A critical look at the functionality of all of these individual miracles of modern technology soon reveals that a considerable degree of integration is both feasible and possible. For example, for only ?100 it is now possible to buy a digital wrist watch with an integrated paging device and display. Just ?1500 will buy you a complete cellular telephone that can be worn on the wrist. The laptop too can be condensed down to an organiser or a pocket device with a considerable saving in space and weight. What then the chance for a complete integration of all these units into one entity in the not too distant future?

Just over 200 years ago the travellers by horse draw carriage would take with them a time piece almost as large as my present brief case. Naturally enough it was called a carriage clock! After due evolution of the technology it became a pocket watch about the same size of a small dinner plate. This soon progressed to become a fob watch and ultimately a wrist watch and today we regard it as jewellery or body furniture. Might we therefore expect a similar progression for my brief case full of individual and itemised units of electronic functionality?

The principle limitation to realising information technology that we wear, and perhaps soon information technology that wears us, is a requirement for batteries that will power up sufficient mobile communication, data processing, storage and most critically of all display. Today the smallest cellular radio is composed of a minimum of 3 integrated circuits. However, it is feasible to reduce the total chip count to a single unit requiring a power consumption of only 1 Watt. Similarly a powerful personal computer can also be reduced to 2 integrated circuits requiring a further 2 watts with a liquid crystal display consuming 3 watts. The principle difficulty we have now encountered is the necessity for back lighting to enabling the display to be read with ease. Black and white print on a newspaper has typically a contrast ratio of 200. A standard domestic television set is between 30 and 50 and a black on grey none back lit liquid crystal display can be as low as 5. This is so low it would be painful and detrimental to our long term vision.

A further impediment to realising the office you wear is the established requirement for a keyboard. Anyone using a laptop computer for long periods will have suffered the Praying Mantis syndrome of rounded shoulders and clawed fingers. The personal organiser is even worse and reduces us to one finger, one key at a time. Perhaps the next vital step lies with voice recognition and synthesis technology that could replace this function. Today voice synthesis has just about reached the point of being adequate for text to speech whilst speech to text still leaves a lot to be desired and will probably require a further 5 years of evolution before it can hope to replace the keyboard. Moreover, it is more power hungry in terms of the total processing required and could add a further 5 watts to our power budget for a complete unit. But, hopefully during the 5 year period the integrated circuit technology will realise sufficiently low power and processing without a significant increase.

An intermediate solution might be tenable with the minimal keypad or PDA stylus input for immediate access with a fold away keyboard for pocket and case transport that could be plugged in when necessary along with a head mounted screen giving a high definition direct into the eye of the user. All of these piece parts are available now and such a device is both feasible and could even be practical. However, it leaves us with one critical problem to solve - that of power storage and the requirement for large and cumbersome batteries.

A full grown human sat doing nothing radiates approximately 60 watts from the torso and head areas. When animated this can exceed over 100 watts and is a potential source of power to drive an office you wear. Alternatively the fundamental process of walking and moving at a casual rate can generate over 10 Watts. It would therefore appear that all solutions to realise a wearable office are to hand! Why then is no one marketing such a device?

As a general rule the human race makes progress by incremental change, with slight extensions of existing paradigms that do not upset or compromise existing working practises or protocols and social sensibilities. The migration from a book full of paper to a book full of electronics - the laptop or from the diary to the personal organiser are obvious examples. More recently the emergence of an electronic purse or wallet with electronic functionality and plug in cards that ghost the earlier coins and paper notes is another. More radical changes that have involved the irradiation of coins and money and seen the migration to the plastic card have taken 20 years to become established. But perhaps computer power and total communication that you wear will not take quite so long. It is likely however, to introduce some very interesting and different modes of operation.

If I were talking to you face to face and someone was to interrupt the conversation we would think it most rude. However, if during our conversation they were to call by telephone I would feel totally relaxed to momentarily ignore you and answer the telephone and start a new conversation then to come back to you. This has become an acceptable mode of operation. How then will you respond when, mid conversation, I gaze into a head mounted screen, adjust controls on my wrist and commence a new conversation with some ethereal being or machine?

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