On Wednesday, he gently explained artificial intelligence research and talked about what might be “the most important problem of this century”: getting AI to learn on its own.

AI is something Facebook (FB, Tech30) has been very vocal about investing in over the past few years. Major tech companies including Google (GOOG) and Apple (AAPL, Tech30) have been competing for AI talent in a rush to build smarter systems. The technology already exists in some facial recognition and voice assistant features. Eventually, it could show up in everything from robots to driverless cars.