I HAVE to admit to secretly coveting a tri-corder ever since I first saw Bones and Jim scanning the horizon of some distant planet to reveal a malevolent life-form concealed close by. What a device! If only I could build one, just imagine the utility and opportunities it would offer. Well, this Star Trek fiction from the Sixties looks like becoming a reality in the not too distant future as yet another facility on a combined mobile phone and GPS locator.

The density of manufactured electronic items already exceeds the number of people alive today. In the next phase they will appear as confetti, far exceeding the number of people who ever lived, or indeed the number of vertebrates on the planet today. At a rough estimate, we are seldom more than 10m away from a rat, and no more than 1mm from an integrated circuit. As most of us wear at least an electronic wristwatch and mobile phone, and traverse homes, cars, and industries strewn with electronic devices, there are easily more chips closer to us than rats. Today there are about 20 billion microprocessors and only six billion of us. Of course, most microprocessors are in the developed world, populated by only 15 per cent of the planet's population. So very soon we shall be outnumbered 100 to one by devices on the Net or electronically accessible. We are migrating to the deployment of chips, sensors and communicators into every artefact, right down to the electronic bar codes on bags of sugar and breakfast cereal.

When everything contains sensors and can communicate by radio and/or optical signals, and is automatically addressable online, we will be able to realise innumerable new and useful applications and services involving everyday objects. The scale of this will certainly eclipse the online computer web world of today.

For me, a practical tri-corder will have the capacity to scan a store, street or town to identify, locate, and point the way to a restaurant. It would indicate the availability of tables and parking spaces, and of course the menu details and prices. It will also pinpoint a particular size, style and colour of jacket and slacks for sale at a good price, or the availability of food. The same device might also spot stolen goods, crimes, and the nearest police car, or people in sudden need of assistance and the nearest medical help.

We might then consider our commercial position. Imagine putting all our possessions permanently up for sale, including homes, cars, bikes, computers, clothes, jewellery and TVs at some price that would persuade us to sell. Our stance might be we don't need to sell, but we do have a price where we would. Then those with a need could seek us out, and if they could afford our asking price, we could close the deal on the spot.

And how about physical transport? We could buy and sell seats in vehicles. Walk into the street, enter your destination and prioritised preferences into your tri-corder/mobile phone, and the nearest available cab, bus, car or truck could be identified, hailed, and pick you up for an electronically negotiated price.

"Well Jim I can see no sign of palatable food. Shall I hail a transporter and begin a search of the city?"

"Yes, Bones, we need food before nightfall." Soon, I hope, soon.

Peter Cochrane holds the Collier Chair for the Public Understanding of Science & Technology at the University of Bristol. His home page is:
http://cochrane.org.uk