) ▁created ▁a ▁model ▁with ▁an ▁observer ▁in ▁the ▁middle ▁between ▁A ▁and ▁B . ▁However , ▁in ▁his ▁description ▁two ▁signals ▁are ▁sent ▁from ▁A ▁and ▁B ▁to ▁the ▁observer . ▁From ▁the ▁perspective ▁of ▁the ▁frame ▁in ▁which ▁A ▁and ▁B ▁are ▁at ▁rest , ▁the ▁signals ▁are ▁sent ▁at ▁the ▁same ▁time ▁and ▁the ▁observer ▁" is ▁hast ening ▁towards ▁the ▁beam ▁of ▁light ▁coming ▁from ▁B , ▁whilst ▁he ▁is ▁r iding ▁on ▁ahead ▁of ▁the ▁beam ▁of ▁light ▁coming ▁from ▁A . ▁Hence ▁the ▁observer ▁will ▁see ▁the ▁beam ▁of ▁light ▁em itted ▁from ▁B ▁earlier ▁than ▁he ▁will ▁see ▁that ▁em itted ▁from ▁A . ▁Ob ser vers ▁who ▁take ▁the ▁railway ▁train ▁as ▁their ▁reference - body ▁must ▁therefore ▁come ▁to ▁the ▁conclusion ▁that ▁the ▁light ning ▁flash ▁B ▁took ▁place ▁earlier ▁than ▁the ▁light ning ▁flash ▁A ." ▁ ▁Sp ac etime ▁physics ▁ ▁M ink owski ' s ▁spac etime ▁ ▁Po inc ar é ' s ▁attempt ▁of ▁a ▁four - dimensional ▁reform ulation ▁of ▁the ▁new ▁mechan ics ▁was ▁not ▁continued ▁by ▁himself , ▁so ▁it ▁was ▁Hermann ▁M ink owski ▁( 1 9 0 7 ), ▁who ▁worked ▁out ▁the ▁consequences ▁of ▁that ▁notion ▁( other ▁contributions ▁were ▁made ▁by ▁Roberto ▁Mar col ongo ▁( 1 9 0 6 ) ▁and ▁Richard ▁H arg re aves ▁( 1 9 0 8 )). ▁This ▁was ▁based ▁on ▁the ▁work ▁of ▁many ▁mathemat icians ▁of ▁the ▁ 1 9 th ▁century ▁like ▁Arthur