Brian Greene: The Speculative Sublime

2018 ◽  
Author(s):  
Alan G. Gross
Keyword(s):  
Standard Form ◽  
Planck Scale ◽  
Complete Analysis ◽  
High Price ◽  
De Sitter ◽  
Distance Cutoff ◽  
Perturbation Spectrum ◽  
Charles Dodgson ◽  
The Mind ◽  
Looking Glass

Charles Dodgson warned a child correspondent of the dangers of living in the looking-glass world of mathematicians like himself, the high price of consistently believing “six impossible things before breakfast”: . . . Don’t be in such a hurry to believe next time—I’ll tell you why—If you set to work to believe everything you will tire out the muscles of the mind, and then you’ll be so weak you won’t be able to believe the simplest true things. Only last week a friend of mine set to work to believe Jack-the-giant-killer. He managed to do it, but he was so exhausted by it that when I told him it was raining (which was true) he couldn’t believe it, but rushed out into the street without his umbrella, the consequence of which was his hair got seriously damp, and one curl didn’t recover its right shape for nearly two days. . . . In all his books, Brian Greene is our tour guide on a journey into his particular looking-glass world—string theory, an exercise in the speculative sublime, a sublime only for aficionados, certainly not for you and me. Here is the abstract of an article cited a respectable 201 times: . . . We show that a string-inspired Planck scale modification of general relativity can have observable cosmological effects. Specifically, we present a complete analysis of the inflationary perturbation spectrum produced by a phenomenological Lagrangian that has a standard form on large scales but incorporates a string-inspired short distance cutoff, and find a deviation from the standard result. We use the de Sitter calculation as the basis of a qualitative analysis of other inflationary backgrounds, arguing that in these cases the cutoff could have a more pronounced effect, changing the shape of the spectrum. Moreover, the computational approach developed here can be used to provide unambiguous calculations of the perturbation spectrum in other heuristic models that modify trans-Planckian physics and thereby determine their impact on the inflationary perturbation spectrum. Finally, we argue that this model may provide an exception to constraints, recently proposed by Tanaka and Starobinsky, on the ability of Planck-scale physics to modify the cosmological spectrum. . . .

scholarly journals Pathways to relativistic curved momentum spaces: de Sitter case study

2016 ◽  
Vol 25 (02) ◽  
pp. 1650027 ◽  
Author(s):  
Giovanni Amelino-Camelia ◽  
Giulia Gubitosi ◽  
Giovanni Palmisano
Keyword(s):  
Momentum Space ◽  
Hopf Algebras ◽  
Affine Connection ◽  
Planck Scale ◽  
Test Case ◽  
De Sitter ◽  
Group Manifold ◽  
The One ◽  
Natural Test

Several arguments suggest that the Planck scale could be the characteristic scale of curvature of momentum space. As other recent studies, we assume that the metric of momentum space determines the condition of on-shellness while the momentum space affine connection governs the form of the law of composition of momenta. We show that the possible choices of laws of composition of momenta are more numerous than the possible choices of affine connection on a momentum space. This motivates us to propose a new prescription for associating an affine connection to momentum composition, which we compare to the one most used in the recent literature. We find that the two prescriptions lead to the same picture of the so-called [Formula: see text]-momentum space, with de Sitter (dS) metric and [Formula: see text]-Poincaré connection. We then show that in the case of “proper dS momentum space”, with the dS metric and its Levi–Civita connection, the two prescriptions are inequivalent. Our novel prescription leads to a picture of proper dS momentum space which is DSR-relativistic and is characterized by a commutative law of composition of momenta, a possibility for which no explicit curved momentum space picture had been previously found. This momentum space can serve as laboratory for the exploration of the properties of DSR-relativistic theories which are not connected to group-manifold momentum spaces and Hopf algebras, and is a natural test case for the study of momentum spaces with commutative, and yet deformed, laws of composition of momenta.

scholarly journals Building models of inflation in no-scale supergravity

2020 ◽  
pp. 2030011
Author(s):  
John Ellis ◽  
Marcos A. G. García ◽  
Natsumi Nagata ◽  
Dimitri V. Nanopoulos ◽  
Keith A. Olive ◽  
...  
Keyword(s):  
Cold Dark Matter ◽  
Planck Scale ◽  
Neutrino Masses ◽  
De Sitter ◽  
Building Models ◽  
Scale Models ◽  
Cosmological Inflation ◽  
Text Model ◽  
Hilbert Action ◽  
Scalar Perturbations

After reviewing the motivations for cosmological inflation formulated in the formalism of supersymmetry, we argue that the appropriate framework is that of no-scale supergravity. We then show how to construct within this framework inflationary models whose predictions for the tilt in the spectrum of scalar perturbations, [Formula: see text], and the ratio, [Formula: see text], of tensor and scalar perturbations coincide with those of the [Formula: see text] model of inflation proposed by Starobinsky. A more detailed study of no-scale supergravity reveals a structure that is closely related to that of [Formula: see text] modifications of the minimal Einstein–Hilbert action for general relativity, opening avenues for constructing no-scale de Sitter and anti-de Sitter models by combining pairs of Minkowski models, as well as generalizations of the original no-scale Starobinsky models of inflation. We then discuss the phenomenology of no-scale models of inflation, including inflaton decay and reheating, and then the construction of explicit scenarios based on SU(5), SO(10) and string-motivated flipped SU(5)×U(1) GUT models. The latter provides a possible model of almost everything below the Planck scale, including neutrino masses and oscillations, the cosmological baryon asymmetry and cold dark matter, as well as [Formula: see text] and [Formula: see text].

Kantowski-Sachs Cosmology, Weyl Geometry and Asymptotic Safety in Quantum Gravity

2020 ◽  
Author(s):  
Carlos Castro Perelman
Keyword(s):  
Black Hole ◽  
Planck Scale ◽  
Dilaton Gravity ◽  
De Sitter ◽  
Schwarzschild Black Hole ◽  
Exterior Region ◽  
Asymptotic Safety ◽  
Sign Change ◽  
Average Action ◽  
Black Hole Interior

A brief review of the essentials of Asymptotic Safety and the Renormalization Group (RG) improvement of the Schwarzschild Black Hole that removes the r = 0 singularity is presented. It is followed with a RG-improvement of the Kantowski-Sachs metric associated with a Schwarzschild black hole interior and such that there is no singularity at t = 0 due to the running Newtonian coupling G(t) (vanishing at t = 0). Two temporal horizons at t _- \simeq t_P and t_+ \simeq t_H are found. For times below the Planck scale t < t_P, and above the Hubble time t > t_H, the components of the Kantowski-Sachs metric exhibit a key sign change, so the roles of the spatial z and temporal t coordinates are exchanged, and one recovers a repulsive inflationary de Sitter-like core around z = 0, and a Schwarzschild-like metric in the exterior region z > R_H = 2G_o M. The inclusion of a running cosmological constant \Lambda (t) follows. We proceed with the study of a dilaton-gravity (scalar-tensor theory) system within the context of Weyl's geometry that permits to single out the expression for the classical potential V (\phi ) = \kappa\phi^4, instead of being introduced by hand, and find a family of metric solutions which are conformally equivalent to the (Anti) de Sitter metric. To conclude, an ansatz for the truncated effective average action of ordinary dilaton-gravity in Riemannian geometry is introduced, and a RG-improved Cosmology based on the Friedmann-Lemaitre-Robertson-Walker (FLRW) metric is explored.

BLACK HOLE QUANTIZATION, THERMODYNAMICS AND COSMOLOGICAL CONSTANT

2004 ◽  
Vol 13 (05) ◽  
pp. 885-898
Author(s):  
LI XIANG
Keyword(s):  
Black Hole ◽  
Cosmological Constant ◽  
Vacuum Energy ◽  
Planck Scale ◽  
Additional Term ◽  
Logarithmic Correction ◽  
De Sitter ◽  
Horizon Area ◽  
Constant Distance ◽  
The Universe

Bekenstein argues that the horizon area of a black hole has a constant distance spectrum. We investigate the effects of such a discrete spectrum on the thermodynamics of a Schwarzchild black hole (SBH) and a Schwarzchild–de Sitter black hole (SdBH), in terms of the time-energy uncertainty relation and Stefan–Boltzman law. For the massive SBH, a negative and logarithmic correction to the Bekenstein–Hawking entropy is obtained, as well as other authors by using other methods. As to the minimal hole near the Planck scale, its entropy is no longer proportional to the horizon area, but is of order of the mass of the hole. This is similar to an excited stringy state. The vanishing heat capacity of such a minimal black hole implies that it may be a remnant as the ground state of the evaporating hole. The properties of a SdBH are similar to the SBH, except for an additional term of square area associated with the cosmological constant. In order to maintain the validity of the Bekenstein–Hawking formula, the cosmological constant is strongly limited by the size of the biggest black hole in the universe. A relation associated with the cosmological constant, Planck area and the Stefan–Boltzman constant is obtained. The cosmological constant is not only related to the vacuum energy, but is also related to the thermodynamics.

scholarly journals RELATIVE LOCALITY IN CURVED SPACETIME

2013 ◽  
Vol 28 (22) ◽  
pp. 1350101 ◽  
Author(s):  
JERZY KOWALSKI-GLIKMAN ◽  
GIACOMO ROSATI
Keyword(s):  
Momentum Space ◽  
Planck Scale ◽  
De Sitter ◽  
Curved Spacetime ◽  
Soccer Ball ◽  
The Core ◽  
Core Feature ◽  
Space Curvature ◽  
Curvature Deformation ◽  
Ball Problem

In this paper we construct the action describing dynamics of the particle moving in curved spacetime, with a nontrivial momentum space geometry. Curved momentum space is the core feature of theories where relative locality effects are present. So far aspects of nonlinearities in momentum space have been studied only for flat or constantly expanding (de Sitter) spacetimes, relying on their maximally symmetric nature. The extension of curved momentum space frameworks to arbitrary spacetime geometries could be relevant for the opportunities to test Planck-scale curvature/deformation of particles momentum space. As a first example of this construction we describe the particle with κ-Poincaré momentum space on a circular orbit in Schwarzschild spacetime, where the contributes of momentum space curvature turn out to be negligible. The analysis of this problem relies crucially on the solution of the soccer ball problem.

scholarly journals A Theory of War

2017 ◽  
Author(s):  
thomas Scheff
Keyword(s):  
Karl Marx ◽  
Feedback Loops ◽  
Emotional Experiences ◽  
Social Emotional ◽  
Social And Emotional ◽  
The Social ◽  
Theory Of War ◽  
The Mind ◽  
Looking Glass

A Theory of War and Violence (First section)Thomas Scheff, G. Reginald Daniel, and Joseph Loe-Sterphone, Dept of Sociology, UCSB(9260 words total) Abstract: It is possible that war in modern societies is largely driven by emotions, but in a way that is almost completely hidden. Modernity individualizes the self and tends to ignore emotions. As a result, conflict can be caused by sequences in which the total hiding of humiliation leads to vengeance. This essay outlines a theory of the social-emotional world implied in the work of C. H. Cooley and others. Cooley’s concept of the “looking-glass self” can be used as antidote to the assumptions of modernity: the basic self is social and emotional: selves are based on “living in the mind” of others, with a result of feeling either pride of shame. Cooley discusses shame at some length, unlike most approaches, which tend to hide it. This essay proposes that the complete hiding of shame can lead to feedback loops (spirals) with no natural limit: shame about shame and anger is only the first step. Emotion backlogs can feed back when emotional experiences are completely hidden: avoiding all pain can lead to limitless spirals. These ideas may help explain the role of France in causing WWI, and Hitler’s rise to power in Germany. To the extent that these propositions are true, the part played by emotions and especially shame in causing wars need to be further studied.“...if a whole nation were to feel ashamed it would be like a lion recoiling in order to spring.” Karl Marx (1975, p. 200)

scholarly journals Dark energy and quantum gravity

2019 ◽  
Vol 28 (14) ◽  
pp. 1944018 ◽  
Author(s):  
Per Berglund ◽  
Tristan Hübsch ◽  
Djordje Minić
Keyword(s):  
Dark Energy ◽  
String Theory ◽  
Quantum Gravity ◽  
Cosmological Constant ◽  
Particle Physics ◽  
Dual Space ◽  
Planck Scale ◽  
De Sitter Spacetime ◽  
De Sitter ◽  
Sitter Spacetime

Realizing dark energy and the observed de Sitter spacetime in quantum gravity has proven to be obstructed in almost every usual approach. We argue that additional degrees of freedom of the left- and right-movers in string theory and a resulting doubled, noncommutatively generalized geometric formulation thereof can lead to an effective model of dark energy consistent with de Sitter spacetime. In this approach, the curvature of the canonically conjugate dual space provides for the dark energy inducing a positive cosmological constant in the observed spacetime, whereas the size of the above dual space is the gravitational constant in the same observed de Sitter spacetime. As a hallmark relation owing to a unique feature of string theory which relates short distances to long distances, the cosmological constant scale, the Planck scale and the effective TeV-sized particle physics scale must satisfy a see-saw-like formula — precisely the generic prediction of certain stringy cosmic brane type models.

scholarly journals Phase transition and geometrical thermodynamics of energy-dependent dilatonic BTZ black holes with power-law electrodynamics

2020 ◽  
Vol 2020 (3) ◽  
Author(s):  
M Dehghani ◽  
M Badpa
Keyword(s):  
Black Holes ◽  
Black Hole ◽  
Power Law ◽  
Scalar Potential ◽  
Standard Form ◽  
Three Dimensional ◽  
Nonlinear Electrodynamics ◽  
De Sitter ◽  
Field Equations ◽  
Energy Dependent

Abstract The coupled scalar, electromagnetic, and gravitational field equations of Einstein–dilaton gravity theory have been solved in a three-dimensional energy-dependent spacetime and in the presence of power-law nonlinear electrodynamics. The scalar potential is written as the linear combination of two exponential functions, and two families of three-dimensional dilatonic black hole solutions have been introduced which indicate the impacts of rainbow functions on the spacetime geometry. Through consideration of curvature scalars, it has been found that the asymptotic behavior of the solutions is neither flat nor anti-de Sitter. It has been illustrated that, with a suitable choice of parameters, the solutions can produce the two-horizon, extreme and naked singularity black holes. By calculating the black hole charge, mass, entropy, temperature, and electric potential, it has been proved that they fulfill the standard form of the first law of black hole thermodynamics. The thermodynamic stability of the black holes has been analyzed by utilizing the canonical and grand canonical ensembles and noting the signature of the black hole heat capacity and Gibbs free energy of the black holes. The points of type-1, type-2, and Hawking–Page phase transitions and the ranges at which the black holes are locally or globally stable have been determined. The geometrical thermodynamics of the black holes has been studied by use of different thermodynamic metrics, and the results of different approaches have been compared.

scholarly journals THERMODYNAMICS OF NONCOMMUTATIVE DE SITTER SPACE–TIME

2009 ◽  
Vol 18 (01) ◽  
pp. 159-171 ◽  
Author(s):  
B. VAKILI ◽  
N. KHOSRAVI ◽  
H. R. SEPANGI
Keyword(s):  
Uncertainty Principle ◽  
Vacuum Energy ◽  
Planck Scale ◽  
Heisenberg Algebra ◽  
De Sitter Space ◽  
Space Time ◽  
De Sitter ◽  
Quantization Rule ◽  
Thermodynamical Properties ◽  
Noncommutative Parameter

We study the effects of noncommutativity of space–time geometry on the thermodynamical properties of the de Sitter horizon. We show that noncommutativity results in modifications in temperature, entropy and vacuum energy and that these modifications are of order of the Planck scale, suggesting that the size of the noncommutative parameter should be close to that of the Planck. In an alternative way to deal with noncommutativity, we obtain a quantization rule for the entropy. Since noncommutativity in space–time geometry modifies the Heisenberg algebra and introduces the general uncertainty principle, we also investigate the above problem in this framework.

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