One of the reasons why rainbows are so special, as Robert Crease writes on page 16, is that they are rare, but not so rare that people are not familiar with them. Most readers of this magazine will have some inkling of how a rainbow is formed, but could you, if pushed to the test, derive what happens from first principles? And what about ice-crystal haloes, fog-bows and glories? Those who need to refresh their memory about any of these beautiful natural optical phenomena should turn to John Hardwick's article in "The subtlety of rainbows".
Rainbows are just one of the applications or manifestations of optics discussed in this month’s magazine. Previous special issues of Physics World on lasers and optics have covered mainstream research, and applications such as biomedical optics, quantum cascade lasers and light-emitting polymers (June 1999). More recently we highlighted fundamental research that was “rewriting the laws of optics” (September 2001). All of these topics – trapping light in atomic gases, sub-wavelength imaging, attosecond experiments and negative-index materials – are still the focus of intense research. However, the articles in this issue look at optics from a number of different, less obvious angles.
The rainbow might be the best known example of optics in the natural world, but we should not forget the fact that much of life on Earth has evolved in response to the small range of wavelengths of light that manage to travel all the way from the Sun to the surface of the planet. And nature has learned some very clever tricks during the 500 million years that this has been happening, as Pete Vukusic describes in “Natural photonics”. Physicists have unwittingly “rediscovered” some of these tricks – which have applications ranging from antireflective surfaces to anticounterfeiting technology – but there is still much to learn.
Physicists applying the laws of optics to visual effects in the movies face different challenges – either recreating on screen realistic scenes that are too difficult or too expensive to film using conventional means, or “rendering” scenes that never have and never will exist. In “The special effect of physics” Jürgen Singer of mental images explains how his company has produced visual effects for films such as Matrix Reloaded. And this is not an isolated example of physics going to Hollywood, as the story of Iain Neil and his 26 Oscars confirms.
When Isaac Newton published Opticks 300 years ago it caused a rift between science and the arts, with John Keats famously accusing Newton of “unweaving the rainbow”. However, the fascination of physicists with the natural world shows no sign of ending.
