system structure where output feeds back as input, modifying subsequent behavior
positive (amplifying) feedback: output reinforces the process, driving exponential growth or collapse
- examples: compound interest, viral spread, ice-albedo effect, bank runs
negative (stabilizing) feedback: output counteracts the process, maintaining equilibrium
- examples: thermostat, blood sugar regulation, predator-prey dynamics
ubiquitous in biology, economics, engineering, and climate
control theory formalizes feedback through transfer functions and stability analysis
delay in feedback loops causes oscillation and overshoot
cybernetics (Wiener) placed feedback at the center of self-regulating systems