Jean M. Carlson

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Jean Marie Carlson (born 1962) is a professor at the University of California, Santa Barbara, who studies complexity in highly connected systems. Her work helps explain real‑world problems such as earthquakes, wildfires, and how the brain and immune system function.

Education and career
Carlson studied electrical engineering and computer science at Princeton University, graduating in 1984. She then earned a master’s degree in applied physics from Cornell University, followed by a PhD in theoretical condensed matter physics in 1988, working with James Sethna on spin glass models. She did a postdoctoral stint at the Kavli Institute for Theoretical Physics with James S. Langer and joined UCSB as faculty in 1990. She received a David and Lucile Packard Foundation fellowship in 1993.

Key ideas and methods
Carlson is known for Highly Optimized Tolerance (HOT), a framework that links how evolving structures in complex systems create power‑law behaviors. She began developing HOT in the early 2000s and has since applied it to many areas, including biology, earthquakes, wildfires, and neuroscience. HOT offers a way to study how systems adapt to their environments, setting it apart from other ideas like self‑organized criticality.

Applications in biology and medicine
- Immune system: She uses computational biology to understand how the immune system changes with age and how autoimmune diseases arise, as well as how the body maintains balance (homeostasis).
- Gut microbiome: With collaborator Eric Jones, she built a mathematical model of how gut bacteria interact in fruit flies to gain insights that may help explain the human gut microbiome. The work shows that how bacteria interact can be as important as how many there are.

Applications in neuroscience
Carlson studies brain networks to see what features stay healthy and how they relate to learning and memory. She combines computer models with brain data from EEG and MRI. She has found that parts of the brain that synchronize during memory tasks become smaller but more numerous with age, shedding light on aging and cognitive function.

Applications in materials and Earth science
- Materials: Using ideas from statistical mechanics, she investigates granular materials (like sand) to understand how they flow or jam, which relates to friction along fault lines.
- Earthquakes: Her work covers dynamic rupture and faster‑than‑usual ruptures (supershear). She also helped develop the HFire model to simulate how wildfires spread and evolve over time, aiding forest management and planning.

Disasters, information, and beyond
Carlson has studied how people make decisions during disasters, aiming to improve evacuations and resource use. She also looks at how information networks influence decisions and how information spreads socially. Her interests also include econophysics, evolution, and control theory. She is a visiting professor at the Santa Fe Institute.

Recognition
In 2021, Carlson was named a Fellow of the American Physical Society for her rigorous, physics‑based models of nonlinear and complex systems that have made an impact in neuroscience, environmental science, and geophysics.