Comment »Posted on Tuesday 30 December 2008 at 5:20 pm by Jacob Aron
In Inventions & Technology, Physics

Last night I watch the first of this year’s annual Christmas Lectures from the Royal Institution. The lectures, first given by Michael Faraday in 1825, are designed to educate and entertain children with science.

This year the overarching topic for the lectures was “The Quest for the Ultimate Computer”, and they were given by Professor Christopher Bishop who works at both Microsoft and the University of Edinburgh. This first lecture was entitled “Breaking the speed limit”, and covered the evolution of the microprocessor, the building block of all computers.

The ever-increasing power of computers is all down to Moore’s law. In 1965 the founder of computing giant Intel, Gordon E. Moore, noticed that the number of transistors that can be placed on a computer chip doubles roughly every two years. Amazingly, this means that computers made two years from now will have as much processing power as every computer ever made in the past.

Prof. Bishop used his first lecture to explain exactly what a transistor is – something that I had never had an easy-to-understand explanation for. A transistor is basically an electronic switch that also uses electric current to turn on and off – in other words, no moving parts. This makes them perfect for the construction of logic gates, the very simplest possible computational element. Logic gates come in many forms, but all of these can be built from transistors.

In a number of practical demonstrations, the audience is shown how chips are be manufactured; it’s a rather clever technique. Since the circuitry of a chip is so small and complex, they are actually designed on a much larger scale and then projected on a screen. Light from this screen is shrunk down by a lens on to a light-sensitive material, which marks out the exact design in miniature.

The “speed limit” that Prof. Bishop talks about is actually a physical limit – we simply can’t squeeze any more transistors on to one chip. The solution at the moment is to include many chips in one computer – most PC’s sold these days are marketed as “dual-” or “quad-core”. Not all tasks can be sped up by splitting the workload however; as Prof. Bishop tells us, it takes a woman nine months to make a baby, but nine women can’t make a baby in one month!

If we can’t figure out a way to make better transistors, computers won’t be able to get any faster, as they will just get too hot. This is comically illustrated by making all the children stand up and sit down as fast as they can. If we continue with current technology, in 10 years time chips would be as hot as the surface of the sun. Not something you want in your laptop!

A future solution could be to use carbon nanotubes, which would produce a transistor capable of switching 1,000 times faster than our current silicon models. We could even one day be using DNA to do our computations, though Prof. Bishop admits this is very far off. It sounds like a neat idea however, as the DNA of just one human being can store more information than all of the computers in the world put together.

If you’re as interested as I am to learn about the future of computing, you can watch the remainder of the Christmas Lectures every day this week on Channel Five at 7.15pm. Tonight’s lecture promises “Chips with everything”, so tune in and find out more!


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