• Login
  • Register

Work for a Member company and need a Member Portal account? Register here with your company email address.

Project

Large Population Models

Copyright

Camera Culture - Media Lab

Ayush Chopra MIT Media Lab

Many of society's most pressing challenges—from pandemic response to supply chain disruptions to climate adaptation—emerge from the collective behavior of millions of individuals making decisions over time. Understanding these complex systems requires seeing how individual choices combine to create outcomes that no one person intended.

Current AI research, driven by Large Language Models (LLMs),  has made remarkable progress creating increasingly sophisticated "digital humans," but has largely overlooked the critical next step: understanding how these individuals combine to form "digital societies." This is where Large Population Models (LPMs) come in—a new computational approach that simulates entire populations with their complex interactions and emergent behaviors.

Imagine a digital microscope revealing an entire city—8.4 million synthetic New Yorkers living their daily lives in a computational world. In this virtual society, each person makes decisions based on their unique circumstances: a nurse weighs the risks of commuting on crowded subways, a restaurant owner adjusts prices as supply costs rise, families decide whether a $500 stimulus check means they can afford to stay home during a pandemic surge. As these millions of individual choices ripple through networks of interactions, patterns emerge that no single decision-maker could foresee. This living laboratory of human behavior is the vision behind Large Population Models (LPMs).

Copyright

Media Lab Copyright


Research: Three Fundamental Breakthroughs

Building these digital societies requires solving three fundamental challenges:

1. The Scale vs. Detail Dilemma: Traditional modeling approaches force an impossible choice—like trying to film a stadium while capturing everyone's facial expressions. You could model complex behaviors for a few hundred people OR simple movements for millions—but not both. We introduce a domain-specific language built on two key insights: i) capture behavior for millions of individuals without prompting each individually by learning patterns across demographic groups, and ii) compute complex interactions between individuals simultaneously through optimized tensor operations. This allows us to simulate 8.4 million unique New Yorkers on a single GPU with full behavioral complexity—achieving a 600× speedup over traditional approaches without sacrificing scale or detail.

2.The Puzzle Piece Challenge: Data about our world comes from disparate sources that don't fit together easily. By making simulations differentiable end-to-end, we transform months of computation into minutes. This allows direct gradient-based learning from heterogeneous data sources—hospital records, mobility patterns, economic indicators—without surrogate models, enabling rapid calibration and real-time analysis of complex scenarios with a 3000× speedup over traditional methods.

3. The Simulation vs. Reality Gap: Traditional simulations remain disconnected from the real world they aim to understand, rely on passive or anonymized data. We bridge this gap by transforming personal devices—that generate data—into simulation agents in a decentralized network. Through secure multi-party computation, these agents compute and securely share simulation outputs and calibration gradients while keeping individual data private. This technical breakthrough enables collaborative population-scale modeling without exposing sensitive information, evolving simulations from passive analysis tools into real-time decision engines that shape reality.

LPMs realize this vision by making fundamental advances in agent-based modeling, decentralized computation and machine learning. Our research has resulted in several publications at top-tier AI conferences, journals and received multiple best-paper awards. Our work has received research awards from industry (e.g. JP Morgan, Adobe) and government (e.g. NSF).

Copyright

Media Lab Camera Culture

AgentTorch: Tools for Digital Societies

AgentTorch, our open-source platform, makes building and running massive LPMs accessible. It integrates GPU acceleration,  differentiable environments, large language model capabilities, and privacy-preserving protocols in a unified platform—allowing researchers to build, calibrate, and deploy sophisticated population models without specialized expertise. Think PyTorch, but for large-scale agent-based simulations. Find below a quick demo and a code-snippet. The AgentTorch platform is open-source at github.com/AgentTorch/AgentTorch

Copyright

Media Lab Camera Culture

Real-world Impact

AgentTorch LPMs are already making impact globally. They've being used to help immunize millions of people by optimizing vaccine distribution strategies, and to track billions of dollars in global supply chains, improving efficiency and reducing waste - across governments and enterprises.  

As your read this, AgentTorch LPMs  are helping the New Zealand crown stop a measles outbreak, facilitate peer-2-peer energy grids in small Indian towns and enable global enterprises to reimagine their supply chains for a sustainable future.  Our long-term goal is to "re-invent the census": built entirely in simulation, captured passively and used to protect global nations.

From pandemic response to climate adaptation to urban planning, LPMs provide a powerful new tool for understanding how millions of individual decisions combine to shape our world—and how we can design better solutions for our most pressing challenges.

Copyright

Camera Culture Media Lab

Curious about LPMs: Learn More

We would love to collaborate with you in advancing fundamental research and deploying LPMs within your enteprise. For thoughts and questions, please reach out to Ayush Chopra at [ayushc] [at] [mit.edu]. We look forward to hearing from you!