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Just heard the discussion about the origins of "in the loop" that arose out of a question regarding whether the writers used it appropriately in a recent episode of Mad Men.
Grant suggested it came out the world of electronics and aviation, specifically discussions in the 1960s about keeping the pilot "in the loop" of the control circuitry of an aircraft or spacecraft. Mechanical, and later, electromechanical feedback loops have indeed been a part of autopilots from as early as the 1920s, but yet, to my knowledge, that specific phrase never gained currency.
I wonder if there's another influence at work that accounts for the phrase's emergence in the 1960s: computer programming. "If/then loops" (such as, "If A is true, then do X, if A is false, then do Y") are a central feature of computer programs and, in the 1960s, digital computers were rapidly becoming essential elements of aeronautical and aerospace engineering, affecting not only the design process but the systems actually installed in aircraft and spacecraft.
I was an avid follower of the space program and recall that the news media made a pretty big deal about the fact that the Mercury missions were controlled "by computer" because it was unknown how well chimps, and then humans, would function in a weightless environment. John Glen's flight was an especially notable test case because he had to be brought back into the control loop when doubts were raised about a safe computer-controlled re-entry because telemetry suggested his heat shield might be loose.
I don't think it's computer related. There is no reason to "keep" someone in an if/then loop. There is plenty of reason to keep someone in the control loop in an aircraft. While autopilots were around long before the 1960s, as the hosts pointed out, computer control, as opposed to just simple electromechanical/gyroscopic control of airplanes was very new in the 1960s. The autopilot does not completely control the airplane. It just maintains a set attitude (heading, altitude, bank angle). Computers can completely control aircraft, thus taking the human operator "out of the (control) loop".
Oops, my bad: the example I gave of an "If/then loop" was actually a branch. I was thinking more of an instruction that applies a test and, depending on the result, the test is either applied again -- the loop -- or the program moves on to another instruction (such as, Test A, If A = false, then repeat test, if A = true, go to...).
Regarding Butch's response, it seems to me he made my point for me but from a slightly different angle. If an airplane, say, is being completely controlled by a computer -- i.e. no pilot "in the loop" -- doesn't allowing a pilot to assume control require the computer to apply a test (such as, Override activated? Yes = allow manual control input, No = maintain computer control) and make a decision depending on the result? So, the computer programs running the show had to be programmed to allow the pilot to make control inputs if certain conditions were met. In my reading of aviation history I just don't recall the "in the loop" phraseology being used before the advent of the use of electronic digital computers.
In the transmission of July 8, 2011 there was mention of the phrase "Keep me in the loop" as originated in the aviation.
I think it may have an older origin, with the telegraph. Here is how:
If you have a battery and a light bulb, you need two wires to make the connection and light the bulb. You need a given amount of current to light the bulb. If you have two light bulbs in series (like in a christmas tree lights chain), the same current goes through one bulb, then into the other, and both bulbs light up. But you may have to increase the voltage of the battery (two batteries in series) to make it happen. When the telegraph come of age, there was a battery, a make/break contact (a wall switch) and in place of the light bulb there was an electromagnet to make the ink marks on a paper ribbon. It needed also two wires to connect the various parts : a loop.
The problem was that the wires, when long (like between towns), behave like another light bulb, and at times the battery was not of high enough voltage to activate the electromagnet (both light bulb-[wire and electromagnet] were too dim to be useful). Therefore the telegraph company set as a standard that the current in the loop was going to be 0.02 Ampere, since that was the amount of current needed to make a reliable ink mark. Then, since the amount of current would be the same everywhere in the loop, at the battery location the current would be measured, and the voltage produced by the battery was changed to ensure that the current would be the correct one. You did not need to know the length of the wire or anything else to ensure that the electromagnet would operate correctly. In this way the current loop was established.
Soon afterwards some operator begun to add a second electromagnet in series to the first (for example at a different location) : the battery voltage would automatically increase to ensure that the 0.02 Ampere current would not change. Both electromagnet would then be "In the loop" and both would record the same exact information.
I imagine that when this modus operandi became diffused, the saying "Keep me in the loop" as a meaning "Share the information with me" did originate, although I do not know when exactly may have happened first.
The 0.02 Ampere loop allowed the circuit to be independent on the batteries and wire lengths, and became to be used in all kind of industrial and aeronautical application, and it is still in use today.
Regards,
Luigi
Martha Barnette
Grant Barrett
Grant Barrett
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