1942 Penicillin1944 First test tube calf 1955 Polio vaccine1967 First heart transplant 1990 Genetic engineering2000? Nanotechnology Nanotechnology The idea of shrinking machines so small that they could be injected into the bloodstream sounds like the plot for a science fiction movie. It has been at least twice. In the mid sixties Fantastic Voyage, which starred a miniature Raquel Welch and more recently in Joe Dante's comedy Innerspace. In his science fiction novel The Diamond Age Neil Stephenson writes of a world where tiny microscopic robots are everywhere. Joe Dante's comedy Innerspace But as engineering skills increase and computing power grows exponentially such imagined conceits - nanotechnology - grow ever closer. By building on an atomic scale, microscopic computers with the equivalent power to the latest Pentium III machines could be manufactured so small, that several hundred would fit inside the space of a single biological cell. Add in mechanics like motors, gears, levers, bearing, plates, sensors, power and communication cables and there would be a 'nanite'. A smart machine that could be programmed to patrol inside the human body, armed with a complete knowledge of a person's DNA, ready to destroy any foreign invaders. Such cell sentinels could eventually create an artificial immune system giving permanent immunity to not only the common cold, but also AIDS and any future viral or bacterial mutations. At the current rate of progress such nanites should be with us within 20 years. Optimists say 10-15. One long-term medical device already proposed is the Drexler artificial immune system, a fleet of microscopic submarines harbouring enough computer power to tell "self" from invading bacteria, and viruses. Already programmed with a person's DNA should something nasty arrive the "Cell Sentinel" would destroy the invader before it had time to cause damage. The "nano" computer would not need to know what disease the invader represented, it would not matter. If it's not included in the DNA code, it is destroyed. In the short term mini subs could be programmed to seek and destroy pre cancerous cells. If that sounds too fantastic think how machines have shrunk in size in the last 20 years. The average home computer contains more computing power than was available at NASA during the moon landing. Calculators have shrunk from big chunky desk tools to the size of a credit card, mobile phones and cameras are a quarter the size they were a decade ago. In medicine microsurgery is highly effective and much less invasive. Fifteen years ago if a footballer tore the cruciate ligament in his knee his career was over and he might never walk properly again. Today surgeons guided by tiny micro cameras can repair the damage and speed up recovery. Cryonics - freezing people for the future - is already happening. In this procedure, scientists take patients who have been labelled as "dead" by current medical criteria, replace their blood and much of their body water with chemicals to inhibit freezing damage, and preserve them in liquid nitrogen. At that temperature, all molecules in the body are locked in solids and can no longer move around to react. An individual can remain unchanged for thousands of years until such time as medical science has found a cure. As the human genetic code is unravelled the body is being revealed as a microscopic blueprint. Life is simply molecular machinery, its atoms arranged in complex relationships, programmed and controlled by DNA. If you have, a fundamental understanding of how it works, an instruction manual and tools to work on it - no matter how small - it can be fixed.