scholarly journals LONG RANGE GRAVITY TESTS AND THE PIONEER ANOMALY

2007 ◽  
Vol 16 (12a) ◽  
pp. 2091-2105 ◽  
Author(s):  
SERGE REYNAUD ◽  
MARC-THIERRY JAEKEL
Keyword(s):  
General Relativity ◽  
Dark Matter ◽  
Dark Energy ◽  
Solar System ◽  
Equivalence Principle ◽  
Experimental Tests ◽  
Pioneer Anomaly ◽  
New Space ◽  
Tests Of Gravity ◽  
Good Agreement

Experimental tests of gravity performed in the solar system show a good agreement with general relativity. The latter is, however, challenged by the Pioneer anomaly, which might be pointing at some modification of gravity law at ranges of the order of the size of the solar system. As this question could be related to the puzzles of "dark matter" or "dark energy," it is important to test it with care. There exist metric extensions of general relativity which preserve the well-verified equivalence principle while possibly changing the metric solution in the solar system. Such extensions have the capability to preserve compatibility with existing gravity tests while opening free space for the Pioneer anomaly. They constitute arguments for new mission designs and new space technologies as well as for having a new look at data of already-performed experiments.

scholarly journals ATLAS probe: Breakthrough science of galaxy evolution, cosmology, Milky Way, and the Solar System

2019 ◽  
Vol 36 ◽  
Author(s):  
Yun Wang ◽  
Massimo Robberto ◽  
Mark Dickinson ◽  
Lynne A. Hillenbrand ◽  
Wesley Fraser ◽  
...  
Keyword(s):  
General Relativity ◽  
Dark Matter ◽  
Dark Energy ◽  
Solar System ◽  
Galaxy Evolution ◽  
Milky Way ◽  
Space Mission ◽  
Field Of View ◽  
Wide Field ◽  
Large Area

AbstractAstrophysics Telescope for Large Area Spectroscopy Probe is a concept for a National Aeronautics and Space Administration probe-class space mission that will achieve ground-breaking science in the fields of galaxy evolution, cosmology, Milky Way, and the Solar System. It is the follow-up space mission to Wide Field Infrared Survey Telescope (WFIRST), boosting its scientific return by obtaining deep 1–4 μm slit spectroscopy for ∼70% of all galaxies imaged by the ∼2 000 deg2WFIRST High Latitude Survey atz> 0.5. Astrophysics Telescope for Large Area Spectroscopy will measure accurate and precise redshifts for ∼200 M galaxies out toz< 7, and deliver spectra that enable a wide range of diagnostic studies of the physical properties of galaxies over most of cosmic history. Astrophysics Telescope for Large Area Spectroscopy Probe and WFIRST together will produce a 3D map of the Universe over 2 000 deg2, the definitive data sets for studying galaxy evolution, probing dark matter, dark energy and modifications of General Relativity, and quantifying the 3D structure and stellar content of the Milky Way. Astrophysics Telescope for Large Area Spectroscopy Probe science spans four broad categories: (1) Revolutionising galaxy evolution studies by tracing the relation between galaxies and dark matter from galaxy groups to cosmic voids and filaments, from the epoch of reionisation through the peak era of galaxy assembly; (2) Opening a new window into the dark Universe by weighing the dark matter filaments using 3D weak lensing with spectroscopic redshifts, and obtaining definitive measurements of dark energy and modification of General Relativity using galaxy clustering; (3) Probing the Milky Way’s dust-enshrouded regions, reaching the far side of our Galaxy; and (4) Exploring the formation history of the outer Solar System by characterising Kuiper Belt Objects. Astrophysics Telescope for Large Area Spectroscopy Probe is a 1.5 m telescope with a field of view of 0.4 deg2, and uses digital micro-mirror devices as slit selectors. It has a spectroscopic resolution ofR= 1 000, and a wavelength range of 1–4 μm. The lack of slit spectroscopy from space over a wide field of view is the obvious gap in current and planned future space missions; Astrophysics Telescope for Large Area Spectroscopy fills this big gap with an unprecedented spectroscopic capability based on digital micro-mirror devices (with an estimated spectroscopic multiplex factor greater than 5 000). Astrophysics Telescope for Large Area Spectroscopy is designed to fit within the National Aeronautics and Space Administration probe-class space mission cost envelope; it has a single instrument, a telescope aperture that allows for a lighter launch vehicle, and mature technology (we have identified a path for digital micro-mirror devices to reach Technology Readiness Level 6 within 2 yr). Astrophysics Telescope for Large Area Spectroscopy Probe will lead to transformative science over the entire range of astrophysics: from galaxy evolution to the dark Universe, from Solar System objects to the dusty regions of the Milky Way.

scholarly journals The local dark sector

2021 ◽  
Author(s):  
Joel Bergé ◽  
Laura Baudis ◽  
Philippe Brax ◽  
Sheng-Wey Chiow ◽  
Bruno Christophe ◽  
...  
Keyword(s):  
General Relativity ◽  
Dark Matter ◽  
Dark Energy ◽  
Solar System ◽  
Gravitational Potential ◽  
Atomic Clock ◽  
Dark Sector ◽  
New Knowledge ◽  
Near Future

AbstractWe speculate on the development and availability of new innovative propulsion techniques in the 2040s, that will allow us to fly a spacecraft outside the Solar System (at 150 AU and more) in a reasonable amount of time, in order to directly probe our (gravitational) Solar System neighborhood and answer pressing questions regarding the dark sector (dark energy and dark matter). We identify two closely related main science goals, as well as secondary objectives that could be fulfilled by a mission dedicated to probing the local dark sector: (i) begin the exploration of gravitation’s low-acceleration regime with a spacecraft and (ii) improve our knowledge of the local dark matter and baryon densities. Those questions can be answered by directly measuring the gravitational potential with an atomic clock on-board a spacecraft on an outbound Solar System orbit, and by comparing the spacecraft’s trajectory with that predicted by General Relativity through the combination of ranging data and the in-situ measurement (and correction) of non-gravitational accelerations with an on-board accelerometer. Despite a wealth of new experiments getting online in the near future, that will bring new knowledge about the dark sector, it is very unlikely that those science questions will be closed in the next two decades. More importantly, it is likely that it will be even more urgent than currently to answer them. Tracking a spacecraft carrying a clock and an accelerometer as it leaves the Solar System may well be the easiest and fastest way to directly probe our dark environment.

scholarly journals Perihelion advances for the orbits of Mercury, Earth, and Pluto from extended theory of general relativity (ETGR)

2014 ◽  
Vol 92 (12) ◽  
pp. 1709-1713
Author(s):  
Luis Santiago Ridao ◽  
Rodrigo Avalos ◽  
Martín Daniel De Cicco ◽  
Mauricio Bellini
Keyword(s):  
General Relativity ◽  
Solar System ◽  
Flat Manifold ◽  
Force Component ◽  
Extended Theory ◽  
Ricci Flat ◽  
The Earth ◽  
Canonical Metric ◽  
Planetary Orbits ◽  
Good Agreement

We explore the geodesic movement on an effective four-dimensional hypersurface that is embedded in a five-dimensional Ricci-flat manifold described by a canonical metric, to applying to planetary orbits in our solar system. Some important solutions are given, which provide the standard solutions of general relativity without any extra force component. We study the perihelion advances of Mercury, the Earth, and Pluto using the extended theory of general relativity. Our results are in very good agreement with observations and show how the foliation is determinant to the value of the perihelion’s advances. Possible applications are not limited to these kinds of orbits.

scholarly journals Entropic Information Theory: Formulae and Quantum Gravity, Bits from bit

2021 ◽  
Author(s):  
olivier denis
Keyword(s):  
Information Theory ◽  
General Relativity ◽  
Dark Matter ◽  
Quantum Mechanics ◽  
Dark Energy ◽  
Quantum Gravity ◽  
Planck Scale ◽  
Basic Structure ◽  
Mathematical Framework ◽  
Information Framework

We show here that entropic information is capable of unifying all aspects of the universe at all scales in a coherent and global theoretical mathematical framework materialized by entropic information framework, theory and formulas, where dark matter, dark energy and gravity are truly informationals processes and where information is code and code is what creates the process, it is itself the process. Mass, energy and movement of information are respectively dark matter, dark energy, and gravity. Here, we reconcile general relativity and quantum mechanics by introducing quantum gravity for the Planckian scale. The formulas of entropic information are expressed in natural units, physical units of measurement based only on universal constants, constants, which refer to the basic structure of the laws of physics: C and G are part of the structure of space-time in general relativity, and h captures the relationship between energy and frequency that is the basis of quantum mechanics. Here we show that entropic information formulas are able to present entropic information in various unifying aspects and introduce gravity at the Planck scale. We prove that Entropic information theory is thus building the bridge between general relativity and quantum mechanics

scholarly journals Observing the Dark Sector

Universe ◽  
2019 ◽  
Vol 5 (6) ◽  
pp. 137
Author(s):  
Valerio Marra ◽  
Rogerio Rosenfeld ◽  
Riccardo Sturani
Keyword(s):  
General Relativity ◽  
Dark Matter ◽  
Dark Energy ◽  
Standard Model ◽  
Dark Sector ◽  
The Standard Model

Despite the observational success of the standard model of cosmology, present-day observations do not tightly constrain the nature of dark matter and dark energy and modifications to the theory of general relativity. Here, we will discuss some of the ongoing and upcoming surveys that will revolutionize our understanding of the dark sector.

scholarly journals Can a negative-mass cosmology explain dark matter and dark energy?

2019 ◽  
Vol 626 ◽  
pp. A5 ◽  
Author(s):  
H. Socas-Navarro
Keyword(s):  
General Relativity ◽  
Dark Matter ◽  
Dark Energy ◽  
Cosmological Model ◽  
Large Scale ◽  
Dark Matter Halos ◽  
Challenging Problem ◽  
Speed Of Light ◽  
Negative Mass ◽  
Galactic Dark Matter

A recent study by Farnes (2018, A&A, 620, A92) proposed an alternative cosmological model in which both dark matter and dark energy are replaced with a single fluid of negative mass. This paper presents a critical review of that model. A number of problems and discrepancies with observations are identified. For instance, the predicted shape and density of galactic dark matter halos are incorrect. Also, halos would need to be less massive than the baryonic component, otherwise they would become gravitationally unstable. Perhaps the most challenging problem in this theory is the presence of a large-scale version of the “runaway effect”, which would result in all galaxies moving in random directions at nearly the speed of light. Other more general issues regarding negative mass in general relativity are discussed, such as the possibility of time-travel paradoxes.

Dark matter (energy) may be indistinguishable from modified gravity (MOND)

2017 ◽  
Vol 26 (12) ◽  
pp. 1743010 ◽  
Author(s):  
C. Sivaram
Keyword(s):  
General Relativity ◽  
Dark Matter ◽  
Dark Energy ◽  
Modified Gravity ◽  
Observational Evidence ◽  
Negative Results ◽  
Newtonian Dynamics ◽  
Special Cases ◽  
The Universe ◽  
Matter Energy

For Newtonian dynamics to hold over galactic scales, large amounts of dark matter (DM) are required which would dominate cosmic structures. Accounting for the strong observational evidence that the universe is accelerating requires the presence of an unknown dark energy (DE) component constituting about 70% of the matter. Several ingenious ongoing experiments to detect the DM particles have so far led to negative results. Moreover, the comparable proportions of the DM and DE at the present epoch appear unnatural and not predicted by any theory. For these reasons, alternative ideas like MOND and modification of gravity or general relativity over cosmic scales have been proposed. It is shown in this paper that these alternate ideas may not be easily distinguishable from the usual DM or DE hypotheses. Specific examples are given to illustrate this point that the modified theories are special cases of a generalized DM paradigm.

THE CONFRONTATION BETWEEN GENERAL RELATIVITY AND EXPERIMENT: A 1992 UPDATE

1992 ◽  
Vol 01 (01) ◽  
pp. 13-68 ◽  
Author(s):  
CLIFFORD M. WILL
Keyword(s):  
General Relativity ◽  
Equivalence Principle ◽  
Experimental Tests ◽  
Advanced Technology ◽  
Theoretical Frameworks ◽  
Binary Pulsar ◽  
Tests Of General Relativity ◽  
Lunar Motion ◽  
The Status ◽  
Einstein's Equivalence Principle

The status of experimental tests of general relativity and of theoretical frameworks for analysing them are reviewed. Einstein’s equivalence principle is well supported by experiments such as the Eötvös experiment, tests of special relativity, and the gravitational redshift experiment. Tests of general relativity have reached high precision, including the light deflection, the Shapiro time delay, the perihelion advance of Mercury, and the Nordtvedt effect in lunar motion. Gravitational wave damping has been detected to half a percent using the binary pulsar, and new binary pulsar systems promise further improvements. The status of the “fifth force” is discussed, along with the frontiers of experimental relativity, including proposals for testing relativistic gravity with advanced technology and spacecraft.

scholarly journals DARK ENERGY, DARK MATTER AND GRAVITY

2007 ◽  
Vol 16 (12a) ◽  
pp. 2003-2012 ◽  
Author(s):  
ORFEU BERTOLAMI
Keyword(s):  
Dark Matter ◽  
Dark Energy ◽  
Solar System ◽  
Physical Theory ◽  
Scalar Fields ◽  
High Accuracy ◽  
Scalar Theory ◽  
General Relativistic ◽  
Cosmological Tests ◽  
Theory Of Gravity

We discuss the motivation for high accuracy relativistic gravitational experiments in the solar system and complementary cosmological tests. We focus our attention on the issue of distinguishing a generic scalar theory of gravity as the underlying physical theory from the usual general-relativistic picture, where one expects the presence of fundamental scalar fields associated, for instance, with inflation, dark matter and dark energy.

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