Elon Musk and Mark Zuckerberg clash over the future of artificial intelligence

Two of the technology industry's most powerful leaders are at odds when it comes to artificial intelligence. Tesla Motors CEO Elon Musk has a pessimistic view of the risks associated with such technology. "I keep sounding the alarm bell," Musk told the National Governors Assn. in June. "But until people see robots going down the street killing people, they don't know how to react because it seems so ethereal." Facebook Chief Mark Zuckerberg on Sunday called Musk's dire warnings overblown and described himself as "optimistic."