When you get involved with a project of this kind, you expect to find the staff lists populated with a great many extremely talented technical types. There will be graduates of all the best schools and universities, conscientious and hard-working, with PhDs and a decade or more of technical challenges under their belts.

But there will almost always be one special one, a more-than-just-passing-grade genius, an intellectual powerhouse who is essential to the success of the project. Indeed, my experience is, if I cannot identify the person who has the solution as a whole already running in his head, then I immediately go out and recruit one. He will undoubtedly be a geek, a nerd of the first water, whose knowledge of not only the technical aspects of the solution, but also a vast range of esoteric science, engineering and technology subjects is encyclopaedic and definitive.

The Project Expert is likely to have an interest in music, literature or art, often with a working knowledge of classic science fiction, and with an intelligent view on just about any subject under the sun. Exactly the person you would want on your quiz team, except that they will be extremely limited when it comes to current affairs, sport and what is euphemistically known as Popular Culture: film, television and celebrities famous for, well, just being famous.

The Bull Nerd is not usually to be found in a lead position, formally in charge, but he will be the person to whom the others will always go when they have a problem. The lesser acolytes will approach tentatively then, if recognised, lay out the issue they are grappling with - which the Resident Genius will invariably comprehend immediately - and wait for an answer. The response will always be honest: rarely, "I don't know"; sometimes, "Come back tomorrow when I've thought about it", but most usually he will immediately respond with a detailed analysis and a recommended solution which will, even with the benefit of 20-20 hindsight, be the right answer.

Now, over the years, I've worked with quite a number of these guys - and, yes, with apologies to the ladies, they are almost always men. They are invariably socially dysfunctional yet astonishingly intelligent, insensitive individuals who need a certain amount of special care and feeding, otherwise their tantrums and childish behaviour is guaranteed to get on the nerves of almost everybody.

But this one was different. John - not his real name, of course, for reasons which will become apparent - had quite a reputation in the industry, even before he joined the Advanced CETI Programme - "C" for Communications, since the Search for Extra-Terrestrial Intelligence had already succeeded. Anyway, John turned up, almost on time - itself something slightly surprising - and was introduced to the management team who were, as usual, nonplussed by his apparent disregard for the importance, secrecy and difficulty of the project ahead.

I'm not going to describe John's appearance; I don't need to, since you'll have seen his face many times before. But even in those days, his eyes were pale blue and piercingly observant. He kept his brown hair in a wave which just reached his shoulders while, perversely, he kept his moustache and beard neatly trimmed.

John's reputation was well-deserved. He probably had the whole solution worked out in his head in the first twenty minutes, while shrunk into a contemplative, even catatonic state, slumped in a chair in the nondescript meeting room which was used for that initial briefing. He already knew how to build a computer system which could complete the immense computational problem of narrowing the virtual focus of the receiver antenna to precisely the coordinates indicated by the earlier transmission. After a while staring into space, he even said so.

Now, a key thing about the nature of these algorithms is that, in their basic form, they are reasonably complex but not really that difficult. A smart student with a working knowledge of a modern computer programming language could probably bash up a program to solve this problem in a couple of days, perhaps a week at the outside. The problem is that such a simple program would never finish running; you would need to wait until the heat death of the universe for the program to complete, or at least an inconveniently long time, at least as measured by ordinary human lifetimes.

The really tricky part was to divide the problem into a million separate pieces which could be deployed on a supercomputer. A supercomputer is, for those who don't know, not so much a very fast computer but more a very large collection of individual computers with an extremely fast connection to all of the others. This subdivision was the critical problem we had to solve.

And John already knew how to do this.

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