Our world stands at the cusp of an unprecedented transformation. As billions of AI agents begin to augment human society, we face a fundamental challenge: coordinating collective behavior at scales far beyond human cognitive limits. While current AI approaches like large language models excel at enhancing individual agent capabilities (Personal AI), they cannot inherently address the massive-scale coordination challenges that define our interconnected world (Population AI). Enter Large Population Models (LPMs): a new AI paradigm simulating millions of interacting agents simultaneously, capturing collective behaviors at population scale. It's like scaling up AI agents exponentially to understand the ripple effects of countless decisions.