4 research outputs found
Spacetime Singularities in String and its Low Dimensional Effective Theory
Spacetime singularities are studied in both the -dimensional string
theory and its -dimensional effective theory, obtained by the Kaluza-Klein
compactification. It is found that spacetime singularities in the low
dimensional effective theory may or may not remain after lifted to the
-dimensional string theory, depending on particular solutions. It is also
found that there exist cases in which spacetime singularities appearing in
high/low dimensional spacetimes do not necessarily happen on the same surfaces.Comment: revtex4, 15 pages, 10 figures. Typos are corrected. Version to appear
in Inter. J. Mod. Phys.
Colliding Branes and Formation of Spacetime Singularities
We construct a class of analytic solutions with two free parameters to the
five-dimensional Einstein field equations, which represents the collision of
two timelike 3-branes. We study the local and global properties of the
spacetime, and find that spacelike singularities generically develop after the
collision, due to the mutual focus of the two branes. Non-singular spacetime
can be constructed only in the case where both of the two branes violate the
energy conditions.Comment: four figure
Colliding branes and formation of spacetime singularities in string theory
Colliding branes without symmetry and the formation of spacetime
singularities in string theory are studied. After developing the general
formulas to describe such events, we study a particular class of exact
solutions first in the 5-dimensional effective theory, and then lift it to the
10-dimensional spacetime. In general, the 5-dimensional spacetime is singular,
due to the mutual focus of the two colliding 3-branes. Non-singular cases also
exist, but with the price that both of the colliding branes violate all the
three energy conditions, weak, dominant, and strong. After lifted to 10
dimensions, we find that the spacetime remains singular, whenever it is
singular in the 5-dimensional effective theory. In the cases where no
singularities are formed after the collision, we find that the two 8-branes
necessarily violate all the energy conditions.Comment: revtex4, 13 figures. Some typos were corrected, and new refereeces
added. Final version to appear in JHE
Colliding branes and formation of spacetime singularities in superstring theory.
Includes bibliographical references (p. 141-147).A systematic study of space-times containing two timelike colliding branes is made, in the framework of 10-dimensional string theory. After developing the general formulas to describe such events, we study several classes of exact solutions and space-time singularities in both the (D+d)-dimensional string theory and its D-dimensional effective theory, obtained by Kaluza-Klein compactification. It is found that space-time singularities in the low dimensional effective theory may or may not remain after lifted to the (D+d)-dimensional string theory, depending on the specific solutions. In some cases, solutions of the low dimensional effective theory are free of singularities, but after they are lifted to string theory, the higher dimensional space-times become singular. Therefore, simply lifting low dimensional effective theories to high dimensions seemingly does not solve the singularity problem, and additional physical mechanisms are needed. In general however, the space-time is singular, due to the mutual focus of the two colliding branes. Non-singular cases also exist, but with the price that both of the colliding branes violate all the three energy conditions, weak, dominant, and strong.by Andreas Constantine Tziolas.Ph.D