Speaker Ph.D. Student, Yongjae Oh
(Department of Physics and Astronomy, Seoul National University)
Date｜Time Nov 26 (Tuesday), 2024｜15:00-16:00
Place Room 316-1, Building 133
Abstract
In recent decades, a subfield of statistical mechanics called ‘stochastic thermodynamics’ has been emerged, aiming to extend classical thermodynamic principles (such as the 2nd law of thermodynamics) to microscopic systems dominated by fluctuations and therefore described with stochastic dynamical systems. This framework allows for the definition of thermodynamic observables at the level of individual random trajectories. Among these observables, entropy production (EP) stands as the direct and full measure of irreversibility. Furthermore, by assigning appropriate energetic interpretations to the EP, one can relate it with the actual amount of useful resources consumed.
In this talk, the presenter will first introduce the physical concepts and theoretical conditions needed to determine whether a system has reached thermodynamic equilibrium, or how much it deviates from equilibrium. Especially, by employing the concept of ‘path probability’ developed in theoretical physics, the modern notion of (trajectory-wise) EP for stochastic dynamical systems as well as the fluctuation theorem (FT) governing the EP will be explored. Next, the advantages and limitations of describing nonequilibrium systems in thermodynamically consistent manner will be illustrated, exemplifying the novel class of soft, nonequilibrium metamaterials known as ‘active matter’. Active matter, which consists of numerous self-propelled particles, exhibits various enhanced mechanical abilities, of which performance can be analyzed through stochastic thermodynamics. Finally, the potential relationship between the control problem of active matter and modern control theory will be briefly discussed.
Biography
Yongjae Oh is a Ph.D. candidate in the Department of Physics and Astronomy at Seoul National University. He is studying nonequilibrium statistical physics under the supervision of Professor Yongjoo Baek. He received bachelor’s degrees at SNU for Electrical Engineering (minor: Aesthetics) and Physics. His primary research areas include stochastic thermodynamics and collective behavior of active matter. He is also interested in information thermodynamics, and statistical-mechanics perspective of deep learning theory.
