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The Fermi Paradox
June 26, 2014 6:01 PM   Subscribe

Some people stick with the traditional, feeling struck by the epic beauty or blown away by the insane scale of the universe. Personally, I go for the old “existential meltdown followed by acting weird for the next half hour.” But everyone feels something. Physicist Enrico Fermi felt something too—”Where is everybody?” It turns out that when it comes to the fate of humankind, this question is very important. Depending on where The Great Filter occurs, we’re left with three possible realities: We’re rare, we’re first, or we’re fucked.
posted by michswiss (141 comments total) 76 users marked this as a favorite

 
What would that tell you about the ecosystem?
posted by the man of twists and turns at 6:05 PM on June 26 [6 favorites]


Maybe they all sublimed.
posted by mrbigmuscles at 6:06 PM on June 26 [8 favorites]


What insights can Donald Trump provide into the Fermi paradox?
Even Donald Trump is making no effort to send his message to the stars ... there's nothing that we're doing that would lead to our footprint being evident at interstellar distances.
posted by the man of twists and turns at 6:10 PM on June 26 [1 favorite]


Technology implies belligerence.
posted by Phssthpok at 6:11 PM on June 26 [8 favorites]


Not many possibilities include "a star trek type universe teeming with intelligent, mostly friendly life, just waiting to be connected with and explored". Pretty disheartening.
posted by mrbigmuscles at 6:16 PM on June 26


Faster-than-light space travel is impossible. Einstein told us that already, but we will come to find there also aren't any loopholes. Sufficiently advanced species, realizing their predicament, become increasingly energy and resource-efficient. All we've got on this planet and those in our solar system and perhaps what we can get at asteroid mining are all we've got, period. Burning energy, or wasting rare minerals, to beam radio waves into the ether becomes the equivalent of setting your couch on fire because your kids are bored. Fun in the short term, devastating thereafter. Wasting resources of any kind becomes a kind of heresy. I imagine such species also become depressed by this knowledge.
posted by 2bucksplus at 6:19 PM on June 26 [14 favorites]


We're Reality TV for Type 2 civilisations.
Type 3's don't own a TV.
posted by fullerine at 6:21 PM on June 26 [33 favorites]


Possibility 10) We’re completely wrong about our reality.

A variant on this is that we have a hard time conceptualizing reality. The galaxy (let alone the universe) spans such an extent that we don't grasp it the way we do the neighborhood we live in. The Fermi Paradox has never struck me as terribly paradoxical. Intelligent, technology-using life could be rare, separated by neigh-on-incomprehensible gulfs of space and time, but the bottom line for me is that we just don't know enough about life and how it emerges in the universe let alone what it tends to do once it emerges. We need more data.
posted by audi alteram partem at 6:21 PM on June 26 [5 favorites]


I have thought for a long time that the Great Filter (nice term for it) was the invention of the eukaryote cell. It's rather difficult to explain how life got started on the Earth when it appeared almost as soon as the surface was cool enough for it to survive, but seeding via extremophile asteroid-hijackers is a believable (to me at least) solution for that. However, it took three billion years after life got firmly started for the Cambrian Explosion to occur, and eukaryotic life is much more fragile than prokaryotes which can be extremophiles. Environments which stay stable enough long enough for eukaryotes to emerge and develop are probably quite rare and widely separated in the Universe. See the "Rare Earth" theory for many reasons why.

Also, our Solar System might well have been visited by the colony ship of another alien species sometime in the distant geological past and used to replicate and continue exploring, only taking with it the note note that the Earth was another ball of slime not of much interest. If that's the case there might be an asteroid out there bearing evidence of their passing but it's unlikely any evidence of their exploration here would have survived weathering on the Earth.
posted by localroger at 6:22 PM on June 26 [6 favorites]


You know all those civilizations that didn't make it though the Great Filter?

They never thought to question what God needed a starship for.
posted by RonButNotStupid at 6:28 PM on June 26 [8 favorites]


This was amazing. Though he forgot

Possibility II 11) Size matters. "For thousands more years, the mighty ships tore across the empty wastes of space and finally dived screaming on to the first planet they came across -- which happened to be the Earth -- where due to a terrible miscalculation of scale the entire battle fleet was accidentally swallowed by a small dog."
posted by Mchelly at 6:28 PM on June 26 [13 favorites]


I've thought a lot about this and I've boiled it down to two possibilities ...

1) Virtual machines all the way down

2) Ranch planet, and we are the livestock. Aren't you gonna finish those McNuggets?
posted by ZenMasterThis at 6:28 PM on June 26 [2 favorites]


Moving forward, we have no choice but to get completely speculative. Let’s imagine that after billions of years in existence, 1% of Earth-like planets develop life (if that’s true, every grain of sand would represent one planet with life on it). And imagine that on 1% of those planets, the life advances to an intelligent level like it did here on Earth.

That's where the entire thing falls apart - 1% is a completely arbitrary guess, and probably way too generous. If the real number is something like 0.01% of Earth-like planets develop life, and of those 0.01% advance to an intelligent level like on Earth, then that comes out to only 10 intelligent civilizations in our galaxy. If only 0.001% of Earth-like planets develop life, then...ding! Only 1 intelligent civilization in our galaxy. No need to speculate further.
posted by pravit at 6:34 PM on June 26 [15 favorites]


I read this article a while back, and liked it a lot. It's a fun question, and it's one of those geeky questions that's even more fun to really get systematic on. My guess is that interstellar space travel is unworkable given the energy available on a planet. Not impossible, just practically unworkable. Sure, interplanetary space travel is doable. But even when smart species imagine space travel, they'd mostly rather do other things with their resources than actually develop it.

The Great Filter is just the heliopause.

This seems sad to me, though, so I want someone to tell me why I'm wrong.
posted by anotherpanacea at 6:37 PM on June 26


The universe is stranger than we can imagine. 99.99999999% of the time truly advanced life forms would consider us unremarkable enough to ignore.

Fermi's paradox is not a paradox. It is an interesting observation but it ain't a paradox.
posted by bukvich at 6:40 PM on June 26 [2 favorites]


I feel like the Fermi Paradox is outmoded. It's a projection of colonialism to the stars, and avidly as human pursued colonization, it's something that we now see as a mistake.

Plus, space is really really big and Einstein is right. Steamship travel does not turn out to be a good analogy for space.
posted by zompist at 6:43 PM on June 26 [6 favorites]


99.99999999% of the time truly advanced life forms would consider us unremarkable enough to ignore.

Earth makes a good picnic spot.
posted by stbalbach at 6:44 PM on June 26 [1 favorite]


That second link is a pretty good catalog and taxonomy of possible answers. Nice post! I'm surprised there isn't a TV Tropes page for the Fermi Paradox, though there seems to be lots of discussion.
posted by XMLicious at 6:48 PM on June 26


I'm still pulling for Earth being embargoed by the Galactic Council for being the kind of place that still merits posts like most of the rest of today's MetaFilter front page.
posted by ob1quixote at 7:01 PM on June 26 [3 favorites]


I tend to believe that interstellar travel is too expensive and difficult to really be worth it. No FTL means spending multiple lifetimes maintaining your life support systems, far far away from the nice comfortable cradle of your home planet. It's really an insane proposition, and immensely cruel to imagine putting actual people up for it: we're simply not designed to move between stars.

This leaves us with a few possibilities for moving forward towards a status as type II or III civilization, involving some combination of robot ambassadors or engineering ourselves to the point where we _are_ ok with interstellar travel.

Game Number 1: Gengineer human-like creatures that are perfectly ok with a few thousand years of deep sleep, and shoot them off towards promising stars, waking up from time to time to check out a planet, harvest some resources, and set a new course. Actually investing resources in this and shooting piles of these intelligent creatures off towards near-certain doom would require either a) extreme moral flexibility or b) extreme desperation on the part of the humans running the program.

Game Number 2: Self-replicating robot colonists, as suggested in the article. These have the advantage of not really requiring life support, and, who knows, if we get god enough at building electronic brains, it may even be hard to distinguish from Game Number 1.

My feeling is that actually getting away from your initial planet is probably the most significant filter. It's extremely difficult and expensive to escape the gravity of your home planet. Having the resources and ingenuity to do this at any appreciable scale may just be extremely rare, and subject to 2bucksplus' hypothesis that wasting resources is the worst possible thing you can do.

Nevermind FTL, of course.

But hey, we'll see where materials science has us in 200 years; maybe space elevators will be easy!
posted by kaibutsu at 7:04 PM on June 26


I've put some thought into the question of random generation of environments for video games. (Bear with me, there is a relevant point to this.)

There's two poles for this kind of procedural generation. One is zero randomness, that is to say, pre-made content made by designers, like most games. And one is complete randomness, which is practically impossible, we don't even know what that would look like, but one interpretation is, take a grid map, and set every space on it to a random possibility.

That isn't often interesting though. Wherever you start out might be surrounded by inescapable walls, for instance, or enemies who will kill you before you can react, or you might have a dearth of things your character needs, by the rules of the game, to survive. Or, alternatively, it might be too easy, and thus a trivial situation to play, and uninteresting for that reason. You might have lots of useful stuff nearby.

The most interesting situations, thus, are in-between, an environment that's been processed, through some algorithm, to make it interesting to explore, yet still randomness to be unpredictable, and thus avoiding the problems with pre-made content (like anthropocentrism and narrative bias). Two points about this: one, that algorithm is still designed by some person and thus still, technically, subject to some degree to the problems with premade content, and two, all the possibilities such an algorithm might generate are also potentially reproducible by complete randomness, although it may be very unlikely.

About point one. If we apply that to our world, one could take it as being a sign of the existence of a God, someone who designed the algorithm that generated it. But we know that mechanisms for increasing natural complexity, under certain circumstances, over time, exist; that's what evolution is. (We might be in a universe selected, via the weak anthropic principle, to create us, but let's set that aside.)

Whatever way our species came about, from a game design standpoint, the randomness in the conditions of our origins, filtered through the limiting factors of the necessities for survival and evolution, have combined to make us a unique and distinctive race. And whenever one of our species cultures has discovered another, often it comes with it either a period of fascination (like when Native American natives were paraded around for European royalty after the discovery of continents in the Western Hemisphere) or xenophobia. Still, though -- different cultures, with different assumptions about the world, different ways of living, different languages, different clothes, different stories, different musics, different ways of thinking! Interesting! And intrinsically valid too, just by virtue of being lived for thousands of years. Alternate solutions to the problem of civilization. You can't make stuff like that up yourself, or at least, not do a great job of it. And you can't just roll dice and invent stuff that way; that's as interesting as television static.

Yet over time, as our planet has become more connected, people travel about and meet each other, the differences between cultures has become less. Distinctiveness has lessened. It's not impossible to imagine that, at some point in the future, humanity will become averaged out; like how every molecule in a sealed room will eventually come to the same temperature, human civilization will eventually homogenize into a culture we might call human. And that state, while good for us in some ways, would probably be less interesting, not to have as much distinctiveness to explore.

So I speculate, just maybe, if there are advanced races out there, they might be watching us but not interacting, because they've already reached that point. But they might be delaying the moment where they contact us, because that would spoil our own distinctiveness, by beginning the process where we become like them.
posted by JHarris at 7:04 PM on June 26 [10 favorites]


There didn't seem much exploration of the possibility of lots of civilisations and radio signals and it's just really hard to detect each other. If SETI was pointed at a modern Earth - a mother lode of signals - from a distance of fifty thousand light years, I would think SETI would see nothing of note and pass on by, for much the same reason that the most powerful telescopes we have can be pointed directly at an exoplanet and have no chance of seeing it except under the most incredible of conditions, which is why we do things like infer from stellar wobble.

If a signal wasn't super-accurately directed at Earth, wouldn't it have to be super-powerful to have a chance to be heard amidst the super-titanic broadcasts of nature? Why would such signals exist? I doubt we humans have any reason to make (m)any.
posted by anonymisc at 7:09 PM on June 26 [5 favorites]


It could be that space is just too damn big and light is too damn slow.
posted by absalom at 7:16 PM on June 26 [8 favorites]


Yup, we're pretty much it for this planet. Easily accessible fossil fuels for plastics and energy? Gone. Easily accessible metals and rare earths? Gone. Fucking shit like graphite for pre-industrials to find? Gone. Easily accessible flint and obsidian? Gone.

We don't get to start over, our Sun doesn't have that long to live, even if a new carboniferous starts right after humanity croaks it.

Either we make it to the stars, or life on this planet never will.
posted by Slap*Happy at 7:16 PM on June 26 [8 favorites]


We are the last civilization that Earth will ever have.
posted by anonymisc at 7:18 PM on June 26 [5 favorites]


If only 0.001% of Earth-like planets develop life, then...ding! Only 1 intelligent civilization in our galaxy. No need to speculate further.

There are other factors, but here's the main bottleneck as presented in Rare Earth:

Plate tectonics are vital as a plantary temperature control mechanism; they pull carbon beneath the surface and release it via volcanoes in a process that helps regulate the CO2 composition of the atmosphere. Without plate tectonics it would be very difficult to escape the Venusian greenhouse trap. (Life helps too of course but, especially in the early going, it isn't enough.)

Plate tectonics require a liquid core and mantle upon which the plates can float. This is critical for another reason, as it generates Earth's relatively powerful magnetic field which deflects the solar wind. Without this magnetic field the solar wind would knock atoms to escape velocity at the top of the atmosphere on a continuous basis, eventually stripping the Earth of its atmosphere. The liquid core and magnetic field are critical for avoiding the near vacuum surface of Mars.

Finally, a planet with a liquid core doesn't rotate about a stable axis, and there would be periods when it would wobble toward a Uranus-like orientation with the rotational axis parallel to the Ecliptic. These aeons would present a very difficult environment for eukaryotic life, because the northern and southern hemispheres would alternately freeze and bake for half a year at a time, rather than the polar extremes freezing while the rest of the planet bastes nicely.

Earth avoids that latter problem by having a large moon which stabilizes its axis of rotation, so instead of wobbling randomly it is constrained and has settled into a 24,000 year top-like precession. And the creation of the Moon was a cosmic crapshoot, a collision that had to happen just so to fling enough mass into Low Earth Orbit to coalesce into the Moon, orbiting in the right direction so tidal forces would drag it outward instead of crashing it back into the Earth.

Mercury, Venus, and Mars all managed to form without the creation of a huge moon. We really don't know how often that would happen, but it could be the final gateway if a liquid core and plate tectonics are necessary. The need for all that to work out just right could easily bring the frequency down to 0.001%.
posted by localroger at 7:19 PM on June 26 [36 favorites]


Faster-than-light space travel is impossible. Einstein told us that already, but we will come to find there also aren't any loopholes.

Well, that's not true. We know how to do faster-than-light space travel, what an Alcubierre drive is, and it's Einstein that laid the blueprint for it. The only thing is that it requires the ability to create an energy-density field lower than that of vacuum - essentially, a volume of negative mass - and we don't know how to do that. Yet.
posted by kafziel at 7:22 PM on June 26 [1 favorite]


We know how to do faster-than-light space travel, what an Alcubierre drive is, and it's Einstein that laid the blueprint for it. The only thing is that it requires the ability to create an energy-density field lower than that of vacuum - essentially, a volume of negative mass - and we don't know how to do that. Yet.

So one day, we figure that out, build it, turn it on, and... thus ends the universe.

"Well!" we would have exclaimed if we still existed, "That would explain the Fermi Paradox!"
After a thoughtful pause, we might have sheepishly added "Oops".

But instead, a new universe is being born, in the endless cycle of life, civilization, and reboot.
posted by anonymisc at 7:32 PM on June 26 [8 favorites]


Dysgenics and immersive MMORPGs. We'll eventually just be stacked, sickly visored knucklehead upon sickly visored knucklehead until something breaks that no one can fix or people just stop breeding. Lather, rinse, repeat.

Interstellar travel's probably as hard as it seems to be. Why bother when everyone can be a king or queen of infinite space?
posted by codswallop at 7:32 PM on June 26 [2 favorites]


Slap*Happy, you mean "easily accessible metals and rare earths" like the gigantic piles of carefully gathered and refined materials that will be found when future intelligences explore our garbage dumps and cities? They will make future mines richer than anything found in nature. And given that our industrial age started before we exploited oil at all and only started to exploit coal, it's hard to see that there is anything blocking a future civilization from advancing with hydroelectric, wind, and biofuels (starting, of course, with that oldest of all biofuels, wood.)
posted by tavella at 7:32 PM on June 26 [8 favorites]


...all the possibilities such an algorithm might generate are also potentially reproducible by complete randomness, although it may be very unlikely.

Does this mean that all of the alien civilizations we can't see are stuck in a continuous Dwarf Fortress world generation loop?

Yup, we're pretty much it for this planet. Easily accessible fossil fuels for plastics and energy? Gone. Easily accessible metals and rare earths? Gone. Fucking shit like graphite for pre-industrials to find? Gone. Easily accessible flint and obsidian? Gone.

We don't get to start over, our Sun doesn't have that long to live, even if a new carboniferous starts right after humanity croaks it.

Either we make it to the stars, or life on this planet never will.


That's not right, is it? Wikipedia has several supercontinents forming and dissolving before plate tectonics cease (at a time well before even the hydrogen exhaustion/subgiant phase of the Sun) - so surface metals and flint and obsidian would be refreshed, and that's enough time for more fossil fuels to develop, isn't it? Great reason not to get cremated, we can take cosmic vengeance on some future intelligent race for our extinction.
posted by XMLicious at 7:33 PM on June 26


Another thing to consider about radio/tv signals from outer space is the fact that the most likely frequencies to hear a signal on are the same ones we use for our own signals. (In many frequencies, the earth actually outshines the sun.) If we want to hear a signal from another star on any of these frequencies we need a big shield to keep from drowning in our own signals. We could do this simply by putting an array of antennas on the far side of the moon, but try getting that funded. :/
posted by sexyrobot at 7:36 PM on June 26


One possible future Great Filter is a regularly-occurring cataclysmic natural event, like the above-mentioned gamma-ray bursts, except they’re unfortunately not done yet and it’s just a matter of time before all life on Earth is suddenly wiped out by one.

I genuinely worry about the gamma-ray burst thing. With an asteroid or catastrophic climate change or whatever, there's at least some hope that we can do something, or that the species can eke out a way to survive even if it is in vastly reduced numbers. But wouldn't we just be completely fucked if we get hit with a gamma-ray burst? Would we even have any sort of warning if we were about to get hit?

I don't know why I don't mind the idea that we're inescapably separated from any other intelligent life by incomprehensibly vast gulfs of time and space and that we'll never overcome that, but I am disturbed by the idea of the gamma-ray burst as the Great Filter.
posted by yasaman at 7:38 PM on June 26 [7 favorites]


We sent people to the Moon, but lost interest, and the capability to do so.

We just sent our first probe outside our solar system. It took almost half a human life time to do so.

The James Webb telescope, set to launch in 2018, might be able to see distant planets. Until then, we just gets hints from Kepler.

In short, we're young, stupid and still can't figure out cats.
posted by Brandon Blatcher at 7:44 PM on June 26 [4 favorites]


But wouldn't we just be completely fucked if we get hit with a gamma-ray burst?

[Strangelove] I would not rule out the chance to preserve a nucleus of human specimens. It would be quite easy... heh heh... at the bottom of ah ... some of our deeper mineshafts. The radioactivity would never penetrate a mine some thousands of feet deep. And in a matter of weeks, sufficient improvements in dwelling space could easily be provided.
...
Of course it would be absolutely vital that our top government and military men be included to foster and impart the required principles of leadership and tradition. Naturally, they would breed prodigiously, eh? There would be much time, and little to do. But ah with the proper breeding techniques and a ratio of say, ten females to each male...


We must not allow a mine shaft gap!
posted by anonymisc at 7:48 PM on June 26 [8 favorites]


We are the last civilization that Earth will ever have.

no - it's entirely likely that after whatever collapse scenario of this civilization you have in mind, that enough knowledge and light resources would survive to make a 16th or 17th century level civilization possible

but we are certainly the last civilization earth will see that will be able to leave earth
posted by pyramid termite at 7:49 PM on June 26


Fermi realized that any civilization with a modest amount of rocket technology and an immodest amount of imperial incentive could rapidly colonize the entire Galaxy.
A couple of posts from Charles Stross' blog (The High Frontier, Redux and The myth of the starship) convinced me that this idea probably isn't true. They are very plausibly discouraging.

I'm not an aerospace engineer, or anything - neither, as far as I know, is Mr. Stross - but even cocktail-napkin-grade calculations show that the project of landing human beings on another star system is monumental, bigger than anything else we humans have ever collectively attempted.

And its not all about technical hurdles, either. Even if we had very cheap energy and technologies indistinguishable from magic, we humans simply haven't shown any aptitude for the kind of multi-generational timelines that slower-than-light travel to other stars would require.

Without faster-than-light communication at the very least, it isn't clear that it's possible to set up an empire - a network of colonies - at all. The "colonies" won't need the empire, can't need it if they're going to survive. The result of sending out a hundred magical colony-seeder-ships wouldn't be an empire of a hundred colonies, but a hundred separate civilizations who can't even say "hello" to each other in a single human lifetime.

So I've been leaning towards Possibility #3 ("The entire concept of physical colonization is a hilariously backward concept to a more advanced species") myself. If there are other civilizations, they're in the same boat we're in - finding the reality of interstellar travel ridiculously difficult and unrewarding.
posted by Western Infidels at 7:53 PM on June 26 [4 favorites]


But wouldn't we just be completely fucked if we get hit with a gamma-ray burst?

Nah. The main effects would be ozone depletion and the resultant fucking up of various ecosystems. Even if the flash did straight kill everyone it hit, that still leaves all the other people on the other side of the planet.

Don't get me wrong, it would suck and perhaps billions would die. But a gamma ray burst just doesn't sound like the sort of thing that could wipe us out as a species.
posted by ryanrs at 8:02 PM on June 26


In short, we're young, stupid and still can't figure out cats.

You're baiting us to do the whole "Metafilter: ______" thing. Well, I won't play your game.

posted by 2bucksplus at 8:02 PM on June 26 [8 favorites]


we are certainly the last civilization earth will see that will be able to leave earth

That seems very...vain? I mean, 65 million years ago the earth was very nearly completely sterilized by an asteroid impact. That's hugely worse than anything we're able to do to the planet. We're simple not capable of messing it up enough to make future intelligent, advanced life impossible.

I could see humanity gradually driving itself to extinction, followed a billion years later by some other form of intelligence, as completely incomprehensible to us as, I don't know, the mind of a trilobite. Our sun's got a good four or five billion years left in 'er, which is such a massive abyss of time it's hard to imagine something that COULDN'T happen.
posted by echo target at 8:06 PM on June 26 [3 favorites]


if we get god enough at building electronic brains

A Freudian slip, surely.

Also ...

MetaFilter: In short, we're young, stupid and still can't figure out cats.
posted by ZenMasterThis at 8:11 PM on June 26 [4 favorites]


we humans simply haven't shown any aptitude for the kind of multi-generational timelines that slower-than-light travel to other stars would require.

Long-term survival, multiple colonial structure, extreme specialization for technological development .... sounds like a job for termites.
posted by the man of twists and turns at 8:13 PM on June 26


When Occam's Razor meets Fermi's Paradox -

"Radio communications aren't terribly useful, here's a better way to communicate! Also, we've shelled-in entire stars with Dyson Spheres. Millions of them, you never noticed as they're completely dark, wait a few hundred years to see one occlude an un-shelled star. This was before we figured out Weak Force Reactors, so those shelled stars are empty now. Also, this universe? No-one who's anyone even lives in this Hilbert Space. It's quaint, tho, we're glad you monkey-creatures like it, we weren't using it anymore."
posted by Slap*Happy at 8:15 PM on June 26 [16 favorites]


Maybe there's lots of life out there, even in outer space, like extremophile microbes living in electrically charged gas clouds and in other exotic forms and environments. There's no real guarantee we've defined life clearly enough to always recognize it when we encounter it. There are terrestrial lifeforms we still haven't recognized as such in all likelihood (certainly at the level of microfauna anyway). And yeah, explanation group II seems the likeliest explanation to me. Maybe any civilization clever enough to make it all the way through the vast reaches of space to come see us would also have to be wise enough to keep their presence secret. Or maybe it's just impossible to sustainably pull off interstellar travel for macrorganisms. DNA could be biosythetic machinery, like Crick (or was it Watson?) claimed as he entered the crank stage of his career--scattered throughout the universe by super-hardy, engineered bugs. Or it could just be everywhere naturally. We just can't really know at this point.
posted by saulgoodman at 8:18 PM on June 26


... or why they're in those scanners...
posted by You Can't Tip a Buick at 8:18 PM on June 26 [2 favorites]


Metafilter: I won't play your game.

In a relatively short amount of time medical science will reach the point where humans can be kept alive indefinitely. When that happens I suspect a voyage of a thousand years will become much more of a possibility to some, and an absolute goal for others. It just takes money.
posted by blue_beetle at 8:18 PM on June 26 [4 favorites]


Even Carl Sagan (a general believer that any civilization advanced enough for interstellar travel would be altruistic, not hostile) called the practice of METI “deeply unwise and immature,” and recommended that “the newest children in a strange and uncertain cosmos should listen quietly for a long time, patiently learning about the universe and comparing notes, before shouting into an unknown jungle that we do not understand.”

Then why did he put our location on the Pioneer plaques and the Voyager record?
posted by sourwookie at 8:18 PM on June 26


Fermi's Paradox seems really silly. Humanity conquered various lands for wealth, via exploiting resources. There ain't much in space or on other planets in our that is a) useful to humans and b)easier to get than right here on Earth.

Everyone is stuck on their home planet, texting and trying to get laid.
posted by Brandon Blatcher at 8:24 PM on June 26 [2 favorites]


I think the most likely answer for Fermi's paradox is that the laws of physics are ultimately an insurmountable barrier. I think it's very likely that FTL travel and communication just plain doesn't exist (after all, it would seem to break causality if it did), and fundamental limitations of planetary resources, material longevity, and engineering keep things like generation ships and Dyson spheres from actually being made (theoretically possible does not mean realistically achievable).

So there might be intelligent life all over the galaxy, but it's not really possible for it to ever communicate or travel to each other, barring the extremely rare case of two habitable planets within the same system or within a hundred light years or so. Maybe the occasional super-overachiever species actually succeeds in sending out a mechanical probe to a couple of nearby stars at great expense, but that's about it.
posted by Mitrovarr at 8:31 PM on June 26


Everybody in this thread should go read Star's Reach right now.
posted by Steely-eyed Missile Man at 8:32 PM on June 26 [1 favorite]


Looks really good but 16 bucks for a paperback?
posted by codswallop at 8:35 PM on June 26


My money is on the Recycle in Your Neighborhood Paradigm (which I just made up): an intelligent life form learns to sustainably inhabit its own system rather than sprawl, because why sprawl if you can recycle? You don't need to mine other systems if you can make whatever you want out of your own asteroids.
posted by Camofrog at 8:43 PM on June 26


It seems to me there could be more than one "Great Filter", too
posted by thelonius at 8:43 PM on June 26 [3 favorites]


Maybe Martians could do
Better than we've done
We'll make great pets, we'll make great pets

posted by oneswellfoop at 8:44 PM on June 26 [5 favorites]


We don't get to start over, our Sun doesn't have that long to live, even if a new carboniferous starts right after humanity croaks it.

The Sun is about half way through it's 10 billion or so year expected lifespan. So, no. Not even remotely accurate.
posted by kjs3 at 8:47 PM on June 26


kjs3: The Sun is about half way through it's 10 billion or so year expected lifespan. So, no. Not even remotely accurate.

There are a lot of planetary scientists who think that the gradually increasing luminosity of the sun and decreasing tectonic activity will render the Earth uninhabitable within less than a billion years. Nevertheless the Earth probably has at least 100-200 million years left in it and that's enough time to evolve a new intelligent species, assuming we don't destroy the ecosystem completely (which could happen if the greenhouse effect runs away).
posted by Mitrovarr at 8:51 PM on June 26 [1 favorite]


Plus they'll have a whole new continent to exploit that we've very thoughtfully left untouched.
posted by ryanrs at 8:53 PM on June 26


Looks really good but 16 bucks for a paperback?

I went with an epub from Smashwords.
posted by Steely-eyed Missile Man at 9:05 PM on June 26


Or the assumption that we aren't the center of the universe is wrong and we really are special beings created by God.
posted by vorpal bunny at 9:45 PM on June 26 [2 favorites]


Nevertheless the Earth probably has at least 100-200 million years left in it and that's enough time to evolve a new intelligent species, assuming we don't destroy the ecosystem completely (which could happen if the greenhouse effect runs away).

This is also the time period in which the next supercontinent will have formed and begun breaking apart, per the various cited estimates around Wikipedia, so if that's accurate said new intelligent species would have new geological resources available over some percentage of the planet, as well as surfaces that are exposed now but currently undersea and inaccessible.
posted by XMLicious at 10:08 PM on June 26


2bucksplus: "In short, we're young, stupid and still can't figure out cats.

You're baiting us to do the whole "Metafilter: ______" thing. Well, I won't play your game.
"

Metafilter: You're baiting us to do the whole "Metafilter: ______" thing.
posted by symbioid at 11:19 PM on June 26 [5 favorites]


"Earth's sole legacy will be a very slight increase (0.01%) of the solar metallicity."

(thanks for that wikipedia link upthread :))
posted by symbioid at 11:20 PM on June 26 [1 favorite]


So much great stuff in this thread.

First, everyone needs to read A Fire Upon the Deep, Diaspora, and all of Atomic Rockets.

Second, seconding the fact that there could well be more than one Great Filter, thus making intelligent life incredibly rare. I for one think the biggest obstacle is between complex multicellular life and technological intelligence. There needs to be a serendipitous combination of brain development, environmental forgiveness, method of physical manipulation, and method of cultural preservation and instruction before anything like complex technology can emerge — that is, we monkeys got lucky with our jungle and savannah and social relations-driven brains and language and HANDS! Let's see crows or dolphins chisel a flint spear! The prokaryote-eukaryote filter is one I hadn't thought of before as a big stumbling block, but it did certainly take us a long time to get over it. Same for the stable conditions necessary for a self-perpetuating chemical reaction to start in the first place, assuming it doesn't get wiped out by a nearby supernova or gamma ray burst.

Third, unless we are in fact completely wrong about our conceptions of other civilizations and how the universe works in general, we SHOULD be seeing other civilizations. No amount of clever trickery (as we can conceive it) can get you past the Law of Conservation of Energy. Doesn't matter how efficiently you trap and use the energy of a star or galaxy, a sizable percentage of it would still get radiated away as infrared radiation if nothing else — and in a highly distinctive way at that, a way which would be very easy to spot if you were looking for it. We should be seeing galaxies out there with too little light and too much infrared/radio. As far as I know, we are not seeing that. It's highly unlikely that we're a First, but SOMEONE has to be, so you never know.
posted by cthuljew at 12:09 AM on June 27 [3 favorites]


Until we're able to model life outside of the constraints of our own intelligence (that is to say, AI), this is all a moot point, isn't it? I always think about ants - from an ants' point of view, ants are pretty much the bad-assedest, most populous creature in the known universe. They probably 'know' we humans exist in that we impact their worlds every now and then, but they can't hear us talk or likely recognize it as a form of communication.

AI comes into play and suddenly, the chance to comprehend 'signals' becomes, eventually, great enough that 'we' are able to recognize the greater universe.
posted by From Bklyn at 12:36 AM on June 27 [1 favorite]


Earth's sole legacy will be a very slight increase (0.01%) of the solar metallicity.

Well, we did sent out a few deep space probes. Someone might happen upon one of those, some day.

(Of course, if one of us humans found something like that, it's an open question whether some rich guy buys/finds it first and walls it off for his own purposes. Self-centered personal exploitation is all the rage these days.)
posted by JHarris at 12:57 AM on June 27


We're rare partially because afawk intelligence has arisen as run away sexual selection. Would you expect every planet to have peacocks?

We must "get god enough at building electronic brains" for our electronic descendants to escape our solar system, otherwise we become extinct.
posted by jeffburdges at 1:37 AM on June 27


I'm concerned, like Vonnegut, that the Great Filter is our own hubris.
posted by Devils Rancher at 1:48 AM on June 27


It's interesting how current events influence predictions of the far future: when I first heard about the Fermi Paradox people believed that a 'uranium limit' precluded super advanced civilisations from forming, as they'd destroy themselves with nuclear weapons first. Now the cold war's ended this isn't such a fear, and people are focussing on other doomsday scenarios. A gamma ray burst is the ultimate natural disaster, and perhaps it resonates with our collective conciousness as focus on the environment has risen recently.
posted by Ned G at 2:02 AM on June 27 [6 favorites]


I would still bet on nuclear annihilation before a gamma-ray burst. Presumably the capability to construct a bomb will become more and more within the grasp of a single person or small group as technology progresses. My thought was that you could work out some nanotechnological filter to extract fissile material atom by atom out of seawater or some other super-low-density but accessible source, perhaps in processes running over the course of decades, to accumulate enough for one weapon. The Aum Shinrikyo of the 21st century has it made.

Maybe the hipster thing in 2114 will be jailbreaking your comestible-3D-printer-slash-oven so that instead of Klein Bottle shaped éclairs served with replicas of the exact porcelain plate and utensils used by Louis XIV at the Palace of Versailles it will make you a steampunk brass-hohlraumed Teller-Ulam device. The hipsters will be the end of us all, I tell you!
posted by XMLicious at 3:03 AM on June 27


I didn't see any mention of another likely possibility: The Great Filter is just a Great Barrier of Molasses.

Billions of civilizations have reached the Type I stage, but the effort required to reach Type II is too large. There's no extinction level events for most of them, they just stay Type I for billions of years.
posted by ymgve at 4:27 AM on June 27 [7 favorites]


I think any list like this should also include:

Possibility 12: The galaxy is full of civilizations, but they're shunning us because they're universally squicked out by cricket. Which is very nasty.
posted by Sonny Jim at 4:34 AM on June 27


The main problem with the Fermi Paradox is that no one has conclusively proved that intelligent life exists on Earth.
posted by Renoroc at 4:49 AM on June 27 [4 favorites]


Oh my god they're made of meat.
posted by BigCalm at 4:56 AM on June 27 [18 favorites]


If interstellar travel seems too energy intensive or long-term for you then I think your thinking of travel as meatbag-humans?

If/when we finally piece someone together digitally (however that could be done) we could be sending people out into the cosmos on a muuuuuuch slower virtual time progression and with far fewer resources facing far fewer risks.

Biologically, as animals, we'd want to keep being the complex grey goo that we are and spread to other planets. If we actually want to get there without FTL, and FTL is one of those if/when's with a seemingly hilariously lower probability than uploads, then we'd need to go the storage route for this fragile meat or upload and not give a shit about the harshness of space.
posted by Slackermagee at 5:00 AM on June 27 [1 favorite]


My favorite explanation is possibility 9. Basically the universe is far stranger than we can comprehend or imagine. So technological civilizations could be all around us and we'd not even notice it. I cringe every time I read about "conditions on this planet are like those necessary for life", as if we believe all life is in our image. In particular the requirement for liquid water. Hell, we have weird-ass shit living off of hydrogen in the earth's crust, completely removed from the sun's energy.

Then again the speed of light is a huge barrier to any sort of interstellar civilization. Although I'd settle for finding a single Type II star that's been harnessed. Kepler has enabled some interesting speculation about what a planet that had been technologized would look like. Would you find evidence of complex hydrocarbons with spectroscopy? That kind of thing. We're not there yet, but it's imaginable.
posted by Nelson at 6:45 AM on June 27 [2 favorites]


It seems to me that the question of where is everyone can kind of be explained by the fact that while multi-cell organism development and FTL travel and all the other shenanigans are things we just started having the ability to even theoretically converse about.

Take the time slice of history that makes up the total time that we could entertain these concepts, even for wildly stretched definitions such as stories of gods and whatnot, and we are definitely looking at what appears to be a flash bulb in a constellation of limitless light.

And if we were having these conversations for a million years, its still the same scale.

If civilizations arise, thrive, expand, and then go on to other things, they also undoubtedly find some way to fail and disappear, through hubris, or bad luck, or just the accumulation of possibilities over long enough time spans. Not all of them can be perpetual.

So here we sit, in this universe, but also in this vast sea of time. All the statistical modeling could prove that civilizations should be there, but the question would still remain, when?

Combine all this with limitations for signal propagation time, and it doesn't seem very surprising to me that we are not hearing incessant chatter. Heck, the first signal we may encounter could be from a lifeform that hasn't existed for millions of years.

But it is a useful concept for stretching our brains, which is its own kind of fun, isn't it?
posted by dglynn at 6:54 AM on June 27


Since no one's posted it.. if you're interested in talking about the probability of their being intelligent life elsewhere, the Drake Equation is the framework to do that in. Basically breaks the whole probability down into smaller probabilities like "number of stars with planets" and "the fraction of civilizations that develop a technology that releases detectable signs of their existence into space". The problem is the plausible range for some of the parameters varies by a factor of a million, so the overall calculation is still impossibly fuzzy. Still it's a useful tool for organizing the discussion.
posted by Nelson at 7:04 AM on June 27


Why focus on Type III civilizations? A priori, we'd imagine that building a Dyson sphere emits considerable radiation, but maybe not after you're done. Is the point just that a civilization building thousands of Dyson spheres simultaneously should be impossible to miss?

As an aside, dark matter does not consist of Dyson spheres because when galaxies collide their dark matter halos behave differently from ordinary mater.
posted by jeffburdges at 7:25 AM on June 27 [1 favorite]


It seems to me there could be more than one "Great Filter", too.

And maybe overlapping or concentric filters, which together create some greater, more daunting filter, a sort of Hyperfilter, or Megafilter, or...ugh...it's on the tip of my tongue, I just can't think of the word I want.
posted by Pater Aletheias at 8:10 AM on June 27 [6 favorites]


Why focus on Type III civilizations? A priori, we'd imagine that building a Dyson sphere emits considerable radiation, but maybe not after you're done.

Either radiation would be emitted into the rest of the universe as heat, or the temperature inside the Dyson sphere would rise perpetually. Can't defeat entropy or conservation of energy in any way as far as we know.
posted by cthuljew at 8:34 AM on June 27 [3 favorites]


I cringe every time I read about "conditions on this planet are like those necessary for life", as if we believe all life is in our image.

Good point. Even the phrase "intelligent life" assumes too much. If Strong AI (or AGI or whatever we are calling it now) is possible then life is not a prerequisite for intelligence. Maybe we are surrounded by civilizations of intelligent, inanimate matter.
posted by mrbigmuscles at 8:36 AM on June 27


Earth avoids that latter problem by having a large moon which stabilizes its axis of rotation, so instead of wobbling randomly it is constrained and has settled into a 24,000 year top-like precession. And the creation of the Moon was a cosmic crapshoot, a collision that had to happen just so to fling enough mass into Low Earth Orbit to coalesce into the Moon, orbiting in the right direction so tidal forces would drag it outward instead of crashing it back into the Earth.

I like to think that the "perfect moon" criteria, combined with the "Goldilocks" requirement of needing to be the exact right distance from a correctly sized sun, means that every planet with life has a sun and a moon of the same relative size in the sky, and every intelligent civilization therefor shares a common reverence for the terrible beauty of total a solar eclipse.
posted by grog at 8:44 AM on June 27 [9 favorites]


Aside from the perfect moon criteria or similar restrictions on the solar system, I believe his good habitable planets estimate runs a few orders of magnitude too high due to issues with the galaxies themselves, which makes his great filter appear excessively nasty :

You cannot just ask for sun-like stars with planets at earth-like distances either because the terrestrial environment will differ wildly nearer the galactic core (see : galactic habitable zone)

Conversely, dwarf galaxies, etc. are unlikely to harbor life because they're poor in heavier elements. So any life in our Local Group would probably be found in the Milky Way, Andromeda, or maybe Triangulum.

Also, we've no evidence of even basic life on mars or elsewhere, and no evidence that eukaryotes evolved multiple times, making them likely filters. Again, there are species who adopted aspects of intelligence for their sexual selection criteria, like whale songs, but that's not like the runaway sexual selection needed for human intelligence.
posted by jeffburdges at 8:54 AM on June 27


pyramid termite: but we are certainly the last civilization earth will see that will be able to leave earth

Seriously, where are people getting this tosh from? We use oxygen and hydrogen for rockets, not fossil fuels, and there are plenty of ways to get the energy to produce those that are not fossil fuels. Please remember that our industrial age began with hydro power -- there are reasons why so many US NE cities are near the 'fall line' of the Atlantic coast.

That's not even going into the span of time we are talking about. It will be hundreds of millions of years before the sun gets too hot and shuts down the biosphere. Volcanoes will spew out new obsidian -- just like they do every day now. Vast new beds of flint will be crushed out of sediments. Future geologists will study the strange tracks of human presence to look for places to mine, the way modern ones track sedimentary history to look for new fossil fuel exploration areas.

Sure, it's probable that they won't have access to the same amount of fossil fuels that fed our extreme population expansion over the last century, but I'm not sure that is actually a *disadvantage* -- that wild speed has led to as many problems as it has advantages in terms of species resources. And it's certainly not a fatal one.
posted by tavella at 9:20 AM on June 27 [2 favorites]


We use oxygen and hydrogen for rockets, not fossil fuels

Just to clarify, 100% of the hydrogen used for rocket propellant is cracked from petrochemicals, most often natural gas. This is far cheaper than electrolysis of water using even the cheapest available energy sources.
posted by localroger at 9:35 AM on June 27 [1 favorite]


Yes, but the fossil fuels aren't _necessary_ for the fuel, just cheaper.
posted by tavella at 9:46 AM on June 27


travella, it isn't just fossil fuels. This neat infographic from the newscientist in 2007, (alternate link for infographic), shows most resources are gone in the next century. Here's a similar chart from the BBC.

And given these facts, some smart people like Larry Page, are getting involved in asteroid mining. Which further corroborates the fact that the planet is running out of viably exploitable raw materials.
"It has often been said that, if the human species fails to make a go of it here on the Earth, some other species will take over the running. In the sense of developing intelligence this is not correct. We have or soon will have, exhausted the necessary physical prerequisites so far as this planet is concerned. With coal gone, oil gone, high-grade metallic ores gone, no species however competent can make the long climb from primitive conditions to high-level technology. This is a one-shot affair. If we fail, this planetary system fails so far as intelligence is concerned.", Sir Fred Hoyle
If you have to move a mountain or go 1km underground to get at an ore of some ridiculously small concentration of iron or other metal. Or if you have to harvest it from the ocean floor, or beneath it. Then that's kind of hard for a pre-industrial civilization to get at it. You have a boot strap problem.

IMHO, the lack of contact with other civilizations are evidence that we will (as other ETs have) destroy ourselves and collapse. So I'd REALLY like to hear from ETs just so I can kick this negative outlook.
posted by ecco at 10:03 AM on June 27 [1 favorite]


It is said, in some creation myths,* that our galaxy was created inside an enormous pickled fish.

Our view then is bounded by the great gefilte.

* - some here approaching zero
posted by zippy at 10:10 AM on June 27


We haven't even explored the 25% of land mass available for all the resources.

Its quite presumptuous to think that earth is running out of resources.

We, humans, might run out of resources but given that majority of earth's surface has not even been explored for resource availability any intelligence coming after us will find the resources, it will be tougher and longer for them but it wont be a brick wall.

I don't think resources are going to be a survival problem for any intelligence on earth ....

Our survival problems will be lack of intelligence (kill ourselves out of dumb actions, not realizing the consequences of our choices in time) or some random event against which a planet bound civilization has no defenses.
posted by TheLittlePrince at 11:08 AM on June 27


I think there is a conceit here that we humans are the apex of evolution and, therefore, any other place where evolution occurs will produce something just like us. In fact, we are a weird anomaly out here on the fringes of the evolutionary bush and there is no reason to believe that we are going to be replicated elsewhere.

Unfortunately, it appears that we have been so successful that we are about to extinguish ourselves. I'm guessing the filter is us.
posted by charlesminus at 11:13 AM on June 27 [1 favorite]


I think there is a conceit here that we humans are the apex of evolution and, therefore, any other place where evolution occurs will produce something just like us.

I like Drake's Equation, linked by Nelson above, because it's a way of saying "well, ok, let's say we're this unusual, now what are the odds of someone else being out there who's like us."

There's nothing in it about us being better, or worse, and anyone can try their own numbers.
posted by zippy at 11:18 AM on June 27


Its quite presumptuous to think that earth is running out of resources.

It is presumptuous to think that companies are expending orders of magnitude more effort than used to be necessary to reach resources, but they're doing this just for shits and giggles because there will be a heap of the stuff just lying on the ground over there like back in the old days, if only they'd bother to check.

The issue isn't how much is left in the earth, it's how much of the fruit is low-hanging enough for a not-yet-technological civilization to be able to reach. The low-hanging fruit is gone.
posted by anonymisc at 11:22 AM on June 27 [5 favorites]


Possibility 13: Language and culture in a large mammal are analogous to extreme virulence in a pathogen, so evolution tends to select against them due to the damage they inflict on their host.
posted by flabdablet at 11:42 AM on June 27 [1 favorite]


We have met the anemone, and he is doing just fine.
posted by flabdablet at 11:44 AM on June 27 [1 favorite]


TheLittlePrince: We haven't even explored the 25% of land mass available for all the resources.

Its quite presumptuous to think that earth is running out of resources.

We, humans, might run out of resources but given that majority of earth's surface has not even been explored for resource availability any intelligence coming after us will find the resources, it will be tougher and longer for them but it wont be a brick wall.

I don't think resources are going to be a survival problem for any intelligence on earth ....


Ah, a "limited resources denier". That tells me everything I need to know about your theories. Why are you wasting time here on Metafilter, when no one has ever checked your back yard for gold ore and surface veins of diamonds yet?

Also, highly eponysterical.
posted by IAmBroom at 11:52 AM on June 27 [1 favorite]


Maybe we are surrounded by civilizations of intelligent, inanimate matter.

Read The Black Cloud?
posted by flabdablet at 11:57 AM on June 27 [1 favorite]


ecco, do you think all those metals evaporated? No, they are sitting, in very refined and concentrated form, in cities and dumps. And what is a city or a dump after a million years of overburden and erosion? A spectacular mine. The issue with running out of non-destroyed materials like metals is population growth and new technologies meaning that we need more and more of the available pool, not that what we are using now won't be accessible for the future if all our billions vanish. Some chunks will be too spread out to be useful -- undersea cables, etc -- but most metals are where people are, and people group together.

Depending on the period of time we are looking out at, some things may be more accessible or less, especially when you spin a hundred million years down the line and large parts of the crust have been subducted or uplifted, but overall, there's *more* metal easily available and concentrated than before humans arrived on the scene. The only real losses would be metals that we primarily use in ways that make them totally unrecyclable and scattered, which I can't think of any at the time (though others may have suggestions.)
posted by tavella at 12:03 PM on June 27 [1 favorite]


tavella: Yes, but the fossil fuels aren't _necessary_ for the fuel, just cheaper.

I think you're poo-pooing a rather crucial point. One can burn charcoal briquettes to keep warm, or diamonds; one is cheaper.

Which brings to mind an interesting point:

Perhaps The Great Filter is simply availability of radioactive resources. A planet without heavy radioactive elements occurring very near the surface in rich ores would never allow a civilization to achieve nuclear power, which in turn might seriously curtail advancement beyond the Otto-cycle engine (fossil fuel power). Sure, they could put a satellite in orbit with just hydrocarbons, but lacking sufficient U-238 might put the cap on their development at the edge of their own solar system - or even make that much exploration incredibly unlikely.

I don't have any idea how common it is for 2nd-generation stars* to have "lots" of U-238 (and similar elements), nor to have them in "rich" veins - probably this ties in to the molten-core plate tectonics issue. Certainly, a HUGE amount of 20th-century physics has been made possible by the contributions of Dr. and Dr. Curie, who could not have discovered Curium were it more evenly distributed throughout the planet (or even throughout the crust!).

How rich is the Earth in radioactive elements? There's actually a natural fission reactor operating deep underneath Gabon, Africa, with groundwater boiloff acting as a control.
posted by IAmBroom at 12:18 PM on June 27


IAmBroom, if you want to discuss the possible advantages and disadvantages of being able to speedily exploit such a convenient source of energy in terms of development, that's fair enough, but people are declaring that _no_ civilization could possibly succeed us, or that we are the last possible civilization that could leave the earth, and that's just nonsense. It's an incredibly nearsighted, humanocentric view of a very long span of time.

We were a tool-using, technology-building, world-spanning species before we exploited coal, and it wasn't until after the industrial revolution (as normally dated) that we started using oil in any substantial way. A civilization that went from Rome-equivalent to space without using mined petrochemicals would no doubt look quite a lot different than our history, but there is no barrier to them doing so.
posted by tavella at 12:58 PM on June 27 [1 favorite]


tavella, A million years after we're all gone, our cities and waste dumps will turn to dust. Literally dust.

High percentage ores are being mined by us now, and made into small bits of useful stuff and are being widely distributed for use by us. Those bits will erode and (entropy being what it is) those eroded bits will tend not to concentrate together.

E.g take something as mind bogglingly large as all the metal in all the sky scrapers in NYC. In a century it'll be underwater. Water is heavy and metals tend to rust in salt water. The bases of those buildings will deteriorate, they will collapse, erode and dissolve. A great deal of the output of a lot of mines went into making all that metal. And in time, it'll be dispersed.

I'm not saying it'll evaporate, transmutate, just natural physical processes.
posted by ecco at 1:15 PM on June 27 [1 favorite]


Eroded bits do tend to concentrate together. That's how a lot of ores are formed.
posted by ryanrs at 1:59 PM on June 27


Wow, the wikipedia page on ore genesis is quite extensive. And you're right about Titanium and zirconium which "... are formed by accumulation ... within beach systems". (Titanium is hard to work with, especially if you don't have easier metals to start with.)

A lot of the ore origins reference magma, so I think that means they came from within the earth and were isolated by specific geologic conditions.

A surprise was iron which "... are overwhelmingly derived from ancient sediments ... Particular environmental conditions are needed ... to form these deposit such as acidic and oxygen-poor atmospheres within the Proterozoic Era."

So what I'm saying is some will concentrate, and some will not unless there are conditions which the earth last saw 2.5 billion to 541 million years ago.
posted by ecco at 3:35 PM on June 27


No, they are referring the process that formed the iron oxides out of iron atoms in seawater. The rust our iron and steel will go to is *already* iron oxide, and iron oxide is generally not very soluble in water, so while some will dissolve a lot will be buried in sediment, and other cities above sea level will decay in place and be buried or become gravel to be washed down into deposits.

Be clear, I'm not advocating that we will never run out of easily accessible resources for _our_ civilization; trying to supply billions of people who have already built their civilization on expecting certain easy resources is a lot more complicated. I'm just saying that the 'woe is me! we have destroyed all possibility of future technological life' stuff is nonsense.
posted by tavella at 4:09 PM on June 27


E.g take something as mind bogglingly large as all the metal in all the sky scrapers in NYC. In a century it'll be underwater.

Wait, what? No it won't?
posted by Justinian at 6:01 PM on June 27


IPCC 2013, fifth report, chapter 13, sea level change. From page 9, 10 and 14, show (pessimistically) either 1.2m or 1m rise in next next 86 years.

There are lots of neat sea level rise websites. This one, when zoomed into NYC, shows the population affected. If you select a 3ft (1m) rise it says
Things below +3ft in
New York, New York
Population 141,230 1.7%
Homes 61,362 1.8%
Acres 9,304 5.0%
We're talking about (so far) unprovables like ETs, and extinction of humans, so allow me the leeway to re-state my previous "in a century" to "by the end of the next century", which would give ~186 years ahead. Well the IPCC graphs sure aren't flat, they're exponential increase. So the data says NYC will be underwater. I'm not saying you'll get your toes wet above the lobby of the Empire state building. But the trend says NYC will be like the Netherlands. And w/o humans mitigating it. Water will flood the foundations, rust, collapse, erode and dissolve. (Though that'll take millennia).
posted by ecco at 7:54 PM on June 27


So NYC will be underwater in 186 years the same way that Venice is underwater today.

More interesting to me, though, is - can you actually burn diamonds to keep warm? Wikipedia makes it sound like it would already need to be up past the boiling point of mercury for diamonds to become flammable in oxygen.
posted by XMLicious at 8:24 PM on June 27 [1 favorite]


Diamonds will slowly burn if heated with an oxyhydrogen torch and then dropped into liquid oxygen.

So yes, diamonds will technically burn, but not in the common, everyday sense of the word.
posted by ryanrs at 9:03 PM on June 27 [4 favorites]


trying to supply billions of people who have already built their civilization on expecting certain easy resources is a lot more complicated. I'm just saying that the 'woe is me! we have destroyed all possibility of future technological life' stuff is nonsense.

I think you seriously underestimate the scale and prosperity a civilization has to be to attain sufficient surplus labor across sufficiently large-scale breadth of sufficiently super-specialized industries enjoying sufficient man-hours to get a technological civilization far beyond the industrial age and into space travel. In our case it was made possible by an unlimited supply of free energy that could not be reached today. Sure, a low-density bronze-age civilization (like the Romans) will always be possible, but a civilization so massive as to have had the resources to develop its technologies so wide and so deep that it can get to space... you need to propose a creature with radically greater intelligence, memory, and lifespan than we ever had to get there without the size of civilization bought with free energy. Sure, we don't know for a fact that such a creature won't appear, but I personally think odds are better that I'll win the lottery.
posted by anonymisc at 9:31 PM on June 27


Just to reiterate what I was saying above, unless the geological length of time that will be long enough for at least two or three more supercontinents to form and break apart, going forward, is insufficient to make existing, inaccessible sources of hydrocarbons accessible and/or generate new ones, future terrestrial civilizations would have access to the same range of resources that human civilization has.

If not even more, in terms of hydrocarbons, if recent hypotheses about the burning of coal during the million-year-long eruption of the Siberian Traps during the Permian extinction are correct:
In January 2011, a team led by Stephen Grasby of the Geological Survey of Canada—Calgary, reported evidence that volcanism caused massive coal beds to ignite, possibly releasing more than 3 trillion tons of carbon. The team found ash deposits in deep rock layers near what is now Buchanan Lake. According to their article, "... coal ash dispersed by the explosive Siberian Trap eruption would be expected to have an associated release of toxic elements in impacted water bodies where fly ash slurries developed ...", and "Mafic megascale eruptions are long-lived events that would allow significant build-up of global ash clouds".[105][106] In a statement, Grasby said, "In addition to these volcanoes causing fires through coal, the ash it spewed was highly toxic and was released in the land and water, potentially contributing to the worst extinction event in earth history."[107]
As far as I can tell, from a layman's perspective without any source to examine, the claim made further up in the thread that We don't get to start over, our Sun doesn't have that long to live, even if a new carboniferous starts right after humanity croaks it is just plain wrong.

The Carboniferous Era ran from "about 358.9 ± 0.4 million years ago, to the beginning of the Permian Period, about 298.9 ± 0.15 Ma". Two to three multiples of the amount of time since the beginning of the Carboniferous will pass before plate tectonics stop and well more than a dozen times as much before we even get close to the Sun beginning the antepenultimate phase of its stellar lifecycle.
posted by XMLicious at 11:28 PM on June 27


Once we can travel at a significant fraction of c, Orion's Arm will be teeming with human colonies in a few millenia. It won't be pretty or quick, but we've already beat the biggest obstacle to scientific progress: knowledge locked into small collections of geographically isolated elites. The creation of the world-system starting circa 1500 (with many important antecedents) has made it unlikely that any local collapse today could lead to centuries-long impoverishment of learning such as those accompanied the Classical and Bronze Age collapses. It also helps prevent the sort of stagnation held sway in Medieval Europe and certain periods in Chinese history, or held back isolated pre-Colombian societies.

I'm no Cornucopian, and I think our present course is going to lead to a very difficult back half of the 21st century, but the overly-simple, lazy "we're fucked" so popular at MetaFilter isn't acknowledging other reasonable outcomes. Global warming is going to put global civilization into extremis. But we're not going to cause a runaway Greenhouse effect; all worst case scenarios still leave the planet easily habitable for humans, and large swaths of it will still be readily be exploitable by our technological kit. We have solid theoretical bases for sub-light interstellar travel now. When we have real motivation to get off this planet, it seems at least as likely that we will do it as that we'll become unable to maintain industrialism.
posted by spaltavian at 8:50 AM on June 28 [2 favorites]


I think you seriously underestimate the scale and prosperity a civilization has to be to attain sufficient surplus labor across sufficiently large-scale breadth of sufficiently super-specialized industries enjoying sufficient man-hours to get a technological civilization far beyond the industrial age and into space travel. In our case it was made possible by an unlimited supply of free energy that could not be reached today.

The sun has all the energy we need. We don't use it today because of certain deformations in our economic structure, not due any lacking in ability or know-how. Once the artificial constraints that reward this particular kind of short-shortsightedness collapse under their own weight, new societies, or recovering present ones, will be free to make different decisions. And, unlike in past collapses, knowledge is both wide and deep in a truly global system.

It's up to us how painful that transition will be, but "cheap energy" is not a major concern on the sort of timescales we're talking about here.

Sure, a low-density bronze-age civilization (like the Romans) will always be possible

Sorry for the pedantry, but the Romans were an Iron Age civilization.
posted by spaltavian at 8:57 AM on June 28 [3 favorites]


a "limited resource denier" is there such a thing? ... anyway your comment is kinda presumptuous about theories and doesn't understand the context of the discussion.

We are talking about resource availability to any alternative intelligent post-human civilization ... which would involve millions of years. thats a long enough time for earth to replenish, recycle and recreate resources ... we are talking about a time span in which continents changes ..land sinks and rises.

to presume that just because humans will exhaust the cheap resources available to them (and thats very much possible), there will be no "low-hanging" resources available to other intelligent societies which comes up say, 200 million years later, is kinda silly.

On a long enough time scale, there will be a galaxy faring civilization ... because universe has a lot of time and even the most improbably event can occur.

Whether that galaxy faring civilization will be us (as we are today)... kinda unlikely.
posted by TheLittlePrince at 2:40 PM on June 28


We should however ask : What might great filters that come in our future look like? Astroids obviously. I dubious about the radiation bursts the article goes on about. What else?

Would intelligent species frequently kill themselves off through nuclear war? I doubt kinda it, imho society would usually go on, albeit radically altered.

Would they kill themselves through pollution or climate change? In our case, the earth has previously been both hotter than possessed more atmospheric carbon-dioxide, actually the oxygen is "pollution" by cyanobacteria. Yes, climate change can wreck our social structure, but extinction appears exceedingly unlikely. Another intelligent species might evolve in a more extreme and vulnerable niche of course.

There might be another type of existential-ish threat for technologically advanced but not yet spacefaring species, that I'll call generalized fascism. In essence, generalized fascism includes any cultural shift that drastically slows our memetic evolution, especially our technological development.

We cannot directly cause our own extinction by pausing our evolution, if anything that preserves the species as is. We do however make ourselves far more vulnerable to other very real existential threats, like asteroids.

We actually try doing this rather regularly throughout history, ala the dark ages. And our impetus towards generalized fascism is seen in everything from religion to internet commenters criticizing whistleblowers. Information technology is dangerous in that it allows (a) vastly more effective enforcement of ideology and (b) real evolutionary horrors like world government.

We avert this threat by escaping our solar system, actually that's kinda the plot of the original Dune series, before it ran off the rails with big bad outside machines.
posted by jeffburdges at 8:17 AM on June 29


We avert this threat by escaping our solar system

Er, no, we don't. Interstellar spaceships are not wooden vessels that a dissident faction can invest in, to be repaid by selling beaver pelts.

See cstross's article on interstellar travel, and how to run a generation ship. In brief: it's a megaproject just to send out a probe the size of a Volkswagen; to send out a colony ship would require that world government and a huge degree of consensus or coercion.

Interstellar travel is not an alternative to solving our problems here, such as resource depletion, ecological collapse, and extremes of inequality. Building a generation ship requires solving those problems. You can't run a libertarian utopia with guns on a spaceship. If you can't figure out how to run a sustainable, large high-tech society on Earth, you can't do it on another planet.
posted by zompist at 1:17 PM on June 29 [2 favorites]


I'm rather shocked that cstross didn't address the most obvious solution to the problem of creating a small scale long-term stable society which I portrayed in my novella about it.
posted by localroger at 3:41 PM on June 29 [1 favorite]


Ain't nothing wrong with world resource aggregation that's not coercive, meaning more a world festival rather than a world government. I certainly agree with cstross' conclusions in his generation ship thought experiment too, but..

We're likely talking about machines that become a successor to humanity, not actual biological humans, so zero basis for social predictions and way less expensive. Also, we're learning more about decision making, non-coercive organization, etc. all the time, just in case we must cart along the meat.

We should absolutely solve our serious problems with resources, the environment, inequality, etc. to speed our escape from this plant and system, but that'll includes minimizing coercive institutions like corporations and governments.
posted by jeffburdges at 4:29 PM on June 29


Mineral Fodder: We may think we are the first organisms to remake the planet, but life has been transforming the earth for aeons
posted by the man of twists and turns at 7:25 AM on June 30 [1 favorite]


jeffburdges: "In our case, the earth has previously been both hotter than possessed more atmospheric carbon-dioxide, actually the oxygen is "pollution" by cyanobacteria. "

ObSF: Larry Niven, "The Green Marauder."
posted by Chrysostom at 11:24 AM on June 30


An interesting little tidbit in a 2011 documentary-type thing I was watching yesterday that made me think of this thread appeared to say that none of the exoplanets discovered at that point had atmospheres that would permit open flames, trying to make a connection between the development of human technology and the Earth's characteristics.
posted by XMLicious at 11:36 AM on June 30


Have we managed to take a look at the atmosphere of any Earth-like planets, though? Oxygen-bearing atmospheres are unlikely to exist without life, at least at Earth-like temperatures and densities (oxygen is too chemically reactive to remain unbound without being refreshed constantly.) Finding an oxygen-bearing atmosphere at a reasonable temperature and pressure would actually constitute very strong evidence that the planet bore carbon-based life.
posted by Mitrovarr at 11:47 AM on June 30 [2 favorites]


I wasn't presenting that as evidence concerning the likelihood of technologically-advanced intelligent life throughout time and space—new exoplanets are being discovered apace, so it quite possibly is no longer true, and that's far too small a sample size for the scale we're talking about, anyway—just mentioning it in passing.
posted by XMLicious at 12:03 PM on June 30


tavella: people are declaring that _no_ civilization could possibly succeed us, or that we are the last possible civilization that could leave the earth, and that's just nonsense.

Citation needed. Show your work.

Really, it's unknowable. We only know of about 2-3 species that achieved language skills (and most of us carry genes from all of them), all developed in roughly the same situation, environment, and from a common ancestor, and from that people are making judgments about what absolutely can or cannot happen under other situations.

The only reasonable conclusion I can draw from the "Fermi Paradox" is that we have no real data on how likely "intelligent civilization" is to develop from Earth-like environments. We might be a study group for 1,000,000 other species, we might be unique in our 1BLY radius of the galaxy, we might be the first to evolve EM communication in that region, or we might be looking in all the wrong places. Dunno.

Some (not here) have posited a theory that civilization cannot advance significantly without raw materials. A post-apocalyptic society might be able to maintain a nuclear thermopile, for instance, but only until the fuel rods ran out; they'd never rediscover the concepts behind its construction. That's an interesting thought to me, but not a certainty.
posted by IAmBroom at 12:53 PM on June 30


localroger : I'm rather shocked that cstross didn't address the most obvious solution to the problem of creating a small scale long-term stable society which I portrayed in my novella about it.

Fucking brilliant story, localroger!
posted by IAmBroom at 1:23 PM on June 30


Some (not here) have posited a theory that civilization cannot advance significantly without raw materials.

That has been said here, (e.g.) that's what tavella is arguing against. Up above, the claim has repeatedly been made that humans have irreversibly depleted all the resources that will ever be accessible on Earth before the collapse of the Sun, so that any future intelligent civilization that might arise could never develop the capability to go into space.

Tavella isn't saying that another spacefaring civilization will definitely develop on Earth, he or she is saying that the reasons that have been presented for why such a thing would be impossible are nonsense.
posted by XMLicious at 1:58 PM on June 30 [1 favorite]


IAmBroom: "A post-apocalyptic society might be able to maintain a nuclear thermopile, for instance, but only until the fuel rods ran out; they'd never rediscover the concepts behind its construction."

This was almost exactly the plot of some bit in Asimov's Foundation novels. Was it in Foundation and Empire?
posted by Chrysostom at 2:09 PM on June 30


Was it in Foundation and Empire?

Yep, the Keepers of the Nuclear Stuff were a hereditary priesthood which had lost true knowledge of the principles behind their work, just doing everything by rote based on ages of handed-down experience. The system was huge enough to keep going through inertia but nobody really knew how it worked any more. This was how the Foundation, which was forced to do original research, was able to smoke them within a couple of centuries despite the very resource scarcity that forced them to start reinventing wheels in the first place (all according to the Seldon Plan, of course). Once the Empire was disrupted sufficiently it no longer had the critical mass to keep such technology working and everything fell apart.
posted by localroger at 3:03 PM on June 30 [1 favorite]


none of the exoplanets discovered at that point had atmospheres that would permit open flames

It's occupational health and safety gone mad.
posted by flabdablet at 9:18 PM on June 30 [1 favorite]


IAmBroom: tavella: people are declaring that _no_ civilization could possibly succeed us, or that we are the last possible civilization that could leave the earth, and that's just nonsense.

Citation needed. Show your work.

Really, it's unknowable. We only know of about 2-3 species that achieved language skills (and most of us carry genes from all of them), all developed in roughly the same situation, environment, and from a common ancestor, and from that people are making judgments about what absolutely can or cannot happen under other situations.

The only reasonable conclusion I can draw from the "Fermi Paradox" is that we have no real data on how likely "intelligent civilization" is to develop from Earth-like environments
.

These are two different arguments. Tavella is responding to the idea that humans will somehow use up the Earth to make it impossible for another civilization to arise on or leave Earth. That is clearly nonsense. You're talking about the comparative rarity of intelligent life to arise; in other words, you're talking about what numbers you would plug into in the second half of the Drake equation. I agree with you (and Jared Diamond) that radiowave-producing intelligent civilizations are probably much, much rarer than the optimistic projections we've heard on the order of 40,000 per galaxy.

However, that isn't too say that humanity has somehow blocked any future intelligent species that does evolve to someday attain that level of development, and it's even more emphatically not to say that a future human society couldn't do it again. Such assertions are based on the idea that any Industrial Revolution analogue can only happen the same way it did in Europe in the 18th and 19th centuries, and there is no basis for that.
posted by spaltavian at 6:11 AM on July 2 [1 favorite]


"That is clearly nonsense."

Again, you have absolutely zero proof of your conviction. It's mere opinion. Literally, science-fiction conjecture.

Myself, I'm not going to go claiming that I know what would happen if our entire planetary species were upended dramatically. That would be nonsense.
posted by IAmBroom at 6:24 PM on July 6


National Geographic: The Hunt For Life Beyond Earth: Are We Alone?
posted by the man of twists and turns at 10:38 PM on July 6


Myself, I'm not going to go claiming that I know what would happen if our entire planetary species were upended dramatically. That would be nonsense.

spaltavian is right. Even the scariest assessments of Earth's future suggest that it has at least a couple of hundred million years of habitability left.

65 million years ago most of the natural resources we are so busy burning today to create our current civilization slash environmental crisis were walking around. After a crisis event which killed every living thing on Earth that weighed over 25 lb and, by implication, 99.99% of all individual living things on Earth, it only took 65 million years for evolution to turn us up. Should we botch it all up a similar timeframe should be sufficient both for evolution to have another go at something like ourselves and for the natural resources we've consumed to be renewed through the same geological processes that created them for us.

Besides which, don't forget that there is an entire continent which we haven't gotten around to exploiting at all. When our current petroleum reserves were walking around eating leaves and hunting each other, Antarctica had a climate comparable to the modern continental United States. It will most likely be available for exploitation again should life need a do-over in our aftermath.
posted by localroger at 5:37 AM on July 7 [1 favorite]


Should we botch it all up a similar timeframe should be sufficient both for evolution to have another go at something like ourselves

Or maybe more trilobites. Because who doesn't love a trilobite? And they're way more durable than your short-lived invasive social mound builders, like your termites and your Homo Sap. You can argue with me, but you can't argue with a quarter of a billion years of success.
posted by flabdablet at 11:21 AM on July 7 [1 favorite]


spaltavian is right. Even the scariest assessments of Earth's future suggest that it has at least a couple of hundred million years of habitability left.

Not if there's a nuclear war.
posted by JHarris at 11:25 AM on July 7 [1 favorite]


Oh, I think bacteria should do just fine in a nuclear winter.
posted by flabdablet at 11:27 AM on July 7


Nuclear war would be a barely noticeable speed bump compared to the disaster that wiped out the dinosaurs 65 million years ago.
posted by localroger at 11:38 AM on July 7 [1 favorite]


We don't know how sudden that disaster was, compared to the practically instantaneous event of highly destrutice nuclear weapons whizzing around. And a planet-covering shroud of long-lived radiation is something the planet has never had to deal with before, we don't know what the effects would be.

Anyway, I was responding to your statement that "the scariest" pronouncement of Earth's habitability said it had hundreds of millions of years left. Well, some of those are very scary.
posted by JHarris at 11:46 AM on July 7


wiped out the dinosaurs

except the ones that are going to lay me my breakfast tomorrow. They look at me funny when I tell them they're all supposed to be extinct.

Just as well for us that we have Bruce Willis. Can you imagine trying to deal with this kind of thing without Bruce Willis? Doesn't bear thinking about.
posted by flabdablet at 11:52 AM on July 7 [1 favorite]


planet-covering shroud of long-lived radiation

Meh. If it's long-lived, that's because it isn't intense. Any self-respecting rapid replicator is well up to that challenge, I'm sure, even it it might take a few years to get going properly.
posted by flabdablet at 11:58 AM on July 7


We don't know how sudden that disaster was

Since the discovery of the Chicxulub crater we actually know quite a bit about it. The physical simulations of the strike are quite detailed. For example we know that the entire surface of the Earth was bombarded with molten debris. It's well accepted that everything both animal and plant exposed on the surface, everywhere on Earth, was burned. Everything in the ocean that couldn't go fairly deep and deal with an extended period of darkness and some pretty radical chemical changes died. Everything on the surface that survived the flaming debris bombardment then had to survive several years of darkness with hardly any photosynthesis going on. Those are things we know happened because we have the crater and the various debris like the iridium layer and shocked quartz shards which tell us how much energy was released, among other things.

Humans are incapable of putting up an insult anything like that. On review flabdablet has saved me the trouble of pointing out why radiation doesn't make it appreciably worse.
posted by localroger at 12:01 PM on July 7 [3 favorites]


If one of these hits home, nobody is going to me much fussed about radiation.
posted by flabdablet at 12:06 PM on July 7


I think there's still debate about how totally scorched the surface was, and the total shutdown of photosynthesis is currently thought to have lasted only a period of months, but it was long enough that all pure herbivores died, as did all pure carnivores, as far as current science can tell. The only things that survived were the flexible omnivores, and only the ones under 10kg. Basically, the ones who could live on relatively little food, scavenge anything dead that there was, and eat the saphrophytes that were doing the same.

And there will be multiple time periods equal to the period since then before earth becomes unlivable, so nuclear war, nasty for us, a big pfft as the long view goes.
posted by tavella at 12:10 PM on July 7 [1 favorite]


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