Phase Space by Stephen Baxter Read Free Book Online Page B

Jupiter and Saturn a few times, and you could slingshot your way out of the system for free. Of course it might take you ten thousand years to reach your destination, at Barnard’s Star or E Eradini or E Indi. But what the hell; you probably had with you more water than in the whole of the Atlantic Ocean.
    Greenberg accepted the necessity of the migration. But to him it had been a drain, not just on the system’s titanic population, but on the human spirit.
    The solar system had been left a drab, depopulated place. All the engineering types had gone, leaving behind the navel-gazing seals of Ra, and similar relics scattered around the system.
    The Weissmans, turned in on themselves, had their own interests. They were probing into a lot of areas well beyond his expertise. Like the possibility of tapping into zero-point field energy, the energy of the vacuum itself, so dense you could – it was said – boil all the oceans of Earth itself with the energy contained in a coffee cup of empty space. Then there was the compact energy stored in topological defects, little packets of space that had gotten tangled up and folded over in the Big Bang, containing some of the monstrous primeval energies within, just waiting to be tapped and opened up …
    Research and development, carried on by a community of goddamn seals, with no hands or tools. Greenberg didn’t know how they did it. It was one of the many things about the Weissmans he didn’t understand.
    He did know they were trying to extend their consciousness. Mind, it seemed, was a quantum process, intimately bound to the structure of space and time. And in space, after ten thousand years free of the distortions of the muddy pond of atmosphere at the bottom of Earth’s gravity well, consciousness – the Weissmans claimed – was taking a huge evolutionary leap forward, to new realms of power and control and depth.
    Maybe.
    To Greenberg, it was all very well to dream of super-minds of the future, but right now, he suspected there was nobody left, for instance, who was giving thought to pushing a troublesome asteroid out of its orbit, where once the children of man had rearranged worlds almost at will.
    And, Greenberg was coming to realize, that might make a big difference in the future.
    He still had some of his old monitoring systems, or patiently reconstructed copies anyhow. He studied Ra’s evolving trajectory around the sun.
    And, gradually, he’d learned something that had disturbed him to his core.
    Near-Earth asteroids wandered in steadily from the main belt, their orbits tweaked by the gravity of Jupiter, Venus, Mars and Earth itself. They hung around for thirty megayears or so, their orbits slowly evolving. Then they would encounter one of three fates, with equal probability: they would hit Earth, or hit Venus, or be slingshot out of the system altogether.
    The cratering record on Earth showed this had been going on for billions of years. The smaller the object type, the more frequent the collision. Every few thousand years, for instance, Earth would be hit by an object a hundred metres or so across, big enough to dig out a new Meteor Crater, as in Arizona, where Apollo Moonwalkers had once trained. Earth had actually suffered a few fresh strikes like that while Greenberg had been observing.
    And every few tens of millions of years, a much larger body would strike.
    Such an object had struck the Earth sixty-five million years ago, at Chicxulub in Mexico. It had caused the extinction of most of the species extant at that time.
    It was known as the dinosaur killer.
    Earth was overdue for another impact like that.
    Near-Earth asteroid orbits were pretty much chaotic. It was like the weather used to be, back when he lived in a place that had weather. But as computers had gotten smarter, the path of Ra-Shalom had been pushed out, in the computer’s digital imagination, further and further. Finally it had become clear to Greenberg what Ra’s ultimate fate would be.
    Ra