Quantum graphity: A model of emergent locality

Konopka, Tomasz; Markopoulou, Fotini; Severini, Simone

doi:10.1103/physrevd.77.104029

Cited by 164 publications

(256 citation statements)

References 33 publications

(58 reference statements)

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“…In fact, over the years, various arguments questioning whether the spacetime metric should be treated quantum mechanically have been put forward (see for instance [25,28,29]). The idea is that the spacetime geometry might emerge from deeper, non-geometrical and fundamentally quantum mechanical degrees of freedom (see, e.g., [30][31][32][33][34]); and, just as one does not directly quantize macroscopic, thermodynamic variables or the degrees of freedom of, say, the heat equation, one would not think of quantizing the metric if it were non-fundamental.…”

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confidence: 99%

Reassessing the link betweenB-modes and inflation

et al. 2017

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We reevaluate the predictions of inflation regarding primordial gravity waves, which should appear as B-modes in the CMB, in light of the fact that the standard inflationary paradigm is unable to account for the transition from an initially symmetric state into a non-symmetric outcome. We show that the incorporation of an element capable of explaining such a transition dramatically alters the prediction for the shape and size of the B-mode spectrum. In particular, we find that by adapting a realistic objective collapse model to the situation at hand, the B-mode spectrum gets strongly suppressed with respect to the standard prediction. We conclude that the failure to detect B-modes in the CMB does not rule-out the simplest inflationary models.The exquisite matching between observations of temperature anisotropies in the CMB and the generic predictions of inflation provides a powerful justification for the recent consolidation of the inflationary paradigm as a cornerstone of modern cosmology. However, such a paradigm also makes predictions for the shape and amplitude of primordial gravity waves, which should be observable in the B-mode polarization of the CMB. The fact that, so far, such B-modes have not been observed, has been used to severely constrain the set of viable inflationary models [1][2][3]. Moreover, the recent detection of gravity waves by LIGO [4] removes all lingering doubts about the reality of such waves (if there were any remaining, given the dramatic indirect evidence provided by the Binary Pulsar studies [5]). This only increases the urgency to resolve the tension generated by the predictions regarding B-modes and our failure to detect them.As initially argued in [6], the standard inflationary account for the emergence of the primordial perturbations lacks a crucial element capable of accounting for the transition from the initially homogeneous and isotropic quantum state into a state lacking such symmetries. The objective of this letter is to show that the adoption of a framework that explicitly introduces this element drastically modifies the predictions for the shape and amplitude of the primordial gravity waves (without also altering confirmed predictions of inflation) [7]. As a result, we conclude that the impact of the B-polarization nullresults on the viability of various inflationary models has to be reexamined. In particular, we establish that, contrary to what has been argued, the failure to detect Bmodes in the CMB does not rule-out the simplest inflationary models.The crucial observation overlooked by the standard account is concerned with the way in which the quantum fluctuations of the completely homogeneous and isotropic state that characterizes the early stages of inflation (i.e., the Bunch-Davies vacuum or related states), are supposed to transform into actual inhomogeneities and anisotropies. The problem is that such "fluctuations" are nothing more than a characterization of the width of the wave function for the corresponding field degrees of freedom and not acutal, physical...

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Reassessing the link betweenB-modes and inflation

et al. 2017

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“…In the arena of quantum gravity it is not unusual to find discrete theories [49] that are in some way underneath spacetime theory and theories of "matter" such as QFT, e.g., causal dynamical triangulations [50], quantum graphity [51] and causets [52]. While these approaches are interesting and promising, the approach taken here for theory X will look more like Regge calculus quantum gravity (see Bahr & Dittrich [53] and references therein for recent work along these lines) modified to contain no vacuum lattice structure.…”

Section: Discrete Path Integral Is Fundamentalmentioning

confidence: 99%

Being, Becoming and the Undivided Universe: A Dialogue Between Relational Blockworld and the Implicate Order Concerning the Unification of Relativity and Quantum Theory

2012

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In this paper two different approaches to unification will be compared, Relational Blockworld (RBW) and Hiley's implicate order. Both approaches are monistic in that they attempt to derive matter and spacetime geometry 'at once' in an interdependent and background independent fashion from something underneath both quantum theory and relativity. Hiley's monism resides in the implicate order via Clifford algebras and is based on process as fundamental while RBW's monism resides in spacetimematter via path integrals over graphs whereby space, time and matter are co-constructed per a global constraint equation. RBW's monism therefore resides in being (relational blockworld) while that of Hiley's resides in becoming (elementary processes). Regarding the derivation of quantum theory and relativity, the promises and pitfalls of both approaches will be elaborated. Finally, special attention will be paid as to how Hiley's process account might avoid the

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“…As it emerges from a simple graph, we call it "graphitation". A similar word game has already been used for an approach to quantum physics in a graph, called "Quantum Graphity" (Markopoulou & Smolin, 2004;Konopka, Markopoulou & Severini, 2008). But the approaches are different; physicists have built several discrete models, graphs or networks, to implement continuous physical equations, by keeping the current models in discreet format.…”

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confidence: 99%

New “Graphiton” Model: a Computational Discrete Space, Self-Encoded as a Trivalent Graph

Aschheim¹,

Femmam²,

Faouzi³

2011

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The new graphiton models described here are trivalent graphs which encode topologically binary information. They permit defining intrinsic discrete spaces which constitute supernode crystals. Besides encoding its own metric, the model supports disturbances due to fault tolerance through the redundancy of information in the paths of connection between supernodes. Coming from theoretical physics, they may find applications in network management and artificial intelligence. For the first time, an information system structure, rich enough to model the universe itself, but relying ultimately on set theory, traverses set theory, topology, information theory, graph theory, geometry, algebra, theoretical physics and even computer and network science, in a logical straightforward and elegant way.

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Quantum graphity: A model of emergent locality

Cited by 164 publications

References 33 publications

Reassessing the link betweenB-modes and inflation

Reassessing the link betweenB-modes and inflation

Being, Becoming and the Undivided Universe: A Dialogue Between Relational Blockworld and the Implicate Order Concerning the Unification of Relativity and Quantum Theory

New “Graphiton” Model: a Computational Discrete Space, Self-Encoded as a Trivalent Graph

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