Casimir effect

American  

[kaz-uh-meer-i-fekt] / ˈkæz əˌmɪər ɪˌfɛkt /

noun

1. the effect produced by an attractive force (Casimir force) between objects in close proximity to each other, caused by a disparity in quantum vacuum fluctuations.

---

Casimir effect Scientific  

/ kăz′ə-mîr′ /

1. The effect of a net attractive force between objects in a vacuum, caused by quantum mechanical vacuum fluctuations creating radiation pressure. The radiation can be thought of as an atmosphere of virtual particles. The amount of radiation pressure on the objects is decreased in the gap between them, due to limits on the wavelength of the radiation in the gap. The gap is thus an area of lower radiation pressure, drawing the objects toward it. This force is strong enough to be of great importance at scales encountered in nanotechnology. The Casimir effect is named after Dutch physicist Hendrik Casimir (1909–2000).

---

Example Sentences

The attractive force, known as the Casimir effect, causes the gold flakes to draw closer together and toward the substrate.

From Science Daily • Oct. 23, 2025

One example is the Casimir effect, predicted by Dutch physicist Hendrik Casimir in 1948.

From Scientific American • Apr. 29, 2023

Now Calloni and his colleagues hope to use the Casimir effect to measure the energy of the void.

From Scientific American • Apr. 29, 2023

But “a missing signal could also be because there is no Casimir effect in cuprates, or it is very weak,” says experimental physicist Markus Aspelmeyer of the University of Vienna.

From Scientific American • Apr. 29, 2023

An example of how quantum theory can allow negative energy densities is provided by what is called the Casimir effect.

From "A Brief History of Time: And Other Essays" by Stephen Hawking