Trapping of Light by a Black Hole

Trapping of Light by a Black Hole
(a) The paths and colors of light rays departing from a main-sequence, giant, or supergiant star are affected very little by the star’s gravitational force.
(b) Light leaving the vicinity of a white dwarf curves and redshifts more, whereas (c) near a neutron star, some of the photons actually return to the
star’s surface. (d) Inside a black hole, all light remains trapped. Most photons curve back in, except those that fly straight upward, which become infinitely
redshifted, thereby disappearing.