scholarly journals CLOSED INFLATIONARY UNIVERSE MODELS IN BRANE WORLD COSMOLOGY

2005 ◽  
Vol 14 (05) ◽  
pp. 861-872 ◽  
Author(s):  
SERGIO DEL CAMPO ◽  
RAMÓN HERRERA ◽  
JOEL SAAVEDRA
Keyword(s):  
General Relativity ◽  
Scalar Field ◽  
Brane World ◽  
Inflationary Universe ◽  
Closed Universe ◽  
Cosmological Context ◽  
The One ◽  
Universe Models ◽  
Einstein’S General Relativity

In this article we study closed inflationary universe models proposed by Linde in a brane world cosmological context. In this scenario we determine and characterize the existence of a closed universe, in presence of one self-interacting scalar field with an inflationary stage. We have found that our model, which takes into account a Brane World Cosmology, is less restrictive than the one that uses standard Einstein's General Relativity cosmology.

CLASSICAL PERTURBATIONS FROM DECOHERENCE OF QUANTUM FLUCTUATIONS IN THE INFLATIONARY UNIVERSE

1990 ◽  
Vol 05 (28) ◽  
pp. 2311-2317 ◽  
Author(s):  
ROBERT BRANDENBERGER ◽  
RAYMOND LAFLAMME ◽  
MILAN MIJIĆ
Keyword(s):  
Scalar Field ◽  
Coherence Length ◽  
Quantum Fluctuations ◽  
Inflationary Universe ◽  
De Sitter ◽  
Density Perturbations ◽  
Hubble Radius ◽  
Universe Models

The evolution of a scalar field interacting with an environment in the de Sitter phase of an inflationary Universe is studied. The environment is taken to be a second scalar field. It is shown that the coherence length of the quantum fluctuations rapidly decreases after the wavelength of the perturbation crosses the Hubble radius. Hence, the fluctuations can be interpreted as classical. This lends support to the usual derivation of the spectrum of density perturbations in inflationary Universe models.

Effects of a brane world on gravitational time advancement

2018 ◽  
Vol 33 (19) ◽  
pp. 1850110 ◽  
Author(s):  
Xue-Mei Deng
Keyword(s):  
General Relativity ◽  
Proper Time ◽  
Brane World ◽  
Laser Ranging ◽  
Round Trip ◽  
Time Duration ◽  
World Model ◽  
The Earth ◽  
The One ◽  
Charge Parameter

Solar System tests of a brane world, which is called DMPR model, were studied in recent works. The correction of DMPR model to the general relativity (GR) in the four-dimensional curved spacetime can be parametrized by a “tidal charge” parameter [Formula: see text]. The parameter [Formula: see text] in this model was obtained and improved as [Formula: see text] by the Earth–Mercury ranging. A new test of the DMPR model based on gravitational time advancement is proposed and investigated in this work. The advancement is a gravitational consequence on round-trip proper time duration of a photon. For ranging a distant spacecraft, it is shown that (1) the “tidal charge” parameter can make the advancement larger or smaller than the one of GR, depending on the sign of [Formula: see text]; (2) the superior conjunction (SC) and the inferior conjunction (IC) are all suitable for detecting the advancement; (3) the advancement can be complementary to the classical test of Shapiro time delay for detecting the brane world; and (4) the implementation of optical clocks and planetary laser ranging will provide more insights on the brane world model in the future.

scholarly journals Do Child Abuse Pediatricians Search for a “Pediatric Vulcan Planet”? Comparison of Controversies about the Vulcan-Must-Exist-Theory and the Infant-Must-Have-Been-Shaken-Theory

2020 ◽  
Vol 3 (2) ◽  
pp. p162
Author(s):  
Niels Lynøe ◽  
Niklas Juth ◽  
Chris B Brook ◽  
Anders Eriksson
Keyword(s):  
General Relativity ◽  
Child Abuse ◽  
Head Trauma ◽  
Abusive Head Trauma ◽  
The Other ◽  
Relativity Theory ◽  
General Relativity Theory ◽  
The One ◽  
Legal Consequences ◽  
Einstein’S General Relativity

We argue that there are similarities between the Vulcan-must-exist-theory, derived from the Original Unrestricted Newtonian Gravitational (OUNG) theory, on the one hand, and on the other hand the infant-must-have-been-shaken-theory, derived from the Original Unrestricted Abusive Head Trauma (OUAHT) theory. Although the Vulcan-must–exist-theory was apparently supported by observations over a period of 50 years, after the introduction of Einstein’s general relativity theory in 1915 and its corroboration in 1919, the alleged planet was subsequently neither observed nor needed. In analogy with the Einstein/Vulcan reasoning, we suggest that the introduction of the non-shaken baby theory by Geddes et al. in 2001-2004 indicates that in cases where an infant displays no external signs of trauma, the infant-must-have-been-shaken-theory is no longer needed. Moreover we argue that the two new theories -Einstein’s and Geddes et al.’s- have relevant similarities in terms of the effect on the respective original, unrestricted theory. Just as acceptance of Einstein’s general relativity theory led to the abandonment of the Vulcan-must-exist-theory, it is reasonable to claim that the infant-must-have-been-shaken-theory should also be abandoned. We finally argue that while the consequences of abandoning the Vulcan-must-exist-theory were restricted to some scientific and astronomical issues, the infant-must-have-been-shaken-theory has not yet been abandoned because of the societal and legal consequences.

PARTICLE PRODUCTION DURING INFLATIONARY REHEATING

1992 ◽  
Vol 07 (09) ◽  
pp. 2033-2044 ◽  
Author(s):  
M. BASLER ◽  
B. KÄMPFER
Keyword(s):  
Scalar Field ◽  
Particle Production ◽  
Field Model ◽  
Particle Creation ◽  
Background Field ◽  
Time Development ◽  
Parameter Dependence ◽  
Inflationary Universe ◽  
Numerical Investigations ◽  
Universe Models

A possible reheating mechanism in inflationary universe models is studied in some detail. Results are presented of numerical investigations of particle creation and corresponding reheating within a self-coupled scalar field model. By using the method of Hamiltonian diagonalization attention is devoted to the time development of the process and its parameter dependence. The effect of particle production is found to depend strongly on the anharmonicity of the potential around its minimum and on the amplitude of the oscillations of the scalar background field.

scholarly journals TACHYONIC UNIVERSES IN PATCH COSMOLOGIES WITH Ω > 1

2009 ◽  
Vol 24 (30) ◽  
pp. 2445-2458 ◽  
Author(s):  
SERGIO DEL CAMPO ◽  
RAMÓN HERRERA ◽  
JOEL SAAVEDRA ◽  
PEDRO LABRAÑA ◽  
CARLOS LEIVA
Keyword(s):  
General Relativity ◽  
General Treatment ◽  
Inflationary Universe ◽  
Tachyonic Field ◽  
Astronomical Observations ◽  
Universe Models

In this paper we study closed inflationary universe models by means of a tachyonic field. We described a general treatment for created a universe with Ω > 1 in patch cosmology, which is able to represent General Relativity, Gauss–Bonnet or Randall–Sundrum patches. We use recent data from astronomical observations to constrain the parameters appearing in our model.

scholarly journals WARM-POLYTROPIC INFLATIONARY UNIVERSE MODEL

2013 ◽  
Vol 22 (08) ◽  
pp. 1350041 ◽  
Author(s):  
M. R. SETARE ◽  
M. J. S. HOUNDJO ◽  
V. KAMALI
Keyword(s):  
Exact Solution ◽  
Scalar Field ◽  
Hubble Parameter ◽  
Inflationary Universe ◽  
Universe Model ◽  
Polytropic Gas ◽  
Slow Roll ◽  
Universe Models ◽  
Explicit Expressions

In this paper, we study warm inflationary universe models in the context of a polytropic gas. We derive the characteristics of this model in slow-roll approximation and develop our model in two cases: (1) for a constant dissipative parameter Γ; (2) Γ as a function of scalar field ϕ. In these cases, we will obtain exact solution for the scalar field and Hubble parameter. We will also obtain explicit expressions for the tensor-scalar ratio R, scalar spectrum index ns and its running αs in slow-roll approximation.

Particle and Astro-physics Challenge Kant’s Phenomenolism

1998 ◽  
pp. 323-333
Author(s):  
Lawrence H. Starkey
Keyword(s):  
General Relativity ◽  
Black Hole ◽  
Physical Basis ◽  
Primary Sources ◽  
One Dimension ◽  
Space Curves ◽  
Slowing Down ◽  
Parity Conservation ◽  
Charge Parity ◽  
Einstein’S General Relativity

For two centuries Kant's first Critique has nourished various turns against transcendent metaphysics and realism. Kant was scandalized by reason's impotence in confronting infinity (or finitude) as seen in the divisibility of particles and in spatial extension and time. Therefore, he had to regard the latter as subjective and reality as imponderable. In what follows, I review various efforts to rationalize Kant's antinomies-efforts that could only flounder before the rise of Einstein's general relativity and Hawking's blackhole cosmology. Both have undercut the entire Kantian tradition by spawning highly probable theories for suppressing infinities and actually resolving these perplexities on a purely physical basis by positing curvatures of space and even of time that make them reëntrant to themselves. Heavily documented from primary sources in physics, this paper displays time’s curvature as its slowing down near very massive bodies and even freezing in a black hole from which it can reëmerge on the far side, where a new universe can open up. I argue that space curves into a double Möbius strip until it loses one dimension in exchange for another in the twin universe. It shows how 10-dimensional GUTs and the triple Universe, time/charge/parity conservation, and strange and bottom particle families and antiparticle universes, all fit together.

scholarly journals Weak cosmic censorship with self-interacting scalar and bound on charge to mass ratio

2021 ◽  
Vol 2021 (3) ◽  
Author(s):  
Yan Song ◽  
Tong-Tong Hu ◽  
Yong-Qiang Wang
Keyword(s):  
Scalar Field ◽  
Scalar Fields ◽  
Cosmic Censorship ◽  
Mass Ratio ◽  
Quartic Coupling ◽  
Scalar Theory ◽  
Free Scalar ◽  
The One ◽  
Nonzero Scalar ◽  
Large Charge

Abstract We study the model of four-dimensional Einstein-Maxwell-Λ theory minimally coupled to a massive charged self-interacting scalar field, parameterized by the quartic and hexic couplings, labelled by λ and β, respectively. In the absence of scalar field, there is a class of counterexamples to cosmic censorship. Moreover, we investigate the full nonlinear solution with nonzero scalar field included, and argue that these counterexamples can be removed by assuming charged self-interacting scalar field with sufficiently large charge not lower than a certain bound. In particular, this bound on charge required to preserve cosmic censorship is no longer precisely the weak gravity bound for the free scalar theory. For the quartic coupling, for λ < 0 the bound is below the one for the free scalar fields, whereas for λ > 0 it is above. Meanwhile, for the hexic coupling the bound is always above the one for the free scalar fields, irrespective of the sign of β.

scholarly journals WEYL GEOMETRY AS CHARACTERIZATION OF SPACE-TIME

2011 ◽  
Vol 03 ◽  
pp. 87-97 ◽  
Author(s):  
F. P. POULIS ◽  
J. M. SALIM
Keyword(s):  
General Relativity ◽  
Scalar Field ◽  
Riemannian Geometry ◽  
Axiomatic Approach ◽  
Space Time ◽  
Weyl Geometry ◽  
Test Particles ◽  
Variational Formalism ◽  
Physical Fields

Motivated by an axiomatic approach to characterize space-time it is investigated a reformulation of Einstein's gravity where the pseudo-riemannian geometry is substituted by a Weyl one. It is presented the main properties of the Weyl geometry and it is shown that it gives extra contributions to the trajectories of test particles, serving as one more motivation to study general relativity in Weyl geometry. It is introduced its variational formalism and it is established the coupling with other physical fields in such a way that the theory acquires a gauge symmetry for the geometrical fields. It is shown that this symmetry is still present for the red-shift and it is concluded that for cosmological models it opens the possibility that observations can be fully described by the new geometrical scalar field. It is concluded then that this reformulation, although representing a theoretical advance, still needs a complete description of their objects.

scholarly journals Gamma Astrometric Measurement Experiment: testing General Relativity with a small mission

2007 ◽  
Vol 3 (S248) ◽  
pp. 290-291 ◽  
Author(s):  
A. Vecchiato ◽  
M. G. Lattanzi ◽  
M. Gai ◽  
R. Morbidelli
Keyword(s):  
General Relativity ◽  
Solar Eclipse ◽  
Galactic Center ◽  
The Sun ◽  
Measurement Experiment ◽  
The One ◽  
First Time ◽  
Bending Of Light

AbstractGAME (Gamma Astrometric Measurement Experiment) is a concept for an experiment whose goal is to measure from space the γ parameter of the Parameterized Post-Newtonian formalism, by means of a satellite orbiting at 1 AU from the Sun and looking as close as possible to its limb. This technique resembles the one used during the solar eclipse of 1919, when Dyson, Eddington and collaborators measured for the first time the gravitational bending of light. Simple estimations suggest that, possibly within the budget of a small mission, one could reach the 10−6level of accuracy with ~106observations of relatively bright stars at about 2° apart from the Sun. Further simulations show that this result could be reached with only 20 days of measurements on stars ofV≤ 17 uniformly distributed. A quick look at real star densities suggests that this result could be greatly improved by observing particularly crowded regions near the galactic center.

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