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Physicists believe, with some justification, that there should be a correspondence between familiar properties of Newtonian gravity and properties of solutions of the Einstein equations. The Positive Mass Theorem (PMT), first proved over…

Differential Geometry · Mathematics 2007-05-23 Robert Bartnik

Nerd abstract: Observational constraints on spacetime are reviewed, focusing on how the underlying physics (dark matter, dark energy, gravity) can be tested rather than assumed. Popular abstract: Space is not a boring static stage on which…

Astrophysics · Physics 2017-08-23 Max Tegmark

What is the shape of the Universe? Is it curved or flat, finite or infinite ? Is space "wrapped around" to create ghost images of faraway cosmic sources? We review how tessellations allow to build multiply-connected 3D Riemannian spaces…

Astrophysics · Physics 2008-02-18 Jean-Pierre Luminet

It is often said that in general relativity time does not exist. This is because the Einstein equations generate motion in time that is a symmetry of the theory, not true time evolution. In quantum gravity, the timelessness of general…

General Relativity and Quantum Cosmology · Physics 2009-09-11 Fotini Markopoulou

Since ancient times, mathematics has proven unreasonably effective in its description of physical phenomena. As humankind enters a period of advancement where the completion of the much coveted theory of quantum gravity is at hand, there is…

History and Philosophy of Physics · Physics 2015-02-18 Michael Rios

Suppose we have identified three clusters of galaxies as being topological copies of the same object. How does this information constrain the possible models for the shape of our Universe? It is shown here that, if the Universe has flat…

Astrophysics · Physics 2009-11-07 G. I. Gomero

Constructing the Theory of Everything (TOE) is an elusive goal of today's physics. Goedel's incompleteness theorem seems to forbid physics axiomatization, a necessary part of the TOE. The purpose of this contribution is to show how physics…

History and Philosophy of Physics · Physics 2010-01-27 Florin Moldoveanu

It is clarified that Heisenberg quantization was proposed in empty space. Based on established experiments, the generalized Heisenberg quantization in physical space is obtained. Physical space quantization includes important new physics:…

Quantum Physics · Physics 2019-09-25 Jian-Zu Zhang

We observe the past and present of the universe, but can we predict the far future? Observations suggest that in thousands of billions of years from now most matter and radiation will be absorbed by the cosmological horizon. As it absorbs…

General Relativity and Quantum Cosmology · Physics 2013-05-30 Ruxandra Bondarescu , Andrew P. Lundgren , Mihai Bondarescu

The world of mathematics is often considered abstract, with its symbols, concepts, and topics appearing unrelated to physical objects. However, it is important to recognize that the development of mathematics is fundamentally influenced by…

General Physics · Physics 2023-06-08 Biao Wu

The theories of quantum mechanics and relativity dramatically altered our understanding of the universe ushering in the era of modern physics. Quantum theory deals with objects probabilistically at small scales, whereas relativity deals…

General Physics · Physics 2021-04-13 John Skilling , Kevin H. Knuth

The question of determining the spatial geometry of the Universe is of greater relevance than ever, as precision cosmology promises to verify inflationary predictions about the curvature of the Universe. We revisit the question of what can…

Cosmology and Nongalactic Astrophysics · Physics 2010-05-11 Mihran Vardanyan , Roberto Trotta , Joe Silk

The essence of the method of physics is inseparably connected with the problem of interplay between local and global properties of the universe. In the present paper we discuss this interplay as it is present in three major departments of…

General Relativity and Quantum Cosmology · Physics 2008-02-03 Jacques Demaret , Michael Heller , Dominique Lambert

A variational principle is applied to 4D Euclidean space provided with a tensor refractive index, defining what can be seen as 4-dimensional optics (4DO). The geometry of such space is analysed, making no physical assumptions of any kind.…

General Physics · Physics 2007-05-23 Jose B. Almeida

Recently, it is shown that, the quantum effects of matter are well described by the conformal degree of freedom of the space-time metric. On the other hand, it is a wellknown fact that according to Einstein's gravity theory, gravity and…

General Relativity and Quantum Cosmology · Physics 2009-10-31 Ali Shojai

In black hole physics, inflationary cosmology, and quantum field theories, it is conjectured that the physical laws are subject to radical changes below the Planck length. Such changes are due to effects of quantum gravity believed to…

General Physics · Physics 2023-04-21 Arkady Bolotin

The theory of measurement is employed to elucidate the physical basis of general relativity. For measurements involving phenomena with intrinsic length or time scales, such scales must in general be negligible compared to the (translational…

General Relativity and Quantum Cosmology · Physics 2015-06-25 Bahram Mashhoon

This paper forms part of a wider campaign: to deny pointillisme. That is the doctrine that a physical theory's fundamental quantities are defined at points of space or of spacetime, and represent intrinsic properties of such points or…

Classical Physics · Physics 2007-05-23 Jeremy Butterfield

In this paper we present some results obtained in a previous paper about the Cartan's approach to Riemannian normal coordinates and our conformal transformations among pseudo-Riemannian manifolds. We also review the classical and the…

Mathematical Physics · Physics 2010-06-24 A. C. V. V. de Siqueira

This thesis addresses two major problems in the philosophy of physics. The first is how to identify the minimal physical content of a theory; that is, what features of a theory are truly needed to make predictions, and what can be removed…

History and Philosophy of Physics · Physics 2025-09-19 Sean Gryb