Emergent Spacetime for Quantum Gravity

I stress that spacetime is a redundant abstraction, since describing the physical content of all so-called "spacetime measurements" only requires timing (by a physical/material clock) of particle detections (at a physical/material detector). It is interesting then to establish which aspects of our current theories afford us the convenient abstraction of a spacetime. I emphasize the role played by the assumed triviality of the geometry of momentum space, which makes room for an observer-independent notion of locality. This is relevant for some recent studies of the quantum-gravity problem that stumbled upon hints of a nontrivial geometry of momentum space, something which had been strikingly envisaged for quantum gravity already in 1938 by Max Born. If indeed momentum space has nontrivial geometry then the abstraction of a spacetime becomes more evidently redundant and less convenient: one may still abstract a spacetime but only allowing for the possibility of a relativity of spacetime locality. I also provide some examples of how all this could affect our attitude toward the quantum-gravity problem, including some for the program of emergent gravity and emergent spacetime. And in order to give an illustrative example of possible logical path for the "disappearance of spacetime" I rely on formulas inspired by the κ-Poincaré framework.

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Emergent spacetime for quantum gravity

International Journal of Modern Physics D ◽

10.1142/s0218271816450103 ◽

2016 ◽

Vol 25 (13) ◽

pp. 1645010 ◽

Cited By ~ 2

Author(s):

Hyun Seok Yang

Keyword(s):

Dark Matter ◽

Dark Energy ◽

Quantum Gravity ◽

Theoretical Physics ◽

Hierarchy Problem ◽

Cosmological Constant Problem ◽

Cosmic Inflation ◽

Thought Patterns ◽

Emergent Spacetime ◽

New Perspective

We emphasize that noncommutative (NC) spacetime necessarily implies emergent spacetime if spacetime at microscopic scales should be viewed as NC. In order to understand NC spacetime correctly, we need to deactivate the thought patterns that we have installed in our brains and taken for granted for so many years. Emergent spacetime allows a background-independent formulation of quantum gravity that will open a new perspective to resolve the notorious problems in theoretical physics such as the cosmological constant problem, hierarchy problem, dark energy, dark matter and cosmic inflation.

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Thinking about Spacetime

10.1093/oso/9780198844143.003.0006 ◽

2021 ◽

pp. 129-153

Author(s):

David Yates

Keyword(s):

Quantum Gravity ◽

Philosophy Of Mind ◽

Fundamental Theory ◽

True Nature ◽

Fundamental Ontology ◽

Fundamental Structure ◽

Space And Time ◽

Spacetime Structure ◽

Research Programmes ◽

Emergent Spacetime

Several different quantum gravity research programmes suggest, for various reasons, that spacetime is not part of the fundamental ontology of physics. This gives rise to the problem of empirical coherence, which I frame in terms of entailment: how could a non-spatiotemporal fundamental theory entail spatiotemporal evidence propositions? Solutions to this puzzle can be classified as realist or antirealist, depending on whether or not they posit a non-fundamental spacetime structure grounded in or caused by the fundamental structure. These approaches place different constraints on our everyday concepts of space and time. Applying lessons from the philosophy of mind, I argue that only realism is both conceptually plausible and suitable for addressing the problem at hand. I suggest a role-functionalist version of realism, which is consistent with both grounding and causation, and according to which our everyday concepts reveal something of the true nature of emergent spacetime.

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Functionalist explanation of spacetime

Theoria Beograd ◽

10.2298/theo1902119j ◽

2019 ◽

Vol 62 (2) ◽

pp. 119-131

Author(s):

Radmila Jovanovic-Kozlowski

Keyword(s):

Quantum Gravity ◽

Functional Role ◽

Physical Theory ◽

Classical Mechanics ◽

Fundamental Theory ◽

Emergent Spacetime ◽

New Interpretation ◽

New Research ◽

Philosophical Debates ◽

Real Challenge

In contemporary physics, from General relativity and Quantum mechanics to new research programs of Quantum gravity, we can find a vast variety of spacetime structures, which makes the interpretation of this concept a real challenge. Recently, a group of authors advanced a new interpretation of spacetime called ?spacetime functionalism?, with the idea that spacetime should be defined via its functional role in the physical theory, in other words, ?spacetime is what spacetime does?. A material field or an object are spatiotemporal if they play a defined role in a physical theory. The approach is meant to be widely applicable, from classical mechanics to possible new theories of Quantum gravity, where spacetime might not appear at the fundamental theory level. Functionalism can be well combined with the emergent spacetime. It should also shed a new light on traditional philosophical debates between substantivists and relationists and between realists and anti-realists.

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The Measurement Problem for Emergent Spacetime in Loop Quantum Gravity

10.1093/oso/9780198844143.003.0010 ◽

2021 ◽

pp. 222-234

Author(s):

Richard Healey

Keyword(s):

Quantum Theory ◽

Quantum Gravity ◽

Loop Quantum Gravity ◽

Measurement Problem ◽

Scientific Objectivity ◽

Physical Systems ◽

Fundamental Level ◽

Basic Norm ◽

Emergent Spacetime ◽

Theory Of Gravity

Any quantum theory of gravity faces the measurement problem. Carlo Rovelli sees his relational interpretation as offering a solution to this problem when applied to his favored loop quantum gravity (LQG). I examine the prospects of Rovelli’s relationalism in LQG. In LQG it is not clear what physical systems there are at a fundamental level with no spacetime. But implementing Rovelli’s relational interpretation in the context of LQG requires an account of interaction and a model of observer systems whose relational states represent determinate outcomes. Even if no such account is forthcoming at a fundamental level in LQG, it might still be available in a limit at which spacetime has emerged. But to use this account effectively to address the measurement problem, it would be necessary to reconcile the observer-relativity of measurement outcomes with a basic norm of scientific objectivity.

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Foundations of Quantum Gravity

10.1017/cbo9780511919909 ◽

2009 ◽

Cited By ~ 3

Author(s):

James Lindesay

Keyword(s):

Quantum Gravity

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Topology knots and hierarchy problem

10.31219/osf.io/7tqrw ◽

2019 ◽

Author(s):

Vitaly Kuyukov

Keyword(s):

Quantum Theory ◽

String Theory ◽

Quantum Gravity ◽

Dimensional Space ◽

Space Time ◽

Elementary Particles ◽

Hierarchy Problem ◽

Topological Quantum ◽

Dimensional Space Time ◽

New Formula

Many approaches to quantum gravity consider the revision of the space-time geometry and the structure of elementary particles. One of the main candidates is string theory. It is possible that this theory will be able to describe the problem of hierarchy, provided that there is an appropriate Calabi-Yau geometry. In this paper we will proceed from the traditional view on the structure of elementary particles in the usual four-dimensional space-time. The only condition is that quarks and leptons should have a common emerging structure. When a new formula for the mass of the hierarchy is obtained, this structure arises from topological quantum theory and a suitable choice of dimensional units.

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