Base light, as we know it, can be split up into its constituent parts. So white light can be prismed out into lower level colours.
This structural integrity change shows that, when disassembled further, we see many layers of the original.
Galactic Midnight is such that this is possible. A colossal shift and merging of the galaxies protracts down into the smaller components of light and allows it to be split.
Other references in the current spacetime show various and many versions of what is thought to be happening with Galactic Midnight, currently and in the recent past.