forms?), or even energy based ones. We are not even looking for such different life forms, since we have already concluded that: - life must be water based - l…

I'm not sure that's fair. Researchers would be absolutely captivated to discover life forms that were drastically different from anything we've encountered. At the moment though, there's no clear understanding of how such life might form or what it could look like – and there are reasons to think that new life forms might be quite similar to known life forms. After all, we know at a high level what makes matter-based…

My point is that there are vastly more environments different than Earth, than similar ones.

And that while having proof that water based life forms are possible, we do not yet know how common they are. Maybe water is, considered in astronomical terms, an hostile substrate for life.

Re: Saturn moon 'able to support life'

#119

Post by aleksei »

nojvek wrote: post #103
ageofwant wrote: post #79

Earlier quoted context omitted.

If there were any high-intelligence species before they must have exited in a time predating current coal and oil formation, or were not technologically capable, or found some other way of harvesting energy. The fact that we found massive amounts of planet-killing coal and immediately started exploiting it with abandon means that that did not happen before, ergo no technologically capable species on this planet for a…

I absolutely believe that any intelligent species that has enough intelligence to become interstellar will heavily invest in camouflage and become a lurker. Only reacting when something threatens its survival. The universe is like a jungle full of scary things, the only wise move is to watch out, be invisible and not make a lot of noise.

I get your point, but I posit that this is a very human point of view. Once you've cracked the energy needs for interstellar travel, what's the point of raising a war campaign light years away (especially if you need generation ships to attack)? Furthermore, it doesn't seem very intelligent to me that all capable species just hunker down in their own gravity well to die off unnoticed and without having explored the universe. Humans have thus far always endeavoured to go one step beyond; why stop now?

Besides, I'd rather we risk ending up on the galactic buffet table for the chance of finding life forms we can "compare notes with". We're all going to die and go extinct regardless.

Re: Saturn moon 'able to support life'

#120

Post by PhasmaFelis »

gonvaled wrote: post #118
matthewmacleod wrote: post #113

Earlier quoted context omitted.

I'm not sure that's fair. Researchers would be absolutely captivated to discover life forms that were drastically different from anything we've encountered. At the moment though, there's no clear understanding of how such life might form or what it could look like – and there are reasons to think that new life forms might be quite similar to known life forms. After all, we know at a high level what makes matter-based…

My point is that there are vastly more environments different than Earth, than similar ones. And that while having proof that water based life forms are possible, we do not yet know how common they are. Maybe water is, considered in astronomical terms, an hostile substrate for life.

It's really all just guessing, with only one data point. It may be that you're right, and alien life is all incomprehensibly weird in different ways. Or it may be turn out that only semi-Earth-like conditions can produce life, and it all looks rather familiar. Or it may be somewhere in between. I hope I live long enough to find out.
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