# Did Derren do it with computer science?

Super showman Derren Brown really got the nation talking when on his recent TV special he correctly predicted the week’s lottery numbers. In a live show the lottery balls rolled and dropped, producing what must have been a random number, but all the while in sight at the other side of the studio a transparent Perspex rack contained 6 lottery balls, which, after the draw, he turned to show contained all the winning numbers. A nation was amazed – how could he do that?

In a later programme Darren ‘revealed how he did it’ using an interesting mathematical concept called the wisdom of crowds. This concept was first recorded by Francis Galton, who attended a farm fair and observed a ‘guess the weight of the ox’ competition. While no one got exactly the correct value the average of the 800 or so guesses was very close to the real value. Derren suggested he predicted the lottery results by having a group of people guess at each of the ball numbers and then taking the average of their guesses. Hummm. Well, with an ox in front of them most people will make a reasonable guess at its weight, so there will be tendency for the average to settle round the correct value, if you use enough farmers. But perhaps not so for lottery balls. To guess the value of ball number one, it can be from 1 to 49, and on average people will guess all over the place. It’s the same for ball two and so on, so the average would actually end up the same for each ball. Enter some more brilliant Brown showmanship: the group selects their numbers using automatic writing. Ohhh, spooky. Automatic writing was a popular pastime in Victorian séances where you simply let your hand doodle and someone interprets what you wrote. When the averages of the automatic writing predictions were calculated by Darren himself (secretly, of course, so as to not cause a problem with the group rushing out and buying tickets), their numbers correctly predicted the draw, and a nation’s collective jaw dropped. So was this really how it was done? Well, there are always possibilities, and that spooky stuff will convince many, but perhaps there are other more technological ways to do what he did.

## And the answer is… (Version 2.0)

At the start of the ‘explanation’ show, Derren mentioned that there had been loads of speculation about how he had done it, in newspaper articles, blogs, chats at home and at school and so on. Even with today’s information overload his clever stunt had really caught the nation’s attention, like the stunts of magicians of old. The web lit up with ideas of how it was done. Web 2.0 allows us all to put our thought up there for others to see. Some blogs said he used a computer-controlled laser to secretly burn the numbers onto the back of the balls. Others thought that the prediction balls themselves were ‘programmable’, each with a tiny curved screen on them, so when the balls were turned they showed the right numbers. These ideas are fantastic and creative – we can see how our computer technology can literally ‘do the impossible’. Famously, author Arthur C Clarke said that any sufficiently advanced technology is indistinguishable from magic, and here people believed that Derren had pulled of this nation-stumping magical miracle using some super tech. Combined with his obvious showmanship, the computer scientists behind the scenes had made all that astonishing entertainment possible. But was that how it was done?

## And the winner is?

There was one really clever method that may people believed was behind the effect. That front runner was…well first, lets review the facts. The camera in the studio was hand-held – it wobbled a bit throughout even though it was using the rather nifty steadycam system. Derren and the prediction balls were both in sight all the time at opposite sides of the picture. The lottery draw was live; you could flick between TV channels at the time to prove it. The legal situation didn’t allow Derren to show his prediction till after the balls were drawn, and for some reason he didn’t count the bonus ball drawn at the very end. After all six balls were called he helpfully wrote down the numbers in order on a card he was holding, then crossed the studio to reveal his correct prediction. Written like this the clues are there, in days gone by many magical tricks were done with mirrors, by angling a mirror correctly you could reflect another part of the stage to appear to be somewhere else, and behind and under cover of the mirror you could get up to all manner of clever magic making. We are conditioned to passively accept what’s on ‘live TV’ to be, well, live: a real recording of what’s there in a studio far, far away. But many of the 2.0 bloggers believe Derren used the high-tech equivalent of a mirror trick, a TV split screen effect. Was what happened on the ball side of the screen faked?

## Done with a wobbly ‘digital mirror’?

Today’s TV technology would allow the following: even with the natural wobble of a hand-held cam, it would be possible, after Derren had walked past the prediction balls in the introduction, for the whole left hand side of the screen to be replaced by a digital image, synchronised to any camera wobble. In effect half the picture with Derren and the draw could have been live, while the other half functioned like a digital mirror. It would have reflected the situation truthfully at the start, but allowed Derren’s helpers to invisibly change the balls to the correct values before he moved back across, when the digital effect was turned off and he did his reveal. That could be why he didn’t show the prediction at the start. That would also explain why he didn’t bother with the bonus ball and took time to write the numbers down on the card: he needed to give time for the digitally cloaked ball switch to take place. Like all good theories it fits the facts, and explains the assumptions, but is there any real data to support it? Well perhaps. A few keen observers believe that one of the balls in the prediction can be seen to shift up a few millimetres; this would have been caused, they say, by the stagehand putting the correct balls in place too quickly under cover of the split screen before it was switched off. Perhaps some experts in computer vision systems will be able to verify this by analysing the video. The truth is out there, perhaps.

## That’s magic?

Split screens, lasers, smart balls, you name it, what this TV event has shown is that the power of theatrical magic, using science to seemingly break the laws of science, is still strong. Whether it was digital magic or some other yet unknown mechanism, it got us talking because Derren knows how to astound and entertain people. Like software, a magic trick is a combination of a secret method and loads of top notch presentation. If you fancy giving it a go you can download our magic books. There is a trick in them about predicting the lottery, but it’s not as good as Derren’s. In fact you might say we ‘roll over’ in the presence of a lottery prediction master!