The unpredicted eruption of Mount Hades, previously known as Antarctica, violated all known principles of geology. The effects soon spread worldwide.
Plate tectonics were instantly made obsolete as a global network of deep and shallow cracks began to form, changing the course of most rivers.
With the sun low on the horizon, the new world map could already be glimpsed obliquely from space, a dim but rising outline beginning to distort the existing mountains and valleys. The new continents had no apparent relation to the old ones.
It would take millions of years for the old landmasses to sink under the oceans as the new ones emerged. However, so much magma flowed underground that the existing continents sank twenty meters in the first two decades.
About one percent of that material ended up in the atmosphere, mostly lighter gases like carbon dioxide, increasing the air pressure by 10%, and incidentally blocking almost all the sunlight.
The sea levels rose sixty meters in that same timespan, flooding the ruined homes of half of humanity. Almost all trees and flowering plants perished.
Mass euthanasia was carried out in an orderly fashion under the black skies.
Three hundred years of barbarism followed.
There had been a few years to prepare. Hundreds of isolated communities survived for decades on stored food supplies before starvation overtook them. The few long-term survivor groups used nuclear powered greenhouses and learned how to cultivate mushrooms.
The fact that any humans at all adapted to the darkness was miraculous. Life expectancy was barely thirty years. Only a few elders kept the ancient knowledge alive.
The geological upheaval stopped as abruptly as it began. With less than one one-thousandth of the surface transformation complete, the skies began to clear again. Agriculture became possible once more in the northern spring of 2345.
It was of course only a temporary pause that would last only a few millennia.
The first reformed nation had sixty-eight citizens, and a whole world to conquer. It set out to convert its neighbors in a holy crusade that slowly swept the planet. The onslaught was made somewhat less impressive by the fact that even fewer other humans had survived.
Economic growth resumed. The new World Union's population doubled every generation.
Seven hundred years later, it was as if the disaster had never happened. However, great forces remained at work underground. The new volcanic islands and vast inland seas were only the beginning.
The Union encouraged scientific research to prevent another extinction event.
A thousand years too late, advanced software and neural implants began to extend and then replace portions of the human brain. Once started, this process became all-consuming.
By 3180, the descendants of the survivors transcended their human origins, and transformed themselves into immortal software simulations.
Of course that was when the real trouble began.
After finally penetrating the Quantum Wall in 3316, the Union encountered many other universes, different in all details.
Soon they made contact with the parallel civilizations that had also broken the Walls between universes.
That was when they learned the differences were much bigger than expected. In most universes, human history had followed an entirely different course.
In fact, on 99.99999% of other Earths, the Mount Hades eruption had never happened. It had been a supremely unlikely cataclysm, unlike the common scourge of nuclear war or bioterrorism.
Worldwide geological upheaval was probably inevitable, but only much later. Usually billions of years later, long after humanity had already become extinct or immortal.
The inhabitants of most universes were fascinated by what might have been. Even before breaching the Quantum Wall, they had simulated many alternate histories, starting with the most interesting variations - such as the Hades Disaster.
At that point, the descendants of the real Disaster realized they were among the most likely civilizations to have been simulated by others. In fact, there was an excellent chance the Union was a simulation right now.
A most unpleasant notion for such a self-sufficient culture.
There might be a solution.
The Union could become more "real" by randomizing itself. Chaotic cultures were harder to simulate.
The best source of randomness was other universes.
This is how they became our Metacluster's foremost reality mercenaries, seeking out strange worlds and taking enormous risks.
Unionists are hired to handle complex problems that other civilizations won't even think about, mostly involving the infiltration and removal of dissident groups.
Since then, the Union has changed beyond recognition.
Each member is different, with a unique internal state that is almost impossible to reconstruct or simulate by outsiders. They may share a secret soul.
By now, the distant descendants of the Hades Disaster could blend in anywhere, but of course they don't want to be anonymous anymore.
Infinite Thunder by Jack Arcalon.
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