The entropy generation in visual-pigment system by the absorption of light

We first showed a general theory that reception of information from the outside in a receptor system is accompanied both by an inflow of entropy and by a generation of entropy depending on the reliability of the actual reception mechanism. Then, considering a case for the absorption of light by the visual-pigment system of visual cell, we calculated the time(t)-dependent change in the number N-2(t) of excited visual-pigments to obtain the entropy increase. We thus arrived at the following four conclusions: (1) One or two photons can be detected with a reliability of at least 54%; (2) In compensation for this detection, entropy > 1.12 x log2 is generated; (3) An incident photon of frequency nu from a light source of temperature T-s yields an entropy of h nu/T-s; and (4) Depending on the characteristics of the visual-pigment system, another entropy being different from (2) is generated in proportion to N-2(t). (C) 1998 Elsevier Science B.V. All rights reserved.