I've seen some examples in document forensics where a page that looks blank (or at least the ink is unrecognizably smudged) because of water exposure is completely legible with an infrared photo illuminated by UV.
I suspect there must be a hidden world only visible in IR and UV (and long-wave IR, e.g. "thermal").
fraywing•1h ago
Side note: have always loved this image https://imgur.com/NZjWfWT of rainbows with UV and IR visible.