Long dismissed as a technology of the distant future, artificial intelligence was a project once consigned to the fringes of the scientific community. Then two researchers changed everything. One was a 64-year-old computer science professor with a back problem so severe he could not drive or fly. The other was a 36-year-old neuroscientist and chess prodigy. Though they took very different paths, together they helped catapult AI to the forefront of our daily lives and, in the process, created a b...