and you say it is a tool for learning, roving, and constructive community building, but it's unrivaled too in the spread of lies, narrowing of interests and erosion of common cause. please give us some examples of that. >> with the internet we are now individuals are kind of curating their information diets, they're curating their news consumption in a way that they can tune out anything that doesn't fit their pre-existing worldview. they can tuck themselves into echo chambers where they only hear what they already believe, what they want to believe. and we've recently had two horrifying examples of this. i'm going to say his name wrong, but cesar sayoc, who sent the pipe bombs -- allegedly sent the pipe bombs. and then robert bowers with the massacre in pittsburgh. in both cases those men spent enormous time online. and what they were doing online was they were finding communities of people who believed in the same dark things they-d who reinforced their beliefs, who colored them darker still, and we have to ask some really serious questions.