### Stochastic Electrodynamics

Semi-classic stochastic electrodynamics has been well developed since 1960. It postulates that at a microscopic level, the vacuum is filled with numerous plane waves that extend in every direction. It further postulates that the waves come from the zero-point field (ZPF).

“Stochastic electrodynamics postulates that the ZPF is as real as any other radiation field. In such a view the existence of a real ZPF is as fundamental as the existence of the universe itself. The only difference between stochastic electrodynamics and ordinary classical physics is the single assumption of the presence of this all-pervasive, real ZPF, which happens to be an intrinsic part of the universe” (Haische et al. 1994).

### Zero-Point Energy

As mentioned before, quantum mechanics predicts the existence of zero-point energy. The Casimir effect and Lamb shift phenomena are evidences for the presence of ZPE. Additionally, the one-dimensional harmonic oscillator also argues in favor of its presence.

“The theory of electromagnetic radiation is quantized by treating each mode as an equivalent harmonic oscillator. From this analogy, every mode of the field must have hf/2 as its average minimum energy” (Haisch et al. 1994).

The phenomenon has been described in Singularity section. P. S. Wesson from the University of Waterloo, among other physicists, infers, “Search into zero-point physics is justified and should be supported” (Haisch et al. 1994).

At least on paper, it is possible to use ZPF to extract energy. In fact, Haisch and Rueda presented a paper to a NASA conference on spacecraft propulsion in 1997 suggesting the use of ZPF for future space drives (Haisch et al. 1994).

The following is the statement of researchers at the California Institute for Physics and Astrophysics about ZPF and stochastic electrodynamics:

In fact, two distinct views about it exist today. One justification for making such an assumption is that by adding the ZPF to classical physics many quantum phenomena can be derived without invoking the usual laws or logic of quantum mechanics. It is premature to claim that all quantum phenomena could be explained by stochastic electrodynamics (that is, classical physics plus the ZPF), but that claim may one day turn out to be the case. In that event, one would have to make a choice. One could accept the laws of classical physics as only partly true, with a wholly different set of quantum laws required to complete the laws of physics; that is essentially what is done in physics now. Or one could accept the laws of classical physics as the only necessary laws, provided they are supplemented by the presence of the ZPF. (Haisch et al. 1994)

There are outstanding issues regarding ZPE; for instance, if there is such a field in space-time, the gravitational effect must be enormous. Paul Wesson writes,

It is also claimed that if the ZPF really exists, it would be such an enormous source of gravitational force that the radius of curvature of the universe would be several orders of magnitude smaller than the nucleus of an atom.

Of course, this conflicts with everyday experience.The fallacy in the argument is that in the Sakharov-Puthoff model the ZPF as a whole would not itself gravitate. The gravitational force results from perturbations of the ZPF in the presence of matter. In the Sakharov-Puthoff model, then, the uniform ZPF is not a gravitational source and hence would not contribute to curving the universe. (Haisch et al. 1994)

The question is how can an energy field not exhibit gravitational force? In addition, this field must affect the electromagnetic radiation wavebands or other force fields. This effects has not been observed. (For more information about ZPF, please see Haische et al. 1994.) The zero point energy in a cubic meter of space has been estimated to be 10^{−9} Joules (Carroll 2006). However, both quantum electrodynamics (QED) and stochastic electrodynamics (SED) requires it to have a much larger value of 10^{113} Joules per cubic meter (Milonni 1994).

This is obviously wrong. How are we going to come up with a solution?

On the other hand, according to the equivalence principle, if the ZPF gives rise to the phenomenon of inertia, it must also generate the effect of gravity in some way.

### Quantum Vacuum Inertia Hypothesis

The quantum vacuum inertia hypothesis, mainly developed by California Institute for Physics and Astrophysics (CIPA), considers zero-point field (ZPF) to be virtual, because if it were real, it would require a certain cosmological effect that is not consistent with observations. The hypothesis speculates that the electromagnetic quantum vacuum (ZPF) contributes to the inertial mass of a matter. The nature of this effect is explained under the name Rindler flux (Calphysics Institute n.d.[a]). In the Rindler model, the resulting force is proportionate to acceleration.

### Rest Mass in the Quantum Vacuum Inertia Hypothesis (QVIH)

Since a particle continuously interacts with the ZPE fluctuations, it exhibits Brownian-like motion. In the CIPA interpretation, this is the origin for quantum foam. A tiny bit of the ZPE is diverted into kinetic energy. We call this vibration the Compton frequency, which the particle exhibits at rest. In the CIPA view, “One could think of a particle as a localized concentration of zero-point energy which gravitates and resists acceleration” (Calphysics Institute n.d.[b]).

### Inertia in QVIH

The inertial mass in the CIPA model is described as the effect of ZPE on accelerating objects. The accelerating objects interact with random electromagnetic waves of ZPE described above. The movement generates a drag force that is proportionate to acceleration. In CIPA view, this drag force is the origin of inertia and is called the acceleration-dependent drag force.

Therefore, in the CIPA model, when force is applied to an object, it prevents it from following its own trajectory. This is called inertia and is the origin of the notion of mass.