There was a great post and a slightly crazy discussion about infinity and the Hilbert Hotel here a few months ago: http://news.ycombinator.com/item?id=1333424 h

There was a great post and a slightly crazy discussion about infinity and the Hilbert Hotel here a few months ago: http://news.ycombinator.com/item?id=1333424 http://news.ycombinator.com/item?id=1333424 The penultimate paragraph of the present post sounds like a conversation you might hear in one of the infinitely long infinitely many bars at the Hilbert Hotel: Nervous Dude: When I went to grad school, my intention was to study functional analysis. Essentially this means infinite dimensional vector spaces. Unimpressed Girl: That sounds terribly abstract and useless. Nervous Dude: But it can be quite practical. My background in functional analysis served me well when I went on to study partial differential equations and numerical analysis. Seriously Unimpressed Girl: Gotcha.