The Origin of the word Daemon

Professor Corbato

I write a trivia column for a newspaper called The Austin Chronicle. Someone has asked me the origin of the word daemon as it applies to computing. Best I can tell based on my research, the word was first used by people on your team at Project MAC using the IBM 7094 in 1963. The first daemon (an abbreviation for Disk And Executive MONitor) was a program that automatically made tape backups of the file system. Does this sound about right? Any corrections or additions? Thank you for your time!

From Fernando J. Corbato: Your explanation of the origin of the word daemon is correct in that my group began using the term around that time frame. However the acronym explanation is a new one on me. Our use of the word daemon was inspired by the Maxwell's daemon of physics and thermodynamics. (My background is Physics.) Maxwell's daemon was an imaginary agent which helped sort molecules of different speeds and worked tirelessly in the background. We fancifully began to use the word daemon to describe background processes which worked tirelessly to perform system chores. I found a very good explanation of all this online at:

http://www.takeourword.com/TOW129/page2.html (Search on "Maxwell" to locate the pertinent paragraph.)

To save you the trouble, I will cut-and-paste it right here. It comes from a web-column entitled "Take Our Word For It" run by Melanie and Mike Crowley, etymology enthusiasts!

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From Jan Danilo:

I am interested in the origin of the word daemon. I work in information technology and I have always heard of system processes referred to as daemons. I assumed that it is an older spelling of demon. Can you shed some light on this point?

Why certainly. Someone give us some of those phosphorescent genes that have recently been spliced to mice DNA and we'll shed light like mad. Demon and daemon were once used interchangeably. The former came to English from medieval Latin, while the latter was from classical Latin. The earliest use appears to have been in the phrase daemon of Socrates, which was his "attendant, ministering, or indwelling spirit; genius". That was in the late 14th century. It was a short time later that the term demon came to refer to "an evil spirit" by influence of its usage in various versions of the Bible. The Greek form was used to translate Hebrew words for "lords, idols" and "hairy ones (satyrs)". Wyclif translated it from Greek to English fiend or devil. This is how the evil connotation arose. By the late 16th century, the general supernatural meaning was being distinguished with the spelling daemon, while the evil meaning remained with demon. Today daemon can mean "a supernatural being of a nature intermediate between that of gods and men" or "a guiding spirit".

[Warning: This paragraph is about science so, if this topic causes you undue alarm, please close your eyes until you've finished reading it.] The 19th century scientist James Maxwell once daydreamed (the polite term is "thought experiment") about a problem in physics. He imagined a closed container which was divided in half. In the middle of the divider was a tiny gate, just large enough to admit one molecule of gas. This gate, in Maxwell's imagination, was operated by a tiny daemon. This daemon observed the speed (i.e. temperature) of the molecules heading for the gate and, depending on the speed, let them through. If he let only slow molecules pass from side A to side B and only fast molecules pass from side B to side A, then A would get hot while B cooled. Maxwell's daemon was only imaginary, of course, but as it seemed to evade the laws of thermodynamics it caused quite a stir. Eventually, though, the theory of quantum mechanics showed why it wouldn't work. [OK, you may open your eyes, now.]

As you probably know, the "system processes" called daemons monitor other tasks and perform predetermined actions depending on their behavior. This is so reminiscent of Maxwell's daemon watching his molecules that we can only assume that whoever dubbed these "system processes" had Maxwell's daemon in mind. Unfortunately, we have found no hard evidence to support this. [Now, of course, we have!]

We also assume that this is the meaning behind the daemon.co.uk, host to many United Kingdom web sites.

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Professor Jerome H. Saltzer, who also worked on Project MAC, confirms the Maxwell's demon explanation. He is currently working on pinpointing the origin of the erroneous acronym etymology for daemon in this sense. [We have edited Issue 129 to reflect this confirmation of our original assumption. Isn't it wonderful to be able to trace a word to its source so cleanly?]

From: http://www.takeourword.com/page4.html