Casimir effect

The Casimir effect quantum field theory is a physical quantum effect, which causes a force is applied to two parallel conductive plates under vacuum, which both compresses. The effect was predicted by Hendrik Casimir in 1948 and also named after him. In 1956 the experimental confirmation by Boris Derjaguin, II Abrikosova and Yevgeny M. Lifshitz in the Soviet Union and in 1958 by Marcus Sparnaay of the Philips Research Laboratories in Eindhoven.

• 5.1 Video

Van -der- Waals force

The Casimir effect is a van der Waals force between conducting plates. This point was made by R.L.Jaffe 2005. A clear illustration of the relationship with the vacuum energy was given in 2012 by J. Gugnon.

Simplified representation

This force can easily be calculated when it is assumed that the vacuum is a virtual room of particles, referred to as a vacuum fluctuation. Such particles may be a de Broglie wavelength assigned. The distance between the two plates must be a multiple of half the wavelength of the virtual particles. Outside of the panels, however, all possible wavelengths are present, there is an unlimited, continuous spectrum. This includes both the conditions that may occur within the plates, as well as those who do not are possible between the plates due to the boundary conditions.

Thus, outside of the plates, there is a continuum of virtual particles, while inside of the panels can result only a discrete number of particles, namely, meet the conditions of the facing plates. This results in a " photon pressure " from the outside of the plates.

The effect

Virtual particles, which are generated in the short term from the vacuum due to the energy spread may be outside the two panels any pulse

Accept (ie, exhibit a continuous spectrum ) with

• : Reduced Planck constant
• K = angular wave number.

Between the two plates, they have a discrete pulse spectrum. This is due to the boundary conditions to be satisfied by their equations of motion on the plates. This discrete pulse spectrum can be interpreted as standing waves between two plates. Thus, certain states of virtual particles are prohibited between the plates, which can be adopted outside. List of allowed virtual particles but reflects on the plates. Come from the outside more (allowed ) virtual particles as in the space between plates, and there is a pressure difference. This Casimir "Print " acts as a force on the boards of the respective area and presses them together. It is perfect for conducting plates in a vacuum:

With the sizes

• : Kreiszahl
• C: vacuum speed of light
• D: distance between the two plates.

According to this formula, the distance of 190 nm results in a pressure of 1 Pa, at 11 nm is reached 100 kPa (about 1 bar).

Quantitative measurements took Steve Lamoreaux ( Seattle, 1997) and Umar Mohideen and Anushree Roy ( Riverside, 1998) before.

2009 showed Alexej Weber of the University of Heidelberg and Holger Gies from the University of Jena, that the Casimir effect in tilted plates against each other properties shows; he strengthened, for example, with higher temperature of the surface.

The Casimir effect was further investigated in the Breakthrough Propulsion Physics Project of NASA. Since 2008, DARPA operates a research program that Casimir Effect Enhancement program.

Reverse Casimir effect

In 2007, physicist Ulf Leonhardt to have of the University of St Andrews theoretically predicted that it would be with the aid of metamaterial with a negative refractive index (refractive index ) is possible, the Casimir effect to reverse, so to achieve a rejection of the plates. This is called reverse or repulsive Casimir effect or quantum levitation. He was already in 1956 by Yevgeny M. Lifshitz and - been predicted in 2002 by Eyal Buks and Michael L. Roukes - after suitable metamaterials templates.

Scientists are studying the possibilities to make the Casimir effect in nanotechnology for micro systems available.