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We propose the first comprehensive approach for modeling and analyzing the spatiotemporal shape variability in tree-like 4D objects, i.e., 3D objects whose shapes bend, stretch, and change in their branching structure over time as they…

Computer Vision and Pattern Recognition · Computer Science 2024-08-23 Tahmina Khanam , Hamid Laga , Mohammed Bennamoun , Guanjin Wang , Ferdous Sohel , Farid Boussaid , Guan Wang , Anuj Srivastava

We find a choice of variables for the 3+1 formulation of general relativity which casts the evolution equations into (flux-conservative) symmetric-hyperbolic first order form for arbitrary lapse and shift, for the first time. We redefine…

General Relativity and Quantum Cosmology · Physics 2009-10-28 Simonetta Frittelli , Oscar Reula

This paper explores a mathematical technique for deriving dynamical invariants (i.e. constants of motion) in time-dependent gravitational potentials. The method relies on the construction of a canonical transformation that removes the…

Astrophysics of Galaxies · Physics 2015-06-16 Jorge Peñarrubia

A metric-field approach to gravitation is presented. It is based on an idea of dependency of space-time properties on measuring instruments. Some bimetric equations that realize this idea are considered. They were tested by the binary…

General Relativity and Quantum Cosmology · Physics 2009-11-07 L. V. Verozub

In the Entropic Dynamics (ED) framework quantum theory is derived as an application of entropic methods of inference. The physics is introduced through appropriate choices of variables and of constraints that codify the relevant physical…

General Relativity and Quantum Cosmology · Physics 2019-10-04 Selman Ipek , Ariel Caticha

It is proposed that gravity may arise in the low energy limit of a model of matter fields defined on a special kind of a dynamical random lattice. Time is discretized into regular intervals, whereas the discretization of space is random and…

High Energy Physics - Theory · Physics 2008-02-03 Yigal Shamir

Many different forms of the de Sitter metric in different coordinate systems are used in the general relativity literature. Two of them are the most common, the static form and the cosmological (exponentially expanding) form. The staticity…

General Relativity and Quantum Cosmology · Physics 2015-04-01 M. Nouri-Zonoz , J. Koohbor , H. Ramezani-Aval

Traditional approaches to the study of the dynamics of spacetime curvature in a very real sense hide the intricacies of the nonlinear regime. Whether it be huge formulae, or mountains of numerical data, standard methods of presentation make…

General Relativity and Quantum Cosmology · Physics 2013-05-30 Kayll Lake

The concept of deformation of Riemannian geometry is reviewed, with applications to gravitation and cosmology. Starting with an analysis of the cosmological constant problem, it is shown that space-times are deformable in the sense of local…

General Relativity and Quantum Cosmology · Physics 2015-05-28 M. D. Maia

A calculus based on pointer-mark coincidences is proposed to define, in a mathematically rigorous way, measurements of space and time intervals. The connection between such measurements in different inertial frames according to the Galilean…

General Physics · Physics 2011-10-26 J. H. Field

The time development of a model of (2+1)-dimensional torus universe is studied based on background field equations which follow from a string theory. The metrics in various cases are characterized by a real parameter which specifies a ratio…

High Energy Physics - Theory · Physics 2009-10-30 Kenji Hotta , Keiji Kikkawa , Michihiko Sakamoto

A manifest covariant equilibrium statistical mechanics is constructed starting with a 8N dimensional extended phase space which is reduced to the 6N physical degrees of freedom using the Poincare-invariant constrained Hamiltonian dynamics…

Mathematical Physics · Physics 2009-11-11 E. Lehmann

Quantum mechanical unitarity in our universe is challenged both by the notion of the big bang, in which nothing transforms into something, and the expansion of space, in which something transforms into more something. This motivates the…

High Energy Physics - Theory · Physics 2022-02-08 Jordan Cotler , Andrew Strominger

Development of the contemporary theory of physical phenomena in the microcosm is considered to be a result of development of Einstein's ideas on a possibility of the event space modification and on a possibility of stochastic (Brownian)…

General Physics · Physics 2007-05-23 Yuri A. Rylov

We provide a novel approach to model space-time random fields where the temporal argument is decomposed into two parts. The former captures the linear argument, which is related, for instance, to the annual evolution of the field. The…

Statistics Theory · Mathematics 2018-01-18 Alfredo Alegría , Emilio Porcu

It is shown by very simple arguments that the observed 3+1 dimensionality of spacetime may be understood on the basis of four fundamental principles of physics namely, Causality, General Covariance, Gauge Invariance and Renormalizability.…

General Physics · Physics 2013-03-25 Rajat K. Pradhan

We build a model of our spacetime by assuming new particles called "space quanta." In the ambient or bulk spacetime ${\cal S}^{D_{\rm amb}}$ ($D_{\rm amb} \ge 4$), a multitude of space quanta form a nearly three-dimensional object, whose…

General Physics · Physics 2016-05-31 Saebyok Bae

We analyze the dynamical equations obeyed by a classical system with position-dependent mass. It is shown that there is a non-conservative force quadratic in the velocity associated to the variable mass. We construct the Lagrangian and the…

Mathematical Physics · Physics 2013-01-18 Sara Cruz y Cruz , Oscar Rosas-Ortiz

In this letter we discuss the possibility of treating the spacetime by itself as a kind of deformable body for which we can define an fundamental lattice, just like atoms in crystal lattices. We show three signs pointing in that direction.…

General Relativity and Quantum Cosmology · Physics 2007-05-30 M. O. Tahim , R. R. Landim , C. A. S. Almeida

We explore the measurement problem in the entropic dynamics approach to quantum theory. The dual modes of quantum evolution---either continuous unitary evolution or abrupt wave function collapse during measurement---are unified by virtue of…

Quantum Physics · Physics 2015-05-30 David T. Johnson , Ariel Caticha