These advances in science also represent paradigm shifts in how we view the world. From the earliest inception of fire, having light in the dark of night would have helped tribes and armies in their conquest of lands; an understanding of reflection undoubtedly helped perfect mirror surfaces; the laws of perspective brought realism and proportion to early Renaissance paintings and buildings; manipulating optical properties of materials led to the camera obscura, photographs and cinema and now we use optics as our preferred medium in global telecommunications. It wouldn’t be an unfounded statement to say the more we humans understand, and can manipulate light the more it effects our way of life. However confident our culture seems to be in using light, no matter how many scientific laws we use to define light, the question remains unanswered, what is light? “Here we come to one facet of the miracle of light. It has no volume” [Achenbach, 2001]33
One way to prove Achenbach’s statement is by directing vast numbers of high energy lasers at a single point in space, and the light passes through unaffected.34 But it is not necessary to have billion-dollar high-tech laboratory equipment to experience the effects of this illusive quality of light. On a sunny day, when we stretch out our hand and cast a shadow, it is because light is acting as a stream of fast moving particles, that have direction and speed, neither of which we can directly perceive. However the 33 Joel Achenbach, October 2001, National Geographic, p10 34 This is the basic principle at the National Ignition Facility, USA, where lasers beams from 192 high energy sources are concentrated on a single pellet of fuel with the aim of producing a nuclear fusion reaction. http://news.bbc.co.uk/1/ hi/sci/tech/8485669.stm, accessed 23/03/2010 16
fig16 left. Photograph of a Nuclear explosion, a millionth of a second after ignition. This technological optic achievement captured the plasma blast before it even reached the ground. fig17 right. Section through two camera lens. The precision of craft is required to produce a useful, or coherent, manipulator of light.