How will the world end?

Some envision nanos cleansing polluted aquifers, rebalancing sterile swathes of ocean, or sucking carbon from the air.

It’s not that sociopaths are smarter — they generally aren’t.

One sage who helped build the first atom bomb put it pungently: “When has man, bloody down to his soul, invented a new weapon and foresworn using it?”

Some “filter” may winnow the number of sapient races, low enough to explain our apparent isolation.

To get you started, let’s review the vast range of doom scenarios that have already been cataloged by the good (though dour) folks over at Pandora’s Cornucopia:

That average still leaves a billion human beings, out of almost ten billion, who are steeped in rage, or dogmatic rigidity, or delusional repetition of discredited mistakes.

Unlike those elitist compilers over at the Pandora Foundation, our open-source doomsday system invites you, the public, to participate in evaluating how it’s all going to end.

By quest-programs that present you with anything germane to your current interest.

A susceptibility for simplistic/viral notions.

Listen to those dour curmudgeons out there, decrying the faults of our current “Age of Amateurs.”

It seemed that just keeping up would force each of us to focus on ever-narrower fields of study, forsaking the forest in order to zero-in on tiny portions of a single tree.

Millions still live who recall the Soviet-American standoff — the Cold War — when tens of thousands of hydrogen bombs were kept poised in submarines, bombers and silos.

This category is where we’d assign most punishments for mismanaging the world.

The specter at our banquet, slinking between reflection and foresight, as we turn now to examine a long list of threats to our existence.

Monarchy and feudalism heaped more rewards on any king who could talk thousands of virile men into marching and fighting to protect his seraglio.

Or micro black holes, colliding with the Earth and gobbling us from within.

Roughly the time it took tiny mammals to emerge from their burrows, stare at the smoldering ruins of T-Rex, then turn into us.

Autopsies of empires are often inconclusive.

Well, there are solar superflares, supernovae, and giant black holes that might veer past our sun.

Zeus or Moloch could not match the destructive power of a nuclear missile exchange, or a dusting of plague bacilli, or some ecological travesty, or ruinous mismanagement of the intricate aiconomy.

One can imagine countless other species — and our own fragile renaissance — faltering back into the dour scenario that we students mulled on those gloomy nights.

Soon, smart nanobots may cruise your bloodstream, removing a lifetime’s accumulated dross, even pushing back the clock of years.

In his prescient novel “The Cool War,” Frederik Pohl showed a chillingly plausible failure mode in which our nations and factions do not dare wage open conflict, and so they settle for tit-for-tat patterns of reciprocal sabotage, each attempting to ruin the other’s infrastructure and economy.

Which of our past military or commercial or hereditary empires would have unleashed something as powerful as the Internet, letting it spread — unfettered and free — to every tower and hovel?

And we’re overdue.

Descendants of Viking raiders, Centurions and Huns transmuted into pacifists.

Others cogently guess what fraction of those Life Worlds develop technological beings.

Might intelligence be a fluke?

Nations ruled by aristocracies were more impulsive, spendthrift and violent.

To meet the flood of knowledge with eager, eclectic agility.

Our civ evaded that crisis with a technological side-step that seemed so obvious, so easy and graceful, that few even noticed or commented.

For example, eco-decay and resource depletion might be slow enough for a few descendants to eke a threadbare niche.

Or this tech may be perverted for man’s oldest pastime.

The specter at our banquet, slinking between reflection and foresight, as we turn now to examine a long list of threats to our existence.

But, instead, the sort of callous descendants we’d disown … as if such beings would care what we think.

When farming created a surplus that could be stored, markets arose, along with kings and priests, who allocated extra food to subsidize carpenters and masons, scribes and calendar-keeping astronomers.

We might “advance” in some cramped ways.

Monarchy and feudalism heaped more rewards on any king who could talk thousands of virile men into marching and fighting to protect his seraglio.

Some envision nanos cleansing polluted aquifers, rebalancing sterile swathes of ocean, or sucking carbon from the air.

Causes range from nuclear war or spoiling the ecosystem to voraciously unstoppable man-made black holes or ravenous nano-plagues.

They cite our vaunted flexibility, the way we learn and reprogram ourselves, as individuals and cultures.

Descendants of Viking raiders, Centurions and Huns transmuted into pacifists.

And there are other scenarios –– conceivable ways that one lunatic might outweigh all the rest of us, no matter how high a fraction are good and sane.

Chastened and thus saved by an engine of death?

We’re all descended from the harems of fellows like Charlemagne and Genghis Khan who mastered that trick.

Often, late at night, my classmates and I pondered the dour logic of specialization.

Which of our past military or commercial or hereditary empires would have unleashed something as powerful as the Internet, letting it spread — unfettered and free — to every tower and hovel?

Shall we admit that our species passed one test by not plunging into an orgy of atomic destruction?

But suppose someone interferes, deliberately nudging a mile-wide object Earthward.

Suppose we humans blow it, bigtime, leaving only small creatures scurrying through our ruins.

The specter at our banquet, slinking between reflection and foresight, as we turn now to examine a long list of threats to our existence.

But, instead, the sort of callous descendants we’d disown … as if such beings would care what we think.

Refusing to be constrained by official classifications, we let knowledge bounce and jostle into new forms, supplementing professional skill with tides of zealous amateurism.

The professor simply professed, and a dentist had only to dent.

Lurid sci-fi tales warn of replicators eating the biosphere, outcompeting their creators.

Yes, there are rumors and worried models predicting a coming conflagration — one between classes, rather than nation states.

Or are they prescribing another badly needed course correction to stave off disaster?

Oh, they were imbeciles, falling for a sting operation.

Or so the maniacs thought, as they plumbed a hole wide enough to convey a tactical nuclear device.

And this tit-for-tat, negative-sum game is all about the most dismal human pastime.

When farming created a surplus that could be stored, markets arose, along with kings and priests, who allocated extra food to subsidize carpenters and masons, scribes and calendar-keeping astronomers.

In his prescient novel “The Cool War,” Frederik Pohl showed a chillingly plausible failure mode in which our nations and factions do not dare wage open conflict, and so they settle for tit-for-tat patterns of reciprocal sabotage, each attempting to ruin the other’s infrastructure and economy.

And above all, by our new ability to flit — like gods of legend – all over the e-linked globe, meeting others, ignoring guild boundaries and sharing ideas.

By monsters prowling the darkness.

For example, eco-decay and resource depletion might be slow enough for a few descendants to eke a threadbare niche.

Might hordes evolve, adapting to utilize the natural world?

Some obstinate belief?

By Internet connections and search-correlation services that sift the vast sea of knowledge faster than thought.

We modern folk snort at the superstitions of our ancestors.

Were we scared back from that brink, sobered to our senses by the warning image of a mushroom cloud?

Still, the odds change when we meddle.

Knaves, monopolists and fat-cats who use intellectual property to repress knowledge growth instead of spurring it.

And above all, by our new ability to flit — like gods of legend – all over the e-linked globe, meeting others, ignoring guild boundaries and sharing ideas.

Suppose we in this generation are — on average — growing both smarter and more sane at a decent clip.

No matter how contingent or flexible?

A threshold when Earth will no longer be able to shed enough heat, even if we scrubbed every trace of greenhouse gas.

Or else, some may feel stimulated to relish what they have, in the precious here-and-now, especially if our lives and comforts appear to be on temporary loan from a capricious universe.

Fermi listened patiently, then asked: “So? Shouldn’t we have heard their messages by now? Seen their great works? Or stumbled on residue of past visits? These wondrous others … where are they?”

Those fierce dinosaurs and other dominant beasts all met their doom with dull surprise, having no hand, paw or claw in bringing it about.

After reaping the benefits for many generations, it seemed clear that a crisis loomed.

Some were opposites, like too much Christian piety vs. too little.

Those fierce dinosaurs and other dominant beasts all met their doom with dull surprise, having no hand, paw or claw in bringing it about.

Men and women always felt besieged.

There was never any proof that vicious conflict is woven into human DNA.

Isn’t this the nightmare fretting conservatives?

Oh, they were imbeciles, falling for a sting operation.

But who really yearns for such a thing to happen?

The old fear of narrow over-specialization suddenly seemed quaint, as biologists started collaborating with physicists and cross-disciplinary partnerships abounded.

It seemed that just keeping up would force each of us to focus on ever-narrower fields of study, forsaking the forest in order to zero-in on tiny portions of a single tree.

Everyone knows how a giant boulder struck the Yucatan, sixty-five million years ago, slaying the dinosaurs.

One sage who helped build the first atom bomb put it pungently: “When has man, bloody down to his soul, invented a new weapon and foresworn using it?”

Each time we face some worrisome step along our road, from avoiding nuclear war to becoming skilled planetary-managers, to genetic engineering, artificial intelligence and so on, we must ask: “Is this it? The Big Blunder? The trap underlying Fermi’s question?”

As brief as that moment lasts – and it may only be an instant – you’ll have the satisfaction of muttering those most voluptuous of consoling words:

Start putting our eggs in more than one basket.