Persi Diaconis tossed a sealed deck of cards into an overflowing audience Wednesday night in a Willey Hall auditorium. He asked the man who caught it to cut the deck and pass it along the row while each person took a card.
Then Diaconis told each person which card they had picked – and he was right.
While this might seem like an ordinary magic trick, it actually is one of many that magician-turned-mathematician Diaconis has developed to show the connection between math and magic.
“When somebody says they’re going to do a math-magic trick, it sounds as if they’re going to deal cards in piles, and you’ll all fall asleep,” Diaconis said. “I try to develop tricks that are good tricks that don’t look like math, but that have real math hidden in them.”
The idea of math that doesn’t look like math is the reason Fred Owusu, director of human resources at the Academic Health Center, brought his son to the event.
“I thought it would serve them well to see math applied in a way that makes sense to them,” Owusu said. “And what kid doesn’t like magic?”
Those inside the math world, like University math professor Doug Arnold, said Diaconis is known for his magic tricks, but that he also has done a lot of research in statistics and probability.
“He has brought a lot of insight into the way randomness works,” Arnold said. “People think it’s easy, but it’s not.”
But it all began with magic.
Diaconis started doing tricks when he was 5 years old. He said his mother ran a day-care center and he came across a children’s book of magic tricks and started doing them. He gave his first magic show when he was 6 years old.
“It became my hobby. I was the center of attention,” he said. “That’s just the way kids get into it, and I never grew up.”
At the age 14, Diaconis ran away from home to tour with magician Dai Vernon. He spent the next 10 years developing, performing and teaching his magic tricks.
Diaconis said he gained an interest in probability when he started hanging around gamblers, trying to pick up some of their tricks.
“Magicians are very interested in gamblers, because gamblers have to be very skillful,” he said. “If they aren’t, they won’t survive.”
Through his gambling conversations, Diaconis became interested in probability and was pointed toward a book on the topic. The problem was, he said, that he couldn’t read the calculus. So Diaconis, then 24, decided to go to night school in New York.
After he graduated he was accepted to Harvard, where he earned a doctorate in statistics.
“Even when I was in graduate school, I remember thinking, When am I going to get interested in this math stuff?” he said. “Now, I do more math than magic.”
In the end, Diaconis said he’s just happy that there is a link between his interests.
“I don’t find it so different, inventing magic tricks and proving theorems,” he said. “There’s just something wonderful about finding the right solution to a hard problem. It’s intriguing to me.”