Quantum Gravity Phenomenology and Experimental Implications

A special issue of Technologies (ISSN 2227-7080). This special issue belongs to the section "Quantum Technologies".

Deadline for manuscript submissions: closed (15 July 2017) | Viewed by 12484

Special Issue Editor

Department of Physics, Faculty of Science, Benha University, Benha 13518, Egypt
Interests: quantum physics; quantum gravity; cosmology; black holes; relativity; high energy physics

Special Issue Information

Dear Colleagues,

The quantum theory of gravity is expected to give us a concrete picture of the origin and structure of the universe. Various attempts to formulate quantum gravity have been made in recent decades and formulating this theory remains one of the most important problems in physics. These attempts have included superstring theories, loop quantum gravity, non-commutative geometry, casual sets, etc. The main goal of this Special Issue is to provide a collection of state-of-the-art papers on these topics. We invite submissions related to experimental, theoretical or numerical works which provide concrete predictions of quantum gravity theories that can be tested in a laboratory or using cosmological and astrophysical observations.

Potential topics include, but are not limited to:
  1. Quantum gravity phenomenology.
  2. Experimental consequences of quantum gravity theories.
  3. Quantum gravitational effects on astrophysical objects.
  4. Gravitational waves in modified theories of gravity and quantum gravity theories.
  5. Perturbative quantum gravity.
  6. Black holes and quantum gravity.
  7. Dynamics of galaxies with dark matter in modified theories of gravity and quantum gravity models.

Dr. Ahmed Farag Ali
Guest Editor

Manuscript Submission Information

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Keywords

  • Quantum gravity
  • Black holes 
  • Gravitational waves
  • Dark matter and dark energy

Published Papers (3 papers)

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224 KiB  
Article
A Conceptual Test for Cognitively Coherent Quantum Gravity Models
by Simonluca Pinna and Simone Pinna
Technologies 2017, 5(3), 51; https://doi.org/10.3390/technologies5030051 - 15 Aug 2017
Viewed by 3979
Abstract
In quantum gravity interpretations, the role of space- and time-related concepts is debated. Some argue that these concepts are not needed to describe physical reality at the Planck scale. Others object that an operational definition of magnitudes cannot get rid of spatiotemporal notions. [...] Read more.
In quantum gravity interpretations, the role of space- and time-related concepts is debated. Some argue that these concepts are not needed to describe physical reality at the Planck scale. Others object that an operational definition of magnitudes cannot get rid of spatiotemporal notions. We propose a “conceptual test” to assess if the mathematical content of a quantum gravity theory refers to some possibly verifiable empirical model. Given that any physical model describes the evolution of a set of measurables, these must be detectable in any empirical interpretation of a physical theory, including quantum gravity ones. Our test ultimately relies on considerations and studies concerning human cognitive limits in the discrimination of magnitudes. Full article
(This article belongs to the Special Issue Quantum Gravity Phenomenology and Experimental Implications)
253 KiB  
Article
Accelerated Detector Response Function in Squeezed Vacuum
by Salwa Alsaleh
Technologies 2017, 5(2), 17; https://doi.org/10.3390/technologies5020017 - 20 Apr 2017
Viewed by 3747
Abstract
Casimir/squeezed vacuum breaks Lorentz symmetry, by allowing light to propagate faster than c. We looked at the possible transformation symmetry group such vacuum could obey. By solving the semi-classical Einstein field equation in squeezed vacuum, we have found that the background geometry [...] Read more.
Casimir/squeezed vacuum breaks Lorentz symmetry, by allowing light to propagate faster than c. We looked at the possible transformation symmetry group such vacuum could obey. By solving the semi-classical Einstein field equation in squeezed vacuum, we have found that the background geometry describes an Anti-deSitter (AdS) geometry. Therefore, the proper transformation symmetry group is the (A)dS group. One can describe quantum field theory in a finite volume as a quantum field theory (QFT) on AdS background, or vice versa. In particular, one might think of QFT vacuum on AdS as a QFT that posses a squeezed vacuum with boundary conditions proportional to R A d S 2 . Applying this correspondence to an accelerating detector-scalar field system, we notice at low acceleration the system is at equilibrium at ground state, however if the detector’s acceleration (a) is greater than a critical acceleration, the system experience a phase transition similar to Hawking-Page Phase transition at the detector gets excited, with equivalent temperature Θ = a 2 - R A d S 2 2 π . Full article
(This article belongs to the Special Issue Quantum Gravity Phenomenology and Experimental Implications)
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333 KiB  
Technical Note
Semiclassical Length Measure from a Quantum-Gravity Wave Function
by Orchidea Maria Lecian
Technologies 2017, 5(3), 56; https://doi.org/10.3390/technologies5030056 - 08 Sep 2017
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Abstract
The definition of a length operator in quantum cosmology is usually influenced by a quantum theory for gravity considered. The semiclassical limit at the Planck age must meet the requirements implied in present observations. The features of a semiclassical wave-functional state are investigated, [...] Read more.
The definition of a length operator in quantum cosmology is usually influenced by a quantum theory for gravity considered. The semiclassical limit at the Planck age must meet the requirements implied in present observations. The features of a semiclassical wave-functional state are investigated, for which the modern measure(ment)s is consistent. The results of a length measurement at present times are compared with the same measurement operation at cosmological times. By this measure, it is possible to discriminate, within the same Planck-length expansion, the corrections to a Minkowski flat space possibly due to classicalization of quantum phenomena at the Planck time and those due to possible quantum-gravitational manifestations of present times. This analysis and the comparison with the previous literature can be framed as a test for the verification of the time at which anomalies at present related to the gravitational field, and, in particular, whether they are ascribed to the classicalization epoch. Indeed, it allows to discriminate not only within the possible quantum features of the quasi (Minkowski) flat spacetime, but also from (possibly Lorentz violating) phenomena detectable at high-energy astrophysical scales. The results of two different (coordinate) length measures have been compared both at cosmological time and as a perturbation element on flat Minkowski spacetime. The differences for the components of the corresponding classical(ized) metric tensor have been analyzed at different orders of expansions. The results of the expectation values of a length operator in the universe at the Planck time must be comparable with the same length measurements at present times, as far as the metric tensor is concerned. The comparison of the results of (straight) length measures in two different directions, in particular, can encode the pertinent information about the parameters defining the semiclassical wavefunctional for (semiclassicalized) gravitational field. Full article
(This article belongs to the Special Issue Quantum Gravity Phenomenology and Experimental Implications)
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