Fibre Optic Cable Wierdness

You have probably never heard of FLAG - Fibre Optic Link around the Globe. It's an undersea fibre optic communications cable linking the UK and Japan via the Mediterranean, the Red Sea, the Indian Ocean and the South China Sea.

I'm sure it's obsolete by now, but ten years ago it was hot stuff: a 25,000 mile fire-hose for ones and zeros that was switched on just as the internet started getting seriously big. It's significant for several reasons, one of which is that the author Neil Stephenson traveled the length of it during it's construction. He invented the idea of geek tourism and then wrote a long essay which combines a brief history of undersea cables and a bizarre gonzo journalist travelogue of the dozen countries he travelled through - a bit like Hunter S Thompson except lighter on the drugs and heavier on the laptops, satellite phones and technology. It's actually very funny and quite educational. Well worth reading even if your interest in long underwater wires is less than incandescent.

Link to Essay...

Yesterday, my supervisor handed me a length of odd looking wire, about as thick as your arm. "This is a sample length of cable from FLAG," he said. Before recounting what I've just written in response to my blank look.

The outside is covered in tar and hemp - some things haven't changed in 100 years. Inside that, there is a 1cm jacket of steel cables that act as armour plating. This stops 120,000 phone conversations from being simultaneously silenced by some moron with a boat anchor. It also guards against sharks, who like to chew on undersea cables (bet you never knew that!) Under the steel, there are layers of plastic insulation and copper electrical conductors (the light signal needs to be boosted every 40 miles and the boosting circuits need lots of power.) Finally, in the centre, there are the four thread-like gossamer glass fibres which this whole exercise is all about.

So, just because it seemed like a good idea, I held one end of the cable to my eye and held a torch to the other, to see if light would pass down the glass fibres. "That won't work," said my supervisor. "Here, I've got a laser pointer."

Now think about this. Two idiots were holding up to their eyes a 1 foot length of fibre-optic glass that's so transparent, light will happily pass through 40 miles of it. This special glass is more transparent than mountain air; compared to it, normal window glass is as transparent as the side of a cow! On the other end, there was a laser. Perhaps you see were this is going.

I'm happy to report that neither of us is now blind in one eye. The only reason is that the fibre-optic was mangled on both ends when the length of cable was cut of.

I should think about what I'm doing in future.