scholarly journals MASSIVE GRAVITATIONAL WAVES FROM THE R2 THEORY OF GRAVITY: PRODUCTION AND RESPONSE OF INTERFEROMETERS

2008 ◽  
Vol 23 (10) ◽  
pp. 1521-1535 ◽  
Author(s):  
CHRISTIAN CORDA
Keyword(s):  
Dark Matter ◽  
Gravitational Waves ◽  
Longitudinal Force ◽  
High Order ◽  
Gravity Theory ◽  
Theory Of Gravity ◽  
Gravity Theories ◽  
The Universe

We show that from the R2 high order gravity theory it is possible to produce, in the linearized approach, particles which can be seen as massive modes of gravitational waves (GW's). The presence of the mass generates a longitudinal force in addition of the transverse one which is proper of the massless gravitational waves and the response an interferometer to the effect is computed. This could be, in principle, important to discriminate among the gravity theories. The presence of the mass could also have important applications in cosmology because the fact that gravitational waves can have mass could give a contribution to the dark matter of the Universe.

scholarly journals A NON-GEODESIC MOTION IN THE R-1 THEORY OF GRAVITY TUNED WITH OBSERVATIONS

2008 ◽  
Vol 23 (02) ◽  
pp. 109-114 ◽  
Author(s):  
CHRISTIAN CORDA
Keyword(s):  
Dark Matter ◽  
High Order ◽  
Ricci Scalar ◽  
Geodesic Motion ◽  
General Picture ◽  
Test Particles ◽  
Pioneer Anomaly ◽  
Theories Of Gravity ◽  
Theory Of Gravity

In the general picture of high order theories of gravity, recently, the R-1 theory has been analyzed in two different frameworks. In this letter a third context is added, considering an explicit coupling between the R-1 function of the Ricci scalar and the matter Lagrangian. The result is a non-geodesic motion of test particles which, in principle, could be connected with Dark Matter and Pioneer anomaly problems.

A Tale of Two Infinities

2021 ◽  
Author(s):  
Gianfranco Bertone
Keyword(s):  
Black Holes ◽  
Dark Matter ◽  
Gravitational Waves ◽  
Direct Detection ◽  
Traditional Approach ◽  
Fundamental Physics ◽  
Modern Cosmology ◽  
Nobel Prize In Physics ◽  
The Universe ◽  
Modern Astronomy

The spectacular advances of modern astronomy have opened our horizon on an unexpected cosmos: a dark, mysterious Universe, populated by enigmatic entities we know very little about, like black holes, or nothing at all, like dark matter and dark energy. In this book, I discuss how the rise of a new discipline dubbed multimessenger astronomy is bringing about a revolution in our understanding of the cosmos, by combining the traditional approach based on the observation of light from celestial objects, with a new one based on other ‘messengers’—such as gravitational waves, neutrinos, and cosmic rays—that carry information from otherwise inaccessible corners of the Universe. Much has been written about the extraordinary potential of this new discipline, since the 2017 Nobel Prize in physics was awarded for the direct detection of gravitational waves. But here I will take a different angle and explore how gravitational waves and other messengers might help us break the stalemate that has been plaguing fundamental physics for four decades, and to consolidate the foundations of modern cosmology.

scholarly journals What are the wild waves saying? Yet another meditation on the predictions, searches for, and detections of gravitational waves

2018 ◽  
Vol 27 (14) ◽  
pp. 1830009
Author(s):  
Virginia Trimble
Keyword(s):  
General Relativity ◽  
Gravitational Waves ◽  
Point Of View ◽  
Large Majority ◽  
Laboratory Apparatus ◽  
New Information ◽  
Theory Of Gravity ◽  
To Come ◽  
The Universe

A large majority of the physics and astronomy communities are now sure that gravitational waves exist, can be looked for, and can be studied via their effects on laboratory apparatus as well as on astronomical objects. So far, everything found out has agreed with the predictions of general relativity, but hopes are high for new information about the universe and its contents and perhaps for hints of a better theory of gravity than general relativity (which even Einstein expected to come eventually). This is one version of the story, from 1905 to the present, told from an unusual point of view, because the author was, for 28.5 years, married to Joseph Weber, who built the first detectors starting in the early 1960s and operated one or more until his death on 30 September 2000.

Most of the Universe is Missing!

2019 ◽  
pp. 64-72
Author(s):  
Nicholas Mee
Keyword(s):  
Dark Matter ◽  
Galaxy Clusters ◽  
Early Universe ◽  
The World ◽  
Unknown Form ◽  
Theory Of Gravity ◽  
Stable Particles ◽  
The Universe

Most of the matter in the universe exists in an unknown form called dark matter. All estimates of the mass of galaxies and galaxy clusters suggest they contain far more matter than is visible to us in the form of stars. Conventional explanations, such as the existence of large quantities of burnt-out stars known as MACHOs or dark gas clouds, have been ruled out. The most popular explanation is that dark matter consists of vast quantities of hypothetical stable particles known as WIMPs that were produced in vast quantities in the very early universe. Many laboratories around the world are searching for signs of these particles. These include the Italian Gran Sasso laboratory running the XENON100 experiment. Some theorists have suggested the evidence for dark matter would disappear if we had a better theory of gravity. Analysis of the Bullet Cluster indicates such proposals will not work.

Orbits

2018 ◽  
Author(s):  
David M. Wittman
Keyword(s):  
General Relativity ◽  
Dark Matter ◽  
Milky Way ◽  
Extrasolar Planets ◽  
Binary Star ◽  
Milky Way Galaxy ◽  
Newtonian Model ◽  
Theory Of Gravity ◽  
The Masses ◽  
The Universe

Orbits are ubiquitous in the universe: moons orbit planets, planets orbit stars, stars orbit around the center of the Milky Way galaxy, and so on. Any theory of gravity will have to explain the properties of all these orbits. To pave the way for developing the metric theory of gravity (general relativity) this chapter examines the basics of orbits as observed and as explained by the Newtonian model of gravity. We can use our understanding of gravity to infer the masses and other properties of these cosmic systems. Te chapter concludes with four optional sections in this spirit, covering the slingshot maneuver; dark matter; binary star orbits and how they reveal the masses of stars; and extrasolar planets.

Dark Matter

2021 ◽  
pp. 66-78
Author(s):  
Gianfranco Bertone
Keyword(s):  
Dark Matter ◽  
Dark Energy ◽  
Gravitational Waves ◽  
Expansion Rate ◽  
The Earth ◽  
Modern Cosmology ◽  
Large Effort ◽  
The Universe

I introduce here the problem of dark energy, a substance that appears to be pushing the Universe to expand ever faster and discuss the large effort currently in place to understand its origin. I describe the surprising recent discovery of a widening crack in the cathedral of modern cosmology arising from the measurement of the expansion rate of the Universe. And I argue that gravitational waves observations can help us to either repair that crack, or to bring down that magnificent building, in case it turns out to be fatally flawed. Before all women and all men. Before animals, plants, archaeans, bacteria. Before the Earth was formed and the stars were lit. Before everything we know, the Universe was immersed in an amorphous and oblivious darkness.

scholarly journals Unified Description of Dark Energy and Dark Matter within the Generalized Hybrid Metric-Palatini Theory of Gravity

Universe ◽  
2020 ◽  
Vol 6 (6) ◽  
pp. 78 ◽  
Author(s):  
Paulo M. Sá
Keyword(s):  
Dark Matter ◽  
Dark Energy ◽  
Scalar Fields ◽  
Accelerated Expansion ◽  
Late Time ◽  
Intermediate Phases ◽  
Expansion Of The Universe ◽  
Theory Of Gravity ◽  
The Universe ◽  
Unified Description

The generalized hybrid metric-Palatini theory of gravity admits a scalar-tensor representation in terms of two interacting scalar fields. We show that, upon an appropriate choice of the interaction potential, one of the scalar fields behaves like dark energy, inducing a late-time accelerated expansion of the universe, while the other scalar field behaves like pressureless dark matter that, together with ordinary baryonic matter, dominates the intermediate phases of cosmic evolution. This unified description of dark energy and dark matter gives rise to viable cosmological solutions, which reproduce the main features of the evolution of the universe.

scholarly journals A Study on the Detection Method of Dark Matter using Gravitational Waves

2021 ◽  
Vol 2083 (2) ◽  
pp. 022044
Author(s):  
Zheng Li ◽  
Chenyu Yang ◽  
Xinen Zhou
Keyword(s):  
Dark Matter ◽  
Gravitational Wave ◽  
Gravitational Waves ◽  
Laser Interferometer ◽  
Theory Of Relativity ◽  
General Theory Of Relativity ◽  
Detection Schemes ◽  
The Universe ◽  
Matter Detection ◽  
Shed Light

Abstract Dark matter is a type of invisible matter that analytically exists in the universe. Nowadays, scholars have yet detected it and confirmed its presence experimentally. Einstein predicted gravitational waves based on his general theory of relativity. In 2015, the Laser Interferometer Gravitational-Wave Observatory (LIGO) first detected the gravitational wave. This paper reviews the background of dark matter and gravitational waves and introduces the method of detecting dark matter with gravitational waves. Moreover, the feasibility of the scenario has been verified based on information retrieval and theoretical analysis. These results shed light on the future detection schemes of dark matter detection.

scholarly journals Gravitational waves at their own gravitational speed

2018 ◽  
Vol 27 (14) ◽  
pp. 1847015 ◽  
Author(s):  
C. S. Unnikrishnan ◽  
George T. Gillies
Keyword(s):  
General Relativity ◽  
Gravitational Waves ◽  
Light Propagation ◽  
Geometric Theory ◽  
Speed Of Light ◽  
Determining Factors ◽  
Permittivity And Permeability ◽  
Theory Of Gravity ◽  
Permeability Constants ◽  
The Universe

Gravitational waves propagate at the speed of light in general relativity, because of their special relativistic basis. However, light propagation is linked to the electromagnetic phenomena, with the permittivity and permeability constants as the determining factors. Is there a deeper reason why waves in a geometric theory of gravity propagate at a speed determined by electromagnetic constants? What is the relation between gravity’s own constants and the speed of gravitational waves? Our attempt to answer these fundamental questions takes us far and deep into the universe.

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