Special Issue "Varying Constants and Fundamental Cosmology"

A special issue of Universe (ISSN 2218-1997).

Deadline for manuscript submissions: 1 April 2017

Special Issue Editors

Guest Editor
Prof. Mariusz P. Dąbrowski

Cosmology Group, Institute of Physics, University of Szczecin, Wielkopolska 15, 70-451 Szczecin, Poland
Website | E-Mail
Interests: general relativity and cosmology; alternative gravities; superstring and brane cosmology; quantum cosmology; standard and non-standard cosmological singularities; varying constants (theory, observations, experiment); superstring landscape and the multiverse
Guest Editor
Dr. Manuel Krämer

Cosmology Group, Institute of Physics, University of Szczecin, Wielkopolska 15, 70-451 Szczecin, Poland
Website | E-Mail
Interests: general relativity; quantum gravity and quantum cosmology; CMB and density perturbations due to quantum effects, spacetime singularities, multiverse and varying constants
Guest Editor
Dr. Vincenzo Salzano

Cosmology Group, Institute of Physics, University of Szczecin, Wielkopolska 15, 70-451 Szczecin, Poland
Website | E-Mail
Interests: observational cosmology; variability of the physical constants (theory and observations); dark energy

Special Issue Information

Dear Colleagues,

This Special Issue will be the proceedings of the conference “Varying Constants and Fundamental Cosmology”, which will take place in Szczecin, Poland, 12–17 September, 2016. This is the fourth of the fundamental cosmology conferences organized by the Cosmology Group, University of Szczecin (after Cosmofun’2005, Grasscosmofun’09, Multicosmofun’12).

The task of the conference is to bring together specialists dealing with the problems of varying (dynamical) physical constants, standard and fundamental cosmology (based on unification particle physics theories, such as superstring/brane theories, alternative gravities, etc.) and the multiverse idea (Everett many-world interpretation, quantum entanglement, superstring landscape, etc.), who want to exchange current ideas on these topics. Renowned specialists in the fields have confirmed their attendance. Among them, three Templeton Prize Awardees dealing with cosmological implications of varying constants and the mathematical structure of the universe John D. Barrow, Paul C.W. Davies and Michael Heller, the founder of the idea of the anthropic principle–Brandon Carter—as well as many specialists in the field of observational tests of varying constants, such as John Webb, Victor Flambaum, and Michael Murphy. The program of the conference will contain five plenary morning sessions and four afternoon parallel sessions. Morning sessions will mainly (though not exceptionally) be devoted to both theoretical and observational aspects of varying constants, while parallel sessions will also contain a great deal of standard and fundamental cosmology (dark energy, dark matter, inflation and the early universe, cosmic microwave background, gravitational waves, quantum gravity and cosmology, observational cosmology).

This Special Issue of Universe will contain longer review articles by invited speakers, as well as selected by the session conveners short invited articles by parallel session speakers.

For more information about the conference idea see: https://indico.cern.ch/e/varcosmo16

Prof. Mariusz P. Dąbrowski
Dr. Manuel Krämer
Dr. Vincenzo Salzano
Guest Editors

Manuscript Submission Information

Manuscripts should be submitted online at www.mdpi.com by registering and logging in to this website. Once you are registered, click here to go to the submission form. Manuscripts can be submitted until the deadline. All papers will be peer-reviewed. Accepted papers will be published continuously in the journal (as soon as accepted) and will be listed together on the special issue website. Research articles, review articles as well as short communications are invited. For planned papers, a title and short abstract (about 100 words) can be sent to the Editorial Office for announcement on this website.

Submitted manuscripts should not have been published previously, nor be under consideration for publication elsewhere (except conference proceedings papers). All manuscripts are thoroughly refereed through a single-blind peer-review process. A guide for authors and other relevant information for submission of manuscripts is available on the Instructions for Authors page. Universe is an international peer-reviewed open access quarterly journal published by MDPI.

Please visit the Instructions for Authors page before submitting a manuscript. The Article Processing Charge (APC) is waived for well-prepared manuscripts submitted to this issue. Submitted papers should be well formatted and use good English. Authors may use MDPI's English editing service prior to publication or during author revisions.

Published Papers (18 papers)

View options order results:
result details:
Displaying articles 1-18
Export citation of selected articles as:

Research

Jump to: Review, Other

Open AccessArticle From Quantum to Cosmological Regime. The Role of Forcing and Exotic 4-Smoothness
Universe 2017, 3(2), 31; doi:10.3390/universe3020031
Received: 30 January 2017 / Revised: 5 March 2017 / Accepted: 21 March 2017 / Published: 27 March 2017
PDF Full-text (268 KB) | HTML Full-text | XML Full-text
Abstract
Recently, a cosmological model based on smooth open 4-manifolds admitting non-standard smoothness structures was proposed. The manifolds are exotic versions of R4 and S3×R. The model has been developed further and proven to be capable of obtaining some
[...] Read more.
Recently, a cosmological model based on smooth open 4-manifolds admitting non-standard smoothness structures was proposed. The manifolds are exotic versions of R 4 and S 3 × R . The model has been developed further and proven to be capable of obtaining some realistic cosmological parameters from these exotic smoothings. The important problem of the quantum origins of the exotic smoothness of space-time is addressed here. It is shown that the algebraic structure of the quantum-mechanical lattice of projections enforces exotic smoothness on R n . Since the only possibility for such a structure is exotic R 4 , it is found to be a reasonable explanation of the large-scale four-dimensionality of space-time. This is based on our recent research indicating the role of set-theoretic forcing in quantum mechanics. In particular, it is shown that a distributive lattice of projections implies the standard smooth structure on R 4 . Two examples of models valid for cosmology are discussed. The important result that the cosmological constant can be identified with the constant curvature of the embedding ( exotic R 4 ) R 4 is referred. . The calculations are in good agreement with the observed small value of the dark energy density. Full article
(This article belongs to the Special Issue Varying Constants and Fundamental Cosmology)
Open AccessArticle Spin-Field Correspondence
Universe 2017, 3(2), 29; doi:10.3390/universe3020029
Received: 4 January 2017 / Revised: 15 March 2017 / Accepted: 21 March 2017 / Published: 23 March 2017
PDF Full-text (337 KB) | HTML Full-text | XML Full-text
Abstract
In the recent article Phys. Lett. B 2016, 759, 424–429, a new class of field theories called Nonlinear Field Space Theory was proposed. In this approach, the standard field theories are considered as linear approximations to some more general theories characterized
[...] Read more.
In the recent article Phys. Lett. B 2016, 759, 424–429, a new class of field theories called Nonlinear Field Space Theory was proposed. In this approach, the standard field theories are considered as linear approximations to some more general theories characterized by nonlinear field phase spaces. The case of spherical geometry is especially interesting due to its relation with the spin physics. Here, we explore this possibility, showing that classical scalar field theory with such a field space can be viewed as a perturbation of a continuous spin system. In this picture, the spin precession and the scalar field excitations are dual descriptions of the same physics. The duality is studied in the example of the Heisenberg model. It is shown that the Heisenberg model coupled to a magnetic field leads to a non-relativistic scalar field theory, characterized by quadratic dispersion relation. Finally, on the basis of analysis of the relation between the spin phase space and the scalar field theory, we propose the Spin-Field correspondence between the known types of fields and the corresponding spin systems. Full article
(This article belongs to the Special Issue Varying Constants and Fundamental Cosmology)
Figures

Figure 1

Open AccessArticle On the Causality and K-Causality between Measures
Universe 2017, 3(1), 27; doi:10.3390/universe3010027
Received: 31 January 2017 / Revised: 1 March 2017 / Accepted: 11 March 2017 / Published: 20 March 2017
PDF Full-text (257 KB) | HTML Full-text | XML Full-text
Abstract
Drawing from the optimal transport theory adapted to the Lorentzian setting, we propose and study the extension of the Sorkin–Woolgar causal relation K+ onto the space of Borel probability measures on a given spacetime. We show that it retains its fundamental properties
[...] Read more.
Drawing from the optimal transport theory adapted to the Lorentzian setting, we propose and study the extension of the Sorkin–Woolgar causal relation K + onto the space of Borel probability measures on a given spacetime. We show that it retains its fundamental properties of transitivity and closedness. Furthermore, we list and prove several characterizations of this relation, including the “measure-theoretic” analogue of the characterization of K + in terms of time functions. Full article
(This article belongs to the Special Issue Varying Constants and Fundamental Cosmology)
Open AccessArticle Cosmology with Varying Constants from a Thermodynamic Viewpoint
Universe 2017, 3(1), 26; doi:10.3390/universe3010026
Received: 31 January 2017 / Revised: 6 March 2017 / Accepted: 13 March 2017 / Published: 17 March 2017
PDF Full-text (215 KB) | HTML Full-text | XML Full-text
Abstract
We study the variation of fundamental constants in cosmology while dealing with thermodynamic aspects of gravity. We focus on the variation of the speed of light, c, and Newton’s gravitational constant, G, with respect to cosmic time. We find the constraints
[...] Read more.
We study the variation of fundamental constants in cosmology while dealing with thermodynamic aspects of gravity. We focus on the variation of the speed of light, c, and Newton’s gravitational constant, G, with respect to cosmic time. We find the constraints on the possible variation of these constants by comparing varying constants of cosmological models with the latest observational data. Full article
(This article belongs to the Special Issue Varying Constants and Fundamental Cosmology)
Open AccessArticle Cosmological Perturbations in Phantom Dark Energy Models
Universe 2017, 3(1), 22; doi:10.3390/universe3010022
Received: 27 January 2017 / Revised: 24 February 2017 / Accepted: 26 February 2017 / Published: 6 March 2017
PDF Full-text (1066 KB) | HTML Full-text | XML Full-text
Abstract
The ΛCDM paradigm, characterised by a constant equation of state w=1 for dark energy, is the model that better fits observations. However, the same observations strongly support the possibility of a dark energy content where the corresponding equation of state
[...] Read more.
The ΛCDM paradigm, characterised by a constant equation of state w = 1 for dark energy, is the model that better fits observations. However, the same observations strongly support the possibility of a dark energy content where the corresponding equation of state is close to but slightly smaller than 1 . In this regard, we focus on three different models where the dark energy content is described by a perfect fluid with an equation of state w 1 which can evolve or not. The three proposals show very similar behaviour at present, while the asymptotic evolution of each model drives the Universe to different abrupt events known as (i) Big Rip; (ii) Little Rip (LR); and (iii) Little Sibling of the Big Rip. With the aim of comparing these models and finding possible imprints in their predicted matter distribution, we compute the matter power spectrum and the growth rate f σ 8 . We conclude that the model which induces a LR seems to be favoured by observations. Full article
(This article belongs to the Special Issue Varying Constants and Fundamental Cosmology)
Figures

Figure 1

Open AccessArticle 3-Form Cosmology: Phantom Behaviour, Singularities and Interactions
Universe 2017, 3(1), 21; doi:10.3390/universe3010021
Received: 27 January 2017 / Revised: 19 February 2017 / Accepted: 26 February 2017 / Published: 3 March 2017
PDF Full-text (713 KB) | HTML Full-text | XML Full-text
Abstract
The latest cosmological observations by the Planck collaboration (and combined with others) are compatible with a phantom-like behaviour (w<1) for the dark energy equation of state that drives the current acceleration of the Universe. With this mindset, we
[...] Read more.
The latest cosmological observations by the Planck collaboration (and combined with others) are compatible with a phantom-like behaviour ( w < 1 ) for the dark energy equation of state that drives the current acceleration of the Universe. With this mindset, we look into models where dark energy is described by a 3-form field minimally coupled to gravity. When compared to a scalar field, these models have the advantage of more naturally accommodating a cosmological-constant and phantom-like behaviours. We show how the latter happens for a fairly general class of positive-valued potentials, and through a dynamical system approach, we find that in such cases the 3-form field leads the Universe into a Little Sibling of the Big Rip singular event into the future. In this work, we explore the possibility of avoiding such singularity via an interaction in the dark sector between cold dark matter and the 3-form field. For the kind of interactions considered, we deduce a condition for replacing the LSBR by a late time de Sitter phase. For specific examples of interactions that meet this condition, we look for distinctive imprints in the statefinder hierarchy { S 3 ( 1 ) ; S 4 ( 1 ) } , { S 3 ( 1 ) ; S 5 ( 1 ) } , and in the growth rate of matter, ϵ ( z ) , through the composite null diagnostic (CND). Full article
(This article belongs to the Special Issue Varying Constants and Fundamental Cosmology)
Figures

Figure 1

Open AccessArticle Non-Standard Hierarchies of the Runnings of the Spectral Index in Inflation
Universe 2017, 3(1), 17; doi:10.3390/universe3010017
Received: 30 January 2017 / Accepted: 26 February 2017 / Published: 2 March 2017
PDF Full-text (236 KB) | HTML Full-text | XML Full-text
Abstract
Recent analyses of cosmic microwave background surveys have revealed hints that there may be a non-trivial running of the running of the spectral index. If future experiments were to confirm these hints, it would prove a powerful discriminator of inflationary models, ruling out
[...] Read more.
Recent analyses of cosmic microwave background surveys have revealed hints that there may be a non-trivial running of the running of the spectral index. If future experiments were to confirm these hints, it would prove a powerful discriminator of inflationary models, ruling out simple single field models. We discuss how isocurvature perturbations in multi-field models can be invoked to generate large runnings in a non-standard hierarchy, and find that a minimal model capable of practically realising this would be a two-field model with a non-canonical kinetic structure. We also consider alternative scenarios such as variable speed-of-light models and canonical quantum gravity effects and their implications for runnings of the spectral index. Full article
(This article belongs to the Special Issue Varying Constants and Fundamental Cosmology)
Open AccessArticle Bell Violation in Primordial Cosmology
Universe 2017, 3(1), 13; doi:10.3390/universe3010013
Received: 27 December 2016 / Revised: 7 February 2017 / Accepted: 8 February 2017 / Published: 17 February 2017
PDF Full-text (721 KB) | HTML Full-text | XML Full-text
Abstract
In this paper, we have worked on the possibility of setting up an Bell’s inequality violating experiment in the context of primordial cosmology following the fundamental principles of quantum mechanics. To set up this proposal, we have introduced a model-independent theoretical framework using
[...] Read more.
In this paper, we have worked on the possibility of setting up an Bell’s inequality violating experiment in the context of primordial cosmology following the fundamental principles of quantum mechanics. To set up this proposal, we have introduced a model-independent theoretical framework using which we have studied the creation of new massive particles for the scalar fluctuations in the presence of an additional time-dependent mass parameter. Next we explicitly computed the one-point and two-point correlation functions from this setup. Then, we comment on the measurement techniques of isospin breaking interactions of newly introduced massive particles and its further prospects. After that, we give an example of the string theory-originated axion monodromy model in this context. Finally, we provide a bound on the heavy particle mass parameter for any arbitrary spin field. Full article
(This article belongs to the Special Issue Varying Constants and Fundamental Cosmology)
Figures

Figure 1

Open AccessArticle Nonlinear Gravitational Waves as Dark Energy in Warped Spacetimes
Universe 2017, 3(1), 11; doi:10.3390/universe3010011
Received: 14 December 2016 / Revised: 8 February 2017 / Accepted: 10 February 2017 / Published: 15 February 2017
PDF Full-text (277 KB) | HTML Full-text | XML Full-text
Abstract
We find an azimuthal-angle dependent approximate wave like solution to second order on a warped five-dimensional manifold with a self-gravitating U(1) scalar gauge field (cosmic string) on the brane using the multiple-scale method. The spectrum of the several orders of approximation show maxima
[...] Read more.
We find an azimuthal-angle dependent approximate wave like solution to second order on a warped five-dimensional manifold with a self-gravitating U(1) scalar gauge field (cosmic string) on the brane using the multiple-scale method. The spectrum of the several orders of approximation show maxima of the energy distribution dependent on the azimuthal-angle and the winding numbers of the subsequent orders of the scalar field. This breakup of the quantized flux quanta does not lead to instability of the asymptotic wavelike solution due to the suppression of the n-dependency in the energy momentum tensor components by the warp factor. This effect is triggered by the contribution of the five dimensional Weyl tensor on the brane. This contribution can be understood as dark energy and can trigger the self-acceleration of the universe without the need of a cosmological constant. There is a striking relation between the symmetry breaking of the Higgs field described by the winding number and the SO(2) breaking of the axially symmetric configuration into a discrete subgroup of rotations of about 180 . The discrete sequence of non-axially symmetric deviations, cancelled by the emission of gravitational waves in order to restore the SO(2) symmetry, triggers the pressure T z z for discrete values of the azimuthal-angle. There could be a possible relation between the recently discovered angle-preferences of polarization axes of quasars on large scales and our theoretical predicted angle-dependency and this could be evidence for the existence of cosmic strings. Careful comparison of this spectrum of extremal values of the first and second order φ-dependency and the distribution of the alignment of the quasar polarizations is necessary. This can be accomplished when more observational data become available. It turns out that, for late time, the vacuum 5D spacetime is conformally invariant if the warp factor fulfils the equation of a vibrating “drum”, describing standing normal modes of the brane. Full article
(This article belongs to the Special Issue Varying Constants and Fundamental Cosmology)
Open AccessArticle The Relation between Fundamental Constants and Particle Physics Parameters
Universe 2017, 3(1), 6; doi:10.3390/universe3010006
Received: 16 December 2016 / Revised: 12 January 2017 / Accepted: 13 January 2017 / Published: 24 January 2017
PDF Full-text (251 KB) | HTML Full-text | XML Full-text
Abstract
The observed constraints on the variability of the proton to electron mass ratio μ and the fine structure constant α are used to establish constraints on the variability of the Quantum Chromodynamic Scale and a combination of the Higgs Vacuum Expectation Value and
[...] Read more.
The observed constraints on the variability of the proton to electron mass ratio μ and the fine structure constant α are used to establish constraints on the variability of the Quantum Chromodynamic Scale and a combination of the Higgs Vacuum Expectation Value and the Yukawa couplings. Further model dependent assumptions provide constraints on the Higgs VEV and the Yukawa couplings separately. A primary conclusion is that limits on the variability of dimensionless fundamental constants such as μ and α provide important constraints on the parameter space of new physics and cosmologies. Full article
(This article belongs to the Special Issue Varying Constants and Fundamental Cosmology)
Figures

Figure 1

Review

Jump to: Research, Other

Open AccessReview The Geometry of Noncommutative Spacetimes
Universe 2017, 3(1), 25; doi:10.3390/universe3010025
Received: 11 February 2017 / Revised: 10 March 2017 / Accepted: 12 March 2017 / Published: 16 March 2017
PDF Full-text (286 KB) | HTML Full-text | XML Full-text
Abstract
We review the concept of ‘noncommutative spacetime’ approached from an operational stand-point and explain how to endow it with suitable geometrical structures. The latter involves i.a. the causal structure, which we illustrate with a simple—‘almost-commutative’—example. Furthermore, we trace the footprints of noncommutive geometry
[...] Read more.
We review the concept of ‘noncommutative spacetime’ approached from an operational stand-point and explain how to endow it with suitable geometrical structures. The latter involves i.a. the causal structure, which we illustrate with a simple—‘almost-commutative’—example. Furthermore, we trace the footprints of noncommutive geometry in the foundations of quantum field theory. Full article
(This article belongs to the Special Issue Varying Constants and Fundamental Cosmology)
Figures

Figure 1

Open AccessReview Dark Energy and Spacetime Symmetry
Universe 2017, 3(1), 20; doi:10.3390/universe3010020
Received: 23 January 2017 / Revised: 27 February 2017 / Accepted: 1 March 2017 / Published: 3 March 2017
PDF Full-text (280 KB) | HTML Full-text | XML Full-text
Abstract
The Petrov classification of stress-energy tensors provides a model-independent definition of a vacuum by the algebraic structure of its stress-energy tensor and implies the existence of vacua whose symmetry is reduced as compared with the maximally symmetric de Sitter vacuum associated with the
[...] Read more.
The Petrov classification of stress-energy tensors provides a model-independent definition of a vacuum by the algebraic structure of its stress-energy tensor and implies the existence of vacua whose symmetry is reduced as compared with the maximally symmetric de Sitter vacuum associated with the Einstein cosmological term. This allows to describe a vacuum in general setting by dynamical vacuum dark fluid, presented by a variable cosmological term with the reduced symmetry which makes vacuum fluid essentially anisotropic and allows it to be evolving and clustering. The relevant solutions to the Einstein equations describe regular cosmological models with time-evolving and spatially inhomogeneous vacuum dark energy, and compact vacuum objects generically related to a dark energy: regular black holes, their remnants and self-gravitating vacuum solitons with de Sitter vacuum interiors—which can be responsible for observational effects typically related to a dark matter. The mass of objects with de Sitter interior is generically related to vacuum dark energy and to breaking of space-time symmetry. In the cosmological context spacetime symmetry provides a mechanism for relaxing cosmological constant to a needed non-zero value. Full article
(This article belongs to the Special Issue Varying Constants and Fundamental Cosmology)
Figures

Figure 1

Other

Jump to: Research, Review

Open AccessConference Report Dark Energy Constraints from Espresso Tests of the Stability of Fundamental Couplings
Universe 2017, 3(2), 30; doi:10.3390/universe3020030
Received: 30 January 2017 / Revised: 15 March 2017 / Accepted: 17 March 2017 / Published: 24 March 2017
PDF Full-text (278 KB) | HTML Full-text | XML Full-text
Abstract
ESPRESSO is a high-resolution-ultra-stable spectrograph for the Very Large Telescope (VLT), whose commissioning will start in 2017. One of its key science goals is to test the stability of nature’s fundamental couplings with unprecedented accuracy and control of possible systematics. A total of
[...] Read more.
ESPRESSO is a high-resolution-ultra-stable spectrograph for the Very Large Telescope (VLT), whose commissioning will start in 2017. One of its key science goals is to test the stability of nature’s fundamental couplings with unprecedented accuracy and control of possible systematics. A total of 27 nights of the ESPRESSO Consortium’s guaranteed time observations (GTO) will be spent on testing the stability of the fine-structure constant and other fundamental couplings. A set of 14 priority optimal targets have been selected for the GTO period. In this work, we discuss the criteria underlying this selection, describe the selected targets, and present some forecasts of the impact of these measurements on fundamental physics and cosmology, focusing on dark energy constraints and using future supernova type Ia surveys as a comparison point. This report is a summary of the results reported in Phys. Rev. D 2016, 94, 123512, to which we refer the reader for further details. Full article
(This article belongs to the Special Issue Varying Constants and Fundamental Cosmology)
Figures

Figure 1

Open AccessConference Report Quantum Entanglement in the Multiverse
Universe 2017, 3(2), 28; doi:10.3390/universe3020028
Received: 12 January 2017 / Revised: 16 March 2017 / Accepted: 17 March 2017 / Published: 23 March 2017
PDF Full-text (608 KB) | HTML Full-text | XML Full-text
Abstract
In this report, we consider cosmological implications of quantum entanglement between two causally disconnected universes in the multiverse. Supposing that our universe was initially entangled with a causally separated universe, we compute the spectrum of vacuum fluctuations of our universe. To clearly see
[...] Read more.
In this report, we consider cosmological implications of quantum entanglement between two causally disconnected universes in the multiverse. Supposing that our universe was initially entangled with a causally separated universe, we compute the spectrum of vacuum fluctuations of our universe. To clearly see the effect of entanglement, we compare it with the spectrum of an initially non-entangled state. It is found that, due to quantum interference, scale-dependent modulations may enter the spectrum for the case of an initially non-entangled state. We discuss that the existence of causally disconnected universes may be experimentally tested by analyzing correlators in detail. Full article
(This article belongs to the Special Issue Varying Constants and Fundamental Cosmology)
Figures

Figure 1

Open AccessConference Report Infinitesimal Structure of Singularities
Universe 2017, 3(1), 16; doi:10.3390/universe3010016
Received: 9 January 2017 / Revised: 19 February 2017 / Accepted: 20 February 2017 / Published: 27 February 2017
PDF Full-text (232 KB) | HTML Full-text | XML Full-text
Abstract
Some important problems of general relativity, such as the quantisation of gravity or classical singularity problems, crucially depend on geometry on very small scales. The so-called synthetic differential geometry—a categorical counterpart of the standard differential geometry—provides a tool to penetrate infinitesimally small portions
[...] Read more.
Some important problems of general relativity, such as the quantisation of gravity or classical singularity problems, crucially depend on geometry on very small scales. The so-called synthetic differential geometry—a categorical counterpart of the standard differential geometry—provides a tool to penetrate infinitesimally small portions of space-time. We use this tool to show that on any “infinitesimal neighbourhood” the components of the curvature tensor are themselves infinitesimal, and construct a simplified model in which the curvature singularity disappears, owing to this effect. However, one pays a price for this result. Using topoi as a generalisation of spaces requires a weakening of arithmetic (the existence of infinitesimals) and of logic (to the intuitionistic logic). Is this too high a price to pay for acquiring a new method of solving unsolved problems in physics? Without trying, we shall never know the answer. Full article
(This article belongs to the Special Issue Varying Constants and Fundamental Cosmology)
Open AccessConference Report Quantum Correlations in de Sitter Space
Universe 2017, 3(1), 2; doi:10.3390/universe3010002
Received: 5 December 2016 / Revised: 19 December 2016 / Accepted: 20 December 2016 / Published: 1 January 2017
PDF Full-text (391 KB) | HTML Full-text | XML Full-text
Abstract
We study quantum correlation of a massive scalar field in a maximally entangled state in de Sitter space. We prepare two observers, one in a global chart and the other in an open chart of de Sitter space. We find that the state
[...] Read more.
We study quantum correlation of a massive scalar field in a maximally entangled state in de Sitter space. We prepare two observers, one in a global chart and the other in an open chart of de Sitter space. We find that the state becomes less entangled as the curvature of the open chart gets larger. In particular, for the cases of a massless and a conformally coupled scalar field, the quantum entanglement vanishes in the limit of infinite curvature. However, we find that the quantum discord never disappears, even in the limit that entanglement disappears. Full article
(This article belongs to the Special Issue Varying Constants and Fundamental Cosmology)
Figures

Figure 1

Open AccessConference Report New Constraints on Spatial Variations of the Fine Structure Constant from Clusters of Galaxies
Universe 2016, 2(4), 34; doi:10.3390/universe2040034
Received: 30 October 2016 / Revised: 6 December 2016 / Accepted: 12 December 2016 / Published: 21 December 2016
PDF Full-text (671 KB) | HTML Full-text | XML Full-text
Abstract
We have constrained the spatial variation of the fine structure constant using multi-frequency measurements of the thermal Sunyaev-Zeldovich effect of 618 X-ray selected clusters. Although our results are not competitive with the ones from quasar absorption lines, we improved by a factor 10
[...] Read more.
We have constrained the spatial variation of the fine structure constant using multi-frequency measurements of the thermal Sunyaev-Zeldovich effect of 618 X-ray selected clusters. Although our results are not competitive with the ones from quasar absorption lines, we improved by a factor 10 and ∼2.5 previous results from Cosmic Microwave Background power spectrum and from galaxy clusters, respectively. Full article
(This article belongs to the Special Issue Varying Constants and Fundamental Cosmology)
Figures

Figure 1

Open AccessConference Report Experimental Studies on the Lorentz Symmetry in Post-Newtonian Gravity with Pulsars
Universe 2016, 2(4), 29; doi:10.3390/universe2040029
Received: 30 October 2016 / Revised: 17 November 2016 / Accepted: 23 November 2016 / Published: 1 December 2016
PDF Full-text (342 KB) | HTML Full-text | XML Full-text
Abstract
Local Lorentz invariance (LLI) is one of the most important fundamental symmetries in modern physics. While the possibility of LLI violation (LLIv) was studied extensively in flat spacetime, its counterpart in gravitational interaction also deserves significant examination from experiments. In this contribution, I
[...] Read more.
Local Lorentz invariance (LLI) is one of the most important fundamental symmetries in modern physics. While the possibility of LLI violation (LLIv) was studied extensively in flat spacetime, its counterpart in gravitational interaction also deserves significant examination from experiments. In this contribution, I review several recent studies of LLI in post-Newtonian gravity, using powerful tools of pulsar timing. It shows that precision pulsar timing experiments hold a unique position to probe LLIv in post-Newtonian gravity. Full article
(This article belongs to the Special Issue Varying Constants and Fundamental Cosmology)

Journal Contact

MDPI AG
Universe Editorial Office
St. Alban-Anlage 66, 4052 Basel, Switzerland
E-Mail: 
Tel. +41 61 683 77 34
Fax: +41 61 302 89 18
Editorial Board
Contact Details Submit to Special Issue Edit a special issue Review for Universe
Back to Top