Free speech, exercised both individually and through a free press, is a necessity in any country where people are themselves free.

The film is about 100 nanometres (100 x 10-9 metres) thick, roughly 1,000 times thinner than standard office paper. It is built like a sandwich of alternating layers of gold and cadmium sulphide nanoparticles, each separated by insulating polymer sheets just 2 or 3 nanometres thick.

The whole device is hooked up to electrodes that allow a current to flow through the film. When pressed onto a surface, the stress distorts the layers so that electrons can more easily hop across the insulating polymer layers and hit the cadmium sulphide particles. This makes the particles glow — the greater the stress, the more light they emit. A camera then measures the strength of the glow, which relates directly to the pressure felt by different parts of the film.

Of course, using a camera to detect the different levels of pressure may seem pretty impractical when trying to develop a robot skin. But obviously, fiber optics can transmit this information to a processing center (a novel approach). At that point, it would seem like a great idea to look into grafting this stuff onto humans with injuries. Years away, I know. Decades. But it could be done.