Chaos, decoherence and quantum cosmology

Calzetta, Esteban

doi:10.1088/0264-9381/29/14/143001

Cited by 19 publications

(14 citation statements)

References 270 publications

(348 reference statements)

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“…In the semiclassical limit, one thus finds a Schrödinger equation of the form (38), without using an artifical scalar field or dust matter that are often introduced with the sole purpose of defining a time at the exact level, cf. (38). From an empirical point of view, nothing more is needed, because we do not have any access so far to a regime where the semiclassical approximation is not valid.…”

Section: The Problem Of Timementioning

confidence: 99%

Conceptual Problems in Quantum Gravity and Quantum Cosmology

Kiefer

2013

ISRN Mathematical Physics

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The search for a consistent and empirically established quantum theory of gravity is among the biggest open problems of fundamental physics. The obstacles are of formal and of conceptual nature. Here, I address the main conceptual problems, discuss their present status and outline further directions of research. For this purpose, the main current approaches to quantum gravity are briefly reviewed and compared.

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“…For the latest developments of this respect in relation to indefinite Kac-Moody algebra, see [66]. The role of chaos in the decoherence of quantum cosmology and the appearance of a classical spacetime has been pointed out by Calzetta [67].…”

Section: Approach To Cosmological Singularity: Bkl-misnermentioning

confidence: 99%

“…For backreaction due to quantized matter fields, its decoherence effects, and how the semiclassical limits are reached in quantum cosmology, see, e.g., [67,[234][235][236][237].…”

Section: Quantum Backreaction Of Inhomogeneous Superspace Modesmentioning

confidence: 99%

Weyl Curvature Hypothesis in Light of Quantum Backreaction at Cosmological Singularities or Bounces

2021

Universe

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The Weyl curvature constitutes the radiative sector of the Riemann curvature tensor and gives a measure of the anisotropy and inhomogeneities of spacetime. Penrose’s 1979 Weyl curvature hypothesis (WCH) assumes that the universe began at a very low gravitational entropy state, corresponding to zero Weyl curvature, namely, the Friedmann–Lemaître–Robertson–Walker (FLRW) universe. This is a simple assumption with far-reaching implications. In classical general relativity, Belinsky, Khalatnikov and Lifshitz (BKL) showed in the 70s that the most general cosmological solutions of the Einstein equation are that of the inhomogeneous Kasner types, with intermittent alteration of the one direction of contraction (in the cosmological expansion phase), according to the mixmaster dynamics of Misner (M). How could WCH and BKL-M co-exist? An answer was provided in the 80s with the consideration of quantum field processes such as vacuum particle creation, which was copious at the Planck time (10−43 s), and their backreaction effects were shown to be so powerful as to rapidly damp away the irregularities in the geometry. It was proposed that the vaccum viscosity due to particle creation can act as an efficient transducer of gravitational entropy (large for BKL-M) to matter entropy, keeping the universe at that very early time in a state commensurate with the WCH. In this essay I expand the scope of that inquiry to a broader range, asking how the WCH would fare with various cosmological theories, from classical to semiclassical to quantum, focusing on their predictions near the cosmological singularities (past and future) or avoidance thereof, allowing the Universe to encounter different scenarios, such as undergoing a phase transition or a bounce. WCH is of special importance to cyclic cosmologies, because any slight irregularity toward the end of one cycle will generate greater anisotropy and inhomogeneities in the next cycle. We point out that regardless of what other processes may be present near the beginning and the end states of the universe, the backreaction effects of quantum field processes probably serve as the best guarantor of WCH because these vacuum processes are ubiquitous, powerful and efficient in dissipating the irregularities to effectively nudge the Universe to a near-zero Weyl curvature condition.

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“…This apparent conflict between theory and observation can be understood by invoking the influence of additional degrees of freedom in the sense of decoherence, as shown for example in [27] and [28]. The same mechanism should rectifies the situation for classically chaotic cosmologies [29].…”

Section: Introductionmentioning

confidence: 99%

Einstein’s Vision of Time and Infinite Universe without Singularities: The End of Big Bang Cosmology

Šorli¹

2020

JAP

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Cosmology should be built on falsifiability, bijectivity, and experimental data. Speculations are not allowed. NASA has measured universal space has Euclidean shape, which means universal space is infinite in the volume. Einstein’s vision on time as the sequential order of events running in space has bijective correspondence with the physical reality and means that the universe does not run in some physical time; it runs only in space, which is time-invariant. In this timeless universe, there is no singularity of the beginning, there is no singularity inside of black holes. The energy of the universe is non-created, its transformation is eternal without the beginning and without the end.

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“…Complex systems (CS) are frequent in many natural (e.g., geophysics, cosmology, ecology, biology, genetics) and man-made (e.g., economy, computer science, chemical and physical apparatus) systems [1][2][3][4][5][6][7][8][9][10]. They are often constituted by multiple interacting entities that contribute to a collective behavior revealing surprising dynamical phenomena.…”

Section: Introductionmentioning

confidence: 99%

Multidimensional Scaling Visualization Using Parametric Similarity Indices

Machado

Galhano

2015

Entropy

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In this paper, we apply multidimensional scaling (MDS) and parametric similarity indices (PSI) in the analysis of complex systems (CS). Each CS is viewed as a dynamical system, exhibiting an output time-series to be interpreted as a manifestation of its behavior. We start by adopting a sliding window to sample the original data into several consecutive time periods. Second, we define a given PSI for tracking pieces of data. We then compare the windows for different values of the parameter, and we generate the corresponding MDS maps of 'points'. Third, we use Procrustes analysis to linearly transform the MDS charts for maximum superposition and to build a global MDS map of "shapes". This final plot captures the time evolution of the phenomena and is sensitive to the PSI adopted. The generalized correlation, the Minkowski distance and four entropy-based indices are tested. The proposed approach is applied to the Dow Jones Industrial Average stock market index and the Europe Brent Spot Price FOB time-series.

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Chaos, decoherence and quantum cosmology

Cited by 19 publications

References 270 publications

Conceptual Problems in Quantum Gravity and Quantum Cosmology

Weyl Curvature Hypothesis in Light of Quantum Backreaction at Cosmological Singularities or Bounces

Einstein’s Vision of Time and Infinite Universe without Singularities: The End of Big Bang Cosmology

Multidimensional Scaling Visualization Using Parametric Similarity Indices

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