Left: the free falling observer (red) sends a circular ring of photons (green) when he passes r=rₛ/2 inside of a Schwarzschild black hole. Even the photons which are directed radially outwards are moving inwards, although not as fast as those directed radially inwards. Right: two observers send signals to each other when they pass r=rₛ/2. Coordinate system: Gullstrand-Painlevé Raindrop coordinates