All information was passed down orally by people specially-trained to serve as “oral repositories”—in various cultures they were called bards, makars, aoidos, and various other terms. Important information was often set in verse to aid memorization.
There was a transitional period when writing and printing were used, and an even briefer period when these were supplemented by encyclopedias on CD-ROM before the birth of Wikipedia.
My understanding of quantum algorithms is that they set up parallel computations in such a way that incorrect solutions cancel out and correct ones reinforce each other. They indicate the existence of multiple universes to the same extent that the double slit experiment does.