scholarly journals HIDDEN sl(2,R) SYMMETRY IN 2D CFTs AND THE WAVE FUNCTION OF 3D QUANTUM GRAVITY

2004 ◽  
Vol 2004 (01) ◽  
pp. 028-028 ◽  
Author(s):  
F Nitti ◽  
M Porrati
Keyword(s):  
Wave Function ◽  
Quantum Gravity ◽  
R Symmetry

scholarly journals Semi-classical approximations based on Bohmian mechanics

2020 ◽  
Vol 35 (14) ◽  
pp. 2050070 ◽  
Author(s):  
Ward Struyve
Keyword(s):  
Wave Function ◽  
Quantum Theory ◽  
Quantum Gravity ◽  
Quantum Electrodynamics ◽  
Degrees Of Freedom ◽  
Equations Of Motion ◽  
Bohmian Mechanics ◽  
Expectation Values ◽  
Usual Approach ◽  
Classical Approximation

Semi-classical theories are approximations to quantum theory that treat some degrees of freedom classically and others quantum mechanically. In the usual approach, the quantum degrees of freedom are described by a wave function which evolves according to some Schrödinger equation with a Hamiltonian that depends on the classical degrees of freedom. The classical degrees of freedom satisfy classical equations that depend on the expectation values of quantum operators. In this paper, we study an alternative approach based on Bohmian mechanics. In Bohmian mechanics the quantum system is not only described by the wave function, but also with additional variables such as particle positions or fields. By letting the classical equations of motion depend on these variables, rather than the quantum expectation values, a semi-classical approximation is obtained that is closer to the exact quantum results than the usual approach. We discuss the Bohmian semi-classical approximation in various contexts, such as nonrelativistic quantum mechanics, quantum electrodynamics and quantum gravity. The main motivation comes from quantum gravity. The quest for a quantum theory for gravity is still going on. Therefore a semi-classical approach where gravity is treated classically may be an approximation that already captures some quantum gravitational aspects. The Bohmian semi-classical theories will be derived from the full Bohmian theories. In the case there are gauge symmetries, like in quantum electrodynamics or quantum gravity, special care is required. In order to derive a consistent semi-classical theory it will be necessary to isolate gauge-independent dependent degrees of freedom from gauge degrees of freedom and consider the approximation where some of the former are considered classical.

FALLING INTO A BLACK HOLE

2008 ◽  
Vol 17 (03n04) ◽  
pp. 583-589 ◽  
Author(s):  
SAMIR D. MATHUR
Keyword(s):  
Field Theory ◽  
Black Hole ◽  
Wave Function ◽  
String Theory ◽  
Quantum Gravity ◽  
Definition Of

String theory tells us that quantum gravity has a dual description as a field theory (without gravity). We use the field theory dual to ask what happens to an object as it falls into the simplest black hole: the two-charge extremal hole. In the field theory description the wave function of a particle is spread over a large number of "loops," and the particle has a well-defined position in space only if it has the same "position" on each loop. For the infalling particle we find one definition of "same position" on each loop, but there is a different definition for outgoing particles and no canonical definition in general in the horizon region. Thus the meaning of "position" becomes ill-defined inside the horizon.

scholarly journals Does Compton–Schwarzschild duality in higher dimensions exclude TeV quantum gravity?

2018 ◽  
Vol 27 (16) ◽  
pp. 1930001 ◽  
Author(s):  
Matthew J. Lake ◽  
Bernard Carr
Keyword(s):  
Black Holes ◽  
Black Hole ◽  
Wave Function ◽  
Quantum Gravity ◽  
Extra Dimensions ◽  
Planck Length ◽  
Compton Wavelength ◽  
Planck Mass ◽  
Higher Dimensional ◽  
Spatial Dimensions

In three spatial dimensions, the Compton wavelength [Formula: see text]) and Schwarzschild radius [Formula: see text]) are dual under the transformation [Formula: see text], where [Formula: see text] is the Planck mass. This suggests that there could be a fundamental link — termed the Black Hole Uncertainty Principle or Compton–Schwarzschild correspondence — between elementary particles with [Formula: see text] and black holes in the [Formula: see text] regime. In the presence of [Formula: see text] extra dimensions, compactified on some scale [Formula: see text] exceeding the Planck length [Formula: see text], one expects [Formula: see text] for [Formula: see text], which breaks this duality. However, it may be restored in some circumstances because the effective Compton wavelength of a particle depends on the form of the [Formula: see text]-dimensional wave function. If this is spherically symmetric, then one still has [Formula: see text], as in the [Formula: see text]-dimensional case. The effective Planck length is then increased and the Planck mass reduced, allowing the possibility of TeV quantum gravity and black hole production at the LHC. However, if the wave function of a particle is asymmetric and has a scale [Formula: see text] in the extra dimensions, then [Formula: see text], so that the duality between [Formula: see text] and [Formula: see text] is preserved. In this case, the effective Planck length is increased even more but the Planck mass is unchanged, so that TeV quantum gravity is precluded and black holes cannot be generated in collider experiments. Nevertheless, the extra dimensions could still have consequences for the detectability of black hole evaporations and the enhancement of pair-production at accelerators on scales below [Formula: see text]. Though phenomenologically general for higher-dimensional theories, our results are shown to be consistent with string theory via the minimum positional uncertainty derived from [Formula: see text]-particle scattering amplitudes.

Genetic quantum gravity and quantum Darwinism

2019 ◽  
Author(s):  
Vitaly Kuyukov
Keyword(s):  
Wave Function ◽  
Quantum Gravity ◽  
Dominant Gene ◽  
Space Time ◽  
Mathematical Form ◽  
Time Axis ◽  
Quantum Darwinism ◽  
Braid Theory ◽  
Concept Of Information ◽  
Selection Of

The nature of quantum mechanics has various interpretations. In this paper we consider the hypothesis of quantum Darwinism. Quantum theory is closely connected with the concept of information. Perhaps there is an analogue of the genetic code for quantum Darwinism. Here the attempt of the genetic formulation of quantum gravity. It is based on the idea of the quantum of the DNA helix in space-time , directed along the time axis. Twisting together all of the genetic spirals creates the very fabric of space-time. Such a mathematical form exists in braid theory. Matter how information is encoded in the genetic DNA structure of space-time. Natural and artificial selection of quantum Darwinism leads to the collapse of the wave function and the identification of a dominant gene.

scholarly journals HOW FAST CAN A BLACK HOLE RELEASE ITS INFORMATION?

2009 ◽  
Vol 18 (14) ◽  
pp. 2215-2219 ◽  
Author(s):  
SAMIR D. MATHUR
Keyword(s):  
Black Hole ◽  
Wave Function ◽  
String Theory ◽  
Quantum Gravity ◽  
Linear Combination ◽  
Evaporation Time ◽  
Simple Estimate ◽  
Semiclassical Physics ◽  
Gravity Effects ◽  
Spreading Time

When a shell collapses through its horizon, semiclassical physics suggests that information cannot escape from this horizon. One might hope that nonperturbative quantum gravity effects will change this situation and avoid the information paradox. We note that string theory has provided a set of states over which the wave function of the shell can spread, and that the number of these states is large enough that such a spreading would significantly modify the classically expected evolution. In this article we perform a simple estimate of the spreading time, showing that it is much shorter than the Hawking evaporation time for the hole. Thus information can emerge from the hole through the relaxation of the shell state into a linear combination of fuzzballs.

LOW ENERGY EFFECTIVE ACTION OF QUANTUM GRAVITY AND THE NATURALNESS PROBLEM

2013 ◽  
Vol 28 (03n04) ◽  
pp. 1340001 ◽  
Author(s):  
HIKARU KAWAI
Keyword(s):  
Wave Function ◽  
Quantum Gravity ◽  
Effective Action ◽  
Low Energy ◽  
Coupling Constants ◽  
Local Action ◽  
Topology Change ◽  
Dynamical Mechanism ◽  
Lorentzian Signature ◽  
The Universe

In quantum gravity or string theory, it is natural to take the topology change of the space into account. We consider the low energy effective action for such case and show that it does not have a simple form of the local action but has a multilocal form. Actually, in quantum gravity or matrix model, there are some mechanisms that the low energy effective action becomes S eff = ∑ici Si + ∑ijcijSiSj + ∑ijkcijk Si Sj Sk + ⋯, where Si is a local action of the form [Formula: see text]. We further discuss that the topology change of the space naturally leads to the multiverse in which indefinite number of macroscopic universes exist in parallel. In this case, the space–time coordinates x in the multilocal action may sit either in the same universe or in different ones. We then consider the wave function of the entire multiverse, and see how the locality and causality are recovered in such theory. We further discuss the possibility of solving the naturalness problem. In doing so, we need to introduce some assumptions to interpret the multiverse wave function. We consider two different possibilities. One is to simply assume the probabilistic interpretation for the multiverse wave function. The other is to assume infrared cutoff independence of the partition function of the universe. In both cases, we find that the big fix occurs, in which all the coupling constants in the low energy physics are determined by the dynamics of the multiverse. Actually, we find that they are fixed in such a way that the total entropy of the universe at the late stage (in the far future) is maximized. Although the argument here is similar to Coleman's original one given in the late 1980s, our results are based on Lorentzian signature theory and the dynamical mechanism is rather different.

scholarly journals STRUCTURE OF EXTENDED LOOP WAVE FUNCTION IN QUANTUM GRAVITY AND OPERATOR FORMALISM

2005 ◽  
Vol 20 (05) ◽  
pp. 907-921
Author(s):  
MICHIYOSHI SAITO ◽  
HUJIO NODA ◽  
TSUTOMU TASHIRO
Keyword(s):  
Wave Function ◽  
Quantum Gravity ◽  
Operator Formalism ◽  
Loop Function ◽  
The Family

The structure of extended loop wave function is investigated in terms of the operator formalism. It is found that the extended loop wave function is characterized by the family number and classified by the partition of the family number. It is pointed out that the constraints to the extended loop function in quantum gravity exhibit a hierarchy structure.

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