Donald Moffitt - Genesis 02

acquired gravity and left him awkward and abrasive again. When Smeth had invited Ame to watch the hole approach with the astronomy and physics group, he had expected to monopolize her—and now she could not be pried loose from her chums. Smeth still was trying to figure out if Jorv was attached somehow to Abriga or whether he represented sexuai competition.
    As if that weren’t bad enough, Jun Davd was being courtly.
    “No, we believe the Milky Way is reasonably tame now,” Jun Davd said in answer to Ame’s question. “The quasar epoch used up the tremendous quantity of material within the core that might fuel an event on that titanic a scale and stored it conveniently in the form of the black hole we’re orbiting now. The subsequent explosions— like the one that caused the ‘smoke ring’ Smeth mentioned—obviously could not have been violent enough to wipe out life in the Milky Way … though they might have had some minor effect on species.”
    Ame and Jorv exchanged a peculiar glance.
    “When did the last core explosion take place?” Ame asked. “Or is there any way of estimating it?”
    “Yes, indeed, there is,” Jun Davd said. “We’ve been observing the so-called smoke ring over a period of more than fifteen thousand objective years during our dive into the galactic bulge. It keeps expanding and contracting to strike a balance between its rotantional velocity and the gravitational attraction of the center. From the rate of oscillation, we calculate that the last core explosion took place approximately one hundred and forty-one million years ago.” He smiled. “And I gather that Original Man evolved after that event, since he broadcast his Message only seventy-four million years ago.”
    “Jun Davd,” Ame said, hesitating, “when is the next core explosion due?”
    Smeth opened his mouth, but Jun Davd beat him to it.
    “Theoretically, there shouldn’t be one. The last explosion should have depleted the galactic center of the necessary mass. The smoke ring’s velocity and distance suggest an ejected mass of one hundred million solar masses—and an explosion powered by converting the equivalent of ten thousand suns completely into energy. Now a black hole of one hundred million solar masses sits in the center, and except for the observed stars around it, the center should pretty well have been swept clean.” He frowned.
    “But?”
    “By generating artificial profiles of the twenty-one centimeter line, we’ve determined the amount of invisible matter that must be rotating around the galactic center.” He paused, decided to add to his explanation. “You see, that gave us the Doppler shift of the neutral hydrogen present.”
    She seemed to know what he was talking about. “The faster the rotation, the greater the mass?”
    He brightened. “Precisely. And the figure we get is two hundred million solar masses.”
    “Twice what ought to be there?”
    He nodded. “And we don’t know where it came from.”
    “Jao has a theory about that, though,” Bram put in.
    “I’ve heard about Jao’s theories, Bram -tsu. ” Ame laughed. She was a dutiful descendant, always giving him an ancestral honorific in the abbreviated Chin-pin-yin form. He had told her over and over again to simply call him Bram, but like so many of the young people, she was a stickler for convention; it was as if the newest generation were trying to revive a structure of human tradition all by themselves.
    Jao, hearing his name, twisted his shaggy red head around from the console he had been working. “Yah,” he said, “there has to be some kind of mechanism for renewing matter in the core of the galaxy. It doesn’t have to amount to much—about seven-tenths of a solar mass per year.”
    “The problem is,” Jun Davd said indulgently, “that this hypothetical flow of matter isn’t coming from the galactic plane, and it isn’t coming from outside the galaxy, as when the Whirlpool cannibalized the Bonfire.”
    “So that leaves one place, right?” Jao continued. “The nucleus of the galaxy itself. Matter just appears there.”
    Smeth found his voice. “That’s preposterous!” he said. “It’s nothing more than a rehash of the old discredited theory of the continuous origin of matter!”
    “No, listen, this is a new idea based on the heavy-neutrino model of the universe,” Jao insisted. “If neutrinos have mass, then they could account for ninety percent of the mass of the universe, and ordinary