and again here mondaevening. have a ne weekend. i'm jilehrer. thank yoand good night. major funding fothe pbs newshour iprovided by: >> what the rld needs now is energy. e energy to get e economy humminagain. the ener to tackle challges like climate change. what is that energcame from an engy company? everay, chevron invests $62 million in people, in eas-- seeking,eaching, building. eling growth around the worl toove us all ahead. this is thpower of human engy. evron. and monsanto. and by toyota. the national scien foundation. suppting education and research across all fields o sciee and engineering. and with the ongoi support of thesinstitutions and fodations. and... this program was madpossible by the cporation for puic broadcasting. and by contributions tyour pbs station om viewers like you. thank you. captioning sponsor by macneil/lehrer pductions captioneby media acce group at wgbh acce.wgbh.org