Peter Cochrane's Hard Drive 1996
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TV phone-in a strange attractor

JUST 20 years ago all telephones were on the end of a wire and static, with users making an average of two or three telephone calls per day at unrelated times. True, there were busy hours, and mealtimes and tea breaks would see a distinct lack of calls, but by and large calls were governed by random events. This all changed with the arrival of the TV phone-in programme.

Someone singing a song on TV could result in half a million people telephoning London to cast a vote for their local hero in the space of 15 minutes. A new world of network chaos was born which erupted into a new phase with the arrival of the mobile telephone. Traffic jams, train and plane cancellations all trigger correlated activity - everyone calls home or office within a few minutes. Naturally enough, cellular systems become overloaded as thousands demand to be connected at the same time. So a transition has occurred, from a random world of reasonably distributed events, to a highly localised and correlated world of activity triggered by anything causing us to act in unison. Travelling the planet as I do, I have developed a routine to cope with that childish fear of waking up in the dark and not knowing quite where you are.

At 7 every morning my laptop wakes up, and the screen glows to fill the room with a fog-like light. As I stagger to the bathroom it goes online, dials my server, logs on, collects my mail and puts it on the screen ready for my attention as I emerge from the bathroom shaved, showered and ready to go. A few minutes of typing and dressing sees me on my way to breakfast. While I'm eating, my laptop automatically dials in, downloads my mail and retrieves the next batch. This automated process goes on throughout the day.

Many people equate chaos to randomness, but they are very different

However, designers of this product obviously knew nothing of networks. This application only activates on the hour or half hour. Why is this a problem? Well, suppose 20 people book into the same hotel with the same software. At 7 am, and every half hour thereafter, all 20 could be demanding online access, and it is highly unlikely the PBX will have 20 spare lines.

All of this might seem trivial and easy to repair, but consider the prospect of network computers. When five or 10 of us meet, our low-cost NCs will be plugged into the same line or server. At critical times during our discussion, several of us will wish to access information or download to distant colleagues. This will be correlated activity with a vengeance.

Probably the most famous example of correlated activity between machines was the computerisation of the London stock market and the Big Bang. Here machines programmed with similar buy and sell algorithms had no delay built in. Shortly after cutting over from human operators to machines the market went into a synchrony of buy, sell, buy, sell. This is an existence theorem for uncontrolled chaos.

Many people equate chaos to randomness, but they are very different. Chaotic systems exhibit patterns that can be near-cyclic in a manner often difficult for us to perceive. Random systems, on the other hand, are totally unpredictable. Curiously, without computers we would know little or nothing about chaos, and yet they may turn out to be the ultimate generators of network chaos on a scale we might not be able to match.

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

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