Here's how our alien friend did it:
Everyone is familiar with how an alphabet (any alphabet, but take the English alphabet for example) can be encoded into a number system -- each letter and punctuation mark of the alphabet simply has a one-or-two digit representation as a number (i.e. the English alphabet and the base-10 number system.)
Now imagine reproducing all of the data in those volumes of encyclopedias and other books in this decimal format. You would basically have a number with hundreds of thousands of digits, which could be decoded into English or whatever alphabet.
Now all the alien did, was put a (small)notch on the rod, such that the ratio of the smaller side to the longer side, expressed as a decimal, is equal to this number with hundreds of thousands of digits!
Not technically feasible, of course, but its a pretty funny and interesting idea.
I read this in a book some years ago; I believe it was by William Poundstone and was subtitled "Paradox, Puzzles, and the Frailty of Knowledge". (I don't remember the main title.)
Cheers
Garic
