Semper Human by Ian Douglas

far-flung arcs and walls and swirls of hot clouds of molecular gas, of stars showing comet tails streaming away from the central blast, of nebulae torn asunder by ferocious stellar winds, of objects set in such a titanic scale that stars and even clusters of stars were dwarfed to insignificance. His implant began overlaying what he was seeing with identifying blocks of text.
    Humans had last visited the center of the Galaxy in 1111 of the Marine Era…the year 2887 by the old calendar. Marine and naval forces had assaulted a major Xul base, a number of bases, actually, located in and around the Core structures. The largest and most important of these had been a Dyson cloud, a swarm of trillions of Xul artificial wordlets positioned around the supermassive black hole that marked the Galaxy’s exact gravitational center. At the climax of the battle, a red giant star called S-2, in close orbit around thecentral black hole, had been nudged from its high-velocity path by inducing a partial and off-center collapse beneath its surface, triggering an outrushing jet of stellar material that had acted like an immense rocket blast. The fast-dwindling star had fallen closer to the black hole than otherwise would have been the case, sweeping through part of the Xul cloud, then shredding as it whipped around the inner gravitational singularity and down the cosmic drain at the center.
    The Xul hyperstructure had been destroyed, the individual elements of the cloud plunging into the black hole in an eye’s blink because they’d been force-beam anchored in place, rather than circling in orbit. Much of the infalling matter had been swallowed of course, but much more had rebounded outward, generating what had come to be known as the Core Detonation, an out-rushing surge of tortured plasma so hot and bright that a supernova would have been lost in the glare.
    A nearby star cluster, young and hot, just a tenth of a light year out, had been consumed in the fury weeks later, the stars pop-pop-popping into a chain of supernovae as the flood of radiant energy engulfed them. Other supergiant stars close to GalCenter had been swept up as well, adding their mass as fuel to the maelstrom of radiation.
    That had been 1117 years ago. In those eleven centuries, the blast wave had swept outward, the wavefront of electromagnetic radiation traveling 1117 light years in that time, the somewhat slower, following squall of high-energy particles crossing about 900 light years in the same period of time. Stars, thousands of them caught in that deadly firestorm of energy, had exploded as they were engulfed, each adding its own bit of fury to the storm. The Galactic Core was now a seething ocean of blue-white hell, and it was still expanding.
    Any Xul nodes located within that central, two-thousand-light-year-wide pocket of hell, would have been swept up and consumed. The question was how far the blast would expand…how much of the Galaxy might it devour?
    â€œSo,” Garroway wanted to know, “is that stuff going to hitus in another twenty, twenty-five thousand years?” The thought that Humankind’s attack on the Galactic Core eleven hundred years ago might actually have unleashed a beast that was going to devour the entire galaxy was horrifying.
    â€œIt’s attenuating,” Schilling told him. “Twenty-six thousand years, or a little less, after the original Core detonation, the electromagnetic wavefront will pass Earth at the speed of light. Long before that happens, the heavier charged particles and plasmas, the hard, dangerous stuff, will have been absorbed by intervening clouds of dust and gas.”
    â€œ Even so, ” a new voice said, “ the astrophysicists are calling it a microquasar. It won’t scour the Galaxy of life, fortunately, but they estimate the total light output from our Galaxy will more than quintuple, and probably set the astronomers in Andromeda to scratching whatever they use for heads