#  HUCE Special Seminar 

 



####  calendar\_today Date and Time 

 **October 18, 2022** 

 12:00PM - 01:00PM EDT 

####  pin\_drop Location 

 **HUCE 440, 26 Oxford St., Cambridge**  



 

 



 

 "The Micro-Macro Dialogue: A New Look at Complex Systems Far from Steady State" with **John Harte,** Professor of the Graduate School at the University of California, Berkeley.

 "The Micro-Macro Dialogue: A New Look at Complex Systems Far from Steady State" with **John Harte,** Professor of the Graduate School at the University of California, Berkeley.

 **Abstract:** Two types of theories and models dominate the complexity-science literature: bottom-up and top-down. The former calculate macro-level behavior from assumptions about the mechanisms that govern interactions among micro-level “agents”, while the latter infer probability distributions over the micro-level variables from constraints imposed by macro-level “state variables”. Implementation of the top-down approach in ecology, using the information-theoretic maximum entropy principle, yields a wide variety of predictions for ecosystems in steady state, and empirical data generally validate these predictions. But if the state variables are changing in time, as in a highly disturbed ecosystem, these predictions are observed to fail. The dynamics of disturbed systems are especially complex if the macro-level variables influence the interactions among the micro-level agents, yet are also sums or averages over them. After reviewing the static, top-down, theory of ecology, I present a novel way to hybridize top-down and bottom-up theories to describe the behavior of disturbed complex systems. A simple example illustrates general concepts and generates many of the rich behaviors emerging from the theory.

 **Bio:** John Harte is a Professor of the Graduate School at the University of California, Berkeley. He did his undergraduate studies at Harvard and his PhD at the University of Wisconsin. From 1968 to 1973 he was on the Physics faculty at Yale and prior to that was a postdoc at CERN and UC Berkeley. He has received a Guggenheim Fellowship, the Leo Szilard prize from the American Physical Society, and is a co-recipient of a 2006 George Polk award in investigative journalism. He is an elected Fellow of the California Academy of Sciences, the American Physical Society, the Ecological society of America, and the American Association for the Advancement of Science. He has also served on six National Academy of Sciences Committees and has authored over 250 scientific publications, including eight books, one of which, "Consider a Spherical Cow" is a widely used textbook on environmental modeling. John's research focuses on ecology, climate, complexity science, and sustainability.

 Contact: [laura\_hanrahan@harvard.edu](mailto:laura_hanrahan@harvard.edu)



 

 



 

 See also:- [ HUCE Special Seminar ](/lecture-series/huce-special-seminar)
 
 

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