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the temperature is too hot, the strip straightens, the circuit is broken, and the
heating goes off. Nowadays, sensitive temperature sensors have replaced most
metal thermostats, but the principle of how they control the heating system
using feedback from the environment remains the same.
Wiener argued that although the physical sciences had been the dominant
sciences of the past, the future would be more concerned with communication
and control, and he believed that the computer would play a major role in such a
future. He called his new science cybernetics from the Greek word kybernetes , mean-
ing steersman . Wiener used the name to refer to the control of complex systems,
but the prefix cyber- has acquired a variety of computer-related meanings. For
example, we now talk about cyberspace , meaning the online world of computer
networks, and cyberwarfare , for attacks on an enemy's information systems.
Scientists at a neurophysiology meeting in New York in 1942 took the first
steps toward defining the field of artificial intelligence (AI). Wiener, with his col-
leagues Julian Bigelow and Arturo Rosenblueth, argued that an animal's nervous
system could be thought of in engineering terms as a complicated network of
neurons , the cells in the brain that process information, with feedback loops. They
suggested we can think of computing systems in biological terms in the same
way. It was through feedback, they concluded, that an engineering system could
have a “definite purpose.” This discussion marked the beginning of the fields of AI
and cognitive science - the study of thinking, learning, and intelligence - although
these terms were not introduced until more than a decade later. Cognitive sci-
ence is now seen as bringing together computer modeling, neurophysiology, and
psychology to try to understand how the human mind works.
Wiener and von Neumann were not the only ones thinking about the pos-
sibility of AI. In 1941, during World War II, Alan Turing had been exploring
ideas about what he called “machine intelligence.” Turing had helped design
the bombe , a mechanical device used in the British code-breaking center at
Bletchley Park to decrypt secret messages generated by the German Enigma
machine. The bombe had demonstrated the value of performing “guided
searches” to save time by reducing a large range of possible solutions to a man-
ageable number. Turing and his fellow code breaker Donald Michie ( B.13.2 )
had many discussions about how similar ideas could be used to create a com-
puter chess program. In 1950, in his famous paper “Computing Machinery and
Intelligence,” he introduces the idea of what is now known as the Turing Test .
In the Turing Test, if a human being cannot consistently tell whether questions
are being answered by a computer or by another human being, then the com-
puter has passed the test. In his paper, Turing considered the question “Can
machines think?” He proposed replacing this question by another, more prac-
tical question based on what he called the imitation game . The essence of the
game is that there are three people in different rooms - a man A, a woman
B, and an interrogator C. The three people can communicate only by sending
typewritten messages. The object of the game is for the interrogator C to deter-
mine whether A or B is the woman by asking questions of each of them. Turing
now asks the question:
Electrical contact
Electrical contact
Fig. 13.1. Bimetallic thermostat made
from iron (blue) and copper (orange). In
cold, the copper contracts more and it
bends the bimetal strip downward.
B.13.2. Donald Michie (1923-2007)
worked in the British code-breaking
center at Bletchley Park during
World War II. He was one of the
pioneers of AI in the U.K. computer
science research community.
“What will happen when a machine takes the part of A in this game?” Will
the interrogator decide wrongly as often when the game is played like this
 
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