ul ers ▁are ▁not ▁easy ▁to ▁find ▁on ▁cosm ological ▁scales ▁and ▁the ▁times cal es ▁over ▁which ▁a ▁meas urable ▁expansion ▁would ▁be ▁visible ▁are ▁too ▁great ▁to ▁be ▁observable ▁even ▁by ▁multiple ▁gener ations ▁of ▁humans . ▁The ▁expansion ▁of ▁space ▁is ▁measured ▁indirect ly . ▁The ▁theory ▁of ▁relativ ity ▁predict s ▁phen omena ▁associated ▁with ▁the ▁expansion , ▁not ably ▁the ▁red shift - vers us - distance ▁relationship ▁known ▁as ▁Hub ble ' s ▁Law ; ▁functional ▁forms ▁for ▁cosm ological ▁distance ▁measurements ▁that ▁differ ▁from ▁what ▁would ▁be ▁expected ▁if ▁space ▁were ▁not ▁expand ing ; ▁and ▁an ▁observable ▁change ▁in ▁the ▁matter ▁and ▁energy ▁density ▁of ▁the ▁universe ▁seen ▁at ▁different ▁look back ▁times . ▁ ▁The ▁first ▁measurement ▁of ▁the ▁expansion ▁of ▁space ▁came ▁with ▁Hub ble ' s ▁real ization ▁of ▁the ▁velocity ▁vs . ▁red shift ▁relation . ▁Most ▁recently , ▁by ▁comparing ▁the ▁apparent ▁bright ness ▁of ▁distant ▁standard ▁cand les ▁to ▁the ▁red shift ▁of ▁their ▁host ▁galaxies , ▁the ▁expansion ▁rate ▁of ▁the ▁universe ▁has ▁been ▁measured ▁to ▁be ▁H 0 ▁= ▁. ▁This ▁means ▁that ▁for ▁every ▁million ▁parse cs ▁of ▁distance ▁from ▁the ▁observer , ▁the ▁light ▁received ▁from ▁that ▁distance ▁is ▁cosm olog ically ▁red shift ed ▁by ▁about ▁. ▁On ▁the ▁other ▁hand , ▁by ▁assuming ▁a ▁cosm ological ▁model , ▁e . g . ▁L ambda - CD M ▁model , ▁one ▁can ▁infer ▁the ▁Hub ble ▁constant ▁from ▁the ▁size ▁of ▁the ▁largest ▁fl