The Long Utopia

41

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.

‘We can expect the migration to continue, in all directions outward from the Earth, pretty relentlessly once it has started. And the process would be self-financing, and that would have been music to the ears of every money-grubbing university administrator with whom it has been my misfortune to lock horns. That’s because the new colonies would be built from local resources, requiring nothing of Earth. We must invest merely in the cost of the initial generation of probes.

‘But there’s a trap.

‘Suppose we start colonizing the stars, after the manner of Tipler. Earth is suddenly the centre of a growing sphere of colonization – a sphere whose volume has to keep increasing, if a constant growth rate is to be achieved. The leading edge, the colonizing wave, has to sweep on faster and faster, eating up worlds and stars and moving on to the next, because of the pressure from behind …

‘Imagine then a Tipler wave of replicating robots swarming across the Galaxy, turning fallow star systems into copies of themselves, working feverishly just to keep up with the pace of expansion. Even if such a probe arrived in an inhabited system it must immediately crush any native life, transforming all in its path into more copies of itself. It would have no choice; it would have no time to do otherwise, to maintain the momentum of the expansion.

‘Is this infeasible, technologically? Not at all. We could almost build such things.

‘Would it be unethical to unleash such a compound-interest horror on the rest of the universe? Most people would think so, but don’t ask a banker.

‘Is this what the colonists on that godforsaken High Meggers world seem to have discovered in their hole in the ground? A Tipler wavefront? Sounds like it, doesn’t it? …

‘What’s that, Jocasta? What should be done about New Springfield? Well, I should build a very, very high wall around these fellows, metaphorically speaking.

‘Now then, is that enough? I am seventy-eight years old, you know …’