The Quantization Paradigm in Physics and Biology

A fundamental tenet in the study of organization in inanimate and living matter is the quantization of energy. In inanimate systems where temperature is a critical organizing parameter, the quantum of action is an atomic-level phenomenon described in terms of Planck’s constant, first defined as the ratio of the photon energy to the frequency of its electromagnetic wave. In living systems, where the cycle time of metabolic processes is the organizing variable, the quantum of action is a cell-level phenomenon described in terms of an analog of Planck’s constant, namely the ratio of the metabolic energy to the frequency of the enzymatic or mitochondrial oscillators. This chapter elucidates the relation between these two measures of quantum action. We review the role of Planck’s constant in physics, first, as a fundamental parameter for explaining the empirical laws of black body radiation, and its more modern developments. We also describe the theoretical and empirical rationale for the cellular-level quanta. We exploit this analysis to elucidate how energy transformation in physical processes, where temperature is the organizing parameter, relates to energy transduction in biological processes, which are essentially isothermal. We then link the cell level to the organismal level of metabolism and obtain a scaling relationship for the biological Planck quantum of action as a function of the size of the biological system studied. Finally, we discuss these ideas in light of quantum-like processes in biological organisms and systems: identifying generalized quantum principles that apply not just at microscopic levels but also at macroscopic levels, relevant to biology, where we used to consider classical physics alone to be relevant. This chapter provides a direct analogy between quantization of energy in solids first demonstrated by Debye and biochemical energy production in cellular mitochondria. The Planck constant proved to be a fundamental constant of matter as it appeared both in the Schoedinger equation and the Heisenberg uncertainty principle. Recently, quantum biology has garnered major scientific interest, but so far it has only focused on physical quantum effects in biological systems, such as photosynthesis, not truly biological quantization. We point to metabolism, as an indispensable process that underlies all life forms’ existence, and show that its quantization can be better understood in terms of a corresponding quantum of action. We estimate its value, compare it to Planck’s quantum of action in physics and explain their different scales. We hypothesize that energy quantization of metabolism in biological systems is an important conceptual advance that can provide insights into both healthy and pathological physiology.