Common wisdom seems to suggest that living organisms have lower entropy that their environment. For example, the Wikipedia article on "Entropy and Life" mentions that Schrödinger thought that this was the case. On first thought this made sense to me; living organisms are more 'organized' than non-living matter. However, on closer inspection, I believe that this thought is completely wrong.
Although entropy is commonly linked with level of 'organization', a much more precise definition of entropy is a measure of how dispersed is the energy between the various possible energy modes of the molecules and atoms. In a living organism, the energy contained in its matter is highly distributed between many energy modes (translation, vibration, electricity, chemical, potential), while non-living matter this energy is more concentrated in less energy modes (mostly chemical).
As an example, my cat eats only dry cat food and water. Therefore the matter that composes my cat comes completely from the matter contained in the dry food, water and air. The energy in the food is concentrated mostly in chemical energy. However, the energy in my cat is more widely distributed between heat energy (which is really molecular kinetic energy), kinetic and potential energy as it runs around, electrical energy in its nervous system, and chemical energy in its fat and tissues. Clearly the energy is much more dispersed between different energy modes, meaning much higher entropy. Another way to see it, there is much more 'unknown information' about the microstates of the energy, given the macrostate of the energy contained in the cat, as opposed to the energy in the food. It is in this sense that we can say that the energy is more dispersed or 'disorganized' in the cat than in the cat food.
So any way I see it, it seems to me like living organisms are very efficient entropy producing machines. Not only do they increase entropy of their environment (closed system) but their internal entropy (open system) is also much higher.
So is the conventional wisdom wrong? Or am I wrong?
Thanks!
Best Answer
If we consider the body surface of the organism as the boundary of a system, then the organism as a machine tends to lower its internal entropy at the expense of raising entropy in the environment. To accomplish this great feat, the organism must have some means of absorbing energy from the environment - like the process of photosynthesis or feeding.
The clue, evidence that entropy is lowered? - just look at the amazing order, assembly of complexity, complex systems within the organism.