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.

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