IT MAY NOT be the Second Coming, but we will be waiting for the unknown when the inevitable chanted countdown begins in the Dome at 10 seconds to midnight on 31 December next year. Will all the lights go out? How many computers will crash? Will planes, trains and cars stop working?

On the face of it, it seems surprising that a change of date could affect so many computers and things with computer chips in them. The fact that the next number after 1,999 is 2,000 has hardly come out of the blue: programmers have only had 1,998 years to work on it.

And, yes, there are a large number of computer consultants who have a pecuniary interest in crying wolf, not to mention "global recession". But that does not mean that the millennium bug is not a serious problem.

The reason it has caught us unawares is that the computer industry is built on the assumption that no product has a life longer than 10 years. When some machines, chips, software and programming languages turned out to be considerably more durable, the anoraks had moved on and forgotten all about them. The time-bomb was laid by the exhilarating speed of change which has brought us to the threshold of the Information Age.

The truth is that no one knows what will happen when scattered strings of old code decide that it is 1 January 1900. But if it is a conspiracy by computer consultants, then it is a plot which has hoodwinked the Prime Minister, the President of the United States and the European Commission. The millennium bug is on the agenda for the G8 meeting of the industrialised powers in May, and many of the world's biggest corporations have already spent vast sums of money on the problem.

So, yes, it matters. We cannot dismiss predictions of costs running into billions, or forecasts of a world economic downturn, as millennial scare- mongering. But the doom scenario is at one end of a range of possible outcomes. A plausible case can be made that the sudden, panic-driven increase in demand for computer programmers will boost the world economy. It could be that the overhaul of every significant computer network in the world will have the side-effect of making them faster and more efficient. If there are more programmers available for hire once the mess of Y2K (Year 2000 to the rest of us) is cleared up, they could drive the expansion of the Internet and the transition to what our Economics Editor has called the "weightless economy".

Whatever happens, the millennium bug is an important issue which this newspaper at least will take seriously over the next 20 months.