As the cofounder of Google DeepMind, Shane Legg is driving one of the greatest transformations in history: the development of artificial general intelligence (AGI). He envisions a system with human-like intelligence that would be exponentially smarter than today's AI, with limitless possibilities and applications. In conversation with head of TED Chris Anderson, Legg explores the evolution of AGI, what the world might look like when it arrives — and how to ensure it's built safely and ethically.