Terry Pratchett - The Long Utopia

‘But black holes aren’t what we’re here to study,’ Jha said reprovingly. ‘We’re primarily studying the assemblers. Whatever they seem to be doing on this world.’

‘“Doing on this world”,’ Abrahams repeated. ‘They’re clearly not native to Earth. You don’t think they’re native here either?’

Bowring shrugged. ‘Hard to be definitive, we’ve so little evidence. But, those bubbles you see?’ He gestured around the landscape. ‘Sacs of air everywhere. They look biological, like flotation sacs on seaweed – much larger of course—’

‘Yes.’

‘The gaseous contents of the sacs match the contents of the bags you see attached to individual beetles. And they all contain a subtly different suite of gases from the local atmosphere – which itself isn’t far from Earthlike, which is why it’s breathable for us. In the sacs there’s more carbon dioxide, more sulphur compounds and so on. Rather like a dilute industrial smog, from the peak days of the Datum.’

‘Terraforming,’ Jha said. Suddenly she saw it. ‘You think the bugs are manufacturing a different atmosphere. They aren’t native to this world. They’re terraforming it.’

Bowring pursed his lips. ‘Well, that’s the wrong word. Not making it like the Earth, as we would … Delivering conditions that suit them, presumably. Xenoforming – perhaps that’s a better term. They came to this world to make it like their own.’ He looked around, pulling a face. ‘Look at them swarming everywhere. They take the stuff of this world, and are making it into copies of themselves. How disgusting – what greed .’

‘Perhaps,’ Abrahams said. ‘But we aren’t so holy. The European explorers imported their own farm animals, their vermin, even their song birds to the Americas, to Australasia. What have the Europeans done save convert a significant fraction of those continents’ biomass into hundreds of millions of copies of themselves? Just like the beetles. If by a rather low-tech method.’

‘They are disturbingly like us, then,’ Bowring said.

Jha asked, ‘So if they aren’t from this world, then where?’

‘Well, I can only speculate.’

Jha sighed. ‘I have a feeling we don’t have time to get everything peer-reviewed, Dr Bowring. Speculate away.’

‘I think they crossed space, to this world. As opposed to stepping here. They are interstellar travellers. Look up there.’ He pointed to his left, at the sky. ‘It may or may not be visible to your eyes – it isn’t to mine, but the youngsters can see it, and the spectrometers show it clearly. The stars in that direction, many of them, have a greenish tinge.’

‘Dyson spheres,’ Abrahams said immediately. ‘Or some kind of clouds, at least. Another of Freeman Dyson’s big ideas: stars surrounded by life-filled artefacts. Silver beetles, spreading across the stars.’

‘Yes. They are expansionist. Colonizers, as humans have always been. That’s what we see up there, visible in the very sky, a grand, expanding wave of them, coming from somewhere in that direction, to your left, which is to the periphery of the cluster. I suppose it’s possible they didn’t originate in this cluster at all. But they are certainly spreading through it.

‘This particular world, the local star, must be somewhere close to the wavefront. Because in that direction,’ he pointed to his right, ‘we see no green stars.’

‘OK,’ Abrahams said. ‘But they didn’t cross space to get to New Springfield.’

‘No. They stepped there, as we did. I suspect they just stumbled through some kind of warped stepping process into the Gallery, and found themselves on that particular Earth – and they’re treating it quite differently. With the big spin-up, rather than a replacement of the air and what-not, as they’re doing here.’

‘Why the difference?’

‘I do have some ideas about that.’ Bowring pointed directly above his head. ‘Up there , at the edge of the colonization wavefront, we see something else, orbiting the stars. Neither the usual cosmic furniture, the planets and the asteroids of a virgin system, nor the green that characterizes the beetles’ colonization push. We see another kind of cloud, orbiting some of those stars. Big chunks, irregularly shaped.’

Abrahams whistled.

‘Purposeful destruction?’ Jha asked, wondering.

‘If I were not a respectable scientist I would be prepared to speculate that there, at least, somebody is fighting back, against the beetles’ expansion. And that may be why we find so much activity by the beetles, just now, in the New Springfield Earth. It’s no coincidence. It’s because they encountered us . They have learned to anticipate resistance. And so they accelerated whatever programme of work they had, in order to get it done before we have a chance to fight back, to stop them.

‘As to what that programme is, as I said, at New Springfield they seem to have adopted a different strategy. They aren’t xenoforming that world. But what?’

‘I think I know,’ Abrahams said. ‘Dyson didn’t conceive of his spin motor as an end in itself. He was thinking of how to build his great spheres, artefacts that could enclose a whole star.’

‘Ah,’ said Bowring. ‘And the only way you can get enough matter to do that—’

‘Is to dismantle a planet.’

‘ Dismantle .’ That mundane word shocked Jha. ‘How could you do that? … Oh.’

Abrahams said grimly, ‘By spinning it up, faster and faster, until—’

‘Yes.’ Jha took a breath. ‘I need to talk to the Captain.’

Abrahams said, ‘And I need to talk to my wife.’

PROFESSOR EMERITUS WOTAN Ulm, of the University of Oxford East 5, author of the bestselling if controversial memoir Peer Reviewers and Other Idiots: A Life In Academia , had consented to give a recorded lecture on von Neumann replicators to be carried as briefing material on the US Navy twain USS Brian Cowley .

‘… Is this thing on, Jocasta? What do you mean, your name’s not Jocasta? Young lady, I am seventy-eight years old, my childhood home is under ten metres of ice, and I haven’t got time for your nonsense. Eh? What green light? Ah …

‘Von Neumann replicators, then. Like a super matter printer – a printer that could produce another matter printer. A machine that can make a copy of itself. Much like yourself, Jocasta! What could we do with such a technology?

‘How about colonizing the Galaxy?

‘In the last century, in a more innocent age of happy memory, the physicist Frank Tipler proposed a way we humans could colonize the stars, and cheaply into the bargain. Tipler’s scheme assumed nothing much beyond the slower-than-light transport methods we can easily envisage today. Just as in our exploration of the solar system, we would begin with unmanned probes. The first wave would be slow, no faster than we could afford.

‘But the probes would be self-replicating, you see: capable of constructing anything, given raw materials, including copies of themselves. And that’s the clever bit. Earlier the great physicist John von Neumann had shown that such machines are theoretically possible – and, after all, human beings are capable of replication with very little training … Have I made that joke already, Jocasta? Oh, very well. I’m seventy-eight, you know.

‘Now, when such a probe arrived at its target, it would settle down, look around a bit, perhaps grow a few human colonists from some seed bank – you know the kind of thing – and then, crucially, start to build copies of itself, a new generation of probes that will move on, further and deeper into the Galaxy, in search of homes of their own.