Resistance is like friction: a simple dissipative force that turns organized motion into heat. Extend the concept of resistance into the world of complex numbers, so that in addition to slowing down, a flow can also be turned aside (metaphorically speaking). That's impedance.
When a signal goes from one medium to another, like light going from air into glass, part of the wave makes it and part gets reflected. The relative impedance of the two media govern that process. If we're clever, we can match impedances and avoid reflective losses at the interface. For light, thin coatings on a surface can do the trick (e.g., look closely at the lenses on a good camera). For electrical signals, transformers match impedances between circuits.
For people and their conversations, impedance is a useful concept too! Some folks are quick in one subject but slow in another. They don't communicate well with somebody who has a different set of abilities. A conscious impedance-matcher — a person who can translate from, say, the language of art to that of science — can help a message get through. (But when there's enough resistance, alas, no amount of transformation can prevent serious loss of signal!)
Wednesday, December 22, 1999 at 06:34:48 (EST) = 1999-12-22
(correlates: CarnotCycle, PaintingVersusWriting, TiltTheoryOfHistory, ...)