Climbing Montgomery’s Ladder

Peter Montgomery, RIP

Imagine you had to find a book on shelves which spanned up to the top of a building, but you don’t want to give away the shelf that you take the book from. Just imaging you could create a ladder which you could use no matter the shelve it is on, but where the ladder will always be the same length. Then the length of the ladder will not give away the shelf. This is like the way…