This question was posted on Quora.com: “What are some examples of open and closed systems?” Here is are the top three responses:
An open system is a system that freely exchanges energy and matter with its surroundings. For instance, when you are boiling soup in an open saucepan on a stove, energy and matter are being transferred to the surroundings through steam.
Putting a lid on the saucepan makes the saucepan a closed system. A closed system is a system that exchanges only energy with its surroundings, not matter. By putting a lid on the saucepan, matter can no longer transfer because the lid prevents matter from entering the saucepan and leaving the saucepan.
There are no truly closed systems, except for purely conceptual systems, e.g. the physicist’s imaginary box that is isolated from all outside influences.
Even a rock is subject to e.g. changes in temperature which cause it to expand and contract, the influence of water which slowly dissolves it, and the slow growth of lichen which slowly crumbles it’s surface.
All real systems are open systems which we often pretend are closed because we 1) want to understand the internal dynamics of the system or 2) want to understand the major external influences on those systems while ignoring the minor influences.
Let us take simple examples.
A closed system allows only energy transfer but no transfer of mass. Example: a cup of coffee with a lid on it, or a simple water bottle.
An open system is one which can allow mass as well as energy to flow through its boundaries, example: an open cup of coffee.
Isolated systems allow neither mass nor energy to flow through their boundaries. Example: a thermos flask.
In reality, a perfectly isolated system does not exist, for instance hot water in a thermos flask cannot remain hot forever.
Thus, structurally closed systems exist only conceptually; however, operationally closed systems do exist. Social systems are structurally open and operationally closed. To be structurally open means expectations (social structures are expectations) may be perturbed by the environment. Operational closure means that a social system only communicates with itself; there is no communication between system and environment.
For example, if a group of people are sitting together speaking Russian and I walk by, I (as a non-Russian speaker) am excluded from that social system. I exist in that system’s environment. As a social system, the system’s sole operation is communication. Only communication can produce new communication.
From the above example, you might think that the structure of social system consists or language, words, or communicative events. But communication is an operation, not a structure. The structures of a social system are expectations, or the sense of “what’s next.”