Speed of light
The speed of light in vacuum, denoted c {\displaystyle c}
Variable speed of light in PV model
In Harold Puthoff's polarizable vacuum model (PV), the speed of light is not an absolute constant but varies with the local dielectric properties of the vacuum:
c (x) = c 0 K (x) {\displaystyle c(x)={\frac {c_{0}}{K(x)}}}
where K (x) {\displaystyle K(x)}
The PV model's key implication for exotic propulsion: if an advanced technology can decrease the local vacuum K {\displaystyle K}
Standard physics framing
In special relativity, the speed of light in vacuum, c = 299,792,458 m/s, is a universal constant — the same for all observers in all inertial frames. This constancy is the foundational postulate of SR and has been confirmed by every experimental test to extraordinary precision. In general relativity, the coordinate speed of light can vary in the presence of gravity — light slows down near massive objects (producing gravitational time dilation and gravitational lensing) — but the locally measured speed of light is always c for any freely falling observer.
Polarizable vacuum reformulation: detailed metric
In Puthoff's polarizable vacuum model (PV), the same physics is reexpressed in terms of the vacuum's dielectric properties. The vacuum is treated as a medium with variable permittivity ε = Kε₀ and permeability μ = Kμ₀, where K is a dimensionless dielectric function that varies with the local mass-energy distribution. Near a spherical mass M at distance r:
K (r) = exp (2 G M r c 0 2) ≈ 1 + 2 G M r c 0 2 + ⋯ {\displaystyle K(r)=\exp !\left({\frac {2GM}{rc_{0}^{2}}}\right)\approx 1+{\frac {2GM}{rc_{0}^{2}}}+\cdots }
All gravitational effects — light bending, time dilation, redshift, perihelion precession — emerge from this single function K(r). The PV model reproduces GR predictions in the weak-field limit.
Engineering implication
If gravity is equivalent to variations in the vacuum's dielectric constant, then a technology that can locally alter K would alter the local speed of light and thereby produce all gravitational effects artificially:
- Increase K → light slows → equivalent to creating a gravitational well (attraction)
- Decrease K → light speeds up → equivalent to antigravity (repulsion)
- Create a gradient in K → objects follow the gradient → equivalent to a gravitational force
"Faster than light" travel in this framework does not mean exceeding c in the local vacuum — it means engineering a region where K < 1, so the local c is higher than c₀. The craft never exceeds its local speed of light; the light itself is faster in that region. This is the PV interpretation of the Alcubierre drive.
Einstein's 1921 ether lecture
Albert Einstein himself, in his 1920 Leiden lecture published as Sidelights on Relativity (1922), stated: "According to the general theory of relativity, space is endowed with physical qualities; in this sense, therefore, there exists an ether." Einstein clarified that this ether is not a material medium like the luminiferous aether of the 19th century — it has no velocity, no mechanical properties — but it IS a physical entity with properties that vary from point to point and influence the behaviour of matter and light. This is precisely what the PV model formalises: a non-mechanical ether whose dielectric properties determine the local speed of light and thereby all gravitational phenomena.