And as they overlapped, life-forms crossed from one domain into another.

For the federation, the creatures that suddenly came hurtling out of infinity were the stuff of nightmare. These invaders came from a place where the laws of physics were subtly different: the symmetry-breaking which had split gravity from the GUT superforce had occurred differently in different domains, for they had not been in causal contact at the time. That difference drove a divergence of culture, of values. The federation valued its hard-won prosperity, peace, and the slow accumulation of knowledge. The invaders, following their own peculiar imperatives, were intent only on destruction, and fueling their own continuing expansion. It was like an invasion from a parallel universe. Rapprochement was impossible.

The invaders came from all around the federation’s lightspeed horizon. Reluctantly, the federation sought to defend itself, but a habit of peace had been cultivated for too long; everywhere the federation fell back. It seemed extinction was inevitable.

But one individual found a dreadful alternative.

Just as the cosmos had gone through a phase change when gravity had separated from the GUT force, so more phase changes were possible. The GUT force itself could be induced to dissociate further. The energy released would be catastrophic, unstoppable, universal — but, crucially, it would feed a new burst of universal expansion.

The homelands of the invaders would be pushed back beyond the lightspeed horizon.

But much of the federation would be scattered too. And, worse, a universe governed by a new combination of physical forces would not be the same as that in which the spacetime creatures had evolved. It would be unknowable, perhaps unsurvivable.

It was a terrible dilemma. Even the federation was unwilling to accept the responsibility to remake the universe itself. But the invaders encroached, growing more ravenous, more destructive, as they approached the federation’s rich and ancient heart. In the end there was only one choice.

A switch was thrown.

A wall of devastation burned at lightspeed across the cosmos. In its wake the very laws of physics changed; everything it touched was transformed.

The invaders were devastated.

The primordial black holes survived — and, by huddling close to them, so did some representatives of the federation.

But the federation’s scientists had not anticipated how long this great surge of growth would continue. With the domain war long won, the mighty cosmic expansion continued, at rates unparalleled in the universe’s history. Ultimately, it would last sixty times the age of the universe at its inception, and it would expand the federation’s corner of spacetime by a trillion, times a trillion, times a trillion, times a trillion. Human scientists, detecting the traces of this great burst of “inflation,” the single worst catastrophe in the universe’s long history, would always wonder what had triggered it. Few ever guessed it was the outcome of a runaway accident triggered by war.

As the epochal storm continued the survivors of the federation huddled, folding their wings of spacetime flaws over themselves. When the gale at last passed, the survivors emerged into a new, chill cosmos. So much time had passed that they had changed utterly, and forgotten who they were, where they had come from. But they were heirs of a universe grown impossibly huge — a universe all of ten centimeters across.

Quin Base shocked Pirius Red.

Chapter 42

He was dismayed by the cramped corridors and heaped-up bunks of the barracks, the crowding, the stink of shit and urine and semen, the metallic odors of failing life-support systems. The people swarmed through their cavernous lairs, feeding and sleeping, shouting and wrestling and rutting. The only difference he could see between privates and cadets was the gleaming metallized pupils of the “veterans.” He thought their silvery stares made them seem inhuman, like huge, lithe rats, perhaps.

If he had been faced with hostility in the barracks back at Arches, here he was regarded with undisguised loathing. In fact, the station commander, a stern prosthetic-wearer called Captain Marta, insisted that he and Pila were accompanied by guards wherever they went.

Pila, oddly, didn’t seem disturbed by this squalor. “What did you expect? Pirius, you are a pilot; you are relatively skilled and intelligent, and in battle you would be expected to show individual initiative. The conditions of your upbringing and training reflect that. These cadets are animals to be thrown onto some dismal Rock to dig and fight and die. This is a war of economics, remember. How much do you think it is worth spending on their brief, wretched lives?”

Pirius wondered if she was wearing nose filters.

“You just don’t fit in,” said Enduring Hope.

“Thanks,” said Pirius dryly.

Hope and Pirius Red faced each other across the small room in Quin’s cramped Officer Country that had been commandeered for Pirius’s use. This engineer, who had flown with Pirius Blue aboard the Assimilator’s Claw in a different destiny, was one of the first candidates selected by Pila. Pirius Red had only met Hope from across the courtroom, during the hearing on the magnetar episode.

Hope seemed to regard Red as an inferior version of Blue. It was deeply disconcerting to be known so well by somebody Pirius had never properly met before — known, and judged, and found wanting.

“You don’t belong here,” Hope said. “Your adjutant doesn’t either, but she looks like an earthworm, and you can see she doesn’t care.”

“How perceptive,” murmured Pila.

“You, though — you’re neither one thing nor the other. You’re not an earthworm, but you walk around like one. You want us to accept you, to take you back. Everyone can see it in your face. You’re needy. But you can’t come back. You’re polluted.”

“Maybe,” Pirius said tightly. “But I had no choice about what happened to me.”

Hope shrugged. “Doesn’t change the fact.”

“And whatever you think about me, I have a job to do. I want you to help me do it.” He outlined the assignment he wanted Hope to take. On Rock 492, Hope would be in overall charge of the ground crews. He knew Hope had been assigned to artillery batteries here on Quin, and he imagined Hope, a born engineer, would be attracted by the idea of getting back to working on ships.

But Hope said, “Why me? There are plenty of other engineers stranded on this rock.”

Pirius shrugged. “I — I mean, Pirius Blue — once selected you for his crew. I have to trust my own judgment.” He forced a smile at his own weak joke. “And remember, our duty isn’t to do what we want—”

Hope leaned forward, suddenly angry. “Don’t patronize me with crиche slogans, you desk jockey. I know all about duty.”

“I’m sorry. Look, Hope, I won’t have you assigned if you don’t want it. I want to work with you, not against you.”

Enduring Hope stood up. “I’ll do it if Pirius does it. I mean,” he said caustically, “the real Pirius.”

Pirius Red faced other problems when he interviewed other candidates.

He was brought a young woman called Tili, who, it was said, had shown intuitive promise as a navigator before she had been banished to this dismal place for some irrelevant misdemeanor. Her condition shocked him. She had been wounded in action, and though her physical injuries were healed, her eyes were wide and filled with an inchoate pain. He got off to a bad start when she wouldn’t even respond to her name. It seemed she had been one of a set of triplets; since the other two had been killed, she had insisted on being known only by her “family” number, Three.