Figure 9

Figure 9: The function $R (r)$ for the Schwarzschild metric. Light rays that start at $rO$ with initial direction $Θ$ are confined to the region where $R (r) ≥ R (rO) sin Θ$ . The equation $R (3m ) = R (rO )sinδ$ defines for each $rO$ a critical value $δ$ . A light ray from $rO$ with $Θ = δ$ asymptotically approaches $r = 3m$ .