Asked by: Rachel Cattini, London
At a microscopic level, paper is actually quite rough. A metal knife makes a clean straight cut, but paper acts like a saw blade and does a lot more damage to cells and nerve endings. Paper also leaves behind tiny fibres and chemical residues, which irritate the wound even more.
Luis trained as a zoologist, but now works as a science and technology educator. In his spare time he builds 3D-printed robots, in the hope that he will be spared when the revolution inevitably comes.