An important concept in systems, and also ‘post-pandemic’What’s Hysteresis?
Webster’s Seventh New Collegiate Dictionary tells us:hys-ter-e-sis:n [NL, fr. Gk hysteresis shortcoming, fr. hysterein to be late, fall short, fr. hysteros later]
a retardation of the effect when the forces acting upon a body are changed (as if from viscosity or internal friction); esp: a lagging in the values of resulting magnetization in a magnetic material (as iron) due to a changing magnetizing force. –hys-ter-et-ic adjThere seems to be no etymological link between hysteresis and either hysterical (fr. L hystericus of the womb) or history (fr. Gk, inquiry, history, fr. histor, istor knowing, learned). This is too bad, as there are scientific connections to both words. (There is no link, scientific or etymological, to histolysis, the breakdown of bodily tissues, or to blood.)
Hysteresis represent the history dependence of physical systems. If you push on something, it will yield: when you release, does it spring back completely? If it doesn’t, it is exhibiting hysteresis, in some broad sense. The term is most commonly applied, as Webster implies, to magnetic materials: as the external field with the signal from the microphone is turned off, the little magnetic domains in the tape don’t return to their original configuration (by design, otherwise your record of the music would disappear!) Hysteresis happens in lots of other systems: if you place a large force on your fork while cutting a tough piece of meat, it doesn’t always return to its original shape: the shape of the fork depends on its history.