“Then,” she snapped, “maybe you should damn well try. Maybe that’s been the trouble with most of human history. Look at all this: we’re witnessing, here, the death of galaxies. And you’re wondering how it makes me feel? Do you think all this has somehow been set up as a test of my loyalty to the human race?”

“Lieserl — ”

“I’ll tell you how I feel. I feel we need a sense of perspective here, Mark. So what if this — this cosmic discontinuity — is inconvenient for the likes of you and me?” She withdrew from him and straightened her back. “Mark, this is the greatest feat of cosmic engineering our poor Universe will ever see — the most significant event since the Big Bang. Maybe it’s time we humans abandoned our species-specific chauvinism — our petty outrage that the Universe has unfolded in a way that doesn’t suit us.”

He was smiling at her. “Quite a speech.”

She punched him, reasonably gently, beneath the ribs, relishing the way her fist sank into his flesh. “Well, you deserve it, damn it.”

“I didn’t mean to imply — ”

“Yes, you did,” she said sharply. “Well, I’m sorry if I’ve failed your test, Mark. Look, you and I — by hook or by crook — have survived the decline and destruction of our species. I know we’re going to have to fight for survival, and I’ll be fighting right alongside you, as best I can. But that doesn’t remove the magnificence of this cosmic engineering — any more than an ant-hill’s destruction to make way for the building of a cathedral would despoil the grandeur of the result.”

Still holding her hand within his stiff fingers, he turned his face to the galaxy-stained sky. His offense at her words was tangible; he must be devoting a great deal of processing power to this sullen rebuke. “Sometimes you’re damn cold, Lieserl.”

Lethe, she thought. People. “No,” she said. “I just have a longer perspective than you.” She sighed. “Oh, come on, Mark. Show me the Ring,” she said.

The sculpture of string, driving itself into the heart of the scarred galaxy, was not symmetrical. It was in the form of a rough figure-of-eight; but each lobe of the figure was overlaid with more complex waveforms — a series of ripples, culminating in sharp, pointed cusps.

“Do you see it, Spinner?” Mark asked. “That is a loop of string nearly a thousand light-years wide.”

Spinner smiled. “That’s not a loop. That’s a knot.”

“It’s moving toward the galactic core at over half the speed of light. It’s got the mass of a hundred billion stars… Can you believe that? It’s as massive as a medium-size galaxy itself. No wonder it’s cutting this swathe through the stars; the damn thing’s like a scythe, driving across the face of this galaxy.”

Louise laughed. “A knot. Knot-making is a skill, up there in the forest, isn’t it, Spinner? I’ll bet you’d have been proud to come up with a structure like that.”

“Actually,” Mark said, “and I hate to be pedantic, but that isn’t a knot, topologically speaking. If you could somehow stretch it out — straighten up the cusps and curves — you’d find it would deform into a simple loop. A circle.”

Spinner heard Garry Uvarov’s rasp. “And I hate to be a pedant, in my turn, but in fact a simple closed loop is a knot — called the trivial knot by topologists.”

“Thank you, Doctor,” Louise said drily.

Spinner frowned, peering at the detailed image of the string loop; in the false colors of her faceplate it was a tracery of blue, frozen against the remote background of the galaxy core. She realized now that she was looking at one projection of a complex three-dimensional object. Subvocally she called for a depth enhancement and change in perspective.

The loop seemed to loom toward her, lifting away from the starry background, and the string was thickened into a three-dimensional tubing, so that she could see shadows where one strand overlaid another.

The image rotated. It was like a sculpture of hosepipe, rolling over on itself.

Mark commented, “But the string isn’t stationary, of course. I mean, the whole loop is cutting through this galaxy at more than half lightspeed — but in addition the structure is in constant, complex motion. Cosmic string is under enormous tension — a tension that increases with curvature — and so those loops and cusps you see are struggling to straighten themselves out, all the time. Most of the length of the string is moving at close to lightspeed — indeed, the cusps are moving at lightspeed.”

“Absurd,” Spinner heard Uvarov growl. “Nothing material can reach lightspeed.”

“True,” Mark said patiently, “but cosmic string isn’t truly material, in that sense, Uvarov. Remember, it’s a defect in spacetime… a flaw.”

Spinner watched the beautiful, sparkling construct turn over and over. It was like some intricate piece of jewelry, a filigree of glass, perhaps. How could something as complex, as real as this, be made of nothing but spacetime?

“I can’t see it move,” she said slowly.

“What was that, Spinner?”

“Mark, if the string is moving at close to lightspeed — how come I can’t see it? The thing should be writhing like some immense snake…”

“You’re forgetting the scale, Spinner-of-Rope,” Mark said gently. “That loop is over a thousand light-years across. It would take a millennium for a strand of string to move across the diameter of the loop. Spinner, it is writhing through space, just as you say, but on timescales far beyond yours or mine…

“But watch this.”

Suddenly the three-dimensional image of the string came to life. It twisted, its curves straightening or bunching into cusps, lengths of the string twisting over and around each other.

Mark said, “This is the true motion of the string, projected from the velocity distribution along its length. The motion is actually periodic… It resumes the same form every twenty thousand years or so. This graphic is running at billions of times true speed, of course — the twenty millennia period is being covered in around five minutes.

“But the graphic is enough to show you an important feature of this motion. It’s non-intersecting… The string is not cutting itself at any point in the periodic trajectory. If it did, it would bud off smaller sub-loops, which would oscillate and cut themselves up further, and so on… the string would rapidly decay, shrivelling through a thousand cuts, and leaking away its energy through gravitational radiation.”

Spinner wished, suddenly, that she wasn’t human: that she could watch the motion of this loop unfold, without having to rely on Mark’s gaudy projections. How wonderful it would be to be able to step out of time!

…Close your eyes, Spinner.

“What?”

You can step out of time, just as you desire. Close your eyes, and imagine you are a god.

…And here, in her mind’s eye — so much more dramatic than any Virtual! — came the knot of string, sailing out of space. The knot wriggled like some huge worm, closed on itself as if swallowing its own tail.

The knot struck the rim of this defenseless galaxy and scythed toward the core, battering stars aside like blades of grass.

It was a disturbing, astonishing image. She snapped open her eyes, dispelling the vision; fear flooded her, prickling over her flesh.

She wasn’t normally quite so imaginative, she thought drily. Maybe her companion had had something to do with that brief, vivid vision…

She returned her attention to the harmless-looking Virtual display. Now Mark showed Spinner the loop’s induced magnetic field, a yellow glow of energy which sleeved the fake blue of the string itself.

“As it hauls through the galaxy’s magnetic field, that string is radiating a lot of electromagnetic energy,” Mark said. “I see a flood of high-energy photons…”