The two layers, plus the demon, see section 2.8.5, also naturally explain why that difference comes into existence. As we explained above, when a finite-width membrane separating the two segments appears in the volume (due to the evolution or the development of the individual biological object), two thin electrolyte layers will be formed proximal to its surfaces on the two sides, even if the concentrations are equal. As observed, “a membrane potential arises when there is a difference in the electrical charge on the two sides of a membrane, due to a slight excess of positive ions over negative ones on one side and a slight deficit on the other.” [145] We add that some potential difference is created by the presence of the membrane alone, as discussed above. When a demon also appears in the membrane (initially a simple hole), the random movement of ions with finite speed through the finite length of the ion channels may also solve the mystery of why a cell comes into life during evolution. Maybe we can answer E. Scrödinger’s profound question: ”What is life, and how did it emerge from non-life?”
Erwin Schrödinger’s famous book ”What Is Life? The Physical Aspect of the Living Cell” provides a nice example of disciplinary thinking. Schrödinger’s lecture focused on one important question: ”how can the events in space and time which take place within the spatial boundary of a living organism be accounted for by physics and chemistry?” He discussed the living cell’s operation from the point of view of thermodynamics, forgetting that the ions have also charges, so the electric interaction must also be considered. The basic difficulty to consider both of them is that their interaction speed differs by a factor about a million, and physics has no proper approximation to handle them simultaneously. Considering the laws of a single discipline, either theory of thermodynamics, or theory of electricity, is not sufficient. We must elaborate the way how they cooperate in the nature, even if we need to elaborate new mathematical methods for that goal, see section 2.4.