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Journal articles on the topic 'Analogue gravity'

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Author: Grafiati

Published: 4 June 2021

Last updated: 14 March 2023

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1

Blencowe, Miles P., and Hui Wang. "Analogue gravity on a superconducting chip." Philosophical Transactions of the Royal Society A: Mathematical, Physical and Engineering Sciences 378, no. 2177 (July 20, 2020): 20190224. http://dx.doi.org/10.1098/rsta.2019.0224.

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We describe how analogues of a Hawking evaporating black hole as well as the Unruh effect for an oscillatory, accelerating photodetector in vacuum may be realized using superconducting, microwave circuits that are fashioned out of Josephson tunnel junction and film bulk acoustic resonator elements. This article is part of a discussion meeting issue ‘The next generation of analogue gravity experiments’.

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2

Faccio, Daniele. "Laser pulse analogues for gravity and analogue Hawking radiation." Contemporary Physics 53, no. 2 (March 2012): 97–112. http://dx.doi.org/10.1080/00107514.2011.642559.

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3

Liberati, Stefano. "Analogue gravity models of emergent gravity: lessons and pitfalls." Journal of Physics: Conference Series 880 (August 2017): 012009. http://dx.doi.org/10.1088/1742-6596/880/1/012009.

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4

Smolyaninov, Igor I., and Vera N. Smolyaninova. "Analogue Quantum Gravity in Hyperbolic Metamaterials." Universe 8, no. 4 (April 14, 2022): 242. http://dx.doi.org/10.3390/universe8040242.

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It is well known that extraordinary photons in hyperbolic metamaterials may be described as living in an effective Minkowski spacetime, which is defined by the peculiar form of the strongly anisotropic dielectric tensor in these metamaterials. Here, we demonstrate that within the scope of this approximation, the sound waves in hyperbolic metamaterials look similar to gravitational waves, and therefore the quantized sound waves (phonons) look similar to gravitons. Such an analogue model of quantum gravity looks especially interesting near the phase transitions in hyperbolic metamaterials where it becomes possible to switch quantum gravity effects on and off as a function of metamaterial temperature. We also predict strong enhancement of sonoluminescence in ferrofluid-based hyperbolic metamaterials, which looks analogous to particle creation in strong gravitational fields.

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5

Hossenfelder, Sabine, and Tobias Zingg. "Analogue gravity models from conformal rescaling." Classical and Quantum Gravity 34, no. 16 (July 20, 2017): 165004. http://dx.doi.org/10.1088/1361-6382/aa7e12.

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6

Schützhold, Ralf. "Summary of session E1: analogue gravity." Classical and Quantum Gravity 25, no. 11 (May 15, 2008): 114027. http://dx.doi.org/10.1088/0264-9381/25/11/114027.

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7

Barceló, Carlos, S. Liberati, and Matt Visser. "Analogue gravity from Bose-Einstein condensates." Classical and Quantum Gravity 18, no. 6 (March 14, 2001): 1137–56. http://dx.doi.org/10.1088/0264-9381/18/6/312.

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8

Jacquet, M. J., T. Boulier, F. Claude, A. Maître, E. Cancellieri, C. Adrados, A. Amo, et al. "Polariton fluids for analogue gravity physics." Philosophical Transactions of the Royal Society A: Mathematical, Physical and Engineering Sciences 378, no. 2177 (July 20, 2020): 20190225. http://dx.doi.org/10.1098/rsta.2019.0225.

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Analogue gravity enables the study of fields on curved space–times in the laboratory. There are numerous experimental platforms in which amplification at the event horizon or the ergoregion has been observed. Here, we demonstrate how optically generating a defect in a polariton microcavity enables the creation of one- and two-dimensional, transsonic fluid flows. We show that this highly tuneable method permits the creation of horizons. Furthermore, we present a rotating geometry akin to the water-wave bathtub vortex. These experiments usher in the possibility of observing stimulated as well as spontaneous amplification by the Hawking, Penrose and Zeld’ovich effects in fluids of light. This article is part of a discussion meeting issue ‘The next generation of analogue gravity experiments’.

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9

Petty, Jack, and Friedrich König. "Optical analogue gravity physics: resonant radiation." Philosophical Transactions of the Royal Society A: Mathematical, Physical and Engineering Sciences 378, no. 2177 (July 20, 2020): 20190231. http://dx.doi.org/10.1098/rsta.2019.0231.

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The photonic crystal fibre (PCF) is a unique medium giving us the opportunity to perform experiments in carefully chosen regimes with precision and control. Using PCFs, we can perform analogue gravity experiments to study the physics of Hawking radiation and related processes such as resonant radiation. We discuss the similarities and differences between these processes and experimentally investigate the limits of effects of this type, dis- covering a new regime of record efficiency. We measure a 60% energy conversion efficiency from a pump to a visible femtosecond pulse by the process of resonant radiation, and demonstrate its extraordinary tunability in wavelength and bandwidth. Beyond analogue gravity, these femtosecond visible pulses provide a desirable laser source useful across a variety of modern scientific fields. This article is part of a discussion meeting issue ‘The next generation of analogue gravity experiments’.

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10

Visser, Matt, Carlos Barceló, and Stefano Liberati. "Analogue Models of and for Gravity." General Relativity and Gravitation 34, no. 10 (October 2002): 1719–34. http://dx.doi.org/10.1023/a:1020180409214.

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11

Weinfurtner, Silke, Stefano Liberati, and Matt Visser. "Analogue model for quantum gravity phenomenology." Journal of Physics A: Mathematical and General 39, no. 21 (May 10, 2006): 6807–13. http://dx.doi.org/10.1088/0305-4470/39/21/s83.

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12

Rosenberg, Yuval. "Optical analogues of black-hole horizons." Philosophical Transactions of the Royal Society A: Mathematical, Physical and Engineering Sciences 378, no. 2177 (July 20, 2020): 20190232. http://dx.doi.org/10.1098/rsta.2019.0232.

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Hawking radiation is unlikely to be measured from a real black hole, but can be tested in laboratory analogues. It was predicted as a consequence of quantum mechanics and general relativity, but turned out to be more universal. A refractive index perturbation produces an optical analogue of the black-hole horizon and Hawking radiation that is made of light. We discuss the central and recent experiments of the optical analogue, using hands-on physics. We stress the roles of classical fields, negative frequencies, ‘regular optics’ and dispersion. Opportunities and challenges ahead are briefly mentioned. This article is part of a discussion meeting issue ‘The next generation of analogue gravity experiments’.

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13

Rousseaux, Germain, and Hamid Kellay. "Classical hydrodynamics for analogue space–times: open channel flows and thin films." Philosophical Transactions of the Royal Society A: Mathematical, Physical and Engineering Sciences 378, no. 2177 (July 20, 2020): 20190233. http://dx.doi.org/10.1098/rsta.2019.0233.

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Here we review the way to build analogue space–times in open channel flows by looking at the flow phase diagram and the corresponding analogue experiments performed during the last years in the associated flow regimes. Thin films like the circular jump with different dispersive properties are discussed with the introduction of a brand new system for the next generation of analogue gravity experiments: flowing soap films with their capillary/elastic waves. This article is part of a discussion meeting issue ‘The next generation of analogue gravity experiments’.

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14

Liberati, Stefano, Giovanni Tricella, and Andrea Trombettoni. "The Information Loss Problem: An Analogue Gravity Perspective." Entropy 21, no. 10 (September 25, 2019): 940. http://dx.doi.org/10.3390/e21100940.

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Analogue gravity can be used to reproduce the phenomenology of quantum field theory in curved spacetime and in particular phenomena such as cosmological particle creation and Hawking radiation. In black hole physics, taking into account the backreaction of such effects on the metric requires an extension to semiclassical gravity and leads to an apparent inconsistency in the theory: the black hole evaporation induces a breakdown of the unitary quantum evolution leading to the so-called information loss problem. Here, we show that analogue gravity can provide an interesting perspective on the resolution of this problem, albeit the backreaction in analogue systems is not described by semiclassical Einstein equations. In particular, by looking at the simpler problem of cosmological particle creation, we show, in the context of Bose–Einstein condensates analogue gravity, that the emerging analogue geometry and quasi-particles have correlations due to the quantum nature of the atomic degrees of freedom underlying the emergent spacetime. The quantum evolution is, of course, always unitary, but on the whole Hilbert space, which cannot be exactly factorized a posteriori in geometry and quasi-particle components. In analogy, in a black hole evaporation one should expect a continuous process creating correlations between the Hawking quanta and the microscopic quantum degrees of freedom of spacetime, implying that only a full quantum gravity treatment would be able to resolve the information loss problem by proving the unitary evolution on the full Hilbert space.

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15

Barceló, Carlos, Stefano Liberati, and Matt Visser. "Analogue gravity from field theory normal modes?" Classical and Quantum Gravity 18, no. 17 (August 17, 2001): 3595–610. http://dx.doi.org/10.1088/0264-9381/18/17/313.

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16

Jacquet, M. J., S. Weinfurtner, and F. König. "The next generation of analogue gravity experiments." Philosophical Transactions of the Royal Society A: Mathematical, Physical and Engineering Sciences 378, no. 2177 (July 20, 2020): 20190239. http://dx.doi.org/10.1098/rsta.2019.0239.

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17

Faccio, D., S. Cacciatori, V. Gorini, V. G. Sala, A. Averchi, A. Lotti, M. Kolesik, and J. V. Moloney. "Analogue gravity and ultrashort laser pulse filamentation." EPL (Europhysics Letters) 89, no. 3 (February 1, 2010): 34004. http://dx.doi.org/10.1209/0295-5075/89/34004.

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18

Bilic, Neven, and Dijana Tolic. "Analogue cosmology in a hadronic fluid." Facta universitatis - series: Physics, Chemistry and Technology 12, no. 2 (2014): 77–83. http://dx.doi.org/10.2298/fupct1402077b.

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Analog gravity models of general relativity seem promising routes to providing laboratory tests of the foundation of quantum field theory in curved space-time. In contrast to general relativity, where geometry of a spacetime is determined by the Einstein equations, in analog models geometry and evolution of analog spacetime are determined by the equations of fluid mechanics. In this paper we study the analogue gravity model based on massless pions propagating in a expanding hadronic fluid. The analog expanding spacetime takes the form of an FRW universe, with the apparent and trapping horizons defined in the standard way.

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19

POLYAKOV, A. M. "QUANTUM GRAVITY IN TWO DIMENSIONS." Modern Physics Letters A 02, no. 11 (November 1987): 893–98. http://dx.doi.org/10.1142/s0217732387001130.

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Two dimensional induced quantum gravity is analyzed. By the use of light-cone gauge we derive a gravitational analogue of the Wess-Zumino action and discover its amazing connection with SL (2, ℝ) current algebra. The latter permits us to find differential equations for the correlation functions.

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20

Howard, Eric. "Cosmology analogues in optical systems." EPJ Web of Conferences 238 (2020): 11008. http://dx.doi.org/10.1051/epjconf/202023811008.

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We discuss the possibility of exploiting polariton-exciton physics as an analogue experimental tool to study challenging ideas and existing problems arising in the context of gravity theory and theoretical cosmology. We search for cosmology analogues with specific focus on simulating non-equilibrium dynamics across cosmological phase transitions in laboratory as well as employing optical analogue horizons in Bose-Einstein condensates (BECs) and signatures of white hole radiation to study gravitational and cosmological processes. Our analysis aims to uncover conceptual similarities between condensed matter systems and various phenomena in the Early Universe such as the symmetry breaking of the vacuum energy, spontaneous production of particles, false vacuum and cosmic inflation together with a number of unsolved cosmological problems.

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21

Peacock, David C. P. "Analogue Model for the Gravity Sliding of Sediments." Journal of Geoscience Education 54, no. 5 (November 2006): 550–54. http://dx.doi.org/10.5408/1089-9995-54.5.550.

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22

Oikonomou, V. K. "An electric analogue to gravity induced vacuum dominance." Gravitation and Cosmology 19, no. 3 (July 2013): 188–92. http://dx.doi.org/10.1134/s0202289313030092.

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23

Glampedakis, Kostas, and Theocharis A. Apostolatos. "The separable analogue of Kerr in Newtonian gravity." Classical and Quantum Gravity 30, no. 5 (February 5, 2013): 055006. http://dx.doi.org/10.1088/0264-9381/30/5/055006.

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24

Chakraborty, Chandrachur, and Banibrata Mukhopadhyay. "Spin Precession in the Gravity Wave Analogue Black Hole Spacetime." Universe 8, no. 3 (March 20, 2022): 193. http://dx.doi.org/10.3390/universe8030193.

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It was predicted that the spin precession frequency of a stationary gyroscope shows various anomalies in the strong gravity regime if its orbit shrinks, and eventually, its precession frequency becomes arbitrarily high very close to the horizon of a rotating black hole. Considering the gravity waves of a flowing fluid with a vortex in a shallow basin, which acts as a rotating analogue black hole, one can observe the predicted strong gravity effect on the spin precession in the laboratory. Attaching a thread with the buoyant particles and anchoring it to the bottom of the fluid container with a short-length miniature chain, one can construct a simple local test gyroscope to measure the spin precession frequency in the vicinity of the gravity wave analogue black hole. The thread acts as the axis of the gyroscope. By regulating the orbital frequency of the test gyroscope, one can also measure the strong gravity Lense–Thirring effect and geodetic/de-Sitter effect with this experimental set-up as the special cases. For example, to measure the Lense–Thirring effect, the length of the miniature chain can be set to zero, so that the gyroscope becomes static. One can also measure the geodetic precession with this system by orbiting the test gyroscope in the so-called Keplerian frequency around the non-rotating analogue black hole that can be constructed by making the rotation of the fluid/vortex negligible compared to its radial velocity.

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25

Tarafdar, Pratik, and Tapas K. Das. "Dependence of acoustic surface gravity on geometric configuration of matter for axially symmetric background flows in the Schwarzschild metric." International Journal of Modern Physics D 24, no. 14 (December 2015): 1550096. http://dx.doi.org/10.1142/s0218271815500960.

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In black hole evaporation process, the mass of the hole anti-correlates with the Hawking temperature. This indicates that the smaller holes have higher surface gravity. For analogue Hawking effects, however, the acoustic surface gravity is determined by the local values of the dynamical velocity of the stationary background fluid flow and the speed of propagation of the characteristic perturbation embedded in the background fluid, as well as by their space derivatives evaluated along the direction normal to the acoustic horizon, respectively. The mass of the analogue system — whether classical or quantum — does not directly contribute to extremize the value of the associated acoustic surface gravity. For general relativistic axially symmetric background fluid flow in the Schwarzschild metric, we show that the initial boundary conditions describing such accretion influence the maximization scheme of the acoustic surface gravity and associated analogue temperature. Aforementioned background flow onto black holes can assume three distinct geometric configurations. Identical set of initial boundary conditions can lead to entirely different phase-space behavior of the stationary flow solutions, as well as the salient features of the associated relativistic acoustic geometry. This implies that it is imperative to investigate how the measure of the acoustic surface gravity corresponding to the accreting black holes gets influenced by the geometric configuration of the inflow described by various thermodynamic equations of state. Such investigation is useful to study the effect of Einstenian gravity on the nonconventional classical features as observed in Hawking like effect in a dispersive medium in the limit of a strong dispersion relation.

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26

OOGURI, HIROSI, and NAOKI SASAKURA. "DISCRETE AND CONTINUUM APPROACHES TO THREE-DIMENSIONAL QUANTUM GRAVITY." Modern Physics Letters A 06, no. 39 (December 21, 1991): 3591–600. http://dx.doi.org/10.1142/s0217732391004140.

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It is shown that, in the three-dimensional lattice gravity defined by Ponzano and Regge, the space of physical states is isomorphic to the space of gauge-invariant functions on the moduli space of flat SU(2) connections over a two-dimensional surface, which gives physical states in the ISO(3) Chern–Simons gauge theory. To prove this, we employ the q-analogue of this model defined by Turaev and Viro as a regularization to sum over states. A recent work by Turaev suggests that the q-analogue model itself may be related to an Euclidean gravity with a cosmological constant proportional to 1/k2, where q=e2πi/(k+2).

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27

Das, S., T. Sahoo, and M. H. Meylan. "Dynamics of flexural gravity waves: from sea ice to Hawking radiation and analogue gravity." Proceedings of the Royal Society A: Mathematical, Physical and Engineering Sciences 474, no. 2209 (January 2018): 20170223. http://dx.doi.org/10.1098/rspa.2017.0223.

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The propagation of flexural gravity waves, routinely used to model wave interaction with sea ice, is studied, including the effect of compression and current. A number of significant and surprising properties are shown to exist. The occurrence of blocking above a critical value of compression is illustrated. This is analogous to propagation of surface gravity waves in the presence of opposing current and light wave propagation in the curved space–time near a black hole, therefore providing a novel system for studying analogue gravity. Between the blocking and buckling limit of the compressive force, the dispersion relation possesses three positive real roots, contrary to an earlier observation of having a single positive real root. Negative energy waves, in which the phase and group velocity point in opposite directions, are also shown to exist. In the presence of an opposing current and certain critical ranges of compressive force, the second blocking point shifts from the positive to the negative branch of the dispersion relation. Such a shift is known as the Hawking effect from the analogous behaviour in the theory of relativity which leads to Hawking radiation. The theory we develop is illustrated with simulations of linear waves in the time domain.

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28

Bruschi, D. E., N. Friis, I. Fuentes, and S. Weinfurtner. "On the robustness of entanglement in analogue gravity systems." New Journal of Physics 15, no. 11 (November 7, 2013): 113016. http://dx.doi.org/10.1088/1367-2630/15/11/113016.

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29

Dehkordi, Hengameh R., and Alberto Saa. "Huygens’ envelope principle in Finsler spaces and analogue gravity." Classical and Quantum Gravity 36, no. 8 (April 2, 2019): 085008. http://dx.doi.org/10.1088/1361-6382/ab0f03.

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30

Bilić, Neven, and Dijana Tolić. "Analogue surface gravity near the QCD chiral phase transition." Physics Letters B 718, no. 1 (November 2012): 223–27. http://dx.doi.org/10.1016/j.physletb.2012.10.029.

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31

Keser, Aydın Cem, and Victor Galitski. "Analogue stochastic gravity in strongly-interacting Bose–Einstein condensates." Annals of Physics 395 (August 2018): 84–111. http://dx.doi.org/10.1016/j.aop.2018.05.009.

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32

Oliveira, Leandro A., Carolina L. Benone, Amanda L. Almeida, and Luís C. B. Crispino. "Analytical investigation of wave absorption by a rotating black hole analogue." International Journal of Modern Physics D 29, no. 11 (August 2020): 2041018. http://dx.doi.org/10.1142/s0218271820410187.

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Perturbations in a draining vortex can be described analytically in terms of confluent Heun functions. In the context of analogue models of gravity in ideal fluids, we investigate analytically the absorption length of waves in a draining bathtub, a rotating black hole analogue, using confluent Heun functions. We compare our analytical results with the corresponding numerical ones, obtaining excellent agreement.

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33

Bahr, Benjamin, Bianca Dittrich, and James P. Ryan. "Spin Foam Models with Finite Groups." Journal of Gravity 2013 (July 24, 2013): 1–28. http://dx.doi.org/10.1155/2013/549824.

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Spin foam models, loop quantum gravity, and group field theory are discussed as quantum gravity candidate theories and usually involve a continuous Lie group. We advocate here to consider quantum gravity-inspired models with finite groups, firstly as a test bed for the full theory and secondly as a class of new lattice theories possibly featuring an analogue diffeomorphism symmetry. To make these notes accessible to readers outside the quantum gravity community, we provide an introduction to some essential concepts in the loop quantum gravity, spin foam, and group field theory approach and point out the many connections to the lattice field theory and the condensed-matter systems.

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34

Tretyakov, Petr V. "Dynamical stability of extended teleparallel gravity." Modern Physics Letters A 31, no. 14 (May 5, 2016): 1650085. http://dx.doi.org/10.1142/s0217732316500851.

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We discuss modified teleparallel gravity with function [Formula: see text] in the action, where the function depends on two arguments: torsion scalar [Formula: see text] and analogue of Gauss–Bonnet invariant [Formula: see text]. In contradistinction to usual teleparallel gravity [Formula: see text], this theory contains higher derivative terms, which may produce different instabilities. We discuss Minkowski stability problem in such kind of theories and explicitly demonstrate that for stability it must be [Formula: see text], [Formula: see text]. We apply these restrictions for the few types of functions discussed by the early authors.

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35

Das, Tapas Kumar, Neven Bilić, and Surajit Dasgupta. "A black-hole accretion disc as an analogue gravity model." Journal of Cosmology and Astroparticle Physics 2007, no. 06 (June 7, 2007): 009. http://dx.doi.org/10.1088/1475-7516/2007/06/009.

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36

Braidotti, Maria Chiara, Ziad H. Musslimani, and Claudio Conti. "Generalized uncertainty principle and analogue of quantum gravity in optics." Physica D: Nonlinear Phenomena 338 (January 2017): 34–41. http://dx.doi.org/10.1016/j.physd.2016.08.001.

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37

Sarkar, Supratik, and A. Bhattacharyay. "Non-local interactions in a BEC: an analogue gravity perspective." Journal of Physics A: Mathematical and Theoretical 47, no. 9 (February 18, 2014): 092002. http://dx.doi.org/10.1088/1751-8113/47/9/092002.

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38

Bahamonde, Sebastian, Jorge Gigante Valcarcel, Laur Järv, and Joosep Lember. "Black hole solutions in scalar-tensor symmetric teleparallel gravity." Journal of Cosmology and Astroparticle Physics 2022, no. 08 (August 1, 2022): 082. http://dx.doi.org/10.1088/1475-7516/2022/08/082.

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Abstract Symmetric teleparallel gravity is constructed with a nonzero nonmetricity tensor while both torsion and curvature are vanishing. In this framework, we find exact scalarised spherically symmetric static solutions in scalar-tensor theories built with a nonminimal coupling between the nonmetricity scalar and a scalar field. It turns out that the Bocharova-Bronnikov-Melnikov-Bekenstein solution has a symmetric teleparallel analogue (in addition to the recently found metric teleparallel analogue), while some other of these solutions describe scalarised black hole configurations that are not known in the Riemannian or metric teleparallel scalar-tensor case. To aid the analysis we also derive no-hair theorems for the theory. Since the symmetric teleparallel scalar-tensor models also include f(Q) gravity, we shortly discuss this case and further prove a theorem which says that by imposing that the metric functions are the reciprocal of each other (grr = 1/gtt ), the f(Q) gravity theory reduces to the symmetric teleparallel equivalent of general relativity (plus a cosmological constant), and the metric takes the (Anti)de-Sitter-Schwarzschild form.

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39

Jones, KRW. "Newtonian Quantum Gravity." Australian Journal of Physics 48, no. 6 (1995): 1055. http://dx.doi.org/10.1071/ph951055.

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We develop a nonlinear quantum theory of Newtonian gravity consistent with an objective interpretation of the wavefunction. Inspired by the ideas of Schrodinger, and Bell, we seek a dimensional reduction procedure to map complex wavefunctions in configuration space onto a family of observable fields in space-time. Consideration of quasi-classical conservation laws selects the reduced one-body quantities as the basis for an explicit quasi-classical coarse-graining. These we interpret as describing the objective reality of the laboratory. Thereafter, we examine what may stand in the role of the usual Copenhagen observer to localise this quantity against macroscopic dispersion. Only a tiny change is needed, via a generically attractive self-potential. A nonlinear treatment of gravitational self-energy is thus advanced. This term sets a scale for all wavepackets. The Newtonian cosmology is thus closed, without need of an external observer. Finally, the concept of quantisation is re-interpreted as a nonlinear eigenvalue problem. To illustrate, we exhibit an elementary family of gravitationally self-bound solitary waves. Contrasting this theory with its canonically quantised analogue, we find that the given interpretation is empirically distinguishable, in principle. This result encourages deeper study of nonlinear field theories as a testable alternative to canonically quantised gravity.

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40

Aguero-Santacruz, Raul, and David Bermudez. "Hawking radiation in optics and beyond." Philosophical Transactions of the Royal Society A: Mathematical, Physical and Engineering Sciences 378, no. 2177 (July 20, 2020): 20190223. http://dx.doi.org/10.1098/rsta.2019.0223.

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Hawking radiation was originally proposed in astrophysics, but it has been generalized and extended to other physical systems receiving the name of analogue Hawking radiation. In the last two decades, several attempts have been made to measure it in a laboratory, and one of the most successful systems is in optics. Light interacting in a dielectric material causes an analogue Hawking effect, in fact, its stimulated version has already been detected and the search for the spontaneous signal is currently ongoing. We briefly review the general derivation of Hawking radiation, then we focus on the optical analogue and present some novel numerical results. Finally, we call for a generalization of the term Hawking radiation. This article is part of a discussion meeting issue ‘The next generation of analogue gravity experiments’.

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41

BATISTA, A. B., J. C. FABRIS, S. V. B. GONCALVES, and J. TOSSA. "QUANTUM PERFECT FLUID COSMOLOGICAL MODEL AND ITS CLASSICAL ANALOGUE." International Journal of Modern Physics A 17, no. 20 (August 10, 2002): 2749. http://dx.doi.org/10.1142/s0217751x0201176x.

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The quantization of gravity coupled to a perfect fluid model leads to a Schrödinger-like equation, where the matter variable plays the role of time. The wave function can be determined, in the flat case, for an arbitrary barotropic equation of state p = α ρ; solutions can also be found for the radiative non-flat case. The wave packets are constructed, from which the expectation value for the scale factor is determined. The quantum scenarios reveal a bouncing Universe, free from singularity. Such quantum cosmological perfect fluid models admit a universal classical analogue, represented by the addition, to the ordinary classical model, of a repulsive stiff matter fluid1,2. The existence of this universal classical analogue may imply that this perfect fluid coupled to gravity model is not a real quantum system. The quantum cosmological perfect fluid model is, for a flat spatial section, formally equivalent to a free particle in ordinary quantum mechanics, for any value of α, while the radiative non-flat case is equivalent to the harmonic oscillator. The repulsive fluid needed to reproduce the quantum results is the same in both cases.

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42

Rusanov, P. G. "Gravitational analogue of the Earth and its shape." Izvestiya MGTU MAMI 8, no. 4-4 (August 20, 2014): 76–83. http://dx.doi.org/10.17816/2074-0530-67379.

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Method of numerical simulation of shape of the Earth has shown that its real shape does not correspond to the central gravitational field. Two-mass analogue source of noncentral gravity field of the Earth in form of a nucleus and the equatorial ring is proposed. There were calculated two element masses model and radius of ring under which the estimated figure of the Earth and dependence gravitational acceleration on its surface on latitude correspond to experimental data and international agreements.

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43

Liberati, Stefano, Matt Visser, and Silke Weinfurtner. "Analogue quantum gravity phenomenology from a two-component Bose–Einstein condensate." Classical and Quantum Gravity 23, no. 9 (April 5, 2006): 3129–54. http://dx.doi.org/10.1088/0264-9381/23/9/023.

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Goulart, E., M. Novello, F. T. Falciano, and J. D. Toniato. "Hidden geometries in nonlinear theories: a novel aspect of analogue gravity." Classical and Quantum Gravity 28, no. 24 (November 29, 2011): 245008. http://dx.doi.org/10.1088/0264-9381/28/24/245008.

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Evans, P. W., and K. P. Y. Thébault. "On the limits of experimental knowledge." Philosophical Transactions of the Royal Society A: Mathematical, Physical and Engineering Sciences 378, no. 2177 (July 20, 2020): 20190235. http://dx.doi.org/10.1098/rsta.2019.0235.

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To demarcate the limits of experimental knowledge, we probe the limits of what might be called an experiment. By appeal to examples of scientific practice from astrophysics and analogue gravity, we demonstrate that the reliability of knowledge regarding certain phenomena gained from an experiment is not circumscribed by the manipulability or accessibility of the target phenomena. Rather, the limits of experimental knowledge are set by the extent to which strategies for what we call ‘inductive triangulation’ are available: that is, the validation of the mode of inductive reasoning involved in the source-target inference via appeal to one or more distinct and independent modes of inductive reasoning. When such strategies are able to partially mitigate reasonable doubt, we can take a theory regarding the phenomena to be well supported by experiment. When such strategies are able to fully mitigate reasonable doubt, we can take a theory regarding the phenomena to be established by experiment. There are good reasons to expect the next generation of analogue experiments to provide genuine knowledge of unmanipulable and inaccessible phenomena such that the relevant theories can be understood as well supported. This article is part of a discussion meeting issue ‘The next generation of analogue gravity experiments’.

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GONZÁLEZ-FERNÁNDEZ, B., and A. CAMACHO. "FLUID-GRAVITY CORRESPONDENCE UNDER THE PRESENCE OF VISCOSITY." Modern Physics Letters A 27, no. 32 (October 11, 2012): 1250185. http://dx.doi.org/10.1142/s0217732312501854.

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This work addresses the analogy between the speed of sound of a viscous, barotropic, and irrotational fluid and the equation of motion for a non-massive field in a curved manifold. It will be shown that the presence of viscosity implies the introduction, into the equation of motion of the gravitational analogue, of a source term which entails the flow of energy from the non-massive field to the curvature of the spacetime manifold. The stress–energy tensor is also computed and it is found not to be constant, which is consistent with such energy interchange.

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Jusufi, Kimet, and Ali Övgün. "Canonical acoustic thin-shell wormholes." Modern Physics Letters A 32, no. 07 (February 27, 2017): 1750047. http://dx.doi.org/10.1142/s021773231750047x.

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In this paper, we model a canonical acoustic thin-shell wormhole (CATSW) in the framework of analogue gravity systems. In this model, we apply cut and paste technique to join together two spherically symmetric, analogue canonical acoustic solutions, and compute the analogue surface density/surface pressure of the fluid using the Darmois–Israel formalism. We study the stability analyses by using a linear barotropic fluid (LBF), Chaplygin fluid (CF), logarithmic fluid (LogF), polytropic fluid (PF) and finally Van der Waals Quintessence (VDWQ). We show that a kind of analog acoustic fluid with negative energy is required at the throat to keep the wormhole stable. It is argued that CATSW can be a stabile thin-shell wormhole if we choose a suitable parameter values.

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Sahu, Chunendra K., and M. R. Flynn. "Filling box flows in porous media." Journal of Fluid Mechanics 782 (October 9, 2015): 455–78. http://dx.doi.org/10.1017/jfm.2015.555.

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We report upon a theoretical and experimental investigation of a porous medium ‘filling box’ flow by specifically examining the details of the laminar descending plume and its outflow in a control volume having an impermeable bottom boundary and sidewalls. The plume outflow initially comprises a pair of oppositely directed gravity currents. The gravity currents propagate horizontally until they reach the lateral sidewalls at $y=\pm L$. The flow then becomes of filling box type, with a vertically ascending ‘first front’ separating discharged plume fluid below from ambient fluid above. The flow details are described analytically by first deriving a new similarity solution for Darcy plumes with $\mathit{Pe}>O(1)$, where $\mathit{Pe}$ is the Péclet number. From the similarity solution so obtained, we then derive expressions for the plume volume flux and mean reduced gravity as functions of the vertical distance from the source. Regarding the plume outflow, a similarity solution adopted from Huppert & Woods (J. Fluid Mech., vol. 292, 1995, pp. 55–69) describes the height and front speed of the gravity currents, whereas a semi-implicit finite difference scheme is used to predict the first front elevation versus time and horizontal distance. As with high-Reynolds-number filling box flows, that studied here is an example of a coupled problem: the gravity current source conditions are prescribed by the plume volume flux and mean reduced gravity. Conversely, discharged plume fluid may be re-entrained into the plume, be it soon or long after reaching the bottom impermeable boundary. To corroborate our model predictions, analogue laboratory experiments are performed with fresh water and salt water as the working fluids. Our experiments consider as independent variables the porous medium bead diameter and the plume source volume flux and reduced gravity. Predictions for the gravity current front position and height compare favourably against analogue measured data. Good agreement is likewise noted when considering either the mean elevation or the profile of the first front. Results from this study may be adopted in modelling geological plumes. For example, our equations can be used to predict the time required for discharged plume fluid to return to the point of injection in the case of aquifers closed on the sides and below by impermeable boundaries.

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Fagnocchi, S., S. Finazzi, S. Liberati, M. Kormos, and A. Trombettoni. "Relativistic Bose–Einstein condensates: a new system for analogue models of gravity." New Journal of Physics 12, no. 9 (September 30, 2010): 095012. http://dx.doi.org/10.1088/1367-2630/12/9/095012.

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Dardashti, Radin, Karim P. Y. Thébault, and Eric Winsberg. "Confirmation via Analogue Simulation: What Dumb Holes Could Tell Us about Gravity." British Journal for the Philosophy of Science 68, no. 1 (March 1, 2017): 55–89. http://dx.doi.org/10.1093/bjps/axv010.

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