I'm reading a paper sent to me by a friend that is causing me to ponder the definition and nature of "closed systems".
It's interesting that the definition of a "closed system" is not at all consistent across several sources. Here are some examples ...
noun Thermodynamics.
a region that is isolated from its surroundings by a boundary that admits no transfer of matter or energy across it.
A closed system is a physical system that does not allow transfer of matter in or out of the system, though, in different contexts, such as physics, chemistry or engineering, the transfer of energy is or is not allowed.
A closed system is a type of thermodynamic system where mass is conserved within the boundaries of the system, but energy is allowed to freely enter or exit the system.
In chemistry, a closed system is one in which neither reactants nor products can enter or escape, yet which allows energy transfer (heat and light). A closed system may be used for experiments where temperature isn't a factor.
A closed system is a system that is completely isolated from its environment.
This is the definition commonly used in the system literature, which we have chosen to follow. This is different from the thermodynamics definition, which differentiates between systems that are “closed” (no material flow) and “isolated” (no material or energy flow).
The physical universe, as we currently understand it, appears to be a closed system.
- INCOSE
A physical system that does not interact with or receive input from other systems, especially one that obeys conservation laws.
- YourDictionary (ignoring a few of the alternatives)
Maturana asserts that the nervous system is a closed system with the following description ...
The nervous system is, both anatomically and physiologically, a closed network of interacting neuronal elements. As such, the nervous system operates as a closed network of changing relations of activities between the neuronal elements that compose it, in the sense that any change of relations of activity in it leads to further changes in relations of activity in it. Sensors and effectors have a dual character since they operate as neuronal elements and participate in the composition of the nervous system through their structural intersection with some nerve cells. As sensors and effectors they are part of the organism and constitute the surface of encounter between the organism and the medium. So, the organism interacts with the medium through its sensors and effectors, not through the nervous system. What happens is that in their structural intersection with neuronal elements, sensors and effectors operate as components of the nervous system and participate as such in its closed dynamics of changing relations of activities. The nervous system, therefore, does not encounter the medium, and as it operates as a closed network of changing relations of activity between its neuronal components, it does not have input or output relations with the medium in its operation.
- The Biological Foundations of Virtual Realities and Their Implications for Human Existence
Thermodynamically, of course, the nervous system is not at all closed. It requires a continuous injection of energy and materials and continuously ejects heat and waste. This seems to be referring to a different characteristic. If you assert that interfaces are transformations of information from one medium to another and you further assert that interfaces contain within themselves the boundaries between those mediums then I think you get to what Maturana is describing.
If your interest is in the flow of whatever the mediums happen to be, then okay, I get where he's going. If your interest is in information flow then the system is not at all closed. That's generally the point of many interfaces.
The gist of the introductory portion of this paper seems to be that the nervous system structurally morphs in response to interactions across these interfaces. I guess an analogy might be poking a water balloon. As you poke and prod it, it changes shape. No matter has entered or left the balloon, though you may be able to argue that there's been an energy transfer. There's clearly been an information transfer in that the balloon has reacted to the proding finger.
I can see how this can be a useful mental model even though it kind of grates on the semantic implications of "closed". I guess I'm most comfortable with INCOSE's conclusion that ...
The physical universe, as we currently understand it, appears to be a closed system.
I can believe that the physical universe is closed in the material, energy, and information domains and there are likely no other examples. But I also appreciate their tentativeness.
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