Casimir effect

noun

Cas·​i·​mir effect

ˈka-zə-ˌmir-

physics

: an attractive force created by the net action of virtual photons on physical objects in close proximity

Although no one has yet seen negative matter or negative energy in the wild, it has been detected in the laboratory, in the form of something called the Casimir effect. Consider two uncharged, parallel plates. Theoretically, the force between them should be zero. But if they are placed only a few atoms apart, then the space between them is not enough for some quantum fluctuations to occur. As a result, the number of quantum fluctuations in the region around the plates is greater than in the space between. This differential creates a net force that pushes the two plates together.

—Michio Kaku, Discover, December 2004

Word History

Etymology

after Hendrik B.G. Casimir †2000 Dutch physicist

Note: The initial report on the effect was published by Casimir in "On the attraction between two perfectly conducting plates," Proceedings van de Koninklijke Nederlandse Academie van Wetenschappen, vol. B51 (1948), pp. 793-95.

First Known Use

1988, in the meaning defined above

The Ultimate Dictionary Awaits

Expand your vocabulary and dive deeper into language with Merriam-Webster Unabridged.

1. Expanded definitions
2. Detailed etymologies
3. Advanced search tools
4. All ad-free

Discover what makes Merriam-Webster Unabridged the essential choice for true word lovers.

Start Your Free Trial Now

Rhymes for Casimir effect

• affect
• aspect
• bedecked
• bisect
• collect
• connect
• correct
• deflect
• detect
• direct
• dissect
• eject