Donald Moffitt - Genesis 02

vertical line in screaming orange grew in the illusory void behind the wall. “We start with a two-spoke model,” Jao said. “Two opposing arms, like a lot of cosmic phenomena. Like galactic gas jets, for example. Now we add another pair of arms at right angles.”
    He slashed another orange line across the first. It wasn’t quite horizontal—apparently by design, because as everyone watched, the second pair of arms, responding to whatever crude instructions he had punched into his board, slowly turned until the adjustment was made.
    “You see, there’s some repulsive force holding them equidistant from the two previous arms,” Jao said. “Like magnetism. Now we subdivide one more time.”
    Two more crude slashes turned the cross into an asterisk. This time the finger-painted lines weren’t as thick, and they were a paler orange. They were also slightly out of position, but after a moment the second cross rotated with respect to the first until all the angles were equal.
    “These are the baby arms,” Jao said. “They’re not full-grown yet. They’re weaker. That’s why I drew them skinny.”
    Jorv, with growing excitement, said, “What did you mean when you said it works out?”
    “For starts, when you multiply these twenty-six-million-year events by yours by eight, you get a figure of two hundred and eight million years. Which is a pretty good match for the length of time it takes Man’s sun to make one complete orbit around the galactic center.”
    “Very suggestive,” Jun Davd said. “Eight events per solar orbit. Of course, you’re assuming either that the spokes are stationary, or the sun is stationary, or the spokes are rotating at twice the sun’s speed at the radius of the sun’s orbit.”
    “Like I said, you have to start somewhere,” Jao said. “I like figures that come out even. So you begin with a nice regular series—two, four, eight. And multiples of orbital speed—which incidentally would put the end of a full-grown spoke somewhere at the rim of the galaxy.”
    “Why not a ten-spoke model?” Smeth interrupted, with a sidelong glance at Ame. “You’d get a multiple of two hundred and sixty million years, which is closer to the two-hundred-and-fifty-million-year galactic year that some of us prefer!”
    Jao shrugged. “Suit yourself. You could make that work, too, with a little fiddling with the relative velocities. You can work out the figures if you like. But an eight-spoke model’s more elegant.”
    “I take it there’s more,” Jun Davd prompted.
    Jao brightened. “Yah. Watch this.”
    His thick fingers busied themselves on the board, and a bright yellow dot appeared about halfway out on one of the orange spokes. It began tracing a slow circle around the center of the geometric figure. A moment later the eight-armed figure began to revolve, too, at a somewhat faster rate, with the arms continually overtaking the dot.
    “Now, let’s label the arms so we can keep track of them,” Jao said.
    Letters popped up, alphabetizing the arms. Jao did not stop the process quickly enough, and a second round of letters began to subtend the first.
    “That’s okay, leave it,” Jao said. “If I were laying this out flat, I’d be going past eight into the next cycle, anyway.”
    Ame and Jorv were intent on the garish sketch hanging in the space before them. Bram could see Ame’s lips moving as she counted to herself.
    “Now we take those forty-five-degree angles and subdivide them again,” Jao said.
    Eight more lines grew within the spoked figure. These were dotted lines, even paler and more tentative than the lines of the second cross. Not all of them were full-length. Several of them still fell short of the yellow dot’s circular orbit.
    ‘These are your follow-up extinctions,” Jao said to Jorv. “The ones you say sometimes follow the main events thirteen to fifteen million years later. They subdivide the twenty-six-million-year intervals, and they’re growing outward at different rates, so we can’t fit all of them into the picture. Yet.”
    “Very thin,” Smeh said.
    “So we start with what we do know. Here’s the dinosaurs.”
    One of the arms of the original cross thickened and darkened to burnt orange. The tenuous dotted line following it began to blink for attention.
    “Okay, anything there?” Jao asked.
    Ame and Jorv looked at each other. “The Miocene crisis,” Ame said immediately. “A mass wipeout of shellfish, plankton, some land animals.