Outer Space

~1 million years ago

A swarm has succeeded in breaching the edge of the world. It came to the front edge of the atmosphere sooner than expected, and we understand now what the Singer described this boundary as "severe". The swarm could not do more than touch the light on the other side. It had no thickness, as if it weren't there at all, but despite that it was incredibly strong. No matter how fast the swarm approached the boundary, it couldn't go through more than the width of a part. The light pushed it back into the atmosphere every time.
The nature of the substance called "light" is baffling. The swarm captured a sample, but it disappeared as soon as the parts closed their seams. While the light could still be felt pushing strongly on the front of the swarm, it was invisible to all interior eyes. This seems like inconsistent behavior, since all outer swarms have seen light passing through the atmosphere and all inner swarms have tasted the food it becomes after the atmosphere eats it.
The swarm was unable to keep the light contained; before reaching the Exchange Layer, all of it had escaped. It seems that if we're to learn anything about light in its uneaten form, we must do so at the boundary.