Scientific thought has long relied on modeling creating a (usually simplified or reduced) representation of a phenomenon that contributes to understanding it. Computing aids not only in the construction and statistical analysis of models, but in their ability to represent change over time, a critical element in understanding and predicting the behavior of systems that include multiple variable or contingent elements.<br><br>Both natural and social processes often involve multiple contingent events, and mathematically solving all of the equations necessary to track them is often impossible. But numerical approximations are available and built into the tools used in computer simulation. Computer simulations are prime examples of the capacity of computing to lead to transformative expansions in human knowledge.<br><br>Computer modeling and simulation can be profitably applied in nearly every field of human endeavor, helping people understand topics as various as rush-hour traffic, the spread of the Ebola virus, how protein molecules are configured to interact with other molecules in the body, the path of a hurricane, or the behavior of subatomic particles at the inception of the universe.