In 1970, MIT-Professor Jay W. Forrester was invited by the Club of Rome to a meeting in Switzerland. The Club of Rome is an organization devoted to solving what its members describe as the 'predicament of humans'. That is, the global crisis, that may appear sometime in the future, due to the demands being placed on the earth's carrying capacity (its sources of renewable and nonrenewable resources and its sinks for the disposal of pollutants) by the world's exponentially growing population.
Back from this meeting, Forrester created the first draft of a system dynamics model of the world's socio-economic system. He called this model WORLD1 and refined it in preparation for a visit to MIT by members of the Club of Rome. Forrester named the refined version of the model WORLD2 and published it in his book titled 'World Dynamics'. From the outset, World Dynamics drew an enormous amount of attention. The WORLD2 model mapped important interrelationships between world population, industrial production, pollution, resources and food. The model showed a collapse of the world sozio-economic system sometime during the twenty-first century, if steps were not taken to lessen the demands on the earth's carrying capacity. The model was also used to identify policy changes capable of moving the global system to a fairly high-quality state that is sustainable far into the future.
(cf. http://www.systemdynamics.org)
SCIETREX Scientific Software AG presents here an adaption of the 'World Model' for use with smartphones. You can play with it by adjusting the birthrate of humans and the capital rate for industrial production. You will recognize, how the adjustments impact the number of people being able to live on our planet at the same time.