▁for ▁every ▁ 3 . 3 ▁million ▁light ▁years ▁further ▁away ▁from ▁the ▁earth ▁you ▁are , ▁the ▁matter ▁where ▁you ▁are , ▁is ▁moving ▁away ▁from ▁earth ▁ 7 2 ▁kilom eters ▁a ▁second ▁faster . ▁In ▁the ▁summer ▁of ▁ 2 0 1 6 , ▁another ▁measurement ▁reported ▁a ▁value ▁of ▁ 7 3 ▁for ▁the ▁constant , ▁thereby ▁contradict ing ▁ 2 0 1 3 ▁measurements ▁from ▁the ▁European ▁Plan ck ▁mission ▁of ▁slower ▁expansion ▁value ▁of ▁ 6 7 . ▁The ▁dis cre p ancy ▁opened ▁new ▁questions ▁concerning ▁the ▁nature ▁of ▁dark ▁energy , ▁or ▁of ▁neut r inos . ▁ ▁In fl ation ▁as ▁an ▁explanation ▁for ▁the ▁expansion ▁Until ▁the ▁theoretical ▁develop ments ▁in ▁the ▁ 1 9 8 0 s ▁no ▁one ▁had ▁an ▁explanation ▁for ▁why ▁this ▁seemed ▁to ▁be ▁the ▁case , ▁but ▁with ▁the ▁development ▁of ▁models ▁of ▁cos mic ▁infl ation , ▁the ▁expansion ▁of ▁the ▁universe ▁became ▁a ▁general ▁feature ▁resulting ▁from ▁vac u um ▁decay . ▁ ▁According ly , ▁the ▁question ▁" why ▁is ▁the ▁universe ▁expand ing ?" ▁is ▁now ▁answered ▁by ▁understanding ▁the ▁details ▁of ▁the ▁infl ation ▁decay ▁process ▁which ▁occurred ▁in ▁the ▁first ▁ 1 0 − 3 2 ▁seconds ▁of ▁the ▁existence ▁of ▁our ▁universe . ▁During ▁infl ation , ▁the ▁metric ▁changed ▁expon entially , ▁causing ▁any ▁volume ▁of ▁space ▁that ▁was ▁smaller ▁than ▁an ▁atom ▁to ▁grow ▁to ▁around ▁ 1 0 0 ▁million ▁light ▁years ▁across ▁in ▁a ▁time ▁scale