The doors began opening on a Tuesday in early March. Only a few at first–flickering and uncertain because they were operating at the extreme end of their temporal range–and those few from the earliest days of the exodus, releasing fugitives who were unstarved and healthy, the privileged scientists and technicians who had created or appropriated the devices that made their escape possible. We processed about a hundred a week, in comfortable isolation and relative secrecy. There were videocams taping everything, and our own best people madly scribbling notes and holding seminars and teleconferences where they debated the revelations.

Those were, in retrospect, the good old days.

In April the floodgates swung wide. Radiant doors opened everywhere, disgorging torrents of ragged and fearful refugees. There were millions of them and they had every one, to the least and smallest child, been horribly, horribly abused. The stories they told were enough to sicken anyone. I know.

We did what we could. We set up camps. We dug latrines. We ladled out soup. It was a terrible financial burden to the host governments, but what else could they do? The refugees were our descendants. In a very real sense, they were our children.

Throughout that spring and summer, the flow of refugees continued to grow. As the cumulative worldwide total ran up into the tens of millions, the authorities were beginning to panic–was this going to go on forever, a plague of human locusts that would double and triple and quadruple the population, overrunning the land and devouring all the food? What measures might we be forced to take if this kept up? The planet was within a lifetime of its loading capacity as it was. It couldn’t take much more. Then in August the doors simply ceased. Somebody up in the future had put an absolute and final end to them.

It didn’t bear thinking what became of those who hadn’t made it through.