Drunkard's Walk - Leonard Mlodinow [87]
In Einstein’s mathematical analysis the normal distribution again played a central role, reaching a new place of glory in the history of science. The drunkard’s walk, too, became established as one of the most fundamental—and soon one of the most studied—processes in nature. For as scientists in all fields began to accept the statistical approach as legitimate, they recognized the thumbprints of the drunkard’s walk in virtually all areas of study—in the foraging of mosquitoes through cleared African jungle, in the chemistry of nylon, in the formation of plastics, in the motion of free quantum particles, in the movement of stock prices, even in the evolution of intelligence over eons of time. We’ll examine the effects of randomness on our own paths through life in chapter 10. But as we’re about to see, though in random variation there are orderly patterns, patterns are not always meaningful. And as important as it is to recognize the meaning when it is there, it is equally important not to extract meaning when it is not there. Avoiding the illusion of meaning in random patterns is a difficult task. It is the subject of the following chapter.
CHAPTER 9
Illusions of Patterns and Patterns of Illusion
IN 1848 TWO TEENAGE GIRLS, Margaret and Kate Fox, heard unexplained noises, like knocking or the moving of furniture. Their house, it happened, had a reputation for being haunted. As the story goes,1 Kate challenged the source of the noises to repeat the snap of her fingers and to rap out her age. It rose to both challenges. Over the next few days, with their mother’s and some neighbors’ assistance, the sisters worked out a code with which they could communicate with the rapper (no pun intended). They concluded that the rapping originated with the spirit of a peddler who had been murdered years earlier in the home they now occupied. With that, modern spiritualism—the belief that the dead can communicate with the living—was born. By the early 1850s a particular type of spiritual contact, called table rapping, and its cousins, table moving and table turning, had become the rage in the United States and Europe. The enterprise consisted of a group of individuals arranging themselves around a table, resting their hands upon it, and waiting. In table rapping, after some time passed, a rap would be heard. In table moving and table turning, after time passed, the table would begin to tilt or move about, sometimes dragging the sitters along with it. One pictures serious bearded men with jackets reaching their midthigh and ardent women in hoop skirts, eyes wide in wonder as their hands followed the table this way or that.
Table moving became so popular that in the summer of 1853 scientists began to look into it. One group of physicians noted that during the silent sitting period a kind of unconscious consensus seemed to form about the direction in which the table would move.2 They found that when they diverted the sitters’ attention so that a common expectation could not form, the table did not move. In another trial they managed to create a condition in which half the sitters expected the table to move to the left and half expected it to move to the right, and again it did not move. They concluded that “the motion was due to muscular action, mostly exercised unconsciously.” But the definitive investigation was performed by the physicist Michael Faraday, one of the founders of electromagnetic theory, inventor of the electric motor, and one of the greatest experimental scientists in history.3 Faraday first discovered that the phenomenon would occur even with just one subject sitting at the table. Then, enrolling subjects who were both “very honorable” and accomplished table movers, he conducted a series of ingenious and intricate experiments proving that the movement of the sitters’ hands preceded that of the table. Further, he designed an indicator that alerted the subjects in real time whenever that was occurring. He found that “as soon as the…[indicator] is placed before the most earnest