Introduction

Our everyday experience of computers is of marvellously sophisticated and knowledgable things capable of just about anything. Computers can:

• connect us to people in far–flung corners of the planet,
• recommend music and movies to us,
• correct our spelling and grammar,
• create pictures based on descriptions we give them,
• manage our homes and tend our gardens,
• fly spacecraft and drive trains, and
• control entire factories.

It might come as a surprise, then, to know that computers are not actually at all clever—far from it, they are entirely unthinking and brainless. Think of the stupidest person you know: they look like a genius next to even the best computer. What a computer does is follow a clear set of very simple instructions, very quickly. Any task we can describe in a precise and complete set of basic instructions can be given to a computer. These instructions are so simple and basic that the overall task is extremely repetitive and extremely long. The instructions would infuriate and bore any human who tried to follow them for any great period of time. Compared with the way we humans would normally perform the task, a human following the machine’s instructions would be so slow to execute them that it would be embarassing and pointless. And a human following the machine’s instructions would make lots of mistakes, because humans don’t respond well to repetitive and mindless tasks that last a long time.

But because the computer is a mindless machine, there is no notion of boredom, just as a knife or a table doesn’t become bored. If the computer can be made sufficiently fast, it can perform these tasks faster and more accurately than a human can, despite the relative repetition and mindlessness of the instructions it is performing. And in the 1970s, there were quite a few things that computers could do faster than humans. Now, half a century on, in the 2020s, there are considerably more things that a computer can do faster and better than humans. This is because computers have become much faster, much smaller, and much cheaper over time, so

Richard Feynman, in a lecture in 1986, described a computer as a high-class, super-speed, nice filing system. This is not necessarily very helpful to most of us these days, as all of the once-prevalent physical filing systems of the 20th century have long been replaced with computers!