scholarly journals On negative energies, strings, branes, and braneworlds: A review of novel approaches

2020 ◽  
Vol 35 (33) ◽  
pp. 2030020
Author(s):  
Matej Pavšič

On the way towards quantum gravity and the unification of interaction, several ideas have been rejected and avenues avoided because they were perceived as physically unviable. But in the literature there are works in which it was found the contrary, namely that those rejected topics make sense after all. Such topics, reviewed in this paper, are negative energies occurring in higher derivative theories and ultrahyperbolic spaces, ordering ambiguity of operators in curved spaces, the vast landscape of possible compactifications of extra dimensions in string theory, and quantization of a 3-brane in braneworld scenarios.

2019 ◽  
Author(s):  
Vitaly Kuyukov

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.


2015 ◽  
Vol 24 (11) ◽  
pp. 1530028 ◽  
Author(s):  
Steven Carlip ◽  
Dah-Wei Chiou ◽  
Wei-Tou Ni ◽  
Richard Woodard

We present a bird's-eye survey on the development of fundamental ideas of quantum gravity, placing emphasis on perturbative approaches, string theory, loop quantum gravity (LQG) and black hole thermodynamics. The early ideas at the dawn of quantum gravity as well as the possible observations of quantum gravitational effects in the foreseeable future are also briefly discussed.


Open Physics ◽  
2019 ◽  
Vol 17 (1) ◽  
pp. 831-838
Author(s):  
Massimo Fioranelli ◽  
Alireza Sepehri ◽  
Maria Grazia Roccia ◽  
Mahdieh Ghasemi

Abstract Recently, a method for calculating the quantum spectrum of black holes has been proposed. We show that this method can be applied for radiations of 4 + n - dimensional water around a DNA. In this model, DNA acts like a black hole and produces a curved space-time in a water around it. In these conditions, molecules of water in four dimensional universe are entangled with some DNA-like structures in extra dimension. Consequently, the effects of structures of water in extra dimensions can be observed in four dimensions. The entangled structures emit some quantum spectrum which can be transmitted to pure waters. These waves produce a curved space-time in pure water and make an entanglement between structure of water on four and DNA-like structures in extra dimensions. As a result, some signatures of DNAs can be observed in pure water. This model helps us to understand the reason for the emergence of life on the earth. To explain the model better, we unify Darwin’s theory with string theory in a new Darwinian’s string theory. In this theory, a zero dimensional manifold decays into two types of closed strings. One type decays into open strings and then these strings join to each other and form cosmos. Another type decays into open strings which form biological matters like DNAs and molecules of water in universe and anti-DNAs and anti-water in anti-universe. Thus, DNAs and molecules water are connected to each other and anti-DNAs and molecules of anti-water in anti-universe through some closed strings. These strings helps to molecules of water to store their informations in extra dimension and have long time memory. Because, information that are transformed into extra dimensions through closed strings, could be returned into universe. Also, these closed strings could have the main role in DNA transduction. Because, they connect two tubes one including water and DNA and another pure water in universe to two tubes including anti-DNA and water in anti-universe and transform properties of DNA into pure water. As a result, Darwinian string theory can confirm both water memory and DNA transduction. Finally, this theory response to this question that why memory of water couldnt remain for a long time. In this model, open strings which connects atoms in universe with anti-atoms in anti-universe interact with open strings which connects molecules of water and anti-water and decrease their entanglement. This causes that exchanging information between water and anti-water decreases and memory is dis-appeared.


1986 ◽  
Vol 33 (10) ◽  
pp. 2756-2779 ◽  
Author(s):  
I. Antoniadis ◽  
E. T. Tomboulis

1993 ◽  
Vol 312 (4) ◽  
pp. 411-416 ◽  
Author(s):  
Nobuyuki Ishibashi

2005 ◽  
Vol 14 (12) ◽  
pp. 2347-2353 ◽  
Author(s):  
CHRIS CLARKSON ◽  
ROY MAARTENS

If string theory is correct, then our observable universe may be a three-dimensional "brane" embedded in a higher-dimensional spacetime. This theoretical scenario should be tested via the state-of-the-art in gravitational experiments — the current and upcoming gravity-wave detectors. Indeed, the existence of extra dimensions leads to oscillations that leave a spectroscopic signature in the gravity-wave signal from black holes. The detectors that have been designed to confirm Einstein's prediction of gravity waves, can in principle also provide tests and constraints on string theory.


2014 ◽  
Vol 23 (12) ◽  
pp. 1442006 ◽  
Author(s):  
Laurent Freidel ◽  
Robert G. Leigh ◽  
Djordje Minic

In a natural extension of the relativity principle, we speculate that a quantum theory of gravity involves two fundamental scales associated with both dynamical spacetime as well as dynamical momentum space. This view of quantum gravity is explicitly realized in a new formulation of string theory which involves dynamical phase-space and in which spacetime is a derived concept. This formulation naturally unifies symplectic geometry of Hamiltonian dynamics, complex geometry of quantum theory and real geometry of general relativity. The spacetime and momentum space dynamics, and thus dynamical phase-space, is governed by a new version of the renormalization group (RG).


2010 ◽  
Vol 19 (14) ◽  
pp. 2311-2317 ◽  
Author(s):  
VISHNU JEJJALA ◽  
DJORDJE MINIC ◽  
Y. JACK NG ◽  
CHIA-HSIUNG TZE

We apply recent advances in quantum gravity to the problem of turbulence. Adopting the AdS/CFT approach we propose a string theory of turbulence that explains the Kolmogorov scaling in 3 + 1 dimensions and the Kraichnan and Kolmogorov scalings in 2 + 1 dimensions. In the gravitational context, turbulence is intimately related to the properties of space–time or quantum foam.


2015 ◽  
Vol 30 (09) ◽  
pp. 1550044 ◽  
Author(s):  
L. V. Laperashvili ◽  
H. B. Nielsen ◽  
A. Tureanu

We develop a self-consistent Spin (4, 4)-invariant model of the unification of gravity with weak SU(2) gauge and Higgs fields in the visible and invisible sectors of our universe. We consider a general case of the graviweak unification, including the higher-derivative super-renormalizable theory of gravity, which is a unitary, asymptotically-free and perturbatively consistent theory of the quantum gravity.


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