From: Spudboy100@aol.com
Date: Sat Apr 05 2003 - 18:35:19 MST
http://newton.ex.ac.uk/aip/latest.html
>>SPACESHIP TRAVEL TO ANOTHER UNIVERSE THROUGH A BLACK HOLE may be highly
improbable, but it cannot be ruled out, according to a new analysis that
explores the idea of "hybrid singularity." As science fiction fans know,
anyone who wishes to fall into a black hole and re-emerge at some distant
location or even an another universe would have to go through a forbidding
region inside the black hole known as a "space-time singularity."
Traditionally this means negotiating a region of infinite density exerting
destructive, tide-like distortions on any "extended object" such as a
spaceship, molecule, or anything that is not truly point-like. Physicists now
suspect this picture is incomplete and that a second and potentially milder
type of singularity might exist. Known as a "Cauchy horizon singularity," it
would impart only finite tidal distortions on extended objects. The kinder,
gentler singularity should only develop when a regular stream of matter or
energy falls into the hole. Previous analyses have considered only streams
that were brief bursts. But long-duration "non-compact" streams of radiation,
like the cosmic microwave background, can also fall into the black hole. In a
more comprehensive analysis that takes these "non-compact" sources into
account, Lior Burko of the University of Utah (burko@physics.utah.edu)
explores how a black hole's interior is affected by such infalling radiation.
If the non-compact sources are weak, Burko shows, a hybrid singularity forms:
a strong sector (inevitably destructive) and a weak sector (finite tidal
distortions). Conceivably, a spaceship entering through the weak sector could
travel unscathed to another part of space-time. If the perturbations due to
non-compact sources are large, however, Burko shows that the singularity ends
up being strong, and destructive, everywhere in the black hole. Whether black
hole singularities in our universe are strong-only or hybrid in nature
depends on incompletely known cosmological parameters (such as the expansion
rate of the universe and the nature of dark energy). Several factors may
ultimately rule out the possibility of hyperspace travel. They include: (1)
the possibility that "weak" sectors may still be much too hazardous for
travel; (2) overwhelming effects on the black hole from actual non-compact
sources and (3) a working theory of quantum gravity, which may reveal other
factors that rule out hyperspace travel. But for now, Burko says, the
possibilities are open. (Burko, Physical Review Letters, 28 March 2003) <<
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