IN A novel called “The Difference Engine”, published in 1990,
William Gibson and Bruce Sterling described an alternative
Victorian era of mechanical computers driven by steam, with
their results displayed on screens made of mechanical pixels.
Steam-driven computers remain in the realm of science fiction.
Mechanical pixels, however, are beginning to see the light of
day.  Pixels are the dots, or “picture elements” that make up
the picture on a display screen. And one way of making them
change colour is to use what are known as micro-
electromechanical systems, or MEMS, to move part of each pixel
around, creating iridescent interference patterns in the
process. According to Wallen Mphepö of National Chiao Tung
University in Hsinchu, Taiwan, who is one of those working on
this idea, screens made this way should be as easy on the eye in
bright sunlight as the reflective “electronic paper” used in
devices such as the Kindle. They would also use far less power
than today's liquid-crystal displays.  Mr Mphepö's pixel