What is the exact difference between a Cauchy horizon and a chronology horizon? Aren't both frontiers between the events which are caused and the ones that aren't?
$\begingroup$
$\endgroup$
1
-
$\begingroup$ What is a chronological horizon supposed to be? $\endgroup$– Ryan UngerCommented Nov 15, 2016 at 2:49
Add a comment
|
1 Answer
$\begingroup$
$\endgroup$
A Cauchy horizon is a generic term for the boundary of the domain of dependancy (the domain for which every causal curve passing through intersects the hypersurface considered exactly once). It can be caused by either closed timelike curves (the causal curve might intersects the hypersurface more than once) or singularities (the causal curve might not intersect the hypersurface at all).
A chronology horizon is a specific type of Cauchy horizon that is caused by closed timelike curves. Generally it stems from what is called a fountain, which is the "first" close null curve, while a Cauchy horizon caused by a singularity will stem from the singularity itself.
Here's an example of a chronology horizon (from a Misner paper, I think) :
