ing , ▁certain ▁descri ptions ▁of ▁the ▁metric ▁expansion ▁of ▁space ▁and ▁the ▁mis con ception s ▁to ▁which ▁such ▁descri ptions ▁can ▁lead ▁are ▁an ▁on going ▁subject ▁of ▁discussion ▁within ▁education ▁and ▁communication ▁of ▁scientific ▁concepts . ▁ ▁History ▁ ▁In ▁ 1 9 1 2 , ▁V esto ▁S li pher ▁discovered ▁that ▁light ▁from ▁remote ▁galaxies ▁was ▁red shift ed , ▁which ▁was ▁later ▁interpreted ▁as ▁galaxies ▁re ced ing ▁from ▁the ▁Earth . ▁In ▁ 1 9 2 2 , ▁Alexander ▁Fried mann ▁used ▁Ein stein ▁field ▁equations ▁to ▁provide ▁theoretical ▁evidence ▁that ▁the ▁universe ▁is ▁expand ing . ▁In ▁ 1 9 2 7 , ▁Georges ▁L ema ître ▁independently ▁reached ▁a ▁similar ▁conclusion ▁to ▁Fried mann ▁on ▁a ▁theoretical ▁basis , ▁and ▁also ▁presented ▁the ▁first ▁observ ational ▁evidence ▁for ▁a ▁linear ▁relationship ▁between ▁distance ▁to ▁galaxies ▁and ▁their ▁re cess ional ▁velocity .< ref > Ge org es ▁L ema ître , ▁' Un ▁Univers ▁hom og ène ▁de ▁mas se ▁const ante ▁et ▁de ▁ray on ▁cro issant ▁r endant ▁compte ▁de ▁la ▁v ites se ▁rad iale ▁des ▁né b ule uses ▁extra - gal act iques , ▁ <0x09> ▁ <0x09> An n ales ▁de ▁la ▁Société ▁Scient ifique ▁de ▁Bru xelles , ▁A 4 7 , ▁p . ▁ 4 9 - 5 9 , ▁ 1 9 2 7 ▁http :// ads abs . har vard . edu / abs / 1 9 2 7 AS SB ... 4 7