I am interested in understanding biological phenomena through general principles and theoretical models. Instead of studying biological systems for which traditional physics models and methods are applicable, I would like to see how biology offers new types of phenomena and questions that are different from usual physical systems, which require new approaches and may expand the scope of physics. Compared to other forms of physical systems (such as condensed matter), biological organisms (or “living matter”) are special in many aspects. The unique aspects of living organisms offer great opportunities for thinking about the nature of biology and its connection to physics.

Phenotypic heterogeneity within populations

Different organisms exhibit phenotypes, such as morphological and behavioral traits, that are characteristic of their species. However, even within a population of the same species, the phenotypes may vary substantially among individuals. This is in contrast to systems often studied in physics, which are made of identical and indistinguishable particles. Phenotypic heterogeneity within a population can play an important role in the adaptation and evolution of the species. [read more]

Interaction modification by third parties

Biological systems are often described by pairwise interactions between components, such as protein interactions within a cell or species interactions in an ecosystem. However, unlike physical systems where the interactions are determined by fundamental forces with universal coupling constants, the interaction strengths between biological components can be modified by third parties, such as the allosteric regulation of protein interactions. That is because biological components have complex internal structures, and the effective strengths of their interactions can change if the internal structures are altered. [read more]

Internal representation of the environment

Organisms are “evolved matter” whose form and function have been shaped by the environment that they have encountered. Compared to inorganic matter that reacts to external conditions in simple aimless ways, organisms exhibit far more complex responses to environmental stimuli, as seen in remarkable examples of morphological adaptations and behavioral strategies. These sophisticated responses reflect a knowledge of the environment that has been accumulated over the course of evolution as well as during individuals’ lifetime. Such knowledge can be described as an internal representation of the environment that organisms rely on to process information and react accordingly. [read more]