Definition of Casimir effect
: 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
Love words? You must — there are over 200,000 words in our free online dictionary, but you are looking for one that’s only in the Merriam-Webster Unabridged Dictionary.
Start your free trial today and get unlimited access to America's largest dictionary, with:
- More than 250,000 words that aren't in our free dictionary
- Expanded definitions, etymologies, and usage notes
- Advanced search features
- Ad free!
Origin and Etymology of casimir effect
after Hendrik B.G. Casimir †2000 Dutch physicist ◆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: 1988See Words from the same year
Seen and Heard
What made you want to look up Casimir effect? Please tell us where you read or heard it (including the quote, if possible).