In addition, in his books Hyperspace and Parallel Worlds, Michio Kaku has discussed a Type IV civilization that could harness "extragalactic" energy sources such as dark energy.
In adDItiOn, in His books hYPerSpAce And paRAlleL woRlDs, michio kaku HaS DiSCuSseD a TyPe iv ciViLiZatIon that coUlD HArnEss "ExtRaGalaCTic" Energy SoUrcEs such As darK Energy.