Terry is writing a book that he's publishing in several universes (this is distinct from several versions of Terry publishing in their respective universes). He needs to identify which universe he came from, so the other versions of himself don't get credit for HIS hard work.
Generally, universes are numbered anywhere from 0 to 1. This means that most universes can be represented by an irrational number.
Is there anyway practically to identify which universe you are in, when you have limited sheets of paper and limited font size?
In other words, can a given irrational number be written in finite terms? If not, is there some way around this?
Edit: The numbers 0 - 1 are inherent. Terry knows the number of his universe, and his target audience knows their own. The numbers are uncountably infinite.