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What is Black Box

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What is Black Box?

In this tutorial of the black box, we are going to learn about the different aspects of the term black box in different fields of the life. The use of the black box , its history and the ways it is being used in different fields.

A black box is a computer, system, or entity in science, computing, or engineering that can be interpreted solely in terms of its inputs and outputs (or transfer characteristics), with no knowledge of its internal workings. It is implemented in a “opaque” manner (black). A transistor, an engine, an algorithm, the human brain, an organisation, or the government are all examples of black boxes.

In a standard “black box” approach to analyzing anything modeled as an open structure, only the stimulus/response behavior is accounted for in order to infer the (unknown) box.

A white box (also known as a “simple box” or a “glass box”) is the polar opposite of a black box, as it allows inspection of the inner components or logic.


About 1945, the current sense of the word “black box” appeared in the English language.

The process of network synthesis from transfer functions in electronic circuit theory can be traced back to Wilhelm Cauer, who published his ideas in their most refined form in 1941, and led to electronic circuits being known as “black boxes” defined by their response to signals applied to their ports.

While Cauer did not coin the word, it was definitely used by those who followed him to characterize the procedure. Vitold Belevitch] dates the idea of black-boxes much further back, claiming that Franz Breisig was the first to explicitly treat two-port networks as black boxes in 1921, and that 2-terminal components were indirectly regarded as black-boxes before that.

Ross Ashby gave a comprehensive treatment of cybernetics in 1956. Norbert Wiener described a black box in 1961 as an unknown device that needed to be identified using system identification techniques. He saw the ability to copy the performance actions of a black box as the first step toward self-organization.

System theory

The black box is an abstraction in systems theory that represents a class of concrete open systems that can be interpreted exclusively in terms of their stimuli inputs and output reactions:

The box’s composition and construction have no bearing on the solution being considered, which is merely external or phenomenological.

The “explanatory theory,” or the hypothesis of a causal relationship between the input and the output, is used to explain a black box. This theory states that the system’s inputs and outputs are distinct, that the system’s inputs and outputs are measurable (and relatable), and that the system appears black to the observer (non-openable).

Recording of observed states

As a result, any system is fundamentally investigated by compiling a long protocol that is drawn out in time and depicts the sequence of input and output states.

When the observer also controls the data, the inquiry becomes an experiment (illustration), and cause-and-effect theories may be directly checked.

There is active feedback in the box/observer relationship while the experimenter is also driven to manipulate the box, supporting what is known as a feed forward architecture in control theory.

When black-box testing methods ensure that an established black box model is validated, it is focused solely on measurable elements.

When backtesting a black box model, it is always done with out-of-time data. Until data can be pulled for black box input, it must first be written down.

Other theories

Things that are only described in terms of their function are referred to as black box theories. The word “black box theory” refers to any area, including philosophy and science, where some inquiry or concept is made into the relationships between a thing’s appearance (exterior/outside), i.e. the thing’s black box state, and its characteristics and behavior inside (interior/inner).

The investigation is based on a thing that has no readily evident characteristics and therefore has only internal variables to consider that are shielded from immediate observation. Since the bulk of available data is held in an inner situation away from easy inquiries, the observer is believed to be unaware at first.

The black box aspect of the concept is defined as a system in which observable elements enter a possibly imaginary box, from which a collection of different observable outputs emerge.

In our everyday lives, we are constantly faced with structures whose internal processes are not completely open to inspection and must be handled using Black Box methods.

- Ashby

This basic rule proved to be very successful, and it exemplifies how the Black Box theory in cybernetics can be used to manage situations that appear to be very complex when examined in depth.

The human brain is unquestionably a Black Box, and although much neurological study is being conducted to better understand how the brain works, progress in care is also being made by studying patients’ reactions to stimuli.

- Duckworth, Gear and Lockett

The applications

  • Black box testing is used in computer programming and software engineering to ensure that a program’s performance is as intended given those inputs. Since the actual program being executed is not checked, the expression “black box” is used.
  • A black box in physics is a device whose internal configuration is unclear or does not need to be considered for a specific reason.

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