The Casimir effect, responsible for the attraction of two neutral metallic plates separated 1 micron apart, is one of the most outstanding features of the vacuum influence on the macroscopic world, and has been discussed in former articles
. The effect has been measured in a variety of experimental setups, but this is the first time its associated torque has been verified experimentally. The so-called Casimir torque, predicted more than 40 years ago, is a mechanical torque between two optically anisotropic materials, and depends on the electromagnetic fluctuations (EM) of the vacuum -known as vacuum fluctuations- as well as on the dielectric function of the materials, which describes the capacity of an internal charge reorganization property within the material. Optically anisotropic means that the refractive index of the material depends on the polarization and propagation direction of the electromagnetic field. Materials obeying this condition are named birefringent.
When the materials are optically anisotropic, different polarizations of light experience different refractive indices and a torque is expected to occur that causes the materials to rotate to a position of minimum energy
The charge reorganization, also known as polarizability, allows a material to respond to the EM fluctuations with small but sufficient strength to spin mechanically and align to the source of polarization. Through the choice of the materials, researchers at the University of Maryland achieved control over the direction -or sign- of the torque, its strength, and its dependence on the rotation angle and the separation distance between the materials.
Fig 1: The experimental setup used in this research. The solid birefringent crystal (calcite, lithium niobite, rutile or yttrium vanadate) and a liquid crystal (5CB) Credits: Nature https://doi.org/10.1038/s41586-018-0777-8
The interaction through vacuum fluctuations is commonly associated to phenomena such as intramolecular and adhesive forces, Casimir effect, among others. The applications range from atomic and nanoscopic manipulations, up to the controversial impossible drive (see our detailed article here
These results published in Nature are of ultimate importance as they can be directly related to the Planck field using the holo-fractographic model (HFM) derived by N. Haramein. In the HFM, the vacuum is composed of Planck Voxels -referred to as Planck Spherical Units (PSU)- which are vortexes at the Planck scale, moving coherently creating a collective effect that can induce a torque arising from angular-momentum transfer from the vortexes to the birefringent plates.
By: Ines Urdaneta, RSF Research Scientist
Frontal Image Credit: APS/Alan Stonebraker