There are claims that LENR extracts energy from the vacuum. The question naturally arises about how can such an improbable thing possibly happen.
A experiment done using a optical cavity shows how the vacuum can tap into the vacuum fluctuations that occur in empty space to produce real effects.
Dynamical Casimir effect in a Josephson metamaterial
This experiment shows how an optical cavity can be tuned electrically using the KERR effect in such a way to convert virtual photons into real photons through the adjustment of the index of refraction of the vacuum in the cavity to produce a resonance based casimir effect.
The KERR effect is a mechanism to adjust the speed of light in the vacuum so that the cavity can be modified into a resonance condition in such a way as to use the casimir effect to extract real photons from the vacuum.
This KERR effect adjustment mechanism might be operable in LENR as well as the EMDRIVE.
The zero-point energy stored in the modes of an electromagnetic
cavity has experimentally detectable effects, giving rise to an
attractive interaction between the opposite walls, the static Casimir
effect. A dynamical version of this effect was predicted to occur
when the vacuum energy is changed either by moving the walls
of the cavity or by changing the index of refraction, resulting in
the conversion of vacuum fluctuations into real photons. Here, we
demonstrate the dynamical Casimir effect using a Josephson metamaterial
embedded in a microwave cavity at 5.4 GHz. We modulate
the effective length of the cavity by flux-biasing the metamaterial
based on superconducting quantum interference devices (SQUIDs),
which results in variation of a few percentage points in the speed
of light. We extract the full 4 × 4 covariancematrix of the emitted
microwave radiation, demonstrating that photons at frequencies
symmetrical with respect to half of the modulation frequency are
generated in pairs. At large detunings of the cavity from half of the
modulation frequency, we find power spectra that clearly show
the theoretically predicted hallmark of the Casimir effect: a bimodal,
“sparrow-tail” structure. The observed substantial photon
flux cannot be assigned to parametric amplification of thermal
fluctuations; its creation is a direct consequence of the noncommutativity
structure of quantum field theory.