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Published entries: 206
Matching entries: 206. Showing 26–50 of 206.
Paper · 2010
Black hole lasers in Bose-Einstein condensates
- S Finazzi(Author)
- R Parentani(Author)
S. Finazzi and R. Parentani study elongated Bose-Einstein condensates whose flow crosses the speed of sound twice. In the gravitational analogy these flows form a pair of black hole and white hole horizons. Without periodic boundaries, the phonon spectrum has a finite set of complex-frequency modes that produce a laser effect, because the supersonic region acts as a resonant cavity. Numerical computation of the complex frequencies and the density-density correlations gives patterns with very specific signatures. The laser effect is self-amplified Hawking radiation, confirmed by comparing the early outgoing flux with standard black hole radiation. Because the analysis rests on the Bogoliubov-de Gennes equation, none of its results depend on the gravitational analogy itself.
Paper · 1993
Black strings and p-branes are unstable
- Ruth Gregory(Author)
- Raymond Laflamme(Author)
Ruth Gregory and Raymond Laflamme study small perturbations of black strings and branes, low-energy solutions of string theory. In four dimensions black holes are stable and settle into a state fixed by mass, charge and angular momentum. Quantum mechanically, black holes behave quite differently, like thermal systems whose horizon area acts as entropy. For uncharged black strings they find unstable modes over a range of frequencies and wavelengths in the extra dimensions. Compactifying the extra dimensions below the shortest unstable wavelength removes the instability, so large astrophysical black holes are unaffected. They also discuss what the instability means for Penrose's cosmic censorship hypothesis that singularities stay hidden.
Paper · 2011
Bose-Einstein Condensate Theory of Deuteron Fusion in Metal
- Yeong E. Kim(Author)
Yeong Kim develops Bose-Einstein condensation nuclear fusion theory to explain deuteron-induced nuclear reactions seen in metals in electrolysis and gas-loading experiments. The observed reaction rates cannot be explained by the conventional theory of nuclear reactions in free space. It rests on one conventional concept: deuterons forming a Bose-Einstein condensate inside the metal. The theory explains, qualitatively or quantitatively, all ten experimental observations it lists from electrolysis and gas loading. Fusion energy can pass to the metal through its stopping power, without invoking lattice vibrations, and anomalous tritium production follows from a sub-threshold resonance reaction. Key experiments to test its predictions are proposed.
Paper · 2012
Bose-Einstein Condensation Nuclear Fusion: Role of Monopole Transition
- Yeong E. Kim(Author)
- Thomas E. Ward(Author)
Yeong Kim and Thomas Ward extend Bose–Einstein condensation nuclear fusion theory, which builds on one conventional idea: deuterons in a metal forming a Bose–Einstein condensate. They add a monopole transition, assuming helium-4 has a collective vibrational excited state. Using a threshold resonance mechanism, they derive the S-factor and find this channel's reaction rate far exceeds other exit channels. The mechanism can pass fusion energy into vibrations of the metal rather than emitted radiation. They propose tests: inelastic electron scattering from helium-4 to look for the excited state, and measuring the predicted branching ratio.
Paper · 2013
Bose-Einstein condensation versus Dicke-Hepp-Lieb transition in an optical cavity
- Francesco Piazza(Author)
- Philipp Strack(Author)
- Wilhelm Zwerger(Author)
Piazza, Strack and Zwerger solve exactly how Bose-Einstein condensation competes with the Dicke-Hepp-Lieb self-organisation transition for an ideal Bose gas in a single-mode optical cavity driven by a transverse laser. An effective action approach gives the full phase diagram at any temperature, with a bicritical point where the two transitions cross. They compute the atoms' dynamically generated band structure and the resulting drop in the condensation temperature once the density becomes periodically modulated. The polariton spectrum near the transition behaves quite differently above and below the condensation temperature. At low temperature the critical value for self-organisation falls as temperature rises, so thermal fluctuations can strengthen the atoms' tendency to arrange periodically.
Paper · 2003
Can a wormhole supported by only small amounts of exotic matter really be traversable?
- Peter K. F. Kuhfittig(Author)
Peter Kuhfittig builds on results that quantum effects may hold a wormhole throat open and that the total exotic matter can be made arbitrarily small. The catch was that such a wormhole might flare out too slowly to cross in reasonable time and come close to an event horizon at the throat. He presents a model that overcomes both problems while meeting the usual traversability conditions. The wormhole's size allows crossing in a reasonable time, and it satisfies the Ford-Roman constraints without an event horizon at the throat. A wormhole held open by very little exotic matter may be traversable in practice, not just in principle, and the total exotic matter proves vanishingly small.
Paper · 2025
Casimir forces across magnetic plasmas at nuclear separations
- S.K. Panja(Author)
- L. Inacio(Author)
- S. Pal(Author)
- M. Boström(Author)
Panja, Inacio, Pal and Boström present theory and numerical results on the magnetic Casimir interaction produced by vacuum fluctuations of the quantised field, at nuclear distances. They investigate how the zero-temperature Casimir effect at those scales can reach the black-body temperatures needed to create a magnetic electron-positron plasma. The plasma's magnetic permeability and any magnetic fields shape the screened Casimir-Yukawa potentials between perfectly conducting surfaces. They draw out consequences for that potential, its screening length, and a permeability-dependent quantity resembling the meson mass. The work connects to results showing magnetic fields can tune the measured Casimir force and create electrons and positrons from the vacuum.
Paper · 2006
Casimir forces and non-Newtonian gravitation
- Roberto Onofrio(Author)
Roberto Onofrio reviews the search for deviations from Newtonian gravity at micrometre distances, where several theories allow new forces of gravitational strength that could signal unification. In that range the Casimir force is the main background. He reviews micrometre-range Casimir measurements, the limits they place on non-Newtonian gravity and the main sources of false signals. He proposes expressing every Casimir measurement, independent of geometry, as a determination of the constant ħc, which can be checked against its precise microscopic value. Mastering the finite temperature correction, with blind tests, is the key step before future experiments can discover such forces or push their window into theoretically unnatural regions.
Paper · 2019
Chiral Casimir Forces: Repulsive, Enhanced, Tunable
- Qing-Dong Jiang(Author)
- Frank Wilczek(Author)
Qing-Dong Jiang and Frank Wilczek calculate Casimir interactions between similar bodies separated by an optically active or gyrotropic medium. Their author manuscript argues that different propagation of left- and right-circularly polarized light invalidates a step in the attraction theorem for the modeled system. For parallel plates with specified reflection matrices, the calculations predict forces that alternate between attraction and repulsion as separation changes. In the Faraday-medium example, an external magnetic field controls the predicted force through the medium’s optical rotation. The authors also examine frequency-dependent material response, imperfect reflection and finite temperature. The finite-temperature calculation assumes temperature-insensitive dielectric properties; its predictions depend on the chosen intervening medium and reflection matrices.
Paper · 2014
Cold Fusion
- Jean-Paul Biberian(Author)
Jean-Paul Biberian reviews almost 20 years of his own cold fusion experiments, alone and with collaborators, covering solid-state electrolytes, electrolysis and gas diffusion. The work began in 1993 with Francis Forrat's solid-state technique: red LaAlO3 single crystals with lanthanum vacancies turn white when loaded with hydrogen or deuterium, showing the vacancies fill. Across the techniques he reports excess heat: the solid-state electrolyte runs gave a large coefficient of performance but little heat, while deuterium diffusion gave more excess heat at a lower coefficient. He notes that the many other techniques he tried without excess heat are outside this account.
Paper · 2025
Cold Fusion Explained
- Edmund Storms(Author)
Edmund Storms summarises the experimental behaviour behind cold fusion and gives a general description of how the process works. He adds new experimental results on electron emission from the surface and on the effect of an applied electron current. In his account the nuclear process begins with an unusual chemical condition in which many electrons and a few hydrogen nuclei gather at unique sites in a structure and fuse. The mechanism is not yet worked out mathematically, but its key features form a model to guide future studies. It matters because the process promises clean, inexhaustible energy and reveals a new kind of mechanism behind a variety of nuclear interactions.
Paper · 2011
Comment on 'Hawking Radiation from Ultrashort Laser Pulse Filaments'
- Ralf Schützhold(Author)
- William G. Unruh(Author)
Ralf Schützhold and William Unruh respond to the report of an analogue Hawking effect from light pulses in silica glass. They list what a Hawking effect requires, including thermal radiation from a time-independent system driven by exponential tearing of waves at a horizon. Of five conditions, only the negative energy beyond the phase horizon applies, so the experiment is an important step towards observing Hawking radiation. The pulse has phase horizons but no group-velocity horizon, and the estimated Hawking temperature and photon numbers fall orders of magnitude short of the observed signal. They praise the technique and expect such a setup may well give the first observation of spontaneous Hawking emission in an analogue system.
Paper · 2024
Constant Velocity Physical Warp Drive Solution
- Jared Fuchs(Author)
- Christopher Helmerich(Author)
- Alexey Bobrick(Author)
- Luke Sellers(Author)
- Brandon Melcher(Author)
- Gianni Martire(Author)
Fuchs, Helmerich, Bobrick, Sellers, Melcher and Martire present a constant-velocity, slower-than-light warp drive solution that satisfies all of the energy conditions. It combines a stable shell of matter with a shift vector distribution closely matching well-known warp solutions such as the Alcubierre metric. The team generates the metric numerically, evaluates the energy conditions and confirms the shift cannot be removed by a change of coordinates. The result carries observers along geodesics, as the Alcubierre metric does, while satisfying the null, weak, dominant and strong energy conditions. Classic warp spacetimes can meet the energy conditions once a regular matter shell with positive ADM mass is added.
Paper · 2008
Contribution of drifting carriers to the Casimir-Lifshitz and Casimir-Polder interactions with semiconductor materials
- Diego A. R. Dalvit(Author)
- Steve K. Lamoreaux(Author)
Diego Dalvit and Steve Lamoreaux develop a theory of Casimir-Lifshitz and Casimir-Polder forces with semiconductor or insulator surfaces that includes charge drift in the bulk, using the classical Boltzmann equation. Waves inside semiconductors interact with drifting carriers, the basis of effects such as solid-state travelling-wave amplification. They derive frequency-dependent dispersion relations that reduce to the usual Lifshitz results for dielectrics. In the quasi-static limit they match recent results that include Debye screening in the thermal Lifshitz force for surfaces with few carriers. The approach modifies the Casimir-Lifshitz force between such materials and gives a way to describe the effect of small conductivity.
Paper · 1998
Contribution to Inertial Mass by Reaction of the Vacuum to Accelerated Motion
- Alfonso Rueda(Author)
- Bernhard Haisch(Author)
Rueda and Haisch develop a stochastic-electrodynamics model of inertia by transforming electromagnetic zero-point fields for an object undergoing constant proper acceleration. They interpret absorption or scattering of the resulting momentum flux as a reaction opposing acceleration, with an effective mass depending on the object’s volume and frequency-dependent coupling. That coupling must decrease at high frequencies, and the momentum integrals require a specified integration convention. A covariant appendix includes electromagnetic stresses, removes the earlier 4/3 factor and recovers the standard relativistic four-momentum form. The calculation addresses the electromagnetic contribution, leaves microscopic interaction dynamics unspecified and treats extension to general motion as an argument requiring further explicit examples, rather than a completed account of all matter’s inertia.
patent · 2018
Craft using an inertial mass reduction device
- Salvatore Cezar Pais(Author)
Pais’s 2018 patent proposes a craft whose outer wall and electrically insulated inner wall form a resonant cavity surrounding its compartments. Microwave emitters would drive accelerated vibration of the charged outer wall, intended to alter the nearby vacuum and reduce inertia, the resistance to acceleration. The description specifies emitters spanning 300 MHz to 300 GHz and allows noble gas, such as xenon, inside the cavity. It also proposes a rotating forward section and electromagnetic shielding around occupants and equipment. In the second layout, selectively vibrating different parts of the surrounding cavity is intended to steer the craft. The four claims cover the cavity-and-emitter arrangement, noble gas, outer-wall charge and accelerated axial rotation; the proposed vacuum response is the mechanism on which the design depends.
Paper · 2012
Cryogenic Calorimetry of 'Exploding' PdDx Wires
- F. L. Tanzella(Author)
- J. Bao(Author)
- M. C. H. McKubre(Author)
Tanzella, Bao and McKubre build on reports that thin palladium deuteride structures give anomalous heat and nuclear products when stimulated by electro-diffusion. They built a calorimeter working at 77 K that detects less than 0.1 J with an accuracy better than 0.06 J. High-voltage electrolysis of very pure heavy water loads thin palladium wires heavily with deuterium, and high current pulses then make the wires explode into microscopic particles. Output energies reached 150% of input, and every disintegration seen so far produced excess energy. The next step is to collect the headspace gas during these pulses and measure helium isotopes by mass spectroscopy.
Paper · 2016
Damped vacuum states of light
- T G Philbin(Author)
Thomas Philbin builds on the Casimir effect's central lesson, that the zero-point energy of the electromagnetic vacuum has real physical consequences. He models quantum light travelling in one dimension past a block of material, including full dispersion and absorption. The block pushes the zero-point energy below its free-space value at some frequencies and raises it at others. The regularised Casimir energy per frequency also drops below zero, the free-space value, at some frequencies. The total Casimir energy is positive, and single-mode zero-point quantities have direct experimental meaning through homodyne detection and spontaneous emission.
Paper · 2004
Design of a Quantum Source of High-Frequency Gravitational Waves (HFGW) and Test Methodology
- Giorgio Fontana(Author)
Giorgio Fontana designs a quantum source of high-frequency gravitational waves, identified as the breakthrough needed for new forms of space propulsion. Most existing generation schemes are marginally efficient, radiating orders of magnitude less gravitational power than they consume. His answer is the gaser, the gravitational-wave counterpart of the laser, as a quantum route to efficient generation. Quantum systems can be engineered to forbid electric and magnetic transitions so spin-2 gravitational transitions take over, and he identifies solid-state active materials suited to this. He describes how to create coherence, population inversion and higher emission probability, and proposes a proof-of-concept device near 1 THz with experiments to start the research.
Paper · 2007
Deuteron Cluster Fusion and ASH
- Akito Takahashi(Author)
Akito Takahashi reviews his theoretical model of deuteron cluster fusion in condensed matter. Deuterons briefly condense into clusters at focal points of the metal deuteride lattice, and his Electronic Quasi-Particle Screening Theory describes how attracted electrons screen them. Modelling the strong interaction by charged-pion exchange, he proposes multi-body resonance fusion, with tetrahedral fusion of 4 deuterons and octahedral fusion of 8 as major channels ending in helium-4. Tritium and helium-3 are minor products, and neutrons appear at less than 10^-10 of the helium rate. Slowing alpha particles give only low-energy X-rays hard to see outside the cell, so deuteron cluster fusion in condensed matter is clean and almost radiation-free.
Paper · 2024
Direct Electricity Production from NANOR-type ZrO2-PdNiD Components Using Ultrasound
- Mitchell Swartz(Author)
Mitchell Swartz works with NANOR-type components, nanostructured materials in which deuterated palladium-nickel islands are electrically isolated inside a zirconia dielectric. He tests whether ultrasound applied to them can be converted directly into DC electricity, comparing against ohmic controls with and without an added magnetic field. The components produced excess electricity about 655% higher than any control. This electrical output adds to the excess heat these components already produce, though it is much smaller than the heat. Its advantage is bypassing Carnot-limited thermoelectric conversion, and more robust components and harvesting control systems are now being developed.
Paper · 2015
Discrete Excitation Spectrum of a Classical Harmonic Oscillator in Zero-Point Radiation
- Wayne Cheng-Wei Huang(Author)
- Herman Batelaan(Author)
Wayne Cheng-Wei Huang and Herman Batelaan test a common view that classical theories such as stochastic electrodynamics cannot produce discrete energy spectra. They find that a classical harmonic oscillator immersed in classical electromagnetic zero-point radiation, excited by a single pulse, shows a quantised excitation spectrum matching the quantum oscillator. Both spectra come from numerically computing the oscillator's total energy after the pulse, the quantum one by solving Schrödinger's equation. The classical zero-point field theory and quantum mechanics agree within the numerical convergence error. Planck's constant enters the classical theory only as the factor that sets the strength of the zero-point field.
Paper · 2020
Dust content solutions for the Alcubierre warp drive spacetime
- Osvaldo L. Santos-Pereira(Author)
- Everton M. C. Abreu(Author)
- Marcelo B. Ribeiro(Author)
Santos-Pereira, Abreu and Ribeiro study the Alcubierre metric, in which a particle inside a warp bubble can travel arbitrarily faster than light globally while staying subluminal locally. General relativity allows exactly this combination of global superluminal and local subluminal motion. Because the metric was first proposed as a geometry without a source, they solve the Einstein equations for it with dust as the source. Every such solution with pressureless dust turns out to be a vacuum solution. These solutions link the Alcubierre metric to the Burgers equation for shock waves in an inviscid fluid, and the shock waves behave as plane waves.
Paper · 2013
Dynamical Casimir effect in a Josephson metamaterial
- Pasi Lähteenmäki(Author)
- G. S. Paraoanu(Author)
- Juha Hassel(Author)
- Pertti J. Hakonen(Author)
Lähteenmäki, Paraoanu, Hassel and Hakonen report a dynamical Casimir experiment in their four-page author manuscript, using a superconducting microwave cavity containing a Josephson metamaterial. An array of 250 SQUIDs in a 7 mm waveguide changes the cavity’s effective electrical length when its magnetic flux is modulated. At a cavity resonance of 5.4 GHz, pumping at 10.8 GHz generates correlated microwave photon pairs whose frequencies sum to the pump frequency. Measurements near 50 mK show two-mode correlations and a symmetric, double-peaked spectrum when the cavity is detuned, agreeing with the authors’ quantum model. The external modulation supplies the emitted energy; this is not an unpowered extraction device.
Paper · 2009
Dynamical Casimir Effect in a Superconducting Coplanar Waveguide
- J. R. Johansson(Author)
- G. Johansson(Author)
- C. M. Wilson(Author)
- Franco Nori(Author)
J. R. Johansson, G. Johansson, C. M. Wilson and Franco Nori study the dynamical Casimir effect in a superconducting coplanar waveguide ended by a SQUID. Vacuum fluctuations pull two parallel mirrors together, and a moving mirror can turn them into real photons. Changing the magnetic flux through the SQUID modulates the waveguide's boundary condition and so its effective length, acting like a moving mirror. Effective boundary speeds near the speed of light in the waveguide produce broadband photons identical to those predicted for a single oscillating mirror. Estimating the power for realistic parameters, they show this nonclassical radiation should be directly detectable in experiments.