Free Ultima by Stephen Baxter Page A

energy to shock one of their brood to adopt this new form. You never discovered this?”
    â€œMy culture was more cautious than yours. More timid, perhaps. We would never have won approval for such an experiment.” For better or worse, she thought, we cared more about the lives of our technicians than to spend them on such stunts. Even if it had occurred to us to try. “How did you get the idea? I can hardly believe you found such a specific arrangement by trial and error.”
    Eilidh smiled. “We did not. Somebody else found it for us.” Now the
cetus
was rising, turning its prow to the jagged row of mountains on the misty horizon. “We first found the kernels on Mercury—as did you, yes? We were already traveling beyond Terra—well, obviously. We had big ships driven by Xin fire-of-life, and by potent liquid elixirs . . . I fear our common vocabulary is not yet rich enough.”
    Gunpowder and chemical propellants. “I get the idea.”
    â€œSuch substances had been discovered and developed during centuries of war. We had already flown to Luna, to Mars, though many died in those days, and our first attempts to plant
colonia
on those bodies were often catastrophic . . .”
    Stef’s head swam. Without the fall of Rome in the west, without the Dark Ages, could technological development have been that much faster? She imagined a medieval world with crude rocketships lumbering into space, with lessons slowly being learned about the vacuum of space, about radiation, about weightlessness, by cultures utterly unsophisticated in the relevant science—lessons learned the hard way, at the expense of many deaths. She was thrilled at the idea. Thrilled and appalled.
    â€œThen came Mercury,” Eilidh said. “There was a war of acquisition, more intense than most. We all wanted Mercury and its resources to capture the energy of the sun, you see. It was seen as a strategic position in terms of advantage for the future. And just how strategic only became clear when a Xin party stumbled across a field of kernels.”
    â€œAh.”
    â€œAfter the usual blood toll the kernels were tamed, their energies used to drive our ships, and they were unleashed as weapons of war.”
    That simple phrase managed to shock Stef, despite all she’d witnessed in her own home timeline. “Surely not on Earth itself.”
    Eilidh just returned her look. “But we are speaking of the Hatches. The first Hatch of all was found on Mercury, in the kernel field.”
    â€œAs it was for us,” Stef said.
    Eilidh raised her eyebrows. “On a different Mercury too? We do have much to discuss. Of course the Hatch was opened; of course there were attempts to
pass through
 . . . None of those who entered, unwilling slaves, bold soldiers, curious philosophers, ever returned.”
    â€œPerhaps they are still in transit.”
    â€œIn transit?”
    â€œ
Our
Mercury Hatch is connected to one on Per Ardua. Umm, which is a world of Proxima Centauri. Which is—”
    â€œThe nearest star, in the Centaur’s Hoof. For us, it has been given the same name.
Proxima.
” She smiled, a little sourly. “So there are Romans in your country too.”
    â€œWere. Long story. Look, it’s only four years as light travels between Mercury and Proxima. So it’s possible to go there and step back with only eight years elapsing.”
    Eilidh frowned as she puzzled all that out; Stef had no idea how much understanding of such basic physics they shared.
    â€œThe point is,” Stef said, “maybe
your
Hatch on your Mercury was hooked up to somewhere else. Somewhere much farther away.” There was no reason why that shouldn’t be true, she realized. They knew so little, despite the decades that had passed since her own first brush with all this strangeness. “Your travelers may have arrived alive and well, but just haven’t