Alex's Adventures in Numberland - Alex Bellos [142]
Thorp was helped in his endeavour by Claude Shannon, his colleague at the Massachusetts Institute of Technology. He couldn’t have wished for a better co-conspirator. Shannon was a prolific inventor with a garage full of electronic and mechanical gadgets. He was also one of the most important mathematicians in the world, as the father of information theory, a crucial academic breakthrough that led to the development of the computer. The men bought a roulette wheel and conducted experiments in Shannon’s basement. They discovered that if they knew the speed of the ball as it went around the stationary outer rim, and the speed of the inner wheel (which is spun in the opposite direction of the ball), they could make pretty good estimates regarding which segment of the wheel the ball would fall in. Since casinos allow players to place a bet after the ball has been dropped, all Thorp hannon needed to do was figure out how to measure the speeds and process them in the few seconds before the croupier closed the betting.
Once again, gambling pushed forward scientific advancement. In order to predict roulette plays accurately, the mathematicians built the world’s first wearable computer. The machine, which could fit in a pocket, had a wire going down to the shoe, where there was a switch, and another wire going up to a pea-sized headphone. The wearer was required to touch the switch at four moments – when a point on the wheel passed a reference point, when it had made one full revolution, when the ball passed the same point, and when the ball had again made a full revolution. This was enough information for estimating the speeds of the wheel and the ball.
Thorp and Shannon divided the wheel into eight segments of five numbers each (some overlapped, though, as there are 38 pockets). The pocket-sized computer played a scale of eight notes – an octave – through the headphones and the note it stopped on determined the segment where it predicted the ball would fall. The computer could not say with total certainty which segment the ball would land in, but it didn’t need to. All Thorp and Shannon desired was that the prediction would be better than the randomness of guessing. On hearing the notes, the computer-wearer would then place chips on all five numbers of the segment (which, although next to each other on the wheel, were not adjacent on the baize). The method was surprisingly accurate – for the single-number bets they estimated that they could expect to win $4.40 for every $10 wager.
When Thorp and Shannon went to Las Vegas for a test drive, the computer worked, if precariously so. The men needed to look inconspicuous, but the earpiece was prone to popping out and the wires were so fragile that they kept breaking. Still, the system worked, and they were able to convert a small pile of dimes into a few piles of dimes. Thorp was content to have beaten roulette in theory, if not in practice, because his assault on another gambling game was having much more striking success.
Blackjack, or twenty-one, is a card game in which the aim is to get a hand where the total value of the cards is as close as possible to an upper limit of 21. The dealer also deals a hand for himself. To win, you must have a hand higher than his while not exceeding 21.
Like all the classic casino games, blackjack gives a slight advantage to the house. If you play blackjack, in the long run you will lose money. In 1956 an article was published in an obscure statistics journal that