An artisanal miner carries a sack of ore at the Shabara artisanal mine near Kolwezi, DRC, on Oct. Junior Kannah /AFP via Getty ImagesSmartphones, computers and electric vehicles may be emblems of the modern world, but, says Siddharth Kara, their rechargeable batteries are frequently powered by cobalt mined by workers laboring in slave-like conditions in the Democratic Republic of Congo. Even the nightmares and the terrors, it's all worth it