mathematics, for example: Whitehead and Russell’s Principia Mathematica in 1910 was the biggest showoff effort. There were previous attempts by Gottlob Frege and Giuseppe Peano that were a little more modest in their presentation. Ultimately, they were wrong in what they thought they should formalize: They thought they should formalize some process of mathematical proof, which turns out not to be what most people care about. With regard to a modern analog of the Turing Test, it’s an interesting question. There’s still the conversational bot, which is Turing’s idea. That one hasn’t been solved yet. It will be solved—the only question is, What is the application for which it is solved? For along time I would ask, “Why should we care?”—because I thought the principal application would be customer service, which wasn’t particularly high on my list. But customer service, where you’ re trying to interface, 1s just where you need this conversational language. One big difference between Turing’s time and ours is the method of communicating with computers. In his time, you typed something into the machine and it typed back a response. In today’s world, it responds with a screen—as for instance, when you want to buy a movie ticket. How is a transaction with a machine different from a transaction with a human? The main answer is that there’s a visual display. It asks you something, and you press a button, and you can see the result immediately. For example, in Wolfram|Alpha, when it’s used inside Sin, if there’s a short answer, Siri will tell you the short answer. But what most people want is the visual display, showing the infographic of this or that. This is a nonhuman form of communication that turns out to be richer than the traditional spoken, or typed, human communication. In most human- to-human communication, we’re stuck with pure language, whereas in computer-to- human communication we have this much higher bandwidth channel—of visual communication. Many of the mos