AP Photo

Some questions can never be answered. A prominent recent example is whether photographer R. Umar Abbasi, who captured the now-(in)famous image of a man about to be killed by a New York City subway train, could have saved Ki-Suck Han if he hadn't stopped to take the photo of the train bearing down on the victim. Abbasi has insisted that he was too far away, and in the absence of proof one way or the other, we should take his word for it. It won't be all that long, however, before such questions can be answered. The growing presence of video cameras in public places assures that—and we need to think a lot harder about the implications.