▁conducted , ▁confirm ing ▁relativ ity ▁to ▁even ▁higher ▁precision ▁than ▁the ▁original ▁experiment . ▁Another ▁type ▁of ▁inter fer ometer ▁experiment ▁was ▁the ▁Kennedy – Th or nd ike ▁experiment ▁in ▁ 1 9 3 2 , ▁by ▁which ▁the ▁independence ▁of ▁the ▁speed ▁of ▁light ▁from ▁the ▁velocity ▁of ▁the ▁appar atus ▁was ▁confirmed . ▁Also ▁time ▁d ilation ▁was ▁directly ▁measured ▁in ▁the ▁I ves – St il well ▁experiment ▁in ▁ 1 9 3 8 ▁and ▁by ▁meas uring ▁the ▁decay ▁rates ▁of ▁moving ▁particles ▁in ▁ 1 9 4 0 . ▁All ▁of ▁those ▁experiments ▁have ▁been ▁repeated ▁several ▁times ▁with ▁increased ▁precision . ▁In ▁addition , ▁that ▁the ▁speed ▁of ▁light ▁is ▁un re ach able ▁for ▁massive ▁bodies ▁was ▁measured ▁in ▁many ▁tests ▁of ▁relativ istic ▁energy ▁and ▁momentum . ▁Therefore , ▁knowledge ▁of ▁those ▁relativ istic ▁effects ▁is ▁required ▁in ▁the ▁construction ▁of ▁particle ▁acceler ators . ▁ ▁In ▁ 1 9 6 2 ▁J . ▁G . ▁Fox ▁pointed ▁out ▁that ▁all ▁previous ▁experimental ▁tests ▁of ▁the ▁const ancy ▁of ▁the ▁speed ▁of ▁light ▁were ▁conducted ▁using ▁light ▁which ▁had ▁passed ▁through ▁station ary ▁material : ▁glass , ▁air , ▁or ▁the ▁incomplete ▁vac u um ▁of ▁deep ▁space . ▁ ▁As ▁a ▁result , ▁all ▁were ▁thus ▁subject ▁to ▁the ▁effects ▁of ▁the ▁ext inction ▁theorem . ▁ ▁This ▁imp lied ▁that ▁the ▁light ▁being ▁measured ▁would ▁have ▁had ▁a ▁velocity ▁different ▁from ▁that ▁of ▁the ▁original ▁source . ▁ ▁He ▁concluded ▁that