You can encode every book and information in a small rod. Just take a 1 meter long rod and encode your book into binary, eg 01011110111. Now, take your binary string, and transform it into a decimal number in base 2 by prepending 0. , E.g. x=0.01011110111. As this number is finite and smaller than 1, you can just take your rod and cut it at length x. Now when you want to retrieve your information you just need to measure x from your rod with a ruler, take the decimal part and convert it into binary, and voila. You can encode almost infinite amount of data into a simple rod. Assuming you can measure and cut very precisely