How the World3 model worked
The Limits to Growth focuses on the results of the simulation, omitting the israel phone number material technical details of how World3 works. How the model works is explained in a separate 1974 book, The Dynamics of Growth in a Finite World.
World3 was written in the now-forgotten programming language DYNAMO, or DYNAmic MOdels. It was also developed at MIT by programmers Phyllis Fox and Alexander Pugh. The program itself is a list of 150 equations that define the relationships between variables.
Like its predecessors, World1 and World2, the World3 computer model is based on system dynamics. Internal feedback loops in the structure of the system influence the behavior of the entire system.
World3 covers the period from 1900 to 2100 and is built around five variables:
population;
agriculture;
industry;
environmental pollution;
consumption of non-renewable natural resources.
Variables change through flows. For example, the population variable is measured by birth and death flows. Flows also include investment and depreciation, formation and assimilation of pollutants, soil erosion, and its development or withdrawal for urban and industrial use.
