Excerpted from: The Five Stages of Collapse by Dmitry Orlov

The first of these models is the World3 model used in the 1972 book Limits of Growth. World3 is a relatively simple model that ran on a computer less powerful than a smartphone and included just five variables: world population, industrialization, pollution, food production, and resource depletion. This model predicted economic and societal collapse by mid-twenty-first century. The 2004 Limits on Growth: The 30 Year Update confirmed that, thirty years later, the initial predictions are still in excellent agreement with reality. Though your instinct may be to mistrust the predictive abilities of mathematical models in general, this wariness should be tempered somewhat when the model in question is shown to have been correct decades later.