|
Stability reversal in non-homogeneous static fluids in
high-dimensional spaces
Gabriel Nagy
Department of Mathematics
UCSD
Abstract
Fluid models have been used as toy-models of event horizons in general
relativity and its generalizations to more than four spacetime dimensions.
We study here a fluid model for the Gregory-Laflamme instability in black
strings. With consider a Newtonian, incompressible, static,
axially-symmetric fluid with surface tension, in n dimensions plus one
periodic dimension. The fluid configurations are those that minimize the
fluid surface area for fixed volume. Homogeneous fluid configurations are
known to be stationary solutions of this functional, and they are stable
in a dynamical sense above a critical value of the fluid volume. Below
that value Plateau-Rayleigh instabilities occur. We show in this article
that at this critical value of the volume there is a pitchfork bifurcation
point. We prove that there are infinitely many other pitchfork bifurcation
points at smaller values of the fluid volume. Each bifurcation solution
represents a non-homogeneous static fluid configuration and its stability
depends on the space dimension. By stability we mean in the sense of
minimum of the above functional. We show that the non-homogeneous
configurations are all unstable if n less or equal 10, and they all become
stable if n bigger or equal 11. This stability inversion for high space
dimensions could be of interest in gravitational theories in more than
four dimensions and in string theory.
|











