Poincaré horizon
= Poincaré horizon
{c}
{title2=$X_{-1}+X_d=0$}
The boundary of a chosen <Poincare coordinates on anti-de Sitter spacetime> patch inside the full spacetime is a null coordinate horizon. It is not the timelike <conformal boundary>, and not a curvature singularity. Timelike <geodesics> can cross it in finite proper time while the patch time diverges. In a signed-diameter conformal strip, the patch containing $T=\rho=0$ satisfies $|T|<\pi/2+\rho$.