Itay Griniasty, Department of Physics of Complex Systems, Weizmann Institute of Science

Host: James Sethna

Vacuum Fluctuation Effects and the Organization of Wave Noise in Space Time
The case of the Casimir and Unruh effects

In the Unruh effect an accelerated observer perceives the quantum vacuum as thermal radiation. I will discuss the Unruh effect’s classical roots. Although noise like the vacuum noise is random in space, it is organised in space-time, because it is carried by waves. We show that the organisation of wave noise creates the Unruh effect. I will describe a simple experiment with water waves where we see the first indications of a Planck spectrum in the correlation energy, that comprise a first experimental observation of the Unruh effect.

In the Casimir effect, boundaries famously affect the electromagnetic ground state energy and bring about forces between macroscopic objects. Current theory is able to predict the Casimir force between macroscopic bodies with an accuracy only limited by the knowledge of the material parameters. Yet surprisingly after almost 70 years of research, while theory describes the Casimir force between bodies, the force inside bodies is poorly understood. I will show that the Casimir stress inside inhomogeneous planar media can be found by analysing the propagation of electromagnetic waves in the medium. Our theory predicts a characteristic power law for the Casimir stress inside soft walls, a common model for boundaries, where the refractive index is continuous but its derivative jumps. These results show that such edges are not tolerated in the aggregation of fluids at surfaces.

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