This chapter summarizes from a historical perspective the works on gravity-superconductors interactions from the De Witt 1966 brief paper; to the Anandan, Chiao and Ross 1980s theoretical papers; to the Li, Peng, Torr 1990s theories and superconductor experiments as those of Podkletnov et al. in 1992, 1995, & 2001, Chiao et al. in 2003 and Tajmar et al. in the late 2000s with some discussion on other theories and experiments. More detailed work can be found in the other chapters of this eBook.

Interactions between superconductors and high-frequency gravitational waves have been predicted by a number of authors, and also challenged by others. The evidence for and against possible sources of interaction is reviewed. Assuming the veracity of the claims allows a number of possible applications to be considered, which may double as experimental tests of the results, and a number of these are considered in detail as possible ways to clarify the current controversial position.

Orthorhombic Cuprate High Temperature Superconductors (HTSC) are characterized by the presence of both s-wave and d-wave Cooper pairs in their electronic structure, and it is known from theory that electronic transitions between s and d states may produce the emission of gravitational waves. In normal materials, s-d transitions are suppressed by competing electric and magnetic transitions that have much higher probabilities; this is not the case of Cooper pairs in HTSC, which cannot support states other than s-wave or dwave. To give theoretical foundations to a potential technology capable of constructing a quantum source of gravitational waves, this paper will also discuss means for creating coherence and population inversion and means to increase the emission probability, with close resemblance to the conceptual developments that led to the experimentation of the first laser. The expected performances of the device are derived from quantum gravitational theories. Additional properties of the active materials are considered in order to enforce the theoretical foundations of the device. A proof-of-concept device, operating at about 1 THz, is described.

Quantum effects on the Planck scale in the Type II superconductor have the potential for new phenomena stemming from high internal energies associated with symmetry breaking phase transitions, which can give Planck time energy fluctuations of ~6x10²⁴ [J/s] per coherent electron pair in association with the Ginzburg-Landau (GL) scalar field across Josephson junctions; whereby, the Ginzburg-Landau (GL) scalar field provides a medium for producing interactions among quantum energy fluctuations and quantum gravity fields during rapid phase transitions. It is calculated that laboratory scale apparatus could produce radiated Planck scale energies or quantum gravitational waves on the order of 10^-5 [J] per coherent electron pair with gravitational energy absorption on the human scale (i.e., measurable effect) of 10^-4 [J].

It can be proven, using the Feynman path integral, that the vacuum state of Quantum Gravity contains localized fluctuations with large mass. Their interaction gives rise to a complex pattern of excited states. In particular, couples of equal virtual masses can be in a symmetrical superposition Ψ (ground state) or in an anti-symmetrical superposition Ψ^-. Transitions Ψ⁺ can be efficiently “pumped” only by a time-variable vacuum-energy-like term Λ(t) associated with coherent matter. The decay Ψ^- → Ψ⁺ generates off-shell virtual spin 1 gravitons, which can also produce a cascade of stimulated emission, ending with absorption in a target. We compute to leading order the Einstein A and B coefficients of the transition and give magnitude order estimates for the amplification factor in YBCO crystals or melt-textured samples pumped by bulk supercurrents at frequency ≈10 MHz.

Experiments by Tajmar et al. and others, where various devices were placed in the vicinity of superconductors to measure force fields resembling gravitoelectromagnetism, are reviewed. In some of these experiments, an acceleration field, 21 orders of magnitude stronger than that predicted by the GEM theory, was observed during angular acceleration of a niobium ring. The accelerometers picked up the field only when the temperature was below the 9.5 K critical temperature. Ring gyroscopes, sensitive to rotation fields comparable to gravitomagnetism, showed effects with a variety of cold (< 20 K) materials, including niobium, aluminum, Teflon and helium. The effects have a parity asymmetry, showing up only with clockwise rotation in Austria and counter-clockwise rotation in New Zealand. The rotation field measured with niobium in Austria is comparable to the Sagnac field due to rotation of the earth. Neither the acceleration nor the rotation fields are explainable with current theories of quantum mechanics or general relativity. Future experiments in Austria involve a cryostat which can be oriented at various angles relative to the earth’s rotation axis.

The technique used by Raymond Chiao for producing a new type of radiation from a superconductor is reviewed. In this technique, superconductors are used both for the source and detector of the radiation, on the hypothesis that the radiation effects are enhanced in superfluid materials. The coherent conversion in superconductors between electromagnetic and gravitational-like radiation requires modifications to standard model theories. The requirements for such modifications are discussed, assuming that they exist. For example, the gravitational-like disturbance needs to be expressed in terms of a vector field disturbance in a macroscopic number of particles, and where the coupling must be typically 20 orders of magnitude stronger than Newtonian gravity. Analogies with particle physics suggest that superconductors also probe vacuum fields comparable to the QCD (quantum chromodynamics) vacuum or higher dimensions.

An attempt has been made in this work to study the scattering of laser light by the gravity-like impulse produced in an impulse gravity generator (IGG) and also an experiment has been conducted in order to determine the propagation speed of the gravity impulse. The light attenuation was found to last between 34 and 48 ns and to increase with voltage, up to a maximum of 7% at 2000 kV. The propagation time of the pulse over a distance of 1211 m was measured recording the response of two identical piezoelectric sensors connected to two synchronized rubidium atomic clocks. The delay was 631 ns, corresponding to a propagation speed of 64c. The theoretical analysis of these results is not simple and requires a quantum picture. Different targets (ballistic pendulums, photons, piezoelectric sensors) appear to be affected by the IGG beam in different ways, possibly reacting to components of the beam which propagate with different velocities. Accordingly, the superluminal correlation between the two sensors does not necessarily imply superluminal information transmission. Using the microscopic model for the emission given in Chapter 5, we also have estimated the cross-sectional density of virtual gravitons in the beam and we have shown that their propagation velocity can not be fixed by the emission process. The predicted rate of graviton-photon scattering is consistent with the observed laser attenuation.

Over the years, several reports of experiments have been published claiming evidence of an unusual interaction between superconductors and gravitational force fields. One of the best-known examples is the work of E. Podkletnov et al. the “Impulse Gravity Generator” (IGG) experiment. Due to its potential importance in physics, a setup for replication of the IGG experiment has been constructed. The following article describes the experimental setup used to verify or contradict the claims made. The replication follows the requirements specified by E. Podkletnov et al. as closely as possible. Additional modifications, where made, enhanced the experimental possibilities. Superconducting emitters with two or more layers are fabricated, cooled down to 35K and charged with different high-voltage generators to realize different characteristic discharge curves. Two discharge chambers are employed to realize various superconductor gas transitions, as well as superconductor metal transitions. Various sensors are used to measure disturbances and vibrations. As a result, energy from a possible anomalous radiation can be proved to nine orders of magnitude smaller than the smallest “gravity impulse” energy reported by E. Podkletnov et al.

Reports of experimental modifications of gravity over rotating superconductors or of a weight increase or decrease during cool-down of superconductors have prompted many researchers to consider designing and performing their own experiments. However, many of these reports have not dealt in sufficient depth with the considerable difficulties attendant on this type of experiment. In general, there is a large class of phenomena that can mask the sought-after effect and produce spurious or artefactual results which are actually due to prosaic and mundane albeit subtle phenomena. Some of the proposed experiments deal with superconductor-mediated detection of gravitational waves. These will not be dealt with specifically in this paper. Rather, we concentrate on those experiments designed to detect mass anomalies and gravity field anomalies. However, many of the issues raised herein are germane to both types of experiments. We will describe some general types of experiments concentrating on instrumentation and interpretation of results rather than the theory leading to the experiments. We examine specific and subtle thermal phenomena occurring during the transition of superconductors near T_crit. We then enumerate the multitude of experimental pitfalls that lay before the researcher. Examples provided clearly indicate that minimum standards of experimental precision, accounting for boundary conditions, an understanding of thermal exchange between cryogen and superconductor, error analysis and thorough reporting of the experiment are necessary to distinguish a true anomaly from prosaic explanations and artefacts.

Based on theoretical ideas under development since 2002, termed Extended Heim Theory (EHT), as well as experiments performed at AIT Seibersdorf, Austria since 2006, it is argued that there is evidence for the existence of novel gravity-like fields and thus also different types of matter. These gravity-like fields are not described by conventional Newtonian (Einsteinian) gravitation, i.e., by the accumulation of mass. Instead, under certain conditions, they should be producible in the laboratory by small ring or disk shaped masses rotating at cryogenic temperatures. EHT, in describing these novel fields, postulates six fundamental physical interactions, three of them of gravitational nature. The two additional gravity-like fields may be both attractive and repulsive. It is further argued, based on both EHT and experiments, that these gravity-like fields are outside the known four physical fundamental forces, and may result from the conversion of electromagnetic into gravitational fields. The gravitomagnetic effect of these fields is found to be some 18 orders of magnitude larger than classical frame dragging of General Relativity. This fact seems to be in accordance with recent experiments performed at AIT Seibersdorf. A non relativistic semiclassical model will be presented as an attempt to explain the physical nature of the novel gravity-like fields. There seems to be a special phase transition, triggered at cryogenic temperatures, responsible for the conversion of electromagnetic into gravitational fields. The features of the six fundamental physical interactions are utilized to investigate the potential of the novel gravity-like fields for propulsion purposes as well as energy generation.

This paper discusses the connection between dark matter and gravity-superconductor interactions through a hierarchy of density dependent scalar fields from the far Universe field down to the laboratory scale. A hierarchy of scalar fields in the universe suggests a relationship with properties varying with background conditions or a hierarchy from the far background field to the local background field. Such a theory, called the Chameleon theory (presented in 2004 by Khoury and Weltman), is a dark matter model that is fundamentally dependent on the background density and involves mass coupling to the background field. In this paper, a new hierarchy interpretation of the gravitational constant G.. is produced by combining the Chameleon Theory with newly observed astronomical data, where G.. is given in terms of the dark matter particle mass and the hierarchy of the background fields-represented by a hierarchy of coupling constants. Whereby, the data seen by gyroscopes in the Tajmar et al. rotating superconductor experiments can be attributed to dark matter – like the formation of dark matter rings outside the confines of a galaxy. This relationship provides a starting point for using new galactic structures as guidance for defining new gravity-superconductor phenomena in experiments on the laboratory scale.

A numerical analysis is presented of a gravity/superconductor interaction experiment in a suspension balance recently reported in the literature. A central question of the analysis is whether thermal design of the experiment fully exploited the high resolution provided by the balance. For this purpose, we calculate sample temperature evolution, T(x,y,z,t), and the number N_SC(t) of volume elements that have completed phase change, under strongly differing heat transfer conditions (radiation, convection and boiling). Experimental equilibrium generation or decay rates, G_exp(t), of electron pairs initiated by propagation of a thermal perturbation, the phonon aspect, are estimated from dN_SC(t)/dt using the electron pair equilibrium density, ρEP(T), of this material. The counterpart to the phonon aspect, e.g., non-equilibrium decay rates, G_Exc(t), the response of the electron system describing the decay of the “product” of the same thermal disturbance, is analyzed using (i) a diffusion model of their propagation in the solid, and (ii) a sequential model with lifetimes estimated from the uncertainty principle and in analogy to the nucleon-nucleon, pionmediated Yukawa interaction. Items (i) and (ii) describe decay of the disturbance in space and time, respectively. A discrepancy appears between G_exp(t) and G_Exc(t) if the sample is warmed-up solely by radiation, like in the suspension balance experiment. The discrepancy creates dead time intervals large enough to spread out weight vs. time signals that under other experimental conditions (e.g., using large Biot numbers) could be sharply identified, provided a correlation between gravity and superconductivity really exists.