A Quantum Leap Is Actually Very Small
A quantum is the smallest possible amount of something. The popular phrase quantum leap means a huge change, which reverses the physics.
A quantum is the smallest discrete amount of a physical quantity. Which makes *quantum leap* a splendid misunderstanding. In physics a quantum jump is the smallest possible change of state, not the largest; in ordinary English the phrase means a huge advance. Both uses are now established, and only one of them is right.
- The smallest discrete amount. *A quantum of energy.*
- A share or portion. *The quantum of damages.*
- Quantum leap — a sudden large change (informal). *A quantum leap in performance.*
Word forms
| Form | Word | Example |
|---|---|---|
| Noun | quantum | A single quantum. |
| Plural | quanta | Discrete quanta. |
| Adjective | quantum | Quantum mechanics. |
| Related | quantity | A large quantity. |
| Related | quantify | Hard to quantify. |
How it is used in a sentence
- Light comes in quanta called photons.Physics.
- The court assessed the quantum of damages.Law: the amount.
- They promised a quantum leap in speed.Marketing, and technically backwards.
Quantum terms
- Photon — a quantum of light
- Superposition — being in several states at once until measured
- Entanglement — linked particles whose measurements correlate
- Uncertainty principle — limits on knowing certain pairs of properties
- Quantum computing — computation using quantum states
From Latin *quantum*, how much, the neuter of *quantus*. Max Planck used it in 1900 for the discrete packets of energy that started quantum theory.
Is *quantum leap* wrong?
It reverses the physics, where a quantum jump is the smallest possible change. In general English it is established and understood as a large advance.
What is the plural?
Quanta, following the Latin. Quantums is occasionally seen in legal writing about amounts.