  We show that distances of objects at cosmological distances can be measured
directly using interferometry. Our approach to interferometric parallax comes
from analysis of 4-point amplitude and intensity correlations that can be
generated from pairs of well-separated detectors. The baseline required to
measure cosmological distances of Gigaparsec order are within the reach of the
next generation of space-borne detectors. The semi-classical interpretation of
intensity correlations uses a notion of a single photon taking two paths
simultaneously. Semi-classically a single photon can simultaneously enter four
detectors separated by an astronomical unit, developing correlations feasible
to measure with current technology.
