Relativity and Gravitation: Classical and Quantum

D’Olivo, J. C.; Nahmad-Achar, Eduardo; Rosenbaum, M.; Ryan, Michael P.; Urrutia, L. F.; Zertuche, Federico

doi:10.1142/9789814538657

Cited by 10 publications

(22 citation statements)

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“…is the most general form that describes cylindrically symmetric spacetimes, where γ, ψ, ω and W are functions of t and r only. However, it is clear that this metric does not include the rotating cylindrical GW spacetimes studied by Mashhoon and Quevedo (MQ) [233,234,266],…”

Section: Cylindrically Symmetric Spacetimesmentioning

confidence: 99%

Cylindrical systems in general relativity

Бронников

Santos

Wang

2020

Class. Quantum Grav.

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With the arrival of the era of gravitational wave astronomy, the strong gravitational field regime will be explored soon in various aspects. In this article, we provide a general review over cylindrical systems in Einstein's theory of general relativity. In particular, we first review the general properties, both local and global, of several important solutions of Einstein's field equations, including the Levi-Civita and Lewis solutions and their extensions to include the cosmological constant and matter fields, and pay particular attention to properties that represent the generic features of the theory, such as the formation of the observed extragalactic jets and gravitational Faraday rotation. We also review studies of cylindrical wormholes, gravitational collapse and Hoop conjecture, and polarizations of gravitational waves. In addition, by rigorously defining cylindrically symmetric spacetimes, we clarify various (incorrect) claims existing in the literature, regarding to the generality of such spacetimes.

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Section: Cylindrically Symmetric Spacetimesmentioning

confidence: 99%

Cylindrical systems in general relativity

Бронников

Santos

Wang

2020

Class. Quantum Grav.

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“…In this section we will rederive the magnitudes of

(Equation ( 3 )) and

(Equation ( 8 )) by using causal-set theory and (generalized) unimodular gravity. The causal-set theory [ 31 ] stipulates that continuous geometries in classical gravity should be replaced by “causal-sets”, the discrete substratum of spacetime. In the framework of the causal-set theory, the fluctuation in the number of elements N making up the set is of the Poisson type, that is,

.…”

Section: From Causal-set Theory and Unimodular Gravity To Space-timentioning

confidence: 99%

Entropy and Gravitation—From Black Hole Computers to Dark Energy and Dark Matter

2019

Entropy

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We show that the concept of entropy and the dynamics of gravitation provide the linchpin in a unified scheme to understand the physics of black hole computers, spacetime foam, dark energy, dark matter and the phenomenon of turbulence. We use three different methods to estimate the foaminess of spacetime, which, in turn, provides a back-door way to derive the Bekenstein-Hawking formula for black hole entropy and the holographic principle. Generalizing the discussion for a static spacetime region to the cosmos, we find a component of dark energy (resembling an effective positive cosmological constant of the correct magnitude) in the current epoch of the universe. The conjunction of entropy and gravitation is shown to give rise to a phenomenological model of dark matter, revealing the natural emergence, in galactic and cluster dynamics, of a critical acceleration parameter related to the cosmological constant; the resulting mass profiles are consistent with observations. Unlike ordinary matter, the quanta of the dark sector are shown to obey infinite statistics. This property of dark matter may lead to some non-particle phenomenology, and may explain why dark matter particles have not been detected in dark matter search experiments. We also show that there are deep similarities between the problem of "quantum gravity" (more specifically, the holographic spacetime foam) and turbulence.

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“…Example 6 (General emergent 3D-space). Let us start from a known 3D-space, which may be Σ = R 3 or a more general manifold (as in Canonical Quantum Gravity [8]) or even a discrete graph or hypergraph (as in other approaches to Quantum Gravity like causal sets [9], Regge calculus [10], causal dynamical triangulations [11], Loop Quantum Gravity [12,13]). Let P denote the set of all types of particles, and A := P × Σ.…”

Section: Implications Of Non-uniqueness For the Emergence Of Various ...mentioning

confidence: 99%

No-go results on emergent space and other structures

Stoica

2023

J. Phys.: Conf. Ser.

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It is often claimed that, from the abstract quantum state vector and Hamiltonian, everything emerges uniquely (for example the 3D-space, a preferred factorization of the Hilbert space, and a preferred basis). This thesis, called Hilbert-Space Fundamentalism (HSF), is assumed for example in Carroll and Singh’s “Mad-dog Everettianism”, some proposals based on decoherence, proposals that aim to describe everything by the quantum structure alone, and proposals that spacetime emerges from a purely quantum theory of gravity. I show that whenever the 3D-space, a preferred factorization, or any other structure emerges like this, there are infinitely many solutions. This refutes Hilbert-Space Fundamentalism. Implications for various research programs aiming to show that certain structures emerge uniquely, and for various interpretations of Quantum Mechanics, are discussed.

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Relativity and Gravitation: Classical and Quantum

Cited by 10 publications

References 0 publications

Cylindrical systems in general relativity

Cylindrical systems in general relativity

Entropy and Gravitation—From Black Hole Computers to Dark Energy and Dark Matter

No-go results on emergent space and other structures

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