CAN WE PASS THROUGH THE STRONG CURVATURE SINGULARITY BY ACCELERATION IN STRING THEORY?

2002 ◽  
pp. 1001-1002
Author(s):  
K. MAEDA ◽  
T. TORII ◽  
M. NARITA ◽  
S. YAHIKOZAWA
Keyword(s):  
String Theory ◽  
Curvature Singularity ◽  
Pass Through ◽  
Strong Curvature

scholarly journals STATIC SPHERICALLY SYMMETRIC SCALAR FIELD SPACETIMES WITH C0 MATCHING

2011 ◽  
Vol 26 (17) ◽  
pp. 1281-1290 ◽  
Author(s):  
SWASTIK BHATTACHARYA ◽  
PANKAJ S. JOSHI
Keyword(s):  
Scalar Field ◽  
Naked Singularity ◽  
Scalar Fields ◽  
Massless Scalar ◽  
Massless Scalar Field ◽  
Spherically Symmetric ◽  
Curvature Singularity ◽  
Einstein Theory ◽  
Full Class ◽  
Strong Curvature

All the classes of static massless scalar field models currently available in the Einstein theory of gravity necessarily contain a strong curvature naked singularity. We obtain here a family of solutions for static massless scalar fields coupled to gravity, which does not have any strong curvature singularity. This class of models contain a thin shell of singular matter, which has a physical interpretation. The central curvature singularity is, however, avoided which is common to all static massless scalar field spacetime models known so far. Our result thus points out that the full class of solutions in this case may contain non-singular models, which is an intriguing possibility.

scholarly journals GENERALIZED STRONG CURVATURE SINGULARITIES AND COSMIC CENSORSHIP

2002 ◽  
Vol 17 (07) ◽  
pp. 387-397 ◽  
Author(s):  
WIESŁAW RUDNICKI ◽  
ROBERT J. BUDZYŃSKI ◽  
WITOLD KONDRACKI
Keyword(s):  
Causal Structure ◽  
Cosmic Censorship ◽  
Single Type ◽  
Curvature Singularity ◽  
Cosmic Censorship Hypothesis ◽  
Definition Of ◽  
Strong Curvature

A new definition of a strong curvature singularity is proposed. This definition is motivated by the definitions given by Tipler and Królak, but is significantly different and more general. All causal geodesics terminating at these new singularities, which we call generalized strong curvature singularities, are classified into three possible types; the classification is based on certain relations between the causal structure and the curvature strength of the singularities. A cosmic censorship theorem is formulated and proved which shows that only one class of generalized strong curvature singularities, corresponding to a single type of geodesics according to our classification, can be naked. Implications of this result for the cosmic censorship hypothesis are indicated.

scholarly journals Global visibility of a strong curvature singularity in nonmarginally bound dust collapse

2020 ◽  
Vol 102 (4) ◽  
Author(s):  
Karim Mosani ◽  
Dipanjan Dey ◽  
Pankaj S. Joshi
Keyword(s):  
Curvature Singularity ◽  
Strong Curvature

HIGHER DIMENSIONAL CHARGED NULL FLUID COLLAPSE AND COSMIC CENSORSHIP

2002 ◽  
Vol 11 (02) ◽  
pp. 237-244 ◽  
Author(s):  
S. G. GHOSH ◽  
R. V. SARAYKAR
Keyword(s):  
Black Holes ◽  
Energy Condition ◽  
Cosmic Censorship ◽  
Final Outcome ◽  
Spherically Symmetric ◽  
Curvature Singularity ◽  
Naked Singularities ◽  
Dimensional Spacetime ◽  
Higher Dimensional ◽  
Strong Curvature

We analyze here the spherically symmetric collapse of a charged null fluid in a higher dimensional spacetime. Both naked singularities and black holes are shown to be developing as final outcome of the collapse. A relationship between weak energy condition and occurrence of strong curvature singularity is pointed out.

scholarly journals Noncommutative geometry inspired rotating black string

2018 ◽  
Vol 27 (12) ◽  
pp. 1850108 ◽  
Author(s):  
Dharm Veer Singh ◽  
Md Sabir Ali ◽  
Sushant G. Ghosh
Keyword(s):  
Heat Capacity ◽  
Black Hole ◽  
String Theory ◽  
Short Distance ◽  
Thermodynamic Quantities ◽  
Curvature Singularity ◽  
Black String ◽  
Thermodynamical Properties ◽  
Black Strings ◽  
Black Hole Solutions

Noncommutativity is an idea dating back to that early times of quantum mechanics and the string theory induced noncommutative (NC) geometry provided an effective framework to study the short distance spacetime dynamics. Also, string theory, a candidate for a consistent quantum theory of gravity, admits a variety of classical black hole solutions including black strings. In this paper, we study a NC geometry inspired rotating black string to cylindrical spacetime with a source given by a smeared distribution of mass. The resulting metric is a regular everywhere, i.e. curvature-singularity free rotating black string, that in large [Formula: see text] limit interpolates Lemos black string. Thermodynamical properties of the black strings are also investigated and exact expressions for the temperature, the entropy and the heat capacity are obtained. Owing to the NC correction in the solution, the thermodynamic quantities have also been modified and that the NC geometry inspired black string is always thermodynamically stable.

scholarly journals $$ T\overline{T} $$ , black holes and negative strings

2020 ◽  
Vol 2020 (9) ◽  
Author(s):  
Soumangsu Chakraborty ◽  
Amit Giveon ◽  
David Kutasov
Keyword(s):  
Black Holes ◽  
String Theory ◽  
Upper Bound ◽  
Point Of View ◽  
The Other ◽  
Curvature Singularity ◽  
Asymptotically Linear ◽  
Radial Location ◽  
Linear Dilaton ◽  
Single Trace

Abstract String theory on AdS3 has a solvable single-trace irrelevant deformation that is closely related to $$ T\overline{T} $$ T T ¯ . For one sign of the coupling, it leads to an asymptotically linear dilaton spacetime, and a corresponding Hagedorn spectrum. For the other, the resulting spacetime has a curvature singularity at a finite radial location, and an upper bound on the energies of states. Beyond the singularity, the signature of spacetime is flipped and there is an asymptotically linear dilaton boundary at infinity. We study the properties of black holes and fundamental strings in this spacetime, and find a sensible picture. The singularity does not give rise to a hard ultraviolet wall for excitations -one must include the region beyond it to understand the theory. The size of black holes diverges as their energy approaches the upper bound, as does the location of the singularity. Fundamental strings pass smoothly through the singularity, but if their energy is above the upper bound, their trajectories are singular. From the point of view of the boundary at infinity, this background can be thought of as a vacuum of Little String Theory which contains a large number of negative strings.

scholarly journals SINGULARITY IN GRAVITATIONAL COLLAPSE OF PLANE SYMMETRIC CHARGED VAIDYA SPACETIME

2010 ◽  
Vol 25 (33) ◽  
pp. 2831-2836 ◽  
Author(s):  
M. SHARIF ◽  
AISHA SIDDIQA
Keyword(s):  
Gravitational Collapse ◽  
Energy Condition ◽  
Cosmic Censorship ◽  
Final Outcome ◽  
Curvature Singularity ◽  
Field Equations ◽  
Plane Symmetric ◽  
Counter Example ◽  
Cosmic Censorship Hypothesis ◽  
Strong Curvature

We study the final outcome of gravitational collapse resulting from the plane symmetric charged Vaidya spacetime. Using the field equations, we show that the weak energy condition is always satisfied by collapsing fluid. It is found that the singularity formed is naked. The strength of singularity is also investigated by using Nolan's method. This turns out to be a strong curvature singularity in Tipler's sense and hence provides a counter example to the cosmic censorship hypothesis.

Instrumentation for detecting channelling radiation in the high-voltage electron microscope

1983 ◽  
Vol 41 ◽  
pp. 318-319
Author(s):  
J. H. Butler ◽  
C. J. Humphreys
Keyword(s):  
Monochromatic Light ◽  
Incident Beam ◽  
Laboratory Frame ◽  
Relativistic Electrons ◽  
Voltage Electron ◽  
Dipole Emission ◽  
Sinusoidal Oscillations ◽  
Pass Through ◽  
Incident Beam Energy ◽  
Increasing Function

Electromagnetic radiation is emitted when fast (relativistic) electrons pass through crystal targets which are oriented in a preferential (channelling) direction with respect to the incident beam. In the classical sense, the electrons perform sinusoidal oscillations as they propagate through the crystal (as illustrated in Fig. 1 for the case of planar channelling). When viewed in the electron rest frame, this motion, a result of successive Bragg reflections, gives rise to familiar dipole emission. In the laboratory frame, the radiation is seen to be of a higher energy (because of the Doppler shift) and is also compressed into a narrower cone of emission (due to the relativistic “searchlight” effect). The energy and yield of this monochromatic light is a continuously increasing function of the incident beam energy and, for beam energies of 1 MeV and higher, it occurs in the x-ray and γ-ray regions of the spectrum. Consequently, much interest has been expressed in regard to the use of this phenomenon as the basis for fabricating a coherent, tunable radiation source.

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