Elon Musk and Mark Zuckerberg Are Officially in a War of Words Over Artificial Intelligence

Two of Silicon Valley's most powerful figures are officially in a war of words. To recap: During a Facebook Live Q&A session on Sunday, Mark Zuckerberg criticized Elon Musk for saying artificial intelligence is "the biggest threat we face as a civilization." "I think people who are naysayers and try to drum up these doomsday scenarios--I don't understand it," the Facebook CEO said. "It's really negative, and in some ways I think it's pretty irresponsible." Now, Musk has fired back.