Since the distance between the Zeeman sub-levels is a function of the magnetic field, this effect can be used to measure the magnetic field, e.g. that of the Sun and other stars or in laboratory plasmas.
Charley horse: Slang for a cramp in a muscle in the leg, usually caused by a strain or injury. A charley horse can last anywhere from a few seconds to over a quarter of an hour. It is not uncommon for one to recur before it finally resolves.
Charley horse. Dead leg redirects here; in engineering, a dead leg is a redundant length of pipe through which flow is impossible because one end is sealed. Charley horse is a popular colloquial term in Canada and the United States for painful involuntary spasms or cramps in the leg muscles, typically lasting anywhere from a few seconds to about a day.