Beyond the Schwarzschild Metric

2018 ◽  
Author(s):  
David M. Wittman
Keyword(s):  
Black Holes ◽  
General Relativity ◽  
Gravitational Waves ◽  
Test Particle ◽  
Direct Detection ◽  
Relativistic Effects ◽  
Big Bang ◽  
Clusters Of Galaxies ◽  
General Relativistic ◽  
The Universe

General relativity explains much more than the spacetime around static spherical masses.We briefly assess general relativity in the larger context of physical theories, then explore various general relativistic effects that have no Newtonian analog. First, source massmotion gives rise to gravitomagnetic effects on test particles.These effects also depend on the velocity of the test particle, which has substantial implications for orbits around black holes to be further explored in Chapter 20. Second, any changes in the sourcemass ripple outward as gravitational waves, and we tell the century‐long story from the prediction of gravitational waves to their first direct detection in 2015. Third, the deflection of light by galaxies and clusters of galaxies allows us to map the amount and distribution of mass in the universe in astonishing detail. Finally, general relativity enables modeling the universe as a whole, and we explore the resulting Big Bang cosmology.

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.

The Direct Detection of Gravitational Waves

2018 ◽  
pp. 106-109
Author(s):  
Alvaro De Rújula
Keyword(s):  
Black Holes ◽  
General Relativity ◽  
Black Hole ◽  
Gravitational Waves ◽  
Direct Detection ◽  
Space Time ◽  
New Era ◽  
The Third ◽  
Perfect Storm

Gravitational waves emitted by black hole mergers. The first LIGO event: GW150917, the coalescence of two black holes of twenty nine and thirty six solar masses into one of “only” sixty two. The remaining three solar masses were emitted as energy in gravitational waves, a gigantic and perfect storm in the fabric of space-time. This is the dawn of a new era: The opening of the third “window” through which to look at the sky. Yet another triumph of general relativity. How much progress astrophysics has made since my time as a student.

The black hole symphony: probing new physics using gravitational waves

2008 ◽  
Vol 366 (1884) ◽  
pp. 4365-4379 ◽  
Author(s):  
Jonathan R Gair
Keyword(s):  
Black Holes ◽  
Gravitational Waves ◽  
Direct Detection ◽  
New Physics ◽  
Relativity Theory ◽  
New Generation ◽  
Laser Interferometers ◽  
Near Future ◽  
First Time ◽  
The Universe

The next decade will very likely see the birth of a new field of astronomy as we become able to directly detect gravitational waves (GWs) for the first time. The existence of GWs is one of the key predictions of Einstein's theory of general relativity, but they have eluded direct detection for the last century. This will change thanks to a new generation of laser interferometers that are already in operation or which are planned for the near future. GW observations will allow us to probe some of the most exotic and energetic events in the Universe, the mergers of black holes. We will obtain information about the systems to a precision unprecedented in astronomy, and this will revolutionize our understanding of compact astrophysical systems. Moreover, if any of the assumptions of relativity theory are incorrect, this will lead to subtle, but potentially detectable, differences in the emitted GWs. Our observations will thus provide very precise verifications of the theory in an as yet untested regime. In this paper, I will discuss what GW observations could tell us about known and (potentially) unknown physics.

scholarly journals Recent Observations of Gravitational Waves by LIGO and Virgo Detectors

Universe ◽  
2021 ◽  
Vol 7 (5) ◽  
pp. 137
Author(s):  
Andrzej Królak ◽  
Paritosh Verma
Keyword(s):  
Black Holes ◽  
General Relativity ◽  
Neutron Stars ◽  
Gravitational Waves ◽  
Gravitational Radiation ◽  
Direct Detection ◽  
Nobel Prize Winner ◽  
Short Introduction ◽  
Interferometric Detectors ◽  
Laser Interferometric

In this paper we present the most recent observations of gravitational waves (GWs) by LIGO and Virgo detectors. We also discuss contributions of the recent Nobel prize winner, Sir Roger Penrose to understanding gravitational radiation and black holes (BHs). We make a short introduction to GW phenomenon in general relativity (GR) and we present main sources of detectable GW signals. We describe the laser interferometric detectors that made the first observations of GWs. We briefly discuss the first direct detection of GW signal that originated from a merger of two BHs and the first detection of GW signal form merger of two neutron stars (NSs). Finally we present in more detail the observations of GW signals made during the first half of the most recent observing run of the LIGO and Virgo projects. Finally we present prospects for future GW observations.

scholarly journals Light, Gravity, Expansion, Relativity, Black Holes and Black Energy - Considerations at the Scale of Universe

2019 ◽  
Vol 11 (4) ◽  
pp. 61-69 ◽  
Author(s):  
Corneliu BERBENTE ◽  
Sorin BERBENTE ◽  
Marius BREBENEL
Keyword(s):  
Black Holes ◽  
General Relativity ◽  
Refractive Index ◽  
Incompressible Fluid ◽  
Big Bang ◽  
Neutron Decay ◽  
Time Interval ◽  
Proposed Model ◽  
Standard Picture ◽  
The Universe

Light, gravity, the Universe expansion and relativity in a simple but accurate enough model of Universe are studied. The proposed model starts with a singularity (BIG BANG or better said BIG FLASH). Unlike the standard picture where in the first stage there exists a “soup” of light and various particles (electrons, neutrinos, hydrogen, helium etc.), here the light energy is maintained for a longer time interval and a structure by dividing the Universe sphere is introduced. The first stage ends when neutrons (substance) appear by an effect of resonance. Then other particles are first formed by the neutron decay. After the occurrence of the substance, a hydrodynamic model of gravity is introduced through an analogy with the sources interaction in an incompressible fluid. It allows to obtain many interesting results. The model can be easily adapted to include special relativity effects. As regards the general relativity simple expressions for the scale of Universe do not seem to apply to the mass and radius of the Universe, currently accepted. Then, the possibility of using such simple relationships based on the light refractive index in the largest possible regions is studied.

Black Holes

2021 ◽  
pp. 53-65
Author(s):  
Gianfranco Bertone
Keyword(s):  
Black Holes ◽  
Dark Matter ◽  
Dark Energy ◽  
Gravitational Waves ◽  
Nuclear Fuel ◽  
Big Bang ◽  
The Sun ◽  
Modern Physics ◽  
The Big Bang ◽  
The Universe

In the second part of the book, I argue that the four biggest mysteries of modern physics and astronomy—dark matter, dark energy, black holes, and the Big Bang—sink their roots into the physics of the infinitely small. And I argue that gravitational waves may shed new light on, and possibly solve, each of these four mysteries. I start here by introducing the problem of dark matter, the mysterious substance that permeates the Universe at all scales and describe the gravitational waves observations that might soon elucidate its nature. The next time you see the Sun shining in the sky, consider this: what blinds your eyes and warms your skin is an immense nuclear furnace, which transforms millions of tons of nuclear fuel into energy every second. And when you contemplate the night sky, try to visualize it for what it essentially is: an endless expanse of colossal natural reactors, forging the atoms that we, and everything that surrounds us, are made of.

scholarly journals PSEUDO-NEWTONIAN GRAVITATIONAL POTENTIAL FOR SCHWARZSCHILD–DE SITTER SPACE–TIMES

2008 ◽  
Vol 17 (11) ◽  
pp. 2089-2105 ◽  
Author(s):  
ZDENĚK STUCHLÍK ◽  
JIŘÍ KOVÁŘ
Keyword(s):  
Black Holes ◽  
Gravitational Field ◽  
Accretion Disks ◽  
Gravitational Potential ◽  
Test Particle ◽  
De Sitter Space ◽  
Spherically Symmetric ◽  
De Sitter ◽  
General Relativistic ◽  
The Universe

Pseudo-Newtonian gravitational potential describing the gravitational field of static and spherically symmetric black holes in the universe with a repulsive cosmological constant is introduced. In order to demonstrate the accuracy of the pseudo-Newtonian approach, the related effective potential for test particle motion is constructed and compared with its general-relativistic counterpart given by the Schwarzschild–de Sitter geometry. The results indicate that such an approach could be useful in applications of developed Newtonian theories of accretion disks in astrophysically interesting situations in large galactic structures for the Schwarzschild–de Sitter space–times with the cosmological parameter y = Λ M2/3 ≤ 10-6.

scholarly journals Gravitational Waves Carry Information about the Infalling Matter out of Black Holes: a Resolution of the Black Hole Information Paradox

2020 ◽  
Author(s):  
Xueyi Tian
Keyword(s):  
Black Holes ◽  
General Relativity ◽  
Black Hole ◽  
Quantum Mechanics ◽  
Gravitational Waves ◽  
Hawking Radiation ◽  
Information Loss ◽  
Information Paradox ◽  
Black Hole Information ◽  
The Universe

The black hole information paradox is one of the most puzzling paradoxes in physics. Black holes trap everything that falls into them, while their mass may leak away through purely thermal Hawking radiation. When a black hole vanishes, all the information locked inside, if any, is just lost, thus challenging the principles of quantum mechanics. However, some information does have a way to escape from inside the black hole, that is, through gravitational waves. Here, a concise extension of this notion is introduced. When a black hole swallows something, whether it is a smaller black hole or an atom, the system emits gravitational waves carrying the information about the “food”. Although most of the signals are too weak to be detected, the information encoded within them will persist in the universe. This speculation provides an explanation for a large part, if not all, of the supposed “information loss” in black holes, and thus reconciles the predictions of general relativity and quantum mechanics.

scholarly journals Testing General Relativity with Pulsar Timing Arrays

2012 ◽  
Author(s):  
Sydney Chamberlin ◽  
Xavier Siemens
Keyword(s):  
General Relativity ◽  
Gravitational Waves ◽  
Direct Detection ◽  
Promising Tool ◽  
Pulsar Timing ◽  
Theories Of Gravity ◽  
Statistical Detection ◽  
Detection Strategies ◽  
Pulsar Timing Array ◽  
The Universe

Pulsar timing arrays are a promising tool for probing the universe through gravitational radiation. A variety of astrophysical and cosmological sources are expected to contribute to a stochastic background of gravitational waves (GWs) in the pulsar timing array (PTA) frequency band. Direct detection of GWs will provide a new mechanism to test General Relativity and requires the development of robust statistical detection strategies. Here, we investigate the overlap reduction function, a term present in the optimal detection statistic, for GWs in various metric theories of gravity. We show that PTA sensitivity increases for non-transverse gravitational waves when pulsar pairs have small angular separations in the sky. 

Gravity

2021 ◽  
Author(s):  
James B. Hartle
Keyword(s):  
Black Holes ◽  
General Relativity ◽  
Gravitational Waves ◽  
Undergraduate Curriculum ◽  
Physics First ◽  
Cambridge University ◽  
Introductory Course ◽  
Modern Physics ◽  
The Subject ◽  
Curriculum Making

Einstein's theory of general relativity is a cornerstone of modern physics. It also touches upon a wealth of topics that students find fascinating – black holes, warped spacetime, gravitational waves, and cosmology. Now reissued by Cambridge University Press, this ground-breaking text helped to bring general relativity into the undergraduate curriculum, making it accessible to virtually all physics majors. One of the pioneers of the 'physics-first' approach to the subject, renowned relativist James B. Hartle, recognized that there is typically not enough time in a short introductory course for the traditional, mathematics-first, approach. In this text, he provides a fluent and accessible physics-first introduction to general relativity that begins with the essential physical applications and uses a minimum of new mathematics. This market-leading text is ideal for a one-semester course for undergraduates, with only introductory mechanics as a prerequisite.

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