Borders between countries are often dangerous, violent places. From the sands of the Sahel to the islands of the Mediterranean, borders allow governments to define who can enter a country – often deciding whether a person can find refuge or is left behind. Increasingly, borders are also spaces for governments and private companies to test new technology. But how is that technology being used? And what impact is it having for people on the move? Petra Molnar’s new book The Walls Ha...