That was true, Draq conceded. The conditions needed to avoid a simple black-hole collapse were unlikely to occur by chance—an imploding object would need to shed a great deal of entropy to make the gravastar state possible, and nobody knew how that might occur in nature.
Nilis demanded, “Then how do you know the bones of your theory support any meat, eh? And besides, you’re describing spherically symmetric solutions of the equations. If I were to find myself inside a gravastar I would be as cut off and trapped, not to mention doomed to incineration by the shock wave, as if I were in a common black hole! So, Commissary, what use is any of this?”
Draq was clearly nervous, but he fixed his smile like a weapon. “But that’s why we need the Silver Ghosts, Commissary. To go beyond human theory. And to give us experimental verification. . . .”
Nilis joined Draq under his imploding Virtuals, and they launched into a complex and convoluted argument, involving asymptotically matched solutions of partial differential equations and other exotica. Pirius had a pilot’s basic grasp of mathematics, but this was far beyond him.
Mara approached him. She had her hands tucked into the sleeves of her robe. She whispered, “All this is a little rich for my blood, too. Perhaps we should take a walk.” She wouldn’t meet his eyes.
“You don’t want to be with me.”
“No, I don’t,” Mara said. “But it’s my duty to host you. And it’s your duty to understand what we’re doing here on Pluto—”
“Don’t talk to me about duty.”
“—even if that means you’re going to have to confront your feelings about the Silver Ghosts.”
“Why have I got to ‘confront my feelings?’” he snapped. “The Ghosts shouldn’t be here. That isn’t a feeling. It’s a fact.”
“What are you scared of?” she asked blandly.
“That’s a stupid question.”
She didn’t react. “It probably is. Will you come?”
He sighed. It was her, or Draq’s partial differential equations. “All right.”
Suited up, they walked out of the dome. Mara led him perhaps half a kilometer away from the domes of the Christy compound. They didn’t speak.
Once more, the sharp-grained, ultracold frost of Pluto crunched beneath Pirius’s feet, and he tried not to be spooked by the immense mass of Charon poised silently above his head.
They crossed a low ridge, perhaps the worn-down rim of another ancient crater, and approached a new structure. It was an open tangle of cables, wiring, small modules; it looked impractical to Pirius, more like a sculpture. But it seemed oddly familiar, and he dug for the memory, left over from some long-ago training session.
Mara spoke at last. “You understand that the main Ghost reservation, which you saw, is on the far side of the planet. But it was necessary to provide support facilities for the Ghosts who work with us here, at Christy. We decided to take the opportunity to recreate another bit of Ghost technology.”