  Fourier phases contain a vast amount of information about structure in direct
space, that most statistical tools never tap into. We address ALMA's ability to
detect and recover this information, using the probability distribution
function (PDF) of phase increments, and the related concepts of phase entropy
and phase structure quantity. We show that ALMA, with its high dynamical range,
is definitely needed to achieve significant detection of phase structure, and
that it will do so even in the presence of a fair amount of atmospheric phase
noise. We also show that ALMA should be able to recover the actual "amount" of
phase structure in the noise-free case, if multiple configurations are used.
