Can a movement founded on a hashtag really change the world? HARDtalk’s Sarah Montague speaks to Patrisse Khan-Cullors, the woman who first coined the slogan Black Lives Matter. She used it as a hashtag on a friend's Facebook post back in 2013. Since then Black Lives Matter has taken off as a political movement around the world. She’s now written about her own experience growing up in a poor black family in California, and how she’s convinced that if racism and state violence against African Americans can be stopped then other problems in the black community - such as poverty, poor education and crime - would disappear too. Is she right?Image: Patrisse Khan-Cullors (Credit: BBC)