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Published entries: 206

Matching entries: 206. Showing 1–25 of 206.

Paper · 1999
A 'warp drive' with more reasonable total energy requirements
1. Chris Van Den Broeck(Author)
Chris Van Den Broeck shows that a small change to the Alcubierre geometry dramatically cuts the total energy a warp bubble needs to carry macroscopic objects. His spacetime needs total negative mass of only a few solar masses, with a comparable amount of positive energy. That places the warp drive on the mass scale of large traversable wormholes. The new geometry satisfies the quantum inequality on weak energy condition violations and keeps every advantage of the original. The quantum inequality is amply satisfied, proving that warp drive energy requirements need not be as stringent as Alcubierre's original. He presents it as a proof of principle on total energy, with very large local energy densities still to be solved.
Paper · 2021
A brief history of ball lightning observations by scientists and trained professionals
1. Alexander G. Keul(Author)
Alexander Keul addresses ball lightning, an open problem in atmospheric physics with thousands of eyewitness reports but few instrumental records and no agreed theory. Because the phenomenon is so hard to monitor, he turns to reports from scientists and trained professionals. He compiles 20 published cases, 15 from his own work and 6 from a Russian database: 41 cases from eight countries between 1868 and 2020, each summarised and then synthesised. Six influential or notable cases are added. Well-documented cases from trained observers can drive fieldwork and test theories, and scientists with unreported sightings are invited to share them.
Paper · 2022
A Charged Particle Model based on Weber Electrodynamics for Electron Beam Trajectories in Coil and Solenoid Elements
1. Christof Baumgärtel(Author)
2. Simon Maher(Author)
Christof Baumgärtel and Simon Maher model electron beams using Weber electrodynamics, a direct force acting along the line between interacting charges rather than a field. Coils and solenoids often guide, deflect and focus particle beams, so accurate trajectory predictions are needed, especially where the magnetic field spreads out beyond the coil ends. Their experiment sent a 2000 eV electron beam through a 290-turn coil. The Weber model, a standard field model and commercial software all matched the measured deflection and were equally accurate. A solenoid's magnetic field map and the Weber force map were also qualitatively the same.
Paper · 2017
A comment on 'A test of general relativity using the LARES and LAGEOS satellites and a GRACE Earth gravity model'
1. Lorenzo Iorio(Author)
Lorenzo Iorio examines the Ciufolini team's test of the Lense-Thirring frame-dragging effect, built on about 3.5 years of laser ranging to the LAGEOS, LAGEOS II and LARES satellites. That test combines the orbital nodes of the three satellites to cancel errors in the first two even zonal harmonics of Earth's gravity field, J2 and J4. Iorio shows that the spread among recent gravity models in the uncancelled zonals of degree 6, 8 and 10 does not yet allow the expected 1% level to be reached unambiguously. For some pairs of models the differences reach 15% for degree 6, 6% for degree 8 and 36% for degree 10.
Paper · 2000
A general worldline quantum inequality
1. Christopher J Fewster(Author)
Christopher Fewster works on worldline quantum inequalities, lower bounds on the averaged energy density of a quantum field along an observer's worldline. They matter because a quantum field's energy density at a single point has no lower bound. For a linear scalar field in any globally hyperbolic spacetime, he proves an inequality on the normal ordered energy density for any smooth timelike trajectory, any smooth compactly supported weight and any Hadamard state. This generalises an earlier result for static trajectories in static spacetimes. The argument is made rigorous with microlocal analysis and the microlocal spectral condition for Hadamard states, with a compact form given for stationary trajectories.
Paper · 2007
A macroscopic test of the Aharonov-Bohm effect
1. Adam Caprez(Author)
2. Brett Barwick(Author)
3. Herman Batelaan(Author)
Caprez, Barwick and Batelaan investigate force explanations of the magnetic Aharonov–Bohm phase shift through a macroscopic electron time-of-flight experiment. Laser pulses extract electrons from a field-emission tip; the electrons pass between solenoids joined into a magnetic toroid before reaching a channelplate detector. For 40 eV electrons, they report no solenoid-current-dependent delay, with arrival-time scatter of ±0.1 ns. Changing the acceleration voltage confirms sensitivity to electromagnetic forces, while removing magnetic shielding does not change the result. They exclude force explanations producing the delay predicted by their equation, rather than measuring a phase shift and its absence of forces simultaneously.
Paper · 2022
A New Way of Triggering Nuclear Fusion
1. T. Benyo(Author)
2. L. Forsley(Author)
3. B. Steinetz(Author)
4. B. Baramsai(Author)
In this accepted manuscript for IEEE Spectrum, T. Benyo, L. Forsley, B. Steinetz and B. Baramsai explain NASA’s lattice-confinement fusion experiments and their proposed development. Deuterated metal lattices hold dense fuel while electronic screening helps charged nuclei approach one another. An electron accelerator and tantalum target supply photons up to 2.9 MeV to titanium or erbium deuteride, initiating neutron-mediated reactions. The authors describe neutron spectra with a 2.45 MeV fusion peak and higher peaks near 4 and 5 MeV, whose possible origins include boosted fusion or stripping reactions. The demonstrated process is externally driven and subcritical; improved efficiency, reaction-rate scaling and possible fusion–fission coupling remain engineering directions toward useful power.
Paper · 2016
A test of general relativity using the LARES and LAGEOS satellites and a GRACE Earth gravity model
1. Ignazio Ciufolini(Author)
2. Antonio Paolozzi(Author)
3. Erricos C. Pavlis(Author)
4. Rolf Koenig(Author)
5. John Ries(Author)
6. Vahe Gurzadyan(Author)
7. Richard Matzner(Author)
8. Roger Penrose(Author)
9. Giampiero Sindoni(Author)
10. Claudio Paris(Author)
11. Harutyun Khachatryan(Author)
12. Sergey Mirzoyan(Author)
Ciufolini and colleagues test general relativity by measuring how the rotating Earth drags inertial frames. They combine about 3.5 years of laser ranging to the LARES, LAGEOS and LAGEOS 2 satellites with the GGM05S Earth gravity model from the GRACE geodesy mission. Normalised to the general relativity value, the frame dragging comes out as μ = (0.994 ± 0.002) ± 0.05. Here 0.002 is the 1-sigma formal error and 0.05 a preliminary systematic error, mostly from the gravity model. The result is in agreement with the prediction of general relativity. The authors call it an intermediate result, and their final determination will present a careful restudy of the systematic errors.
Paper · 2020
Accurately predicting electron beam deflections in fringing fields of a solenoid
1. Christof Baumgärtel(Author)
2. Ray T. Smith(Author)
3. Simon Maher(Author)
Christof Baumgärtel, Ray Smith and Simon Maher address a design problem for charged-particle instruments: predicting trajectories in solenoids needs accurate fields, especially in the fringing regions at the ends. They describe a model that accurately predicts electron beam deflection both in the fringing field and at the centre of a solenoid. The model uses a direct action-at-a-distance force between charges, based on the Weber force, instead of fields. It is compared with a Maxwell-Lorentz field model and a commercial boundary element package, against experiments on three solenoids of different sizes. The direct-action model matches the experiments more accurately than the field-based models, especially for the shortest, 25 mm solenoid where the field is least uniform.
Paper · 2012
Active control of electromagnetically induced transparency analogue in terahertz metamaterials
1. Jianqiang Gu(Author)
2. Ranjan Singh(Author)
3. Xiaojun Liu(Author)
4. Xueqian Zhang(Author)
5. Yingfang Ma(Author)
6. Shuang Zhang(Author)
7. Stefan A. Maier(Author)
8. Zhen Tian(Author)
9. Abul K. Azad(Author)
10. Hou-Tong Chen(Author)
11. Antoinette J. Taylor(Author)
12. Jiaguang Han(Author)
13. Weili Zhang(Author)
Gu, Singh, Liu, Zhang, Ma, Zhang and colleagues work with metamaterial analogues of electromagnetically induced transparency, which give classical structures features of quantum optical systems. Such analogues promise slow-light units, highly sensitive sensors and nonlinear devices. Optical control of this effect matters for optical networks and terahertz communications. They achieve active optical control of this transparency by tuning the metamaterial's dark mode. Photoconductive silicon in each unit cell lets ultrafast optical pulses switch the transparency window strongly, giving optically tunable group delay for terahertz light. This opens the way to chip-scale ultrafast devices for optical buffering and active terahertz filtering.
Paper · 2022
ADM mass in warp drive spacetimes
1. Sebastian Schuster(Author)
2. Jessica Santiago(Author)
3. Matt Visser(Author)
Sebastian Schuster, Jessica Santiago and Matt Visser ask what happens when a warp bubble has mass. Because a warp drive spacetime is assumed flat far away, they use the ADM mass to make the question precise. Mass can enter in three ways: as a payload, as mass carried by the bubble itself, or as a massive background the drive moves past. Working with zero-vorticity Natário drives, they compute every stress-energy component explicitly. They confirm that the null, weak, strong and dominant energy conditions are all violated, showing explicitly where, while urging that folk wisdom be checked critically.
Paper · 2024
Advancements in the Production of Anomalous Heat Effect in Constantan Wires
1. Francesco Celani(Author)
2. C. Lorenzetti(Author)
3. G. G. Vassallo(Author)
4. E. Purchi(Author)
5. S. Fiorilla(Author)
6. S. Cupellini(Author)
7. N. Nakamura(Author)
8. P. Cerreoni(Author)
9. R. Burri(Author)
10. P. Boccanera(Author)
11. A. Spallone(Author)
12. E. F. Marano(Author)
Since 2011, Francesco Celani and colleagues have developed simple procedures to activate long, thin, surface-modified Constantan wires by Joule heating so that they produce the anomalous heat effect. Their latest work replicates earlier findings and adds tests of isotopic effects with hydrogen and deuterium gas. The reactor keeps their inverse coaxial coil geometry from 2019, and energy balance is measured by thermometry on the reactor wall, faster than flow calorimetry, with helium runs as reference. During long operation in hydrogen they saw, for the first time, a clear isotopic effect between hydrogen and deuterium. Low-cost Constantan closely resembles expensive palladium in anomalous heat and resistance change, opening decades of cold fusion knowledge to a cheaper material.
Paper · 2012
An explanation of interference effects in the double slit experiment: Classical trajectories plus ballistic diffusion caused by zero-point fluctuations
1. G. Grössing(Author)
2. S. Fussy(Author)
3. J. Mesa Pascasio(Author)
4. H. Schwabl(Author)
Grössing, Fussy, Mesa Pascasio and Schwabl propose a classical explanation of interference in the double slit experiment. Each particle carries a thermal context that reflects the boundary conditions of the whole experimental arrangement. They introduce a path excitation field, derived from the thermodynamics of the zero-point vacuum, that represents every path a particle can take through thermal fluctuations. From classical physics alone they derive the exact intensity pattern on the screen, along with the trajectories and the probability current. The trajectories never cross the central line between the slits, matching Bohmian mechanics without needing the quantum potential. The authors present this as showing how a quantum can be understood as an emergent system arising from an oscillator and its thermal environment.
Paper · 2012
An Explanation of Low-energy Nuclear Reactions (Cold Fusion)
1. Edmund Storms(Author)
Edmund Storms identifies where low-energy nuclear reactions take place by ruling out alternatives and finding the one environment shared by every successful method. He proposes that this Nuclear Active Environment is not the lattice itself but cracks or gaps of a critical size, formed by stress relief. Inside them, a resonance process sheds the energy as X-rays through a laser-like mechanism. In the same environment deuterium forms by p + p + e fusion, tritium by d + p + e, and helium by d + d + e followed by beta emission. The model yields many testable predictions and could test the Standard Model of nuclear interaction.
Paper · 2011
Analogue Gravity
1. Carlos Barceló(Author)
2. Stefano Liberati(Author)
3. Matt Visser(Author)
In this 2011 review, Barceló, Liberati and Visser explain how waves in materials can follow equations resembling those for fields in curved spacetime. A sufficiently fast fluid flow can prevent sound from travelling upstream, creating an acoustic counterpart of a black-hole horizon. The review compares water waves, ultracold atomic condensates and optical systems, examining where each analogy applies. It reports classical stimulated Hawking emission in water-wave experiments and a sonic horizon in a condensate kept stable for about eight milliseconds. At that time, reproducible detection of spontaneous quantum Hawking radiation remained an experimental target. The authors distinguish this effective geometry for waves from the equations governing gravity itself: reproducing curved-spacetime propagation does not automatically reproduce Einstein’s gravitational dynamics.
Paper · 2001
Analogue gravity from Bose-Einstein condensates
1. Carlos Barceló(Author)
2. S Liberati(Author)
3. Matt Visser(Author)
Carlos Barceló, S. Liberati and Matt Visser ask how far Bose-Einstein condensates can go in producing a generic effective metric that mimics the kinematics of general relativity. They use a very general nonlinear Schrödinger equation with a position-dependent tensor mass and arbitrary nonlinearity. At low momenta, phase excitations of the condensate obey a d'Alembertian equation for a generic Lorentzian effective metric in 3+1 dimensions set by the background field. At high momenta the eikonal approximation gives a Bogoliubov-like dispersion relation and recovers non-relativistic Newtonian physics. The effective metric appears generically unless interatomic forces are attractive, making condensates an extremely promising system for probing the kinematics of general relativity.
Paper · 2024
Analyzing Warp Drive Spacetimes with Warp Factory
1. Christopher Helmerich(Author)
2. Jared Fuchs(Author)
3. Alexey Bobrick(Author)
4. Luke Sellers(Author)
5. Brandon Melcher(Author)
6. Gianni Martire(Author)
Helmerich, Fuchs, Bobrick, Sellers, Melcher and Martire note that warp research has relied on analytic methods whose simple metric forms limit which solutions can be explored. They introduce Warp Factory, a numerical toolkit that examines general warp geometries by evaluating the Einstein field equations and computing the energy conditions. It also computes metric scalars and produces visualisations in 2D and 3D of metrics and their stress-energy tensors. Physicality checks have usually looked only at energy density seen by Eulerian observers, which is not enough for a full evaluation of the energy conditions. The toolkit lets researchers explore a wide range of warp metrics, especially where analytic work becomes impractical, and the paper applies it to commonly modelled metrics.
Paper · 2026
Anomalous Heat Effects via Longitudinal and Transversal Excitations in Constantan Wires
1. F. Celani(Author)
2. C. Lorenzetti(Author)
3. E. Purchi(Author)
4. S. Cupellini(Author)
5. M. Nakamura(Author)
6. P. Cerreoni(Author)
7. G. Vassallo(Author)
Celani and colleagues pursue anomalous heat in hydrogen-loaded commercial Constantan wire, chosen in 2011 over palladium for its lower cost and higher defect density. The wire runs in a compact INFN-LNF reactor at internal temperatures up to 900 °C while the outer jacket stays below 350 °C. With calorimetry accurate to ±1 W, pulsing plus a pulsed counter-electrode raised net excess heat to 20 to 21 W for 80 W input, peaking at a ratio of 1.27 at 60 W. After two weeks idle the effect weakens but partly returns with in-situ redox cycling and extended pulsing.
Paper · 2025
Anomalous Heat Reaction from Hydrogen and Metals
1. Tadahiko Mizuno(Author)
2. Jed Rothwell(Author)
Tadahiko Mizuno and Jed Rothwell place a cleaned nickel mesh inside a stainless-steel reactor, degas it by heating and vacuum, and bombard it with electrons and ions to strip surface impurities. This yielded excess heat equal to the heating power applied to the reactor, measured by air-flow calorimetry. An unexpected signal in the control reactor led to a key finding: suitably treated stainless steel alone can produce excess heat under certain conditions. Tests with four sample and reactor types included a straight stainless tube reactor with no discharge treatment that still produced excess heat. Even a simple stainless reactor with suitable surface treatment exceeds its input, and the excess heat rises exponentially with temperature.
Paper · 2019
Asymmetry and non-dispersivity in the Aharonov-Bohm effect
1. Maria Becker(Author)
2. Giulio Guzzinati(Author)
3. Armand Béché(Author)
4. Johan Verbeeck(Author)
5. Herman Batelaan(Author)
Becker, Guzzinati, Béché, Verbeeck and Batelaan study the Aharonov-Bohm effect, in which electromagnetic potentials affect electrons even where no field force acts. Zeilinger's theorem describes the missing classical force as the effect being dispersionless, while Shelankov predicted a quantum force in the same system. In the experiment, free electrons pass a magnetised nanorod and their far-field diffraction pattern is recorded. The pattern is asymmetric, confirming one of Shelankov's predictions and giving indirect experimental evidence of a quantum force. Their analysis shows Zeilinger's theorem and Shelankov's result are special cases of a single theorem.
Paper · 1995
Averaged Energy Conditions and Quantum Inequalities
1. L. H. Ford(Author)
2. Thomas A. Roman(Author)
L. H. Ford and Thomas Roman connect the averaged weak and averaged null energy conditions with quantum inequalities, uncertainty-principle-type limits on negative energy. They study a quantised free massless scalar field in flat spacetime in two and four dimensions. In a two-dimensional universe with a compact spatial direction, they bound the difference between the energy density of any quantum state and that of the Casimir vacuum. That difference obeys averaged energy conditions, which is surprising because the Casimir vacuum alone satisfies neither quantum inequalities nor averaged conditions. Such difference inequalities may limit how far energy conditions can be violated beyond a background such as the Casimir vacuum.
Paper · 2011
Axially and spherically symmetric solitons in warm plasma
1. MAXIM DVORNIKOV(Author)
Maxim Dvornikov studies whether stable axially and spherically symmetric plasma structures can exist, using a new nonlinear Schrödinger equation with nonlocal electron nonlinearities. Stable spatial solitons are an important problem in contemporary physics, and the new equation describes Langmuir waves with axial and spherical symmetry in warm plasma. He obtains numerical soliton solutions of the equation and analyses their stability. The model predicts low-energy plasma structures up to about 1.5 m across in thin, hot plasma with electron density near 10^5 cm^-3. Such densities occur in the Earth's ionosphere, and ordinary lightning can supply the heating. The results are applied to the theory of natural plasmoids in the atmosphere.
Paper · 2026
Backreaction of stimulated Hawking radiation in an optical analogue
1. Lorenzo M. Procopio(Author)
2. Raul Aguero-Santacruz(Author)
3. David Bermudez(Author)
4. Ulf Leonhardt(Author)
Procopio, Aguero-Santacruz, Bermudez and Leonhardt address an open question: Hawking radiation draws its energy from the field around a black hole, but how field quanta create Hawking quanta was unknown. In a fibre-optical analogue of an event horizon, they present experimental and theoretical evidence for the generating process. Where a complicated cascade had been assumed, they identify a simple direct process and observe how it reacts back on the field. Such analogues rest on waves in a medium whose flow comes to exceed the wave speed. The findings point to an equally direct process in other analogues and perhaps in gravity, shedding light on how black holes might radiate.
Paper · 2012
Biological Transmutations: Historical Perspective
1. Jean-Paul Biberian(Author)
Jean-Paul Biberian reviews evidence that living systems can transmute one chemical element into another. Over two centuries, experimenters questioned Lavoisier's conservation law for chemical reactions and reported transmutations in plants, bacteria and other organisms. The line runs from Herzeele's experiments through Baranger, Kervran, Goldfein and Holleman to recent work by Vysotskii and Kornilova with modern analytical techniques. He notes that much of the older data comes from the 19th and early 20th centuries or from secondary sources. Taken together, living organisms appear able to produce nuclear reactions under some conditions, and the theory that explains this will likely also explain nuclear reactions in condensed matter.
Paper · 2012
Bird's Eye View of Phonon Models for Excess Heat in the Fleischmann-Pons Experiment
1. Peter L. Hagelstein(Author)
Peter Hagelstein gives an overview of his models for excess heat in the Fleischmann-Pons experiment. More than two decades after the effect was announced, he reviews the approaches pursued in search of a coherent theoretical explanation. The effect is prodigious and helium-4 appears correlated with the energy, yet energetic particles matching that energy are absent. That led him to models that split a large energy quantum into many small ones, which the lossy spin-boson model appears to achieve. Coherent energy exchange in that limit, together with excitation transfer, describes a new set of reactions relevant to the experiments. The resulting models give interpretations for numerous experimental observations that textbook nuclear and condensed matter physics do not explain.