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Universe: Feature Papers 2018 - Gravitational Physics

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

Deadline for manuscript submissions: closed (31 December 2018) | Viewed by 19618

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Prof. Dr. Lorenzo Iorio

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Ministero dell'Istruzione e del Merito, Viale Unità di Italia 68, 70125 Bari, BA, Italy
Interests: general relativity and gravitation; classical general relativity; post-newtonian approximation, perturbation theory, related approximations; gravitational waves; observational cosmology; mathematical and relativistic aspects of cosmology; modified theories of gravity; higher-dimensional gravity and other theories of gravity; experimental studies of gravity; experimental tests of gravitational theories; geodesy and gravity; harmonics of the gravity potential field; geopotential theory and determination; satellite orbits; orbit determination and improvement; astrometry and reference systems; ephemerides, almanacs, and calendars; lunar, planetary, and deep-space probes
Special Issues, Collections and Topics in MDPI journals

Dr. Ana Alonso-Serrano

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Max Planck Institute for Gravitational Physics (Albert-Einstein-Institute) Potsdam, Brandenburg, Germany
Interests: high-energy physics; general relativity; quantum field theory; special and general relativity; quantum physics; cosmology; gravitational physics; fundamental physics; quantum cosmology; black holes; wormholes; universe; multiverse; thermodynamics; relativistic quantum information; philosophy of science
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Prof. Dr. Diego Pavón

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Departamento de Física, Facultad de ciencias, Edificio Cc Universidad Autónoma de Barcelona, Campus Bellaterra, 08193 Barcelona, Spain
Interests: gravitation; mathematical cosmology; thermodynamics and statistical mechanics

Prof. Dr. Antonio Padilla

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School of Physics & Astronomy for Astronomy, University Park, University of Nottingham, Nottingham NG7 2RD, UK
Interests: dark energy; dark matter; particle physics; gravity; cosmological constant problem
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Dr. Gonzalo J. Olmo

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Guest Editor

Depto. Física Teórica & IFIC, Centro Mixto Universidad de Valencia & CSIC, 46100 Burjassot, Valencia, Spain
Interests: quantum gravity; black holes; Hawking radiation; Cosmology; inflation; modified theories of gravity; Palatini formalism; field theory; wormholes
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Special Issue Information

Dear Colleagues,

As Editor-in-Chief of the journal Universe, whose papers have been cited so far 3.1 times, on average, in ADS-indexed journals, and on behalf of its distinguished Editorial Board, it is a pleasure for me to announce the Special Issue “Universe: Feature Papers 2018—Gravitational Physics”, online on 9th March 2018. It aims to set itself at the cutting edge of the most recent advances in

1) our theoretical, phenomenological and experimental understanding of the gravitational interaction and its even more numerous and interwinted ties with other fields at all relevant distance and energy scales;

2) the disagreement between local measurements of Hubble's constant, and the value obtained from the ΛCDM model in conjunction with the data extracted from the Planck satellite mission;

3) the status of modified gravity theories after the discovery, with a high degree of accuracy, that the speeds of propagation of gravitational and light waves are equal;

4) the search for alternative solutions of gravitational field equations representing horizonless compact objects able to mimick the gravitational wave signals attributed to black holes.

Thus, we will strictly select 5–10 papers each year, as of 2018, from excellent scholars around the world to publish for free in order to benefit both authors and readers.

You are welcome to send short proposals for submissions of Feature Papers to our Editorial Office ([email protected]). They will be evaluated by Editors first, and the selected papers will be thoroughly and rigorously peer reviewed.

Prof. Dr. Lorenzo Iorio
Dr. Ana Alonso-Serrano
Prof. Dr. Diego Pavón
Prof. Antonio Padilla
Dr. Gonzalo J. Olmo
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 submissions that pass pre-check are 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 monthly journal published by MDPI.

Please visit the Instructions for Authors page before submitting a manuscript. 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 (4 papers)

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Research

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20 pages, 4542 KiB

Open AccessArticle

On Testing Frame-Dragging with LAGEOS and a Recently Announced Geodetic Satellite

by Lorenzo Iorio

Universe 2018, 4(11), 113; https://doi.org/10.3390/universe4110113 - 29 Oct 2018

Cited by 7 | Viewed by 2555

Abstract

Recently, Ciufolini and coworkers announced the forthcoming launch of a new cannonball geodetic satellite in 2019. It should be injected in an essentially circular path with the same semimajor axis a of LAGEOS (Laser Geodynamics Satellite), in orbit since 1976, and an inclination I of its orbital plane supplementary with respect to that of its existing cousin. According to their proponents, the sum of the satellites’ precessions of the longitudes of the ascending nodes

Ω

should allow one to test the general relativistic Lense–Thirring effect to a ≃0.2% accuracy level, with a contribution of the mismodeling in the even zonal harmonics

J_{ℓ}, ℓ = 2, 4, 6, \dots

of the geopotential to the total error budget as little as

0.1 %

. Actually, such an ambitious goal seems to be hardly attainable because of the direct and indirect impact of, at least, the first even zonal

J_{2}

. On the one hand, the lingering scatter of the estimated values of such a key geophysical parameter from different recent GRACE/GOCE-based (Gravity Recovery and Climate Experiment/Gravity field and steady-state Ocean Circulation Explorer) global gravity field solutions is representative of an uncertainty which may directly impact the summed Lense–Thirring node precessions at a ≃70–80% in the worst scenarios, and to a ≃3–10% level in other, more favorable cases. On the other hand, the phenomenologically measured secular decay

\dot{a}

of the semimajor axis of LAGEOS (and, presumably, of the other satellite as well), currently known at a

σ_{\dot{a}} ≃

0.03 m yr

^{- 1}

level after more than 30 yr, will couple with the sum of the

J_{2}

-induced node precessions yielding an overall bias as large as ≃20–40% after 5–10 yr. A further systematic error of the order of ≃2–14% may arise from an analogous interplay of the secular decay of the inclination

\dot{I}

with the oblateness-driven node precessions. Full article

(This article belongs to the Special Issue Universe: Feature Papers 2018 - Gravitational Physics)

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Figure A1

12 pages, 299 KiB

Open AccessArticle

Is it no Longer Necessary to Test Cosmologies with Type Ia Supernovae?

by Ram Gopal Vishwakarma and Jayant V. Narlikar

Universe 2018, 4(6), 73; https://doi.org/10.3390/universe4060073 - 19 Jun 2018

Cited by 8 | Viewed by 3898

Abstract

We look at the current practice of analyzing the magnitude–redshift relation from the data on Type Ia supernovae. We show that, if the main aim of such analysis were to check the validity of a cosmological model, then the recently advanced arguments do not serve the purpose. Rather, the procedure followed tells us only about the statistical significance of the internal parameters used in the model, whereas the model itself is tacitly assumed to give a good fit to the data. A statistical assessment of the procedure is given and it is argued that given the growing data, the validity of the cosmological model should be checked first rather than the spread of any internal parameters. In passing we also discuss some aspects of the Milne model in the light of the present test. Full article

(This article belongs to the Special Issue Universe: Feature Papers 2018 - Gravitational Physics)

12 pages, 846 KiB

Open AccessEditor’s ChoiceArticle

Perspectives on Constraining a Cosmological Constant-Type Parameter with Pulsar Timing in the Galactic Center

by Lorenzo Iorio

Universe 2018, 4(4), 59; https://doi.org/10.3390/universe4040059 - 26 Mar 2018

Cited by 14 | Viewed by 3192

Abstract

Independent tests aiming to constrain the value of the cosmological constant

Λ

are usually difficult because of its extreme smallness [...] Read more.

Independent tests aiming to constrain the value of the cosmological constant

Λ

are usually difficult because of its extreme smallness

(Λ ≃ 1 \times 10^{- 52} m^{- 2}, or 2.89 \times 10^{- 122} in Planck units)

. Bounds on it from Solar System orbital motions determined with spacecraft tracking are currently at the

≃ 10^{- 43}

–

10^{- 44} m^{- 2}

(5

–

1 \times 10^{- 113} in Planck units)

level, but they may turn out to be optimistic since

Λ

has not yet been explicitly modeled in the planetary data reductions. Accurate

(σ_{τ_{p}} ≃ 1

–

10 μ s)

timing of expected pulsars orbiting the Black Hole at the Galactic Center, preferably along highly eccentric and wide orbits, might, at least in principle, improve the planetary constraints by several orders of magnitude. By looking at the average time shift per orbit

{\bar{Δ δ τ}}_{p}^{Λ}

, an S2-like orbital configuration with

e = 0.8839, P_{b} = 16 yr

would permit a preliminarily upper bound of the order of

|Λ| ≲ 9 \times 10^{- 47} m^{- 2} (≲ 2 \times 10^{- 116} in Planck units)

if only

σ_{τ_{p}}

were to be considered. Our results can be easily extended to modified models of gravity using

Λ

-type parameters. Full article

(This article belongs to the Special Issue Universe: Feature Papers 2018 - Gravitational Physics)

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Review

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12 pages, 8553 KiB

Open AccessFeature PaperEditor’s ChoiceReview

Seeing Black Holes: From the Computer to the Telescope

by Jean-Pierre Luminet

Universe 2018, 4(8), 86; https://doi.org/10.3390/universe4080086 - 09 Aug 2018

Cited by 8 | Viewed by 8993

Abstract

Astronomical observations are about to deliver the very first telescopic image of the massive black hole lurking at the Galactic Center. The mass of data collected in one night by the Event Horizon Telescope network, exceeding everything that has ever been done in any scientific field, should provide a recomposed image in 2018. All this, forty years after the first numerical simulations performed by the present author. Full article

(This article belongs to the Special Issue Universe: Feature Papers 2018 - Gravitational Physics)

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