Writer, broadcaster and National Treasure™ Stephen Fry has struck again. The ubiquitous luvvie revealed the depths of his technical understanding on the the panel show QI XL, the self-styled "the home of highbrow know-how".

First, GPS. How does that work, Stephen?

"You send a signal from your GPS device," he explained. "You've got to be at least three, usually four or five satellites – that receive your signal. And the difference in time it takes to get from one satellite to the other to the other, which is milliseconds, allows them to calculate your position to within 10 metres."

That's amazing.

Warming to his theme – assuming the theme was talking utter tripe – the former Guardian technology columnist then had a crack at explaining TCP/IP.

"Any email or transaction on the internet uses what's called packet-switching, which means the information is broken up into packets, and reassembled on the other side," he said.

"But each side has to be exactly synchronised, otherwise the message is nonsense. So the caesium atomic clocks are necessary to make all this technology work."

There you go. The interwebs would fall apart without atomic clocks.

An Apple user, Fry has cruelly been described as "a stupid person's idea of a clever person" – but he has carved out a niche as an in-demand technology expert and pundit. The BBC hired him to sing the praises of DAB, and Sky enlisted him to explain 3D TV, so who are we to argue? But the depth of his understanding revealed by the ad-libbing suggests that to Fry, perhaps everything is just a voiceover script.

You can find the QI clip on iPlayer here [UK readers only], around the 14:45 mark.

Thanks to stalwart Reg reader Eponymous Cowherd for the tip. ®

http://www.theregister.co.uk/2011/01/18 ... n_frytard/

*puts head into hands*

I think they're being rather harsh expecting to get detailed descriptions of technical issues on a half hour chuffing comedy panel show.

Jon

He is still a damn sight cleverer than the majority of people. We should treat him as such. I might have my talents but still know that I am not the world authority on any of them. I am sure that he knows that he is not the expert on everything.

Although I agree with you Jon, fundamentally what he said was wrong. It would have been relatively easy to have briefly explained GPS in a more correct fashion. On TCP he could have said that it didn't matter what order the packets arrive in, the other computer knows what order they go in thanks to a timestamp would have been more correct (though still incorrect in itself).

The only thing he got wrong re. GPS is that the devices are receivers, not transmitters.
Isn't it?

The problem is, having just watched the video, he says it with such authority that many people would believe he actually knew it as a fact.

It would have been fine if he'd said "or so I'm led to believe", but he didn't. He's a lot like a young child who just heard something and is now repeating it to everyone, but not quite understanding it correctly and drawing incorrect inferences.

You can run IP over carrier pigeon (IPoAC). They do not need accurate watches: http://tools.ietf.org/html/rfc1149

You could say you boil water in a tea pot then brew tea in a kettle. Someone who doesn't care for tea may see this as "ah, there we go then", while those who generally brew tea see that he really should have said it the other way around...

I knew that about the data packets, and they did not have to be in order. But not much more than that.

Yeah, the satellites send out a signal that is picked up by your device, not the other way around.

Apart from that he's pretty much spot on.

And they need the atomic clocks in the satellites I think. Maybe that's where he got confused.

Quite so. IIRC, The satellites are effectively broadcasting what time they think it is 24/7. Your gizmo reads these signals from several satellites and compares the timestamps. From this, - taking the closest one as a base time - it can figure out how far it is from each satellite and thence using some neat trigonometry, exactly where you actually are. The more accurate the time, the more accurately it can figure out the distances and therefore the more accurately it can pinpoint your position.

The only thing he actually got wrong is he seemed to think your GPS 'polls' the satellites, which of course they don't - a satellite might have to cope with millions of requests at once if that was the case. He was right on the general principle but sketchy on the details. That's polymaths for you.

Jon

They also have to adjust it daily otherwise you would be miles out very quickly.

Indeed. In fact the number one contributor to the increased accuracy is the increased accuracy of the clocks onboard the satellites and not the increase in the number of satellites in the sky.