Cybernetics

Cybernetics

Cybernetics is the study of the communication and control processes of both living and artificial systems in order to understand the similarities and the differences between the two. The behavior of living nervous systems has been studied by biologists and cyberneticists in detail, and efforts to develop equivalent electronic systems have been based on these studies.

The term cybernetics is derived from the ancient Greek word for the craft of steering ships, kybernetikos. Two of the main branches of cybernetics are artificial intelligence and robotics. The American mathematician and social philosopher Norbert Wiener (1894-1964), generally considered the founder of modern cybernetics, first applied the word in 1948 to the theory of control mechanisms in his book Cybernetics: or, Control and Communication in the Animal and the Machine. Wiener explicitly related cybernetics to both the theory of automatic control and to the physiology of the nervous system. The birth of cybernetics as an independent field of study is generally dated to Wiener's 1948 publication.

Computer science and related areas of mathematics have been a strong influence on cybernetics because the computer can be used not only for pure calculation but also for the conversion of information from one form to another, including those forms used in control systems or robotic devices. This dual capacity of the computer--pure calculation and interface between action and calculation--has given rise to two distinct views of cybernetics. The viewpoint common in the Western hemisphere has emphasized cybernetics as the science of the control of complex systems of various types, with concentration given to control systems modeled on living organisms. Computer science and cybernetics have developed, for the most part, in under the guidance of this view. A more general view of cybernetics developed in Europe, particularly Russia and the other former Soviet republics, and included not only control, but all types of information processing.

Cybernetics (in the Western sense) has developed through the investigation of the techniques, natural and artificial, by which pure information is transformed into desired physical performance. Even before Wiener coined the word "cybernetics" his field was being advanced by the challenges of World War II, especially in the development of calculating devices (then often called "electronic brains") and of automatic control mechanisms such as bomb-sights, antiaircraft aiming devices, and simple robots.

Cybernetics researchers develop models of systems in which a monitor (human or machine) compares what is happening in a physical process at a certain time with some standard of what should be happening. The difference (or error) between what should be happening and what is happening is fed back to a device controlling some aspect of the physical process in an effort to reduce the error. This self-correcting loop connecting action to calculation is called a "feedback loop." For example, the controller in the loop could be a human brain receiving visual signals from the eyes (the "monitor") about the spatial relationship between a reaching hand and an object to be picked up. Understanding the rules of control by which this very successful living system functions can aid in constructing artificial limbs or purely robotic systems for use in manufacturing. This topic was indeed part of the earliest work in cybernetics.

One of the basic principles of cybernetics is that information is statistical in nature. The American mathematician and engineer Claude Shannon (1916-2001), often considered the "father" of the information sciences, elucidated the nature of information, thus founding the field of study known as information theory. In Shannon's cybernetic methodology, errors are analyzed to reveal their inherent patterns or characteristic modes of behavior, which can then be taken into precise account by the control system. Shannon called his measure of informational variety entropy, a concept closely related to the thermodynamic measure of entropy. According to the principles of cybernetics, any spontaneous state of increased order (lower entropy) is less probable and any spontaneous state of chaos (higher entropy) is more probable. Orderly machine behavior therefore requires control mechanisms--cybernetic systems--that maintain order (keep entropy down) by counteracting the natural tendency of all systems toward disorganization. It must be noted that the entropy principle applies only to all self-contained systems: matter on Earth can become spontaneously more orderly (e.g., evolve the nervous systems studied by cybernetics) because the entropy of the Sun, from which the Earth is not isolated, is continually increasing.