Grand challenges for modeling and simulation: simulation everywhere—from cyberinfrastructure to clouds to citizens

Modeling u0026 Simulation (Mu0026S) is making successful contributions to different areas in industry and academia. However, there are certain key issues that are preventing the field from addressing larger domains and from achieving wide-scale impact. Formulating these as grand challenges arguably focuses attention on these key issues and may bring a critical mass of effort to bear that could result in a major leap forward. This article is one of several concurrent activities aimed at reinvigorating the debate on grand challenges in Mu0026S. These grand challenges include Big Simulation, human behavior, composability, cloud-based Mu0026S, reproducibility in Mu0026S research and the democratization of Mu0026S. Two themes emerge: the need for large-scale cloud-based cyberinfrastructures for Mu0026S and the democratized access to Mu0026S and its outputs.