During the Biden administration (2021–2024), the U.S. immigration system was under a lot of pressure. There was a record-high asylum backlog, not enough detention space, and policy changes that made more people eligible to apply, all while the system struggled to keep up. This model reflects those challenges. It shows how more and more asylum seekers were entering an already overwhelmed system, while slow processing times and uneven funding made it hard to move cases forward. As a result, detention numbers kept rising, but deportations stayed relatively low. Instead of resolving cases efficiently, the system settled into a kind of uneasy balance, leaving many people stuck in limbo, neither fully processed nor removed.

A simple model of economic growth where a government taxes the economy, and spends it on capital and revenue goods.

Simple model of the global economy, the global carbon cycle, and planetary energy balance.

The statement that there can be no economic activity without  energy and that fossil fuels are finite contrasts with the fact that money is not finite and can be created by governments via their central banks at zero marginal cost whenever needed.

An important fact about COAL, GAS and OIL (especially when produced via fracking) is that their net energy ratios are falling rapidly. In other words the energy needed to extract a given quantity of fossil fuels is constantly increasing. The falling ratio 'EROI' (Energy Return on Energy Invested ) provides yet another warning that we can no longer rely on fossil fuels to power our economies. In 1940 it took the energy of only one barrel of oil to extract 100. Today the energy of 1 barrel of oil will yield only 15. We cannot wait until the ratio falls to 1/1 before we invest seriously in alternative sources of energy, because by then industrial society as we know it doday will have ceased to exist. An EROI of 1:1 means that it takes the energy of one barrel of oil to extract one barrel of oil - oil production would simply stop! 

Buying and storing electricity when it is cheap, and selling it when it is expensive. What are the benefits, both public and private?

Butterfly Effect
Sensitivity To Initial Conditions
(sensitive dependence on initial conditions)
Navier Stokes Equations
Lorenz Attractor
Chaos Theory, Disorder and Entropy



If M is the state space for the map , then  displays sensitive dependence to initial conditions if for any x in M and any δ > 0, there are y in M, with  such that

Structure of model in Nathan Forrester's 1983 MIT Thesis comprising 4 models

Economic capital growth model, Figure 27 from Thinking in Systems by Donella H. Meadows

How education causes the gap between socio-economic status?

WIP Overview model structures of Khalid Saeed's 2014 WPI paper Jay Forrester’s Disruptive Models of Economic Behavior  See also General SD and Macroeconomics CLDs IM-168865

Goodwin business cycle model, modified from Keen and Blatt

The World3 model is a detailed simulation of human population growth from 1900 into the future. It includes many environmental and demographic factors.

Use the sliders to experiment with the initial amount of non-renewable resources to see how these affect the simulation. Does increasing the amount of non-renewable resources (which could occur through the development of better exploration technologies) improve our future? Also, experiment with the start date of a more environmentally focused policy.

To maintain economic wealth (roads, hospitals, power lines, etc.) power needs to be consumed. The same applies to economic activity, since any activity requires the consumption of energy. According to the Environmental Protection Agency, the burning of fossil fuels was responsible for 79 percent of U.S. greenhouse gas emissions in 2010. So whilst economic activity takes place fossil fuels will be burned and CO2 emissions are unavoidable - unless we use exclusively renewable energy resources, which is not likely to occur very soon. However, the increasing CO2 concentrations in the atmosphere will have negative consequences, such droughts, floods, crop failures, etc. These effects represent limits to economic growth. The CLD illustrates some of the more prominent negative feedback loops that act as a break on economic growth and wealth.  As the negative feedback loops (B1-B4) get stronger, an interesting question is, 'will a sharp reduction in economic wealth and unavoidable recession lead to wide-spread food riots and disturbances?'

Economic capital growth in a system constrained by a non-renewable resource, Figure 37 from Thinking in Systems by Donella H. Meadows

Causal loop representations of macroeconomics taken from the System Dynamics literature contrasted with Forrester's main analysis of social and business organization layers See also Saeed's Forrester Economics IM-183285

Like previous models, this model shows the operation of a simple economy, the influence of changes in the consumption rate, and the effect of government intervention. In addition, this model shows changes in the hypothetical general price level. It gives an idea of changes in price trends based on changes in the quantity of money. NOTE: No general price level exists. Prices provide information for the exchange of individual economic goods.

WIP of several books of Karl Polanyi's thoughts and papers around social science economic history and capitalism. . See also Summary of the Great Transformation IM-10640

Circular equations WIP for Runy.

Solow model without external factors.

Simulation of Goodwin01 Minsky Model CLD in IM-172002 Compare with Part3 slide 3 of presentation in patreon. See extension Goodwin02 at IM-172145

Overview of Part F Ch 25 and 26 of Mitchell Wray and Watts Textbook see IM-164967 for book overview