Heat Remembers Past
Auburn researchers develop framework to track heat's memory, challenging 200-year-old Fourier's law with major implications for electronics.
Heat has a memory, and researchers have developed a new theoretical framework to describe it. Jianjun Dong, the Thomas and Jean Walter Professor in the Department of Physics at Auburn University, and Yi Zeng, an Auburn alumnus, have created a unified way to describe heat conduction in nonuniform media.
The study, 'Unified Statistical Theory of Heat Conduction in Nonuniform Media', was published in Physical Review B. It challenges the traditional Fourier's law, which has been used to describe heat conduction for roughly two centuries. Fourier's law assumes that heat flow at a particular location responds immediately to the temperature gradient at that same location.
However, at very small length scales and short times, Fourier's law may no longer tell the complete story of heat conduction. The new framework provides a way to track how heat flowing at one place and time may still carry the influence of a temperature disturbance that occurred earlier or somewhere else in the material.
The memory of heat is stored in the microscopic motion of the material. This means that heat can retain a kind of physical memory, where the heat flowing at this moment can still carry information about a temperature disturbance that occurred earlier.
## Why it matters The new theoretical framework is significant because it provides a more accurate description of heat conduction in nonuniform media. This is particularly important at the scale of modern computer chips, where heat flow can be affected by tiny variations in temperature. The framework could lead to new insights and innovations in fields such as electronics and materials science.
The research was conducted by Jianjun Dong and Yi Zeng, who is now a research scientist at the Department of Energy's National Laboratory of the Rockies. Zeng earned his Ph.D. in mechanical engineering from Auburn University in 2019.
The study's findings have the potential to challenge our understanding of heat conduction and its behavior in different materials. As researchers continue to explore the properties of heat, the new framework could provide a foundation for further discoveries and advancements in the field.
