If one accepts the existence of black holes, would it be plausible to assume that a “white hole” exists on the opposite end due to captured light by the black hole?
I think not. Depending on your frame of reference, the passage of material into a simple black hole—one that isn’t spinning very fast and that doesn’t have a great deal of electric charge in it—has one of two results. If you are traveling with the material, things proceed more or less normally as you pass the point of no return—the so-called “event horizon” from which even light can’t escape. You accompany the material all the way to the center of the black hole—its “singularity”—and are crushed to infinite density. If instead of traveling with the material, you remain outside the black hole looking in toward it, you see the material approach the event horizon but without ever quite entering its surface. In fact, all of the material that went into forming the black hole in the first place, plus all the material that has fallen into the black hole since its formation, appear to reside forever on the event horizon surface. In effect, the material never quite gets to the black hole. Since the material never quite gets to the black hole, there is no need for it to reemerge elsewhere from a “white hole.”
However, there are more complicated black holes—ones involving angular momentum and electric charge—that have more complicated structures. In falling into one of these black holes, it is apparently possible to miss the singularity. There is some discussion of such material reemerging from the “other end” of one of this black holes but I believe that there are serious problems with such two-ended interpretations of the equations governing such black holes.