Closed System – What is it, concept, examples and characteristics

We explain what a closed system is, its characteristics and various examples. Also, what are open and isolated systems.

system closed
A refrigeration system is closed even though it exchanges energy with the environment.

What is a closed system?

When we use the term closed system, we refer to a portion of the universe taken for study as something separate from the rest, that is, a system whose characteristic feature is not allowing free exchange with the environment. In other words, it is a system separated from the rest of the environment, closed in on itself: the opposite of open systems.

This approach to reality comes from the General Systems Theory, an interdisciplinary perspective that emerged in the mid-twentieth century, and applicable to the natural sciences and the social sciences alike. A totally closed system, that is, one that does not allow any type of exchange with the environment, is called an isolated system.

The idea of ​​a totally closed system is useful only as an abstraction: one can consider a system as closed in order to be able to focus on its internal elements, without taking into account the outside, as long as the functioning of the system allows it.

For that reason, in natural sciences such as physics, closed systems are those that only exchange energy (heat, for example) with the environment, and not matter. While in the social sciences, closed systems are those that enjoy a certain margin of autonomy, that is, that do not require a constant injection of resources from outside, or that do not allow the entry of foreign elements to it.

Characteristics of closed systems

Closed systems are characterized by the following:

  • They are clearly separated from the environment, either through barriers or separations, or simply because they have very clear boundaries between inside and outside. In any case, no significant element can cross these limits, neither from the inside out, nor vice versa.
  • In some cases may have energy exchange, but not freely and the entry of new resources from outside is not possible either.
  • They are, therefore, autonomous systems, which do not require anything that is not within the system itself. Therefore, your resources are limited.
  • Totally closed systems are called isolated and they exist only on a theoretical plane.

Examples of closed systems

In its various possible fields of application, the following cases are examples of a closed system:

  • From a philosophical point of view, there is no other closed system that the universe: what is in it is all that exists, therefore nothing enters or leaves its system (that we know, at least): there is no outside of the universe.
  • In thermodynamics, closed systems are considered to be those that only exchange energy, but not matter, with the environment. Such is the case, for example, of the gas that circulates in a cooling circuit (a refrigerator, for example), in which it is not possible for gas (matter) to escape, but energy (in the form of heat, usually at the back of the appliance).
  • In the business world, they are considered as closed organizations companies that do not have any type of dialogue or interference in their environment, limiting themselves to their own functions no matter where they are.
  • In computing, closed systems are considered to be those computer systems that do not allow the entry and exit of information, so they are not in connection with any other system. It is also common to use the term to refer to traditional software, as opposed to open source software, which allows users to intervene in its programming.

Open systems

isolated closed open system
Systems differ in their interaction with the environment.

Open systems, as we said at the beginning, are the complete opposite of closed ones. In them there are no limits or impediments that prevent the free movement of information between the inside and the outside, and therefore they are systems of infinite resources, but external, in constant connection with the environment.

Isolated systems

Isolated systems are a consideration of thermodynamic physics. They are called that because are too far removed from other systems to interact effectively with them. In other cases they have borders that restrict the exchange between the inside and the outside, as in the case of thermal insulators that prevent the loss of heat from a thermal container, in thermal winter clothing, or on the edges of a refrigerator.