an extraordinary property of factors of type II_1, such as the hyperfinite factor R, is the complete classification of the equivalence classes of projection e ϵ R by a real number dim(e) ϵ  [0,1] that can take on any value between 0 and 1. the Grassmanian of the projections e ϵ  R thus no longer describes the lines, planes, etc. of ordinary geometry but instead “spaces of dimension α ϵ [0,1]”, in other words a continuous geometry. the force of this discovery comes across very clearly as one reads the original texts of Murray and von Neumann