08-14-2022, 08:24 AM | #31 |
Join Date: Oct 2007
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Re: Number of habitable worlds within170 light years?
Of course after we go extinct maybe raccoons evolve radi, then after some more megayears the mongooses, then rats…
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08-15-2022, 01:38 AM | #32 | ||||
Join Date: Feb 2007
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Re: Number of habitable worlds within170 light years?
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We just don't know. Quote:
We only have the example of one world to judge from, so we really can't assign a meaningful probability to things like oceanic tool use (or land-based tool use, or technological sapience, for that matter). We can observe that there appears to have been life on Earth for over 3 billion years, complex multicellular life for at least hundreds of millions, vertebrates for almost that long, land-based vertebrates since the Devonian (or thereabouts), mammals since at least the middle Mesozoic, but AFAWK human style high-tool sapience only goes back at most a megayear or so, or 1/4500 of Earth's existence. That would seem to hint that life might be easy, complex life not much worse, but full-on technological sapience hard and rare. Which would be one of the standard 'solutions' to the Fermi Paradox, 'technological aliens are rare'. But it's still a tissue of assumptions based on one data sample. Based on the data available, it would be just about as plausible that techno-sapience is easy and Earth is the exception. One data point, no way to judge. Quote:
The scientific community has oscillated back and forth for over a century on the subject of alien life, it goes back and forth from 'life is probably common' to 'life is probably exceedingly unlikely and rare', it's cycled back and forth probably at last three times in the last two centuries. We have absolutely no idea which is true, because we have no data other than to generalize from Earth. Quote:
We have precisely zero data to plug into that final component of the Drake Equation. The only known high-tech civilization continues to exist, with no guarantee of either longevity or imminent demise. Absolutely any figure you slot in the final factor is a total, 100% WAG.
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08-15-2022, 02:04 AM | #33 | ||
Join Date: Apr 2005
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Re: Number of habitable worlds within170 light years?
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Obviously, that's a terrestrial-biased point of view, but I just don't see how you get from paleolithic technology to neolithic technology without fire and the ability to safely use it. Aquatic creatures could conceivably use geothermal vents to heat things, but they would need to lower whatever it is they wanted to heat into the vent using long ropes to avoid being boiled themselves. My take is that purely aquatic species might be sapient, but they aren't likely to become highly technologically advanced without going onto land. If that is inherently lethal due to radiation by high energy UV and cosmic rays, it's going to be a huge drag technological development. Furthermore, constant bombardment of a planet's surface by radiation is going to make it much harder for terrestrial plants and terrestrial or amphibious animals to evolve. Quote:
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08-15-2022, 07:07 AM | #34 | ||
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Join Date: Mar 2012
Location: far from the ocean
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Re: Number of habitable worlds within170 light years?
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I suspect we'll see some dramatic movement in the next five years. Now is a terrible time to be making real guesses, and a wonderful time to be making bets, because JWST is going to start analyzing exoplanet atmospheres.
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08-16-2022, 02:39 PM | #35 |
Join Date: Dec 2004
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Re: Number of habitable worlds within170 light years?
Regarding the Fermi paradox, there was an interesting recent take that argued revious estimates of the Drake equation made hard assumptions about each probability. If on the other hand you modelled the uncertainty of each factor it suggested we're probably alone in the galaxy. It's an interesting take.
If I've got my math right, this should determine the average distance between habitable worlds: D=R/((N*0.75)/pi)^(⅓) Where pi is pi R=Radius of inhabited space N=Number of habitable worlds D=average distance between habitable worlds So if the territory has a radius of 175 light years and 1,000 habitable worlds, there's typically 28 light years between each habitable world. |
08-17-2022, 03:11 PM | #36 |
Banned
Join Date: Jul 2022
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Re: Number of habitable worlds within170 light years?
If you want to add some weird worlds that stretch the definition of habitable then you could read Niven's known space series. He had a few worlds that were only partially habitable. Plateau was more or less Venus like, with a hufe plateau that rose above the dense toxic atmosphere into a habitable layer where the air was breathable.
A planet called warhead was more like mars but had a deep fissure in it that had atmosphere dense enough to breath. Wemadeit (we made it!) had breathable atmosphere but due to orbital mechanics was scoured by 1000mph winds during parts of it's orbit making underground cities the only way to survive on it. Jinx was a heavy planet that was habhitable only in two bands that were above the equator and below the poles, the equator region's atmosphere was too dense to breath, the poles had very thin atmosphere. Another variant on habitable might be worlds with livable gravity, radiation, etc and have things like oxygen, carbon, nitrogen, etcbut are not habitable as is. Such worlds could be lived on in dome type cities that process basic atmosphere from local elements. If you stretch 'habitable' to cover worlds that are possible to live on under some conditions or only in some parts, you could end up with a lot more than just 'earth clones'. Last edited by sjard; 08-20-2022 at 11:25 PM. Reason: Removed attack on moderator |
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