The Deep Synoptic Array: fast radio burst probes of the unseen universeThe origins of fast radio bursts (FRBs) at extragalactic distances remain shrouded in mystery. FRBs nonetheless form exquisite tracers of the contents and physical conditions of baryons along their sightlines. For example, FRBs are dispersed in intervening plasma columns, and these columns are typically dominated by gas around and in ...