It is conjectured that space-time and momentum space may be both conformally compactified and correlated by conformal inversion, rendering a priori impossible the empirical realization of the concept of both infinity and infinitesimal. It appears that in such a world momentum space is appropriate for the description of quantum mechanics in spinorial form. An exactly soluble, two-dimensional model is presented and discussed.

PACS numbers: 12.90.+b