Quantum Defined
Book cover for Textus de Sphera Johannis de Sacrobosco: cum Additione (Quantum Necessarium est) Adiecta.
Photo credit: Florian Carle
"Quantum" originates from Latin as a determination of quantity according to the Oxford English Dictionary. An astronomy textbook written in Latin from 1511 in the collection of the Beinecke Rare Book and Manuscript Library includes quantum in its title, Textus de Sphera Johannis de Sacrobosco: cum Additione (Quantum Necessarium est) Adiecta. One of the earliest English meanings of quantum (1567) goes back to philosophy for “Something that has quantity.” One of the earliest scientific uses of the term was in physics as “The quantity of electric fluid present in an electrically neutral body” (1870). In 1910, a new meaning in physics prevailed, “A minimum amount of a physical quantity which can exist, and in multiples of which it can vary.” In 1952, there was use of quanta (singular of quantum) in physiology as in “a small voltage of which integral multiples go to make up the end-plate potential measured at a neuromuscular junction.”
Now quantum can be found used in computing, energy, physics electronics, chemistry, chromodynamics, cryptography, mechanics, electrodynamics, gravity, and more. A current definition from physics and as a noun is “A discrete quantity of electromagnetic energy proportional in magnitude to the frequency of the radiation it represents, such that energy of that frequency may only be transmitted in multiples of the quantity.” (OED, 2021).
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