A cu­bic cen­time­ter of emp­ty space around us (about the tip of one's lit­tle fin­ger in vol­ume) has so much raw en­er­gy in it that, if con­densed in­to mat­ter, there would be more mat­ter than is ob­serv­able in the uni­verse through the largest tele­scope! So even a tiny ef­fi­cien­cy of tap­ping could and will ex­tract all the en­er­gy any­one could wish.