Without direct perception, and using such poor tools as symbols and narratives to externalize memory, we're deeply impoverished as to the nature of memory and our ability to access it. But once we have a better grasp of the neuronal units, spatial-syntax, we will unlock every memory.
https://pmc.ncbi.nlm.nih.gov/articles/PMC10500127/
Also to consider are the shapes and phases between oscillation. "It’s high dimensional complexity; the mind is an attractor in high dimensional phase space formed between neural oscillators." Emergent properties are not reducible to their constituent parts.
to my knowledge practical fourier transforms set a number of sine waves they will calculate for, and a window of time to look at. these limitations result in loss.
but, just taking the brain, at some point the person will die and decompose. how are you gonna get the oscillations back out of the rotted flesh? there has to be some form of loss to the brain
In terms of brains, the math is used to model the irreducible occurrences in brains - that everything is still in there. So the math only gives us a window into the complexity. Brains don't compute or calculate necessarily. As an analog, or analoga of differences, it never has to exclude, or experience loss.
For the details: Rhythms of the Brain or Unlocking the Brain both volumes.