A Thermodynamic Approach towards the Question "What is Cellular Life?"

The question "What is life?" has been asked and studied by the researchers of various fields. Nevertheless, no global theory which unified various aspects of life has been proposed so far. Considering that the physical principle for the theory of birth should be the one known for the unanimated world, and that the life processes are irreversibly selective, we showed by a deductive inference that the maximum entropy production principle plays an essential role for the birth and the evolution of life in a fertile environment. In order to explain the survival strategy of life in a barren period of environment, we also proposed that life had simultaneously developed a reversible on and off switching mechanism of the chemical reactions by the dynamics of equilibrium thermodynamics. Thus, the birth and evolution of life have been achieved by the cooperation between the driving force due to the non-equilibrium thermodynamics and the protective force due to the equilibrium thermodynamics in the alternating environmental conditions.