Diskussion:Julian Bigelow

message: http://www.rheingold.com/texts/tft/5.html "During this wartime mathematical work related to radar-directed antiaircraft fire, Wiener recognized the fundamental relationship between two basic problems -- communication and control. The communication problem in the earliest days of radar was that the radar apparatus was like a badly tuned radio receiver. The true signal of attacking planes was often drowned out by false signals -- noise -- from other sources. Wiener recognized that this too was a kind of cryptography problem, if the location of the enemy aircraft is seen as a message that must somehow be decoded from the surrounding noise.
The noisy radar was more than an ordinary "interesting problem," because once you understand messages and noise in terms of order and information measured against disorder and uncertainty, and apply statistics to predict future messages, it becomes clear (to a mathematician of Wiener's stature) that the issue is related to the basic processes of order and disorder in the universe. Once it is seen in statistical and mathematical terms, the communication problem leads to the heart of something more important, called information theory. But that branch of the story belongs to Claude Shannon as much as, or more than, it does to Wiener.
The control problem was where Wiener, and his very young and appropriately brilliant assistant, an engineer by the name of Julian Bigelow, happened upon the general importance of feedback loops. Assuming that it is possible to feed information about a plane's path into the aiming apparatus of a gun, how can that information be used to predict the probable location of the plane? The use of statistics and probability theory was one clue. A method for predicting the end of a message based on information about the beginning was another clue. The device in Parkinson's dream was another clue.
Then it occurred to Wiener and Bigelow that the human organism had already solved the problem they were facing. How is any human being, or a chimpanzee for that matter, able to reach out a hand and pick up a pencil? How are people able to put one foot in front of the other, fall face-forward for a short distance, and end up taking a step? Both processes involve continuous, precise readjustments of muscles (the servomechanisms that move the gun), guided by continuous visual information (radar), controlled by a continuous process of predicting trajectories. The prediction and control take place in the nervous system (the control circuits of the animating automata).
Wiener and Bigelow looked more closely at other servomechanisms, including self-steering mechanisms as simple as thermostats, and concluded that feedback is the concept that connects the way brains, automatic artillery, steam engines, autopilots, and thermostats perform their functions. In each of those systems, some small part of the past output is fed back to the central processor as present input, in order to steer future output. Information about the distance from the hand to the pencil, as seen by the eye, is fed back to the muscles controlling the hand. Similarly, the position of the gun and the position of the target as sensed by radar are fed back to the automatic aiming device.
The MIT team had wondered whether someone more informed about neurophysiology had come across analogous mathematics of pencil pushing, with similar results. As it happened, there was another team that, like Wiener and Bigelow, was made up of one infant prodigy and one slightly older genius, by the names of Pitts and McCulloch respectively, who were coming down exactly the same trail from the other direction. A convergence of ideas that was both forced and fortuitous, related to but distinctly different from the convergence on digital computation, was taking place under the pressure of war." -- Kyber 22:45, 22. Jul 2006 (CEST)
thread_title: Erstmal geht´s ihnen um Kriegstechnik:

message: http://julian_bigelow.lexikona.de/art/Julian_Bigelow.html diese Seite hat mich stutzig gemacht, ein Wikipediaklon der Aktueller ist als Wikipedia selbst. --tox 00:00, 23. Jul 2006 (CEST)
replies: text: Damit ich ihn nicht wieder verliere: der Link zur gelöschten Version --Michael 10:53, 23. Jul 2006 (CEST)
thread_title: DDR-URV