A Proposal to Search for Transparent Hidden Matter Using Optical Scintillation

It is proposed to search for scintillation of extragalactic sources through the last unknown baryonic structures. Appropriate observation of the scintillation process described here should allow one to detect column density stochastic variations in cool Galactic molecular clouds of order of $\sim 3\times 10^{-5} \mathrm{g/cm^2}$ -- that is $10^{19} \mathrm{molecules/cm^2}$ -- per $\sim 10 000 \mathrm{km}$ transverse distance.