Peter Cochrane's Hard Drive 1996
Homepage > Publication & Opinion > Hard Drive

INFORMATION WAVES
Anyone who drives on motorways will have experienced traffic waves created by some unseen event ahead. Probably the best place to experience this phenomenon is on the M25 when, for no apparent reason, the traffic speed can oscillate between 10 and 70 mph for long periods. Sometimes the traffic comes to a complete halt and then lurches forward to 40 mph and back down to 0. This is the classic behaviour of a system of independent entities in a serial queue having a delay between observation and action. In this case the observation might be an accident, a breakdown, or someone driving foolishly. The delay is between our eye, brain and foot. As soon as we see something and we reach for the break pedal then very shortly afterwards so does everyone else, and so the wave starts.

There is no doubt about it but rubber necking when driving a car is very dangerous, but people do it. An accident or incident occurs and people slow down to take a look, and then on the far side they speed up. Strangely when the incident has been cleared away the wave that has been set in motion may last the rest of the day. Whilst the traffic is dense, the wave motion persists long after the event has subsided. The system has an unseen memory - us. Might we then expect similar phenomena in electronic systems for communication between people and machines. This is a racing certainty and the technology and phenomenon is already with us.

Packet switching and transmission systems so beloved of the computer industry are ideal for the creation of information waves. To date these have largely gone unnoticed because terminal equipment?s assemble packets to construct a complete message, file or picture. The end user sees nothing of the chaotic action inside the network as the information packets jostle for position and queue for transmission. Only when we try to use computer networks for real time communication do we experience any arrival uncertainties. Our speech sounds strange with varying delays in the middle of utterances and moving pictures contain all manner of distortion and deviation from the truth.

The reality is packet systems are fundamentally unsuited to real time communication between people and machines. So why use them? It turns out that for data communication where arrival time is not an issue, they are highly efficient in their use of bandwidth. These systems were born in an era where bandwidth was expensive and they represent an entirely different paradigm for switching and transmission compared to the telephone network. However, the champions of ?packet everything? always like to tell you that this is the true way for information to be communicated. Curiously they often do this by sending you a single line e-mail message with a 35 line header.

So what of the future? We now have a world of optical fibre and infinite bandwidth. A world of shrinking geography, where distance is becoming irrelevant and where the fundamental reliability of networks, communication and computing is increasingly dependent upon the electronics used for transmission and switching. If we are to see significant advances in reliability and performance then the eradication of much of the electronics used today has to be inevitable. The contest will then be between two philosophies, the circuit switching of the telephone network and the path or packet switching of the computer industry. But because an optical fibre is like the M25 with a million lanes and no bad drivers, it might just be that these two diverse approaches will coalesce with the switching of light.

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

? Copyright Telegraph Group Limited 2000.

Telegraph Group Limited endeavours to ensure that the information is correct but does not accept any liability for error or omission.

Users are permitted to copy some material for their personal use, but may not republish any substantial part of the data either on another website or as part of any commercial service without the prior written permission of Telegraph Group Limited.