in which acid was sprayed inside a london nightclub in the early hours of this morning. now on bbc news, it s time for click. this week, fighting crime before it happens. and keeping warm in the arctic. oh, my god! i said keeping warm. 0h, forget it. we are now more surveilled than we have ever been. cities are covered in cctv cameras. authorities are gathering data on its citizens. it would be all too easy to confuse the real world with a sci fi dystopia. mr marks, my mandate of the district of columbia pre crime division. i m placing you under arrest for the future murder of sarah marks and donald dubin, that was due to take place today, april 22, at 0800 hrs and four minutes. no, i didn t do anything. in the movie minority report, the pre crimes unit race to arrest would be offenders before they have a chance to commit their crimes. now, they use psychics but it turns out something similar is being attempted using big data. in chicago, where the violent crime rate has expl