/g*-don'kn/ adj. Ungrounded; impractical; not
well-thought-out; untried; untested. `Gedanken' is a German word
for `thought'. A thought experiment is one you carry out in your
head. In physics, the term `gedanken experiment' is used to
refer to an experiment that is impractical to carry out, but useful
to consider because you can reason about it theoretically. (A
classic gedanken experiment of relativity theory involves thinking
about a man in an elevator accelerating through space.) Gedanken
experiments are very useful in physics, but you have to be careful.
It's too easy to idealize away some important aspect of the real
world in contructing your `apparatus'.
Among hackers, accordingly, the word has a pejorative connotation.
It is said of a project, especially one in artificial intelligence
research, that is written up in grand detail (typically as a Ph.D.
thesis) without ever being implemented to any great extent. Such a
project is usually perpetrated by people who aren't very good
hackers or find programming distasteful or are just in a hurry. A
`gedanken thesis' is usually marked by an obvious lack of
intuition about what is programmable and what is not, and about
what does and does not constitute a clear specification of an
algorithm. See also AI-complete