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Louis Witten

Publications and source records attributed to Louis Witten.

24 records · Page 2Linked to original sources

Quantum Naked Singularities in 2d Dilaton Gravity

Roughly speaking, naked singularities are singularities that may be seen by timelike observers. The Cosmic Censorship conjecture forbids their existence by stating that a reasonable system of energy will not, under reasonable conditions, collapse into a naked singularity. There are however many (classical) counter-examples to this conjecture in the literature. We propose a defense of the conjecture through the quantum theory. We will show that the Hawking effect and the accompanying back reaction, when consistently applied to naked singularities in two dimensional models of dilaton gravity with matter and a cosmological constant, prevent their formation by causing them to explode or emit radiation catastrophically. This contrasts with black holes which radiate slowly. If this phenomenon is reproduced in the four dimensional world, the explosion of naked singularities should have observable consequences.

hep-th↗

Do Naked Singularities Form?

A naked singularity is formed by the collapse of a Sine-Gordon soliton in 1+1 dimensional dilaton gravity with a negative cosmological constant. We examine the quantum stress tensor resulting from the formation of the singularity. Consistent boundary conditions require that the incoming soliton is accompanied by a flux of incoming radiation across past null infinity, but neglecting the back reaction of the spacetime leads to the absurd conclusion that the total energy entering the system by the time the observer is able to receive information from the singularity is infinite. We conclude that the back reaction must prevent the formation of the naked singularity.

gr-qc↗

Soliton Induced Singularities in 2 d Gravity and their Evaporation

Positive energy singularities induced by Sine-Gordon solitons in 1+1 dimensional dilaton gravity with positive and negative cosmological constant are considered. When the cosmological constant is positive, the singularities combine a white hole, a timelike singularity and a black hole joined smoothly near the soliton center. When the cosmological constant is negative, the solutions describe two timelike singularities joined smoothly near the soliton center. We describe these spacetimes and examine their evaporation in the one loop approximation.

gr-qc↗

Wilson Loops and Black Holes in 2+1 Dimensions

In 2+1 dimensional Chern-Simons gravity, Wilson loops in the three dimensional Anti de Sitter group, $SO(2,2)$, reproduce the spinning black hole of Bañados, Teitelboim and Zanelli (BTZ) by naturally duplicating the necessary identification of points of a four dimensional globally $SO(2,2)$ invariant space in which the hole appears as an embedding.

gr-qc↗

Formation and Evaporation of a Naked Singularity in 2D Gravity

We describe a classical configuration of conformal matter forming a naked singularity and discuss its subsequent Hawking evaporation within the context of two dimensional dilaton gravity. The one loop analysis is credible for a large mass naked singularity and suggests the existence of a weak cosmological censorship that would cause it to explode into radiation upon forming. (Hardcopies of figures available on request)

hep-th↗

Do Black Holes Form?

We argue that the collapse of a non-rotating object into a black hole has not been proved to be dynamically stable. There are unstable modes and one should explore whether they may be excited. This paper is withdrawn for revisions and clarification

hep-th↗