Figure 6

Figure 6: The region of space-time $ℳ$ under consideration has an internal boundary $Δ$ and is bounded by two Cauchy surfaces $M1$ and $M2$ and the time-like cylinder $τ∞$ at infinity. $M$ is a Cauchy surface in $ℳ$ whose intersection with $Δ$ is a spherical cross-section $S$ and the intersection with $τ∞$ is $S∞$ , the sphere at infinity.