Varying physical 'constants'

Varying the electric (permittivity), magnetic (permeability) of free space

These propose varying permittivity ε and permeability μ equally, while keeping impedance √(μ/ε) constant, but hence varying speed of light c=1/√(με)

H. Puthoff (1999) Polarizable-Vacuum (PV) representation of general relativity (copy)

Standard pedagogy treats topics in general relativity (GR) in terms of tensor formulations in curved space-time. Although mathematically straightforward, the curved space-time approach can seem abstruse to beginning students due to the degree of mathematical sophistication required. As a heuristic tool to provide insight into what is meant by a curved metric, we present a polarizable-vacuum (PV) representation of GR derived from a model by Dicke and related to the "THε?" formalism used in comparative studies of gravitational theories.

H. Puthoff (2002) Polarizable-Vacuum (PV) Approach to General Relativity, Foundations of Physics, 32, pp 927-943 (src, draft, copy)

Standard pedagogy treats topics in general relativity (GR) in terms of tensor formulations in curved space-time. An alternative approach based on treating the vacuum as a polarizable medium is presented here. The polarizable vacuum (PV) approach to GR, derived from a model by Dicke and related to the "THμε" formalism used in comparative studies of gravitational theories, provides additional insight into what is meant by a curved metric. While reproducing the results predicted by GR for standard (weak-field) astrophysical conditions, for strong fields a divergence of predictions in the two formalisms (GR vs. PV) provides fertile ground for both laboratory and astrophysical tests to compare the two approaches.

H. Puthoff and S.A. Little (2012) Engineering the Zero-Point Field and Polarizable Vacuum For Interstellar Flight (copy)

A theme that has come to the fore in advanced planning for long-range space exploration is the concept of "propellantless propulsion" or "field propulsion." One version of this concept involves the projected possibility that empty space itself (the quantum vacuum, or space-time metric) might be manipulated so as to provide energy/thrust for future space vehicles. Although such a proposal has a certain science-fiction quality about it, modern theory describes the vacuum as a polarizable medium that sustains energetic quantum fluctuations. Thus the possibility that matter/vacuum interactions might be engineered for space-flight applications is not a priori ruled out, although certain constraints need to be acknowledged. The structure and implications of such a far-reaching hypothesis are considered herein.

Varying permittivity and permeability, while keep speed of light constant.

I. Thompson (2021) How the Non-Physical Influences Physics and Physiology: a proposal, Dualism Review, Vol 3, pp 1-21 (src, copy)

The causal closure of the physical world is assumed everywhere in physics but has little empirical support within living organisms. For the spiritual to have effects in nature, and make a difference there, the laws of physical nature would have to be modified or extended. I propose that the renormalized parameters of quantum field theory (masses and charges) are available to be varied locally in order to achieve ends in nature. This is not adding extra forces to nature but rescaling the forces which already exist. We separate metric time in 4 dimensions from process time as the order of actualization of potentialities. This is to allow iterative forward and reverse steps in metric time to influence intermediate variations in the vacuum permittivities to move charged bodies towards achieve specific targets at a later time. Then mental or spiritual influx could have effects in nature, and these should be measurable in biophysics experiments. With this proposal, we see after some centuries how 'final causes' could once again be seen active in nature.

Varying the effective speed of light c with metamaterials

J. Sarfatti (2022) Is Low Power Warp Drive Possible? Breaking the Space-Time Stiffness Barrier (copy, slides)

All conventional forms of spacecraft propulsion are unlikely to motivate large-scale private capital because the time scales for interstellar travel even to the nearest exo-planet are simply too long for practical commerce, the habitat problems are likely to be too difficult, and the cost in our declining world economy on the brink of financial if not environmental collapse in 2011 appear to be too great. Recent discoveries in the slowing of the speed of light in Bose-Einstein condensates and the negative electric permittivity and magnetic permeability in metamaterials suggests a low power speculative possibility for warp drive based on Einstein's orthodox field equation for gravity coupled to the electromagnetic field. Suppose we can slow down the speed of light to 3 cm/sec keeping the magnetic response χ_B close to 1 with an anti-gravitating non-propagating negative near-field low frequency negative dielectric response susceptibility χ_E . Therefore, since c scales as the inverse square root of χ_E yielding a dimensionless amplification of the repulsive anti-gravity field of perhaps as much as order of the cube of χ_E ~ 10⁶⁰. This would break the space-time stiffness barrier to low power warp-wormhole technology. This conjecture is entirely new and needs further investigation.