We briefly summarize the idea of cosmological models with compact, flat
spatial sections. It has been suggested that, because of the COBE satellite's
maps of the microwave background, such models cannot be small in the sense of
Ellis, and hence are no longer interesting. Here we use Lehoucq et al.'s method
of cosmic crystallography to show that these models are physically meaningful
even if the size of the spatial sections is of the same order of magnitude as
the radius of the observational horizon.Comment: 8 pages, 1 figure. Revision includes comment on "top-down" and
"bottom-up" pictures of structure formation. Figure is unmodifie