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Spectra from the Keck HIRES instrument of the Lyman alpha forests in thelines of sight to the A and C components of the gravitationally lensed QSOQ1422+231 were used to investigate the structure of the intergalactic medium atmean redshift z = 3.3 on sub-kpc scales. We measured the cross-correlationamplitude between the two Lyman alpha forests for a mean transverse separationof 120 pc, and computed the RMS column density and velocity differences betweenindividual absorption systems seen in both lines of sight. The RMS differencesbetween the velocity centroids of the Lyman alpha forest lines were found to beless than about 400 m/s, for unsaturated absorption lines with column densitiesin the range 12<log N(HI)<14.13. The rate of energy transfer into the lowdensity IGM on a typical scale of 100 pc seems to be lower by 3-4 orders ofmagnitude than the rate measured earlier for strong CIV metal absorptionsystems. The tight correlation between HI column density and baryonic densityin the intergalactic medium was used to obtain an upper limit on the RMSfluctuations of the baryonic density field. The fraction of the absorptionlines that are different across the lines of sight was used to determine thefilling factor of the universe for gas which has suffered recent hydrodynamicdisturbances. We thereby derived upper limits on the filling factor of galacticoutflows at high redshift. Short-lived, short-range ancient winds areessentially unconstrained by this method but strong winds blowing for asubstantial fraction of a Hubble time (at z = 3.3) appear to fill less than 20percent of the volume of the universe.Comment: latex file plus 12 postscript figures (36 pages in total); accepted  for publication by the Ap

Small‐Scale Structure at High Redshift. III. The Clumpiness of the Intergalactic Medium on Subkiloparsec Scales