Complexity_ A Guided Tour - Melanie Mitchell [89]
The physicist Hideki Yukawa explains the nuclear force by using an analogy with the electromagnetic force, on which basis he postulates a mediating particle for the nuclear force with properties analogous to the photon. The particle is subsequently discovered, and its predicted properties are verified. Yukawa wins a Nobel prize.
This list is a small sampling of analogies ranging from the mundane everyday kind to the once-in-a-lifetime-discovery kind. Each of these examples demonstrates, at different levels of impressiveness, how good humans are at perceiving abstract similarity between two entities or situations by letting concepts “slip” from situation to situation in a fluid way. The list taken as a whole illustrates the ubiquity of this ability in human thought. As the nineteenth-century philosopher Henry David Thoreau put it, “All perception of truth is the detection of an analogy.”
Perceiving abstract similarities is something computers are notoriously bad at. That’s why I can’t simply show the computer a picture, say, of a dog swimming in a pool, and ask it to find “other pictures like this” in my online photo collection.
My Own Route to Analogy
In the early 1980s, after I had graduated from college and didn’t quite know what to do with my life, I got a job as a high-school math teacher in New York City. The job provided me with very little money, and New York is an expensive city, so I cut down on unnecessary purchases. But one purchase I did make was a relatively new book written by a computer science professor at Indiana University, with the odd title Gödel, Escher, Bach: an Eternal Golden Braid. Having majored in math and having visited a lot of museums, I knew who Gödel and Escher were, and being a fan of classical music, I knew very well who Bach was. But putting their names together in a book title didn’t make sense to me, and my curiosity was piqued.
Reading the book, written by Douglas Hofstadter, turned out to be one of those life-changing events that one can never anticipate. The title didn’t let on that the book was fundamentally about how thinking and consciousness emerge from the brain via the decentralized interactions of large numbers of simple neurons, analogous to the emergent behavior of systems such as cells, ant colonies, and the immune system. In short, the book was my introduction to some of the main ideas of complex systems.
It was clear that Hofstadter’s passionate goal was to use similar principles to construct intelligent and “self-aware” computer programs. These ideas quickly became my passion as well, and I decided that I wanted to study artificial intelligence with Hofstadter.
Douglas Hofstadter. (Photograph courtesy of Indiana University.)
The problem was, I was a young nobody right out of college and Hofstadter was a famous writer of a best-selling book that had won both a Pulitzer Prize and a National Book Award. I wrote him a letter saying I wanted to come work with him as a graduate student. Naturally, he never responded. So I settled for biding my time and learning a bit more about AI.
A year later I had moved to Boston with a new job and was taking classes in computer science to prepare for my new career. One day I happened to see a poster advertising a talk by Hofstadter at MIT. Excited, I went to the talk, and afterward mingled among the throng of fans waiting to meet their hero (I wasn’t the only one whose life was changed by Hofstadter’s book). I finally got to the front of the line, shook Hofstadter’s hand, and told him that I wanted to work in AI on ideas like his and that I was interested in applying to Indiana University. I asked if I could visit him sometime at Indiana to talk more. He told me that he was actually living in Boston, visiting the MIT Artificial