In 2005, futurist Ray Kurzweil made a bold prediction: by 2045, machines would be smarter than humans. He called this moment the "singularity." It sounded like science fiction, but Kurzweil’s ideas caught the attention of many, especially in Silicon Valley.

Now, Kurzweil is updating his prediction. In his new book, The Singularity is Nearer: When We Merge with A.I., he says the singularity might come even sooner—by 2029! That’s just five years away. Kurzweil believes that recent advances...