Where Cyberspace Went

One winter the wrong type of snow caused chaos on the British railway network: soft powdery stuff that infiltrated the electrical systems of trains and, when it settled, wasn't deep enough for snowploughs to remove. Now, it turns out out that the latest refinement in transmission of share-trading information is stymied by the wrong kind of rain.

Once upon a time, high-frequency share trading relied on data piped through fibre-optic cables. But in the glass threads of the cables light travels at about two-thirds its speed in a vacuum. And when nanoseconds count in the frenzied automatic trading that's far too slow. In the US, that information is blurted through the skies via microwaves, high-frequency millimetre waves, and now, beams of infra-red laser light. A good fraction of cyberspace, the place where billions of pounds of currency and shares are traded every day, now inhabits the sky, and the traffic is entirely between machines that shuffle gigabytes of data in the space of a single human heartbeat.

But the rise of the machines is not yet complete. The average droplet size of London's rain is smaller, disrupting laser-light transmissions. As Donald MacKenzie points out in his article on the arm's race in high-frequency-trading communications, 'if you’re a Londoner, and are spooked by the idea of lasers flashing stock-market data overhead, be grateful for drizzle.' Engineers working for trading companies strain at the outer limits of physics, but as yet there's nothing they can do about the British weather.