▁my ▁clo ak ▁of ▁in visibility ▁around ▁my ▁shoulders , ▁I ▁would ▁sit ▁in ▁the ▁inf irm ary ▁for ▁sometimes ▁six ▁hours ▁at ▁a ▁time .... ". ▁ ▁In ▁science ▁ ▁On ▁October ▁ 1 9 , ▁ 2 0 0 6 , ▁a ▁clo ak ▁was ▁produced ▁that ▁rout ed ▁mic row aves ▁of ▁a ▁particular ▁frequency ▁around ▁a ▁co pper ▁cyl inder ▁in ▁a ▁way ▁that ▁made ▁them ▁emer ge ▁almost ▁as ▁if ▁there ▁were ▁nothing ▁there . ▁The ▁clo ak ▁was ▁made ▁from ▁met am aterial s . ▁It ▁cast ▁a ▁small ▁shadow , ▁which ▁the ▁design ers ▁hope ▁to ▁fix . ▁ ▁The ▁device ▁obsc ures ▁a ▁defined ▁two ▁dimensional ▁region ▁and ▁only ▁at ▁a ▁particular ▁mic row ave ▁frequency . ▁Work ▁on ▁ach ieving ▁similar ▁results ▁with ▁visible ▁light ▁is ▁in ▁progress . ▁Other ▁types ▁of ▁in visibility ▁clo ak ▁are ▁also ▁possible , ▁including ▁ones ▁that ▁clo ak ▁events ▁rather ▁than ▁objects . ▁ ▁However , ▁clo aking ▁a ▁human - s ized ▁object ▁at ▁visible ▁w avel ength s ▁appears ▁to ▁have ▁low ▁probability . ▁ ▁Indeed , ▁there ▁appears ▁to ▁be ▁a ▁fundamental ▁problem ▁with ▁these ▁devices ▁as ▁" in visibility ▁clo aks ": ▁ ▁On ▁the ▁other ▁hand , ▁a ▁group ▁of ▁research ers ▁connected ▁with ▁Ber keley ▁Lab ▁and ▁the ▁University ▁of ▁California , ▁Ber keley ▁believe ▁that ▁clo aking ▁at ▁optical ▁ ▁frequencies ▁is ▁indeed ▁possible . ▁Furthermore , ▁it ▁appears ▁within ▁reach . ▁Their ▁solution ▁to ▁the ▁hur d les ▁presented