▁associated ▁with ▁the ▁" ac cel er ating ▁universe " ▁the ▁" cos mic ▁j erk ". ▁The ▁ 2 0 1 1 ▁Nobel ▁Prize ▁in ▁Physics ▁was ▁given ▁for ▁the ▁discovery ▁of ▁this ▁phenomen on . ▁ ▁In ▁October ▁ 2 0 1 8 , ▁scient ists ▁presented ▁a ▁new ▁third ▁way ▁( two ▁earlier ▁methods , ▁one ▁based ▁on ▁red sh ifts ▁and ▁another ▁on ▁the ▁cos mic ▁distance ▁lad der , ▁gave ▁results ▁that ▁do ▁not ▁agree ), ▁using ▁information ▁from ▁gravit ational ▁wave ▁events ▁( es pecially ▁those ▁involving ▁the ▁mer ger ▁of ▁neut ron ▁stars , ▁like ▁G W 1 7 0 8 1 7 ), ▁of ▁determ ining ▁the ▁Hub ble ▁Constant , ▁essential ▁in ▁establish ing ▁the ▁rate ▁of ▁expansion ▁of ▁the ▁universe . ▁ ▁Me as uring ▁distances ▁in ▁expand ing ▁space ▁ ▁At ▁cosm ological ▁scales ▁the ▁present ▁universe ▁is ▁geomet r ically ▁flat , ▁which ▁is ▁to ▁say ▁that ▁the ▁rules ▁of ▁E uclidean ▁geometry ▁associated ▁with ▁Eu cl id ' s ▁fifth ▁post ulate ▁hold , ▁though ▁in ▁the ▁past ▁spac etime ▁could ▁have ▁been ▁highly ▁cur ved . ▁In ▁part ▁to ▁accommod ate ▁such ▁different ▁geomet ries , ▁the ▁expansion ▁of ▁the ▁universe ▁is ▁inher ently ▁general ▁relativ istic ; ▁it ▁cannot ▁be ▁mode led ▁with ▁special ▁relativ ity ▁alone , ▁though ▁such ▁models ▁exist , ▁they ▁are ▁at ▁fundamental ▁odd s ▁with ▁the ▁observed ▁interaction ▁between ▁matter ▁and ▁spac etime ▁seen ▁in ▁our ▁universe . ▁ ▁The ▁images ▁to ▁the