“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 matter is a film wrapped around great clumps of neutrinos. And where do the clumps come from? I’m glad you asked that. They’re simply the walls of a great spongy cellular structure, one of whose bubbles is our own dear old universe. This all takes place in eleven-dimensional space-time, needless to say. The different domains are a necessary consequence of the first moments of creation—and you’ll notice that the domains would be nonregular in shape, and that fits in well with the observed fibrous structure of the universe. So how do we create matter in the nuclei of galaxies without violating baryon conservation?”
He glared around at everybody.
“I have a feeling he’s going to tell us,” Bram said.
“We don’t!” Jao proclaimed triumphantly. “We have an exchange of neutrinos and un-neutrinos through the walls of the domains. The walls leak. Why are the leaks located in the centers of galaxies? Easy. Because of the hypermasses there—the super black holes sinking deep into the plenum and stretching the warp and woof of space-time to its limits. You may well ask why no right-handed neutrinos have ever been observed, despite the predictions of theory! Because the scales are balanced in other domains, that’s why! So symmetry is preserved in the larger sense. Baryons—like protons and neutrons—can’t cross the domain walls without instantly decaying. But un-neutrinos exhibit antidecay and assemble themselves into elementary particles, in the reverse of beta decay.”
Smeth was beside himself. His face was red as a tomato, and he seemed in danger of bursting.
“You can’t do that!” he said, his voice cracking. “How can you change leptons into baryons?”
“With mesons as the mediators, naturally,” Jao said. “And while we’re at it, what do you think happened to those missing solar neutrinos you tried to detect in that chlorine tank experiment of yours back on the Father World? I’ll tell you. They were falling in, not out. They were being funneled through the domain wall to another domain. There must have been a black hole on the other side.”
Smeth opened his mouth indignantly to reply, but Ame cut in to get the subject back on track.
“So what it boils down to is that, by whatever mysterious process, there’s enough material in the center of the galaxy for another explosion, even though it shouldn’t be there?” she asked.
“Admirably put,” Jun Davd said.
“And that presumably this process acted in the past to cause periodic explosions?”
“Yes.”
Ame mulled it over. “Could core explosions be a byproduct of some other process? Or vice versa?”
Jun Davd pursed his lips. “That’s an interesting question. More interesting than you know. Why do you ask?”
“I’m trying to pin down periodicity. You said that the last core explosion in the Milky Way must have taken place one hundred and forty-one million years ago?”
“Thereabouts.”
“It’s a very interesting coincidence.”
Her zoologist friend, Jorv, nodded energetically.
“Coincidence? How?” Jun Davd asked.
“Because one hundred and thirty-nine million years ago was when the dinosaurs became extinct.”
Jorv burst out, “Practically on the heels of the explosion!”
“What is a dinosaur?” Jun Davd inquired.
“It was a very large animal that predated humans on Earth. Though they couldn’t have been as large as the Message described them—there must be some error or misinterpretation of scale. We have line sketches of several of the main types. They were the dominant form of life on Earth for about one hundred and thirty million years, then they abruptly vanished.”
“Like Original Man,” Jun Davd murmured. “I take your point.’
“How big were they?” Jao asked.
“They were built on the same general plan as human beings,” Ame said. “Four limbs, bilateral symmetry, bony skeleton—so I suppose it’s possible that they could have been as much as three or four times human size. We’ve done computer simulations of them, and with a thicker bone cross section as compared to a human, certain efficiencies in oxygenating tissues, a slower metabolism, and so forth, we think it’s possible for them to have weighed as much as a ton.”
Jao whistled. “That big?”
“The Message data has some of them attaining a length of ninety feet and weighing as much as fifty tons.” She smiled. “But of course that’s nonsense. No creature with an internal skeleton could attain that size. It would have to have some sort of exoskeleton supporting its weight like a scaffolding, or an external shell, like the orthocone creatures on the Father World—and of course, then they couldn’t be very active.”