The Rules of Contagion: Why Things Spread - and Why They Stop

Adam Kucharski examines the mathematical blueprints that govern how viral phenomena behave, ranging from infectious diseases like Ebola and COVID-19 to social media trends and financial crises. He identifies the specific variables that determine whether an outbreak will ignite or fizzle out, focusing on the R number, superspreading events, and the structure of social networks. By tracing the history of epidemiological modeling, the text shows how the same predictive equations used to understand pathogens now explain the spread of gun violence, misinformation, and global stock market instability.

This book serves researchers, analysts, and anyone interested in the invisible forces shaping public health and digital culture. Readers learn to identify the crossover between biological infection and information theory, gaining a technical vocabulary for how clusters form and how interventions can halt a contagion. It provides a toolkit for understanding the mechanics of the modern world, helping the reader recognize the difference between a self-limiting fad and a systemic threat before it reaches a tipping point.