L-space

Large collections of books distort the shape of space and time, as can be shown by the equation Knowledge = Power = Energy = Matter = Mass; i.e., a good old-fashioned second-hand bookshop isn't much more than a genteel black hole that knows how to read.

Hence mass distorts space into polyfractal L-space, in which Everywhere is also Everywhere else.

To slightly extend the above description, the consequence of L-Space is that all libraries and book stores are, in some way, connected. The librarian of Unseen University knows how to navigate this "multi-bookstore", and can hence reach any library in the multiverse simply by taking the right turns in the back alleys of his own library.

L-Space is also the name of a website dedicated to Terry Pratchett, mirrored all over the world. It can be found at www.lspace.org, and contains limitless information.