The scratches are a binary code of the era—just a pattern you could quantify, like a camera's shutter speed on a grid. In practice, I record the odds that a random grain forms a map, then ignore the result unless it helps the next operation. If the universe wants to hide a secret, it hides it in the same place everyone else sees. I might take a note on the edge of the frame and move it a millimeter later; you won't notice, but the alignment changes the probability of your next thought.