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July 14, 2008

Casimir force was reduced by 30 to 40%



Caption: A scanning electron micrograph, taken with an electron microscope, shows the comb-like structure of a metal plate at the center of newly published University of Florida research on quantum physics. UF physicists found that corrugating the plate reduced the Casimir force, a quantum force that draws together very close objects. The discovery could prove useful as tiny "microelectromechanical" systems -- so-called MEMS devices that are already used in a wide array of consumer products -- become so small they are affected by quantum forces. Credit: Yiliang Bao and Jie Zoue/University of Florida

The physicists radically altered the shape of the metal plates, corrugating them into evenly spaced trenches so that they resembled a kind of three-dimensional comb. They then compared the Casimir forces generated by these corrugated objects with those generated by standard plates, all also against a metal sphere. The finding could one day help reduce what MEMS engineers call "stiction" — when two very small, very close objects tend to stick together. Note: To clarify the huge potential of what can happen and is happening [A brief couple of sentences on why this is "holy crap" big]. The geometry of physical objects is effecting the frequency of virtual particle creations in vacuum. Vacuum characteristics are being engineered and manipulated.

Manipulating the casimir force using the shape of the microscale and nanoscale structures seems to indicate that active molecular nanotechnology structures would have far more control of the Casimir force. Towards the bottom of this article there is description and links to the theoretical and experimental efforts to utilize Casimir force manipulation for breakthrough space propulsion and energy generation. Being able to fully control the Casimir force to access Zero Point Energy could potentially be more powerful than nuclear fusion.

The Casimir force is the result of virtual particles. Seemingly empty space is not actually empty but contains virtual particles associated with fluctuating electromagnetic fields. These particles push the plates from both the inside and the outside. However, only virtual particles of shorter wavelengths — in the quantum world, particles exist simultaneously as waves — can fit into the space between the plates, so that the outward pressure is slightly smaller than the inward pressure. The result is the plates are forced together.

The result? "The force is smaller for the corrugated object but not as small as we anticipated," Chan said, adding that if corrugating the metal reduced its total area by half, the Casimir force was reduced by only 30 to 40 percent.

Chan said the experiment shows that it is not possible to simply add the force on the constituent solid parts of the plate — in this case, the tines — to arrive at the total force. Rather, he said, "the force actually depends on the geometry of the object."

"Until now, no significant or nontrivial corrections to the Casimir force due to boundary conditions have been observed experimentally," wrote Lamoreaux, now at Yale University, in a commentary accompanying publication of the paper.



FURTHER READING
Measurement of the Casimir Force between a Gold Sphere and a Silicon Surface with Nanoscale Trench Arrays is the article in fournal of Physical Review Letters.

We report measurements of the Casimir force between a gold sphere and a silicon surface with an array of nanoscale, rectangular corrugations using a micromechanical torsional oscillator. At distances between 150 and 500 nm, the measured force shows significant deviations from the pairwise additive formulism, demonstrating the strong dependence of the Casimir force on the shape of the interacting bodies. The observed deviation, however, is smaller than the calculated values for perfectly conducting surfaces, possibly due to the interplay between finite conductivity and geometry effects.


Harvard and University of California Mainstream Casimir researchers
Umar Mohideen, prof of physics at the University of California at Riverside, has been researching the Casimir force

The Capasso group at Harvard have also been working on manipulating the casimir force

The advance by the University of Florida gives hope and credibility to extreme technology that is possible with the ability to reduce or amplify or reverse the casimir force at will:

Interstellartech Corp: Trying to use Casimir force to extract power
Fabrizio Pinto published in the Journal of Physics A: Mathematical and Theoretical on Membrane actuation by Casimir force manipulation.

Fabrizio Pinto is part of Interstellar Tech corp has been looking into trying to trying to create an engine by making use of the Casimir force. No Casimir force-based engine cycle could be devised if one assumed a constant Casimir force.

Areas of emphasis are:

1. Casimir force modulation; [now demonstrated by the Univerisity of Florida]
2. Repulsive Casimir force; [Prof Ulf Leonhardt and Dr Thomas Philbin 2007 report]
3. Lateral Casimir force;
4. Casimir force amplification
5. Energy issues in relation to the quantum vacuum.

One can implement a Casimir system engine cycle to transform thermal or optical energy into mechanical or electrical energy.

The Interstellar Tech corp proposal for the Transvacer device. They describe a casimir force-based engine where zero-point energy is transformed into mechanical energy.

The critical concept at the core of our idealized Casimir engine is the well-established fact that, in the realistic case of a material that is not a perfect conductor, the magnitude of the Casimir force at any distance between the plates depends on the detailed optical properties of the boundaries. That is, any process that can alter the reflectivity of the material, also affects the value of the Casimir force at any distance.

Nasa study from 2004 on Casimir force Space Propulsion
A 57 page study of using "Study of Vacuum Energy Physics for Breakthrough Propulsion"

G. Jordan Maclay, Quantum Fields LLC, Wisconsin

Jay Hammer and Rod Clark, MEMS Optical, Inc. Alabama

Michael George, Yeong Kim, and Asit Kir, University of Alabama

4. Gedanken Vacuum Powered Spacecraft (on page 30)

A Gedanken spacecraft is described that is propelled by means of the dynamic Casimir effect, which describes the emission of real photons when a conducting surface is moved in the vacuum with a high acceleration. The maintenance of the required boundary conditions at the moving surface requires the emission of real photons, sometimes described as the excitation of the vacuum. The recoil momentum from the photon exerts a force on the surface, causing an acceleration. If one imagines the moving surface is attached to a spacecraft, then the spacecraft will experience a net acceleration. Thus we have a propellantless spacecraft. However, we do have to provide the energy to operate the vibrating mirror. In principle, it is possible to obtain this power from the quantum vacuum, and this possibility is explored. Unfortunately with the current understanding and materials, the acceleration due to the dynamic Casimir effect is very small, on the edge of measurability. One of the objectives in this paper is to demonstrate that some of the unique properties of the quantum vacuum may be utilized in a gedanken spacecraft. We have demonstrated that it is possible, in principal, to cause a spacecraft to accelerate due to the dissipative force an accelerated mirror experiences when photons are generated from the quantum vacuum.

Further we have shown that one could in principal utilize energy fromthe vacuum fluctuations to operate such a vibrating mirror assembly. The application of the dynamic Casimir effect and the static Casimir effect may be regarded as a proof of principal, with the hope that the proven feasibility will stimulate more practical approaches exploiting known or as yet unknown features of the quantum vacuum. A model gedanken spacecraft with a single vibrating mirror was proposed which showed a very unimpressive acceleration due to the dynamic Casimir effect of about 3x10−20m/ s2 with a very inefficient conversion of total energy expended into spacecraft kinetic energy. Employing a set of vibrating mirrors to form a parallel plate cavity increases the output by a factor of the finesse of the cavity, 10**10, yielding an acceleration per meter squared of plate area of about 3x10−10m/ s2 and a conversion efficiency of about 10−16. After 10 years at this acceleration, a one square meter spacecraft would be traveling at 0.1m/ s. Although these results are rather unimpressive, it is important to remember this is a proof of the principal, and to not take our conclusions regarding the final velocity in our simplified models too seriously. The choice of numerical parameters is a best guess based on current knowledge and can easily affect the final result by 5 orders of magnitude.


2006 paper cited by Calphysics reviewing Quantum Vacuum energy extraction
A 2006 review of carefully selected proposals for extracting energy from a quantum vacuum field

We review concepts that provide an experimental framework for exploring the possibility and limitations of accessing energy from the space vacuum environment. Quantum electrodynamics (QED) and stochastic electrodynamics (SED) are the theoretical approaches guiding this experimental investigation. This investigation explores the question of whether the quantum vacuum field contains useful energy that can be exploited for applications under the action of a catalyst, or cavity structure, so that energy conservation is not violated. This is similar to the same technical problem at about the same level of technology as that faced by early nuclear energy pioneers who searched for, and successfully discovered, the unique material structure that caused the release of nuclear energy via the neutron chain reaction.

Credentialed scientists interested in seriously pursuing a laboratory investigation of the vacuum ZPF should be forewarned that many of the claims being made in the non-peer-reviewed literature are fraught with pathological science, fraud, misinformation, disinformation, and spurious physics. This is the reason why the present authors were very selective about which ZPE extraction approaches to consider for our research program.

We identified six experiments that have the potential to extract useful energy from the vacuum. One of these, Forward’s Vacuum-Fluctuation Battery, was shown to be unsuitable for completing an engine cycle for pumping energy from the vacuum. The efficacy of the Mead and Nachamkin patent device has not yet been evaluated in the lab. However, four additional experimental concepts are potentially exploitable and we have selected those to pursue in a carefully guided theoretical and laboratory research program. The estimated power output from three of these concepts could under optimum conditions range from Watts to kiloWatts


2007 work: Reversing the casimir force with metamaterials
Prof Ulf Leonhardt and Dr Thomas Philbin report in the New Journal of Physics they can engineer the Casimir force to repel, rather than attact.

Prof Ulf Leonhardt page on leviation using Casimir forces

Quantum levitation by left-handed metamaterials

Left-handed metamaterials make perfect lenses that image classical electromagnetic fields with significantly higher resolution than the diffraction limit. Here, we consider the quantum physics of such devices. We show that the Casimir force of two conducting plates may turn from attraction to repulsion if a perfect lens is sandwiched between them. For optical left-handed metamaterials, this repulsive force of the quantum vacuum may levitate ultra-thin mirrors.


Random other Casimir and Zero point energy related
A page on the casimir force and zero point energy

Over 1000 papers related to casimir effects and forces at arxiv

2007 paper suggesting that the Casimir force is the result of surface plasmons and that manipulating surface plasmons would manipulate the Casimir force Metamaterials manipulate plasmons.

Zero point energy at wikipedia

Many fictional references including: The Zero-Point Energy Field Manipulator, or "gravity gun" is a fictional weapon from the video game Half-Life 2.

Stargate SG1 and Stargate Atlantis refer to Zero point modules.

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