. ▁For ▁a ▁quarter - century ▁D ys on ▁was ▁unh appy ▁about ▁how ▁the ▁government ▁conduct s ▁space ▁travel : ▁ ▁D ys on ▁still ▁hoped ▁for ▁cheap ▁space ▁travel , ▁but ▁was ▁res igned ▁to ▁waiting ▁for ▁private ▁entrepr ene urs ▁to ▁develop ▁something ▁new ▁and ▁in exp ensive . ▁ ▁Space ▁expl oration ▁ ▁D ys on ' s ▁et ernal ▁intelligence ▁ ▁D ys on ▁proposed ▁that ▁an ▁imm ort al ▁group ▁of ▁intellig ent ▁be ings ▁could ▁escape ▁the ▁prospect ▁of ▁heat ▁death ▁by ▁extending ▁time ▁to ▁infinity ▁while ▁exp ending ▁only ▁a ▁finite ▁amount ▁of ▁energy . ▁This ▁is ▁also ▁known ▁as ▁the ▁D ys on ▁scenario . ▁ ▁D ys on ' s ▁transform ▁ ▁His ▁concept ▁" D ys on ' s ▁transform " ▁led ▁to ▁one ▁of ▁the ▁most ▁important ▁le mm as ▁of ▁Oliv ier ▁Ram ar é ' s ▁theorem : ▁that ▁every ▁even ▁integer ▁can ▁be ▁written ▁as ▁a ▁sum ▁of ▁no ▁more ▁than ▁six ▁pr imes . ▁ ▁D ys on ▁series ▁The ▁D ys on ▁series , ▁the ▁formal ▁solution ▁of ▁an ▁explicitly ▁time - dependent ▁Sch r öd inger ▁equation ▁by ▁iteration , ▁and ▁the ▁corresponding ▁D ys on ▁time - order ing ▁operator ▁ ▁an ▁entity ▁of ▁basic ▁importance ▁in ▁the ▁mathematical ▁form ulation ▁of ▁quantum ▁mechan ics , ▁are ▁also ▁named ▁after ▁D ys on . ▁ ▁Quant um ▁physics ▁and ▁prime ▁numbers ▁D ys on ▁and ▁Hugh ▁Mont gom ery ▁discovered ▁an ▁intr igu ing