I just went and folded a piece of paper fifty times. It's about 5mm thick. Oh, did you mean fold in half fifty times so that its thickness becomes 2^50 * (thic

I just went and folded a piece of paper fifty times. It's about 5mm thick. Oh, did you mean fold in half fifty times so that its thickness becomes 2^50 * (thickness of one sheet)? Well, that's clearly physically impossible, so I just concertina-ed it.