▁cosm ological ▁expansion ▁taking ▁place . ▁Once ▁one ▁goes ▁beyond ▁the ▁Local ▁Group , ▁the ▁in ert ial ▁expansion ▁is ▁meas urable , ▁though ▁system atic ▁gravit ational ▁effects ▁imply ▁that ▁larger ▁and ▁larger ▁parts ▁of ▁space ▁will ▁eventually ▁fall ▁out ▁of ▁the ▁" Hub ble ▁Flow " ▁and ▁end ▁up ▁as ▁bound , ▁non - expand ing ▁objects ▁up ▁to ▁the ▁scales ▁of ▁super cl ust ers ▁of ▁galaxies . ▁We ▁can ▁predict ▁such ▁future ▁events ▁by ▁knowing ▁the ▁precise ▁way ▁the ▁Hub ble ▁Flow ▁is ▁changing ▁as ▁well ▁as ▁the ▁masses ▁of ▁the ▁objects ▁to ▁which ▁we ▁are ▁being ▁grav itation ally ▁pulled . ▁Currently , ▁the ▁Local ▁Group ▁is ▁being ▁grav itation ally ▁pulled ▁towards ▁either ▁the ▁Sh ap ley ▁Super cluster ▁or ▁the ▁" Gre at ▁Att ractor " ▁with ▁which , ▁if ▁dark ▁energy ▁were ▁not ▁acting , ▁we ▁would ▁eventually ▁merge ▁and ▁no ▁longer ▁see ▁expand ▁away ▁from ▁us ▁after ▁such ▁a ▁time . ▁ ▁A ▁consequence ▁of ▁metric ▁expansion ▁being ▁due ▁to ▁in ert ial ▁motion ▁is ▁that ▁a ▁uniform ▁local ▁" expl os ion " ▁of ▁matter ▁into ▁a ▁vac u um ▁can ▁be ▁locally ▁described ▁by ▁the ▁F LR W ▁geometry , ▁the ▁same ▁geometry ▁which ▁describes ▁the ▁expansion ▁of ▁the ▁universe ▁as ▁a ▁whole ▁and ▁was ▁also ▁the ▁basis ▁for ▁the ▁simpler ▁Mil ne ▁universe ▁which ▁ign ores ▁the ▁effects ▁of ▁gravity . ▁In ▁particular , ▁general ▁relativ ity ▁predict s ▁that ▁light ▁will ▁move ▁at ▁the ▁speed ▁c ▁with ▁respect ▁to ▁the