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Original titles, attribution, publication details and summaries in the selected language.

Published entries: 206

Matching entries: 206. Showing 101–125 of 206.

Paper · 1998
Magnetic force exerted by the Aharonov-Bohm line
1. A. L Shelankov(Author)
A. L. Shelankov revisits the debated transverse force exerted by an Aharonov-Bohm magnetic flux line, using a new paraxial solution to Aharonov-Bohm scattering. Although the scattering cross-section is left-right symmetric, a beam of finite width is deflected by the flux line as if by a Lorentz force. The asymmetry and the force come from quantum interference in the forward direction, within the angular size of the incoming wave. The force is tied to the incident current at the line, and the S-matrix, not the scattering amplitude, is the right language for forward scattering. For superfluid helium-4, the result confirms the Iordanskii force on vortex lines.
Paper · 2020
Mass and Heat Flow Calorimetry in Brillouin's Reactor
1. Francis Tanzella(Author)
2. Robert Godes(Author)
3. Jin Liu(Author)
4. Robert George(Author)
Tanzella, Godes, Liu and George report calorimetry on Brillouin Energy's coated ceramic catalyst tubes in hydrogen, stimulated with nanosecond pulses across the coatings. The Energy Research Center has verified this calorimetry for over 18 months, since 2 calorimeters moved from SRI International to Brillouin's laboratory. Pulses of several hundred volts lasting tens of nanoseconds concentrate current at the outer metal-ceramic interface through the skin effect. Pulse power is measured with fast oscilloscopes, and a system identification heat-flow model built for this calorimeter tracks power reaching its five temperature sensors. Between 200 and 350 °C in hydrogen, the stimulated catalyst substrates produced thermal power, comparing heater-only runs with heater plus pulse runs.
Paper · 2016
Materials perspective on Casimir and van der Waals interactions
1. L. M. Woods(Author)
2. D. A. R. Dalvit(Author)
3. A. Tkatchenko(Author)
4. P. Rodriguez-Lopez(Author)
5. A. W. Rodriguez(Author)
6. R. Podgornik(Author)
Woods, Dalvit, Tkatchenko, Rodriguez-Lopez, Rodriguez and Podgornik review van der Waals and Casimir forces, which fluctuations of the electromagnetic field create at every length scale between any finite systems. These forces matter both for the basic science of materials and for designing micro- and nano-structured devices. The review summarises major breakthroughs and stresses that the two interactions share a common origin. It covers ab initio modelling, materials with Dirac-like spectra, controlling the force through nontrivial boundary conditions, and van der Waals forces in organic and biological matter. Materials may hold the answers to several open problems in fluctuation-induced phenomena.
Paper · 2007
Measurement of Gravitomagnetic and Acceleration Fields around Rotating Superconductors
1. Martin Tajmar(Author)
2. Florin Plesescu(Author)
3. Bernhard Seifert(Author)
4. Klaus Marhold(Author)
Tajmar, Plesescu, Seifert and Marhold pursue their proposal that a rotating superconductor produces, besides its London moment, a large gravitomagnetic field that would explain an apparent mass increase of niobium Cooper pairs. A similar field follows from general relativity combined with the observed amount of dark energy. They built a facility to measure small acceleration and gravitomagnetic fields near a fast rotating, accelerating superconductor. Niobium measurements show first signs within a factor of 2 of their prediction, and possible error sources are reviewed. If this gravitomagnetic London moment exists, acceleration fields could be generated in the laboratory.
Paper · 2017
Measurement of non-monotonic Casimir forces between silicon nanostructures
1. L. Tang(Author)
2. M. Wang(Author)
3. C. Y. Ng(Author)
4. M. Nikolic(Author)
5. C. T. Chan(Author)
6. A. W. Rodriguez(Author)
7. H. B. Chan(Author)
Tang, Wang, Ng, Nikolic, Chan, Rodriguez and Chan tackle a practical barrier: novel geometries that should give repulsive or non-monotonic Casimir forces are hard to align at close range. An on-chip platform with integrated force sensors and actuators removes the alignment problem and measures the force between two silicon surfaces with nanoscale protrusions. The Casimir force depends non-monotonically on displacement. At some displacements it confines the motion and effectively stiffens the nanomechanical spring. This opens the way to using the Casimir force in nanomachines built from unconventional shapes, and the same scheme can measure lateral Casimir forces between other novel structures.
Paper · 2011
Measurement of Stimulated Hawking Emission in an Analogue System
1. Silke Weinfurtner(Author)
2. Edmund W. Tedford(Author)
3. Matthew C. J. Penrice(Author)
4. William G. Unruh(Author)
5. Gregory A. Lawrence(Author)
Weinfurtner, Tedford, Penrice, Unruh and Lawrence use the mathematical analogy between fields in curved spacetime and long surface waves on moving water. Long waves moving upstream over a streamlined obstacle are blocked in the fast flow and converted into short waves, the analogue of stimulated emission at a white hole. Measured amplitudes of the converted waves follow a Boltzmann distribution, showing the conversion is thermal. The ratio stays thermal even though water waves have a different dispersion relation from the one Hawking used, which strengthens trust that the effect does not depend on short-wavelength physics. The effect survives turbulence and viscosity, attesting to the generality of the Hawking process.
Paper · 2002
Measurement of the Casimir force between parallel metallic surfaces
1. G. Bressi(Author)
2. G. Carugno(Author)
3. R. Onofrio(Author)
4. G. Ruoso(Author)
Bressi, Carugno, Onofrio and Ruoso start from a basic consequence of the uncertainty principle: the vacuum is not empty. The evidence for an accelerating universe gives a compelling reason to understand how the quantum vacuum contributes to spacetime curvature, and forces between neutral bodies are a direct probe of it. They measure the Casimir force between two conducting surfaces held parallel, the geometry of Casimir's original prediction. The force acts between a chromium-coated silicon cantilever and a similar rigid surface. It is detected through shifts in the cantilever's resonant frequency as the surfaces approach. Its scaling with distance was tested from 0.5 to 3.0 µm, and the force coefficient was determined to 15% precision.
Paper · 2007
Measurement of the enhanced screening effect of the d + d reactions in metals
1. A. Huke(Author)
2. K. Czerski(Author)
3. P. Heide(Author)
Huke, Czerski and Heide study deuteron-deuteron fusion inside metals at energies below the Coulomb barrier, which calls for techniques beyond standard nuclear physics procedures. With an electrostatic accelerator and various self-implanted metal targets, they measure fusion cross-sections enhanced compared with gas-target experiments. The electron screening energies come out about an order of magnitude larger than in gas targets and well above theoretical predictions. Two effects strongly shape the raw data: deuterium's high mobility in solids and contamination layers that form on the surface under ion beams in high vacuum. They describe a differential acquisition and analysis method, because standard procedures that ignore these effects give badly wrong screening energies.
Paper · 2024
Microscopic Insights into the Anomalous Heat Effect that Unify Disparate Experimental Results
1. Graham K. Hubler(Author)
Graham Hubler looks at the anomalous heat effect across its many forms: electrolytic loading, hydrogen gas over heated nanostructures, ultrasound and glow discharge. His hypothesis is that the effect needs an optical phonon resonance at one specific frequency, coupled to electromagnetic radiation of that frequency, and that sustaining the resonance produces the heat. The idea draws on his perturbed angular correlation results on palladium hydrides at CERN, X-ray diffraction of superconducting palladium hydrides and 40-year-old internal friction data. Practical rules follow: about 30% of deuterium in tetrahedral sites or many vacancies in bulk palladium, nanoparticles under 10 nm, and a sustained trigger to keep the resonance active.
Paper · 2010
Minimum accelerations from quantised inertia
1. M. E. McCulloch(Author)
M. E. McCulloch addresses an unexplained cutoff: no disc galaxies are observed with masses below about 10^9 solar masses. His model assumes inertia comes from Unruh radiation and that this radiation is limited by a Casimir effect on the scale of the Hubble horizon. As acceleration falls, inertial mass falls even faster, holding acceleration at a minimum close to the observed cosmic acceleration. For disc galaxies it predicts a minimum apparent mass of 1.1 × 10^9 solar masses, close to observation, and it also predicts the Hubble mass. The inertia assumption could be tested by accelerating particles until the Unruh radiation they see can be supplemented with man-made radiation, making a change in inertia detectable.
Paper · 2012
Modified Szpak Protocol for Excess Heat
1. Dennis Letts(Author)
2. Peter L. Hagelstein(Author)
Dennis Letts and Peter Hagelstein start from theory showing that vacancies in palladium deuteride can host molecular D2, conjectured to be necessary for Fleischmann-Pons excess heat. Researchers in the field are sure the Fleischmann-Pons excess heat effect is real and new. In the original experiment, those vacancies probably came from accidental codeposition at high loading. That points to experiments with controlled palladium codeposition, such as the Szpak experiment. They attribute the difficulty of replicating Szpak's work to low deuterium-to-palladium loading. Their modified protocol codeposits at higher current density with less palladium chloride, and every test run so far with it has given positive results, measured by Seebeck calorimetry.
Paper · 2012
Neutron production from the fracture of piezoelectric rocks
1. A Widom(Author)
2. J Swain(Author)
3. Y N Srivastava(Author)
A. Widom, J. Swain and Y. N. Srivastava explain experimental evidence that fracturing piezoelectric rocks produces neutrons. As micro-cracks build to a fracture, the piezoelectric effect turns mechanical energy into electric field energy. That energy decays through microwave-frequency oscillations of the electric field. Sound modes trapped on micro-cracks in rock oscillate at microwave frequencies, which sets the frequency of these fields. These fields accelerate electrons in the solid, which collide with protons to produce neutrons and neutrinos. Quartz-rich rocks such as granite respond strongly to mechanical disturbance, so large-scale fracturing in earthquakes brings strong electromagnetic responses.
Paper · 2006
Newtonian limits of warp drive spacetimes
1. José Natário(Author)
José Natário notes that the warp drive spacetime illuminates general relativity, but its meaning as a gravitational field is unclear. Newtonian limits are a standard tool for understanding and interpreting relativistic spacetimes. He therefore seeks a Newtonian limit of the warp drive spacetime. He defines Newtonian spacetimes with a potential function and shows they closely mirror their counterparts in Newtonian theory, especially with a dust source and cosmological constant. Such spacetimes always have a Newtonian limit with the same potential. He finds a class of warp drive spacetimes with Newtonian limits and applies the same method to the Schwarzschild solution and flat Friedmann-Robertson-Walker cosmologies.
Paper · 2017
Nickel-hydrogen reactors: heat generation, isotopic and elemental composition of fuel
1. Alexander G. Parkhomov(Author)
2. Sergey N. Zabavin(Author)
3. Timur R. Timerbulatov(Author)
4. Kirill A. Alabin(Author)
5. Stepan N. Andreev(Author)
6. Alexander G. Sobolev(Author)
Parkhomov and colleagues survey experiments in which hydrogen interacting with nickel and other metals produces anomalously large heat and changes in isotopic and elemental composition. They then analyse fuel and nearby material from their own nickel-hydrogen reactors before and after runs that produced up to 790 MJ of excess energy. Nickel and lithium showed no significant isotopic change except in the AP2 fuel analysis at Uppsala University. Instead, concentrations of several impurity nuclides rose significantly, in the fuel and in structural parts next to the active zones. They conclude that heat far beyond chemical processes is confirmed across laboratories and point toward practical, efficient and clean technologies.
Paper · 2014
Nonlinear lattice dynamics as a basis for enhanced superconductivity in YBa2Cu3O6.5
1. R. Mankowsky(Author)
2. A. Subedi(Author)
3. M. Först(Author)
4. S. O. Mariager(Author)
5. M. Chollet(Author)
6. H. T. Lemke(Author)
7. J. S. Robinson(Author)
8. J. M. Glownia(Author)
9. M. P. Minitti(Author)
10. A. Frano(Author)
11. M. Fechner(Author)
12. N. A. Spaldin(Author)
13. T. Loew(Author)
14. B. Keimer(Author)
15. A. Georges(Author)
16. A. Cavalleri(Author)
Mankowsky, Subedi and colleagues investigate how resonant mid-infrared excitation changes the crystal structure of YBa2Cu3O6.5, rather than directly measuring a new equilibrium superconducting transition. They drive a lattice vibration and probe four Bragg reflections with 50-femtosecond X-ray pulses at 100 K, above the sample’s 52 K equilibrium transition. Fitting the diffraction measurements with calculated phonon displacements yields expansion within copper-oxide bilayers, contraction between bilayers and increased bond buckling. Density-functional calculations predict accompanying electronic changes that the authors consider favorable to superconductivity. The structural response lasts only picoseconds, and its relationship to earlier optical signatures of enhanced interlayer transport motivates further electronic measurements and a full many-body treatment.
Paper · 2003
Null energy conditions in quantum field theory
1. Christopher J. Fewster(Author)
2. Thomas A. Roman(Author)
Christopher Fewster and Thomas Roman show, by explicit construction for the massless scalar field in four-dimensional flat spacetime, that weighted null averages of the stress-energy tensor have no lower bound over Hadamard states. So no quantum inequality holds along null geodesics in four dimensions, unlike two-dimensional flat spacetime where one does. The difference arises because in two dimensions any two field modes move either parallel or antiparallel, while the four-dimensional proof uses modes almost parallel to the geodesic. These states still satisfy the averaged null energy condition. In any globally hyperbolic spacetime, null-contracted stress-energy averaged along a timelike worldline does obey a quantum inequality, for massive and massless fields alike.
Paper · 2008
Numerical observation of Hawking radiation from acoustic black holes in atomic Bose-Einstein condensates
1. Iacopo Carusotto(Author)
2. Serena Fagnocchi(Author)
3. Alessio Recati(Author)
4. Roberto Balbinot(Author)
5. Alessandro Fabbri(Author)
Carusotto, Fagnocchi, Recati, Balbinot and Fabbri report numerical evidence of Hawking emission of Bogoliubov phonons from a sonic horizon in a flowing one-dimensional atomic Bose-Einstein condensate. Hawking radiation is so weak that it has never been observed directly, so the work builds on the analogy between waves in moving media and fields in curved spacetime. The radiation shows up as distinctive long-range patterns in the gas's density-density correlation function. In the hydrodynamic limit their fully microscopic calculations agree quantitatively with analogue-model predictions. They predict new features and examine how robust the Hawking signal is at finite temperature.
Paper · 2017
Observation of Excess Heat by Activated Metal and Deuterium Gas
1. Tadahiko Mizuno(Author)
Tadahiko Mizuno builds on reports that excess heat in nickel-hydrogen systems depends on an extremely clean system. He minimised impurities by carefully cleaning the electrode and making nanoparticles inside the test system without exposure to air, using deuterium gas. Energy far above the input was produced continuously, at best double the electrical input and several hundred watts. Output rises exponentially with temperature, reaching 1 kW at a reactor temperature of 300 °C, and higher temperatures are expected to raise it further. An improved electrode preparation, described in the appendix, raised both reproducibility and excess heat.
Paper · 2008
Observation of negative-frequency waves in a water tank: a classical analogue to the Hawking effect?
1. Germain Rousseaux(Author)
2. Christian Mathis(Author)
3. Philippe Maïssa(Author)
4. Thomas G Philbin(Author)
5. Ulf Leonhardt(Author)
Rousseaux, Mathis, Maïssa, Philbin and Leonhardt target the mechanism at the heart of Hawking radiation: conversion of positive-frequency waves into negative-frequency waves at a horizon. Astrophysical Hawking radiation is too feeble to detect, so laboratory horizons are the way to demonstrate its physics. Instead of a quantum fluid they use water, where a horizon forms wherever the flow outruns the waves. Hawking's theory links three separate disciplines: quantum mechanics, general relativity and thermodynamics. They report the first direct observation of negative-frequency waves converted from positive-frequency waves in a moving medium. The measured conversion was significantly stronger than simple-model simulations predicted.
Paper · 2014
Observation of self-amplifying Hawking radiation in an analogue black-hole laser
1. Jeff Steinhauer(Author)
Jeff Steinhauer builds a narrow, dilute, ultracold atomic Bose-Einstein condensate with an analogue black hole horizon and an inner horizon, as in a charged black hole. He observes Hawking radiation leaving the analogue black hole, the output of a black hole laser. A standing wave grows exponentially between the horizons, from interference between the negative-energy partners of the Hawking radiation and negative-energy particles reflected from the inner horizon. The emitted Hawking radiation is clearly visible in the density-density correlation function. The lasing mode sits at about 0.3 of the Hawking temperature. The work suggests a way to probe inside black holes: strong laser-like Hawking radiation from an astrophysical black hole would reveal an inner horizon.
Paper · 2011
Observation of the thermal Casimir force
1. A. O. Sushkov(Author)
2. W. J. Kim(Author)
3. D. A. R. Dalvit(Author)
4. S. K. Lamoreaux(Author)
Sushkov, Kim, Dalvit and Lamoreaux report the experimental observation of the thermal Casimir force, driven by thermal rather than quantum fluctuations of the electromagnetic field. Earlier measurements had not settled whether the Drude model or the plasma model correctly describes the low-frequency dielectric response. They measured the attraction between a flat and a spherical gold plate at separations from 0.7 µm to 7 µm, including the electrostatic force from surface potential patches. The data agree excellently, with a reduced χ2 of 1.04, with the Drude-model Casimir force including the 300 K thermal force. The thermal force dominates the quantum one beyond 3 µm, and the plasma model is excluded across the measured range.
Paper · 2019
Observation of thermal Hawking radiation and its temperature in an analogue black hole
1. Juan Ramón Muñoz de Nova(Author)
2. Katrine Golubkov(Author)
3. Victor I. Kolobov(Author)
4. Jeff Steinhauer(Author)
Muñoz de Nova, Golubkov, Kolobov and Steinhauer measure the correlation spectrum of Hawking radiation from an analogue black hole and find it thermal, at the temperature set by the analogue surface gravity. The radiation sits in the linear dispersion regime, as for a real black hole. Inside the analogue horizon, the radiation consists only of negative-energy partner particles. The work confirms Hawking's predictions for both the value of the temperature and the thermal shape of the spectrum. Correlations between Hawking and partner particles show the analogue black hole has no analogue firewall, bearing directly on the information paradox.
Paper · 2017
Oscillating excess power gain and magnetic domains in NANOR-type CF/LANR components
1. Mitchell R. Swartz(Author)
Mitchell Swartz studies NANOR-type components, hermetically sealed preloaded nanomaterials built as two-terminal electrical parts that can yield significant excess heat. Without magnetisation, their peak excess power gain always fell off slowly and exponentially over time. After exposure to a magnetic field, the activity instead oscillates, with a cyclic component near 1.3 × 10^-4 Hz, within 0.2 to 5 × 10^-4 Hz. This oscillation appears only in magnetised components and only while an electric field drives them. He models remnant magnetic domains in the lattice and uses the Maxwell stress tensor to compute their force density and the expected oscillation frequency.
Paper · 2021
Perfect fluid warp drive solutions with the cosmological constant
1. Osvaldo L. Santos-Pereira(Author)
2. Everton M. C. Abreu(Author)
3. Marcelo B. Ribeiro(Author)
Santos-Pereira, Abreu and Ribeiro solve the Einstein equations with a cosmological constant for the Alcubierre warp drive metric, with a perfect fluid as the source. They also treat dust with a cosmological constant, generalising their earlier dust solution, which linked the warp drive to shock waves through the Burgers equation. Alcubierre's original metric was guessed rather than solved from the Einstein equations; this work solves them and analyses all energy conditions. The shift vector along the bubble's motion couples the Einstein equations so that the energy-momentum source needs off-diagonal terms. Warp speeds thus call for a complex distribution of energy, matter and momentum, richer than dust for stable solutions, and negative matter may not be strictly required.
Paper · 2025
Photon Radiation Calorimetry for Anomalous Heat Generation in NiCu Multilayer Thin Film
1. J. Kasagi(Author)
2. T. Itoh(Author)
3. Y. Iwamura(Author)
4. Y Shibasaki(Author)
5. T. Takahashi(Author)
6. S. Yamauchi(Author)
Kasagi, Itoh, Iwamura and colleagues developed photon radiation calorimetry for the anomalous heat effect in nickel-copper multilayer films, using three detector types covering 0.3 µm to 5.5 µm. Comparing spectra with and without hydrogen shows sample-specific excess heat, largest for the nickel-copper composite layers. A heat flow model gives 4 to 6 W of excess heat, with 460 ± 120 kJ generated over 80 hours. That is at least 410 ± 108 keV per hydrogen atom, far beyond chemistry and at the level of nuclear reactions. Because the spectrum fits gray-body radiation, emissivity and temperature can be deduced directly, an advantage over thermometry at high temperature.