Black box facts for kids

Imagine you have a mysterious gadget. You can press buttons or give it commands (these are its inputs), and it does something or gives you a result (these are its outputs). But you can't see what's happening inside! This mysterious gadget is called a black box.

In science, computers, and engineering, a black box is a system you only understand by its inputs and outputs. You don't need to know how it works internally. Think of a remote control: you press a button (input), and the TV changes channels (output). You don't need to know the tiny circuits inside the remote.

The opposite of a black box is a white box (or "clear box"). With a white box, you can see and understand all its inner parts and how they work.

History of the Idea

A black box model can be used to describe the outputs of systems.

The idea of a "black box" became common in English around 1945. Scientists and engineers started thinking of complex systems this way.

One important person was Wilhelm Cauer. He worked with electronic circuits in the 1940s. He showed how to understand circuits by their inputs and outputs, even if you didn't know every tiny detail inside.

Later, in the 1950s and 60s, scientists like Ross Ashby and Norbert Wiener used the black box idea in a field called cybernetics. This field studies how systems control themselves and communicate. They saw the human brain, for example, as a black box because we don't fully understand its inner workings, but we can observe its inputs (what we see, hear, feel) and outputs (our actions, thoughts).

How Black Boxes Work

The open systems theory is the foundation of black box theory. Both focus on input and output flows, showing exchanges with the surroundings.

In systems theory, a black box is like a sealed container. You can only see what goes in and what comes out. You don't care about its internal structure.

Think of it this way:

• Input: What you put into the box or what affects it.
• Output: What the box does or produces in response.

The main idea is that there's a causal relation (cause and effect) between the input and the output. The input makes the output happen. You can't open the box, but you can still learn a lot by watching its behavior.

Watching and Learning

To understand a black box, you watch it over time. You record what inputs you give it and what outputs it produces.

For example, imagine you found a strange box from a flying saucer:

By collecting many observations like this, you can start to guess how the box works. If you can also control the inputs, you can do experiments. This helps you test your ideas about what causes what.

Making a Model

After observing a black box for a while, you can try to create a mathematical model. This is like building a set of rules or equations that predict what the box will do. You use the data you've collected to build this model.

Testing Your Model

Once you have a model, you need to test it. This is called black-box testing. You give the model new inputs and see if its predicted outputs match what the real black box actually does. If they match, your model is good!

Other Ways of Thinking About Black Boxes

The observed hydrograph shows how a watershed (a black box) responds with runoff (red) to rainfall (blue).

The "black box" idea isn't just for machines. It can be used in many areas where we only see the outside behavior of something. For example, Isaac Newton's theory of gravity describes how objects attract each other, but it doesn't explain why they do. In that sense, it's a "black box" theory.

In Human Studies

In fields like philosophy and psychology, the black box idea helps us understand human behavior. For example, when studying how people decide what to buy (consumer behavior), we might look at what influences them (inputs) and what they buy (outputs). We don't always know exactly what goes on in their minds, so the mind acts like a black box.

As Ross Ashby explained:

The child who tries to open a door has to manipulate the handle (the input) so as to produce the desired movement at the latch (the output); and he has to learn how to control the one by the other without being able to see the internal mechanism that links them. In our daily lives we are confronted at every turn with systems whose internal mechanisms are not fully open to inspection, and which must be treated by the methods appropriate to the Black Box.

Another example is how doctors treat patients. The human brain is a very complex black box. While scientists study how the brain works, doctors also make progress by observing how patients respond to treatments (inputs) and how their health changes (outputs).

Where Black Boxes Are Used

When an observer (an agent) can also give a stimulus (input), the relationship with the black box is not just observation, but an experiment.

Computers and Math

• In computer programming, black box testing is a way to check if a program works correctly. Testers give the program inputs and check the outputs, without looking at the program's code.
• A "black box program" is software you use without seeing its inner workings. Many apps on your phone are like this. You don't see the code, but you know what they do.
• Sometimes, a company gives you a piece of equipment to use their product. This equipment might be called a "black box" because the company manages it, and you don't need to know how it works inside.

Science and Technology

• In physics, a black box is a system whose internal structure isn't known or doesn't need to be considered for a specific purpose.
• In neural networks (which are like "learning" computer programs), a black box can describe parts of the program that are constantly changing and hard for programmers to test directly.

Other Uses

• In philosophy and psychology, the idea of behaviorism treats the human mind as a black box. It focuses on observable behaviors (outputs) in response to stimuli (inputs).

See also

In Spanish: Caja negra (sistemas) para niños