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Understanding large amounts of spatiotemporal data from particle-based simulations, such as molecular dynamics, often relies on the computation and analysis of aggregate measures. These, however, by virtue of aggregation, hide structural…

Computational Physics · Physics 2019-10-10 Juraj Pálenik , Jan Byška , Stefan Bruckner , Helwig Hauser

Cosmological perturbations are generally described by quantum fields on (curved but) classical space-times. While this strategy has a large domain of validity, it can not be justified in the quantum gravity era where curvature and matter…

General Relativity and Quantum Cosmology · Physics 2015-06-12 Ivan Agullo , Abhay Ashtekar , William Nelson

A review is made of recent efforts to define linear connections and their corresponding curvature within the context of noncommutative geometry. As an application it is suggested that it is possible to identify the gravitational field as a…

General Relativity and Quantum Cosmology · Physics 2009-10-28 J. Madore

We present a new code for solving the coupled Einstein-hydrodynamics equations to evolve relativistic, self-gravitating fluids. The Einstein field equations are solved on one grid using pseudospectral methods, while the fluids are evolved…

General Relativity and Quantum Cosmology · Physics 2016-11-15 Matthew D. Duez , Lawrence E. Kidder , Saul A. Teukolsky

We consider a general formulation of gradient flow evolution for problems whose natural framework is the one of metric spaces. The applications we deal with are concerned with the evolution of {\it capacitary measures} with respect to the…

Analysis of PDEs · Mathematics 2011-09-27 Dorin Bucur , Giuseppe Buttazzo , Ulisse Stefanelli

A new type of fluid matter model in general relativity is introduced, in which the fluid particles are subject to velocity diffusion without friction. In order to compensate for the energy gained by the fluid particles due to diffusion, a…

General Relativity and Quantum Cosmology · Physics 2015-06-04 Simone Calogero

We develop a method to estimate space-time flow statistics from a limited set of known data. While previous work has focused on modeling spatial or temporal statistics independently, space-time statistics carry fundamental information about…

Fluid Dynamics · Physics 2020-01-08 Aaron Towne , Adrian Lozano-Duran , Xiang Yang

In a novel application of the tools of topological data analysis (TDA) to nonperturbative quantum gravity, we introduce a new class of observables that allows us to assess whether quantum spacetime really resembles a ``quantum foam" near…

High Energy Physics - Theory · Physics 2025-10-08 J. van der Duin , R. Loll , M. Schiffer , A. Silva

The properties of some locally rotationally symmetric (LRS) perfect fluid space-times are examined in order to demonstrate the usage of the description of geometries in terms of the Riemann tensor and a finite number of its covariant…

General Relativity and Quantum Cosmology · Physics 2009-10-28 Mattias Marklund

This series of works revisits the geometry, dynamics, and covariant phase space of spherically symmetric spacetimes with the aim of exploring the thermodynamics of spacetime from their dynamical properties. In this first paper, we examine…

General Relativity and Quantum Cosmology · Physics 2026-01-07 Puttarak Jai-akson , Yuki Yokokura

The main purpose of this paper is to seek a mechanical interpretation of gravitational phenomena. We suppose that the universe may be filled with a kind of fluid which may be called the $\Omega (0)$ substratum. Thus, the inverse-square law…

General Physics · Physics 2017-12-29 Xiao-Song Wang

We review the study of inhomogeneous perturbations about a homogeneous and isotropic background cosmology. We adopt a coordinate based approach, but give geometrical interpretations of metric perturbations in terms of the expansion, shear…

Astrophysics · Physics 2010-04-23 Karim A. Malik , David Wands

Spatio-temporal forecasting has numerous applications in analyzing wireless, traffic, and financial networks. Many classical statistical models often fall short in handling the complexity and high non-linearity present in time-series data.…

Machine Learning · Statistics 2021-06-14 Soumyasundar Pal , Liheng Ma , Yingxue Zhang , Mark Coates

The recent introduction of the gradient flow has provided a new tool to probe the dynamics of quantum field theories. The latest developments have shown how to use the gradient flow for the exploration of symmetries, and the definition of…

High Energy Physics - Theory · Physics 2015-06-16 Luigi Del Debbio , Agostino Patella , Antonio Rago

Finding diffeomorphism-invariant observables to characterize the properties of gravity and spacetime at the Planck scale is essential for making progress in quantum gravity. The holonomy and Wilson loop of the Levi-Civita connection are…

General Relativity and Quantum Cosmology · Physics 2020-09-24 N. Klitgaard , R. Loll , Marcus Reitz , Reiko Toriumi

Analogue gravity offers an approach for testing the universality and robustness of quantum field theories in curved spacetimes and validating them using down-to-earth, laboratory-based experiments. Fluid interfaces are a promising framework…

General Relativity and Quantum Cosmology · Physics 2023-06-27 Vitor S. Barroso , Cameron R. D. Bunney , Silke Weinfurtner

The change of the effective dimension of spacetime with the probed scale is a universal phenomenon shared by independent models of quantum gravity. Using tools of probability theory and multifractal geometry, we show how dimensional flow is…

High Energy Physics - Theory · Physics 2012-08-16 Gianluca Calcagni

There are many complementary approaches to the construction of solutions to the field equations of general relativity. Among these, numerical approximation offers the only possibility to compute a variety of dynamical spacetimes, and so has…

General Relativity and Quantum Cosmology · Physics 2024-05-13 David Hilditch

It is well known that in quantum gravity, the very geometry of space and time is subject to continual fluctuation. The mathematical formulation for this old theory is still lacking. This article formulates this more than forty-year-old…

General Relativity and Quantum Cosmology · Physics 2024-09-27 Behzad Tajahmad

I present a way to visualize the concept of curved spacetime. The result is a curved surface with local coordinate systems (Minkowski Systems) living on it, giving the local directions of space and time. Relative to these systems, special…

General Relativity and Quantum Cosmology · Physics 2008-11-26 Rickard Jonsson