Light in its many forms is so central to human existence that we often tend to take it for granted. Even so, many scientists have long struggled to explain the nature of light. According to the Old Testament Book of Genesis (quoted above), light preceded the creation of Adam and Eve. Astronomers would argue that light appeared with the Big Bang that signaled the creation of the universe. But Homo sapiens has had a hard time understanding the exact nature of light. It was not until 1666, when the British scientist Isaac Newton performed his famous experiment splitting white light with a prism, that a tenable theory of light was first developed.
The English writer Alexander Pope is said to have composed an intended epitaph for Newton: "Nature and Nature`s laws lay hid in night: God said `Let Newton be!` and all was light." Pope was, of course, referring to much more than Newton`s experiments with prisms. Newton`s contributions to the understanding of physics shed light on much more than light itself. I was reminded of Newton`s discoveries of the nature of light on reading a recently published paperback edition of Sidney Perkowitz`s book, Empire of Light: a History of Discovery in Science and Art (Joseph Henry Press/ National Academy of Science, Washington, DC, 1998; hardcover edition). This little book (less than 200 pages) is the most concise view of light I`ve ever read. I highly recommend you get a copy. If your local bookstore doesn`t stock the book, amazon.com can have it in your mailbox in a few days.
Powerful magic of the laser
Perkowitz, who is Charles Howard Candler Professor of Physics at Emory University (Atlanta, GA), discusses the nature of light, how the eye sees and how our understanding of these phenomena has developed over time. He begins in his own lab, saying, "When I walk into my laser laboratory, I command every kind of light." He describes his laser`s light as carrying "powerful magic." The author goes on to show how this sense of wonder is further evoked by the light that is reflected by the visual arts and in particular by the paintings of such artists as Vincent Van Gogh and Claude Monet. He returns to examples in painting throughout the book as he lucidly explains the discoveries and developments in the nature of light.
From his initial chapter on the birth and meaning of light, the author moves on to consider how we see light, the classical and modern theories of light, how light is made and shaped, and how light is used. The tone of the book is serious but not academic. That Perkowit¥is decidedly in love with his subject comes through clearly in the text.
I wish I could have read this book during my undergraduate years: it does not contain a single line of mathematics or a single ray diagram, yet the author manages to relate the theories of light and the work of scientists in an understandable manner without losing rigor. There are several color photographs of paintings that Perkowit¥uses as examples but the only scientific illustrations are a photograph of the experimenters at the National Synchrotron Light Source at Brookhaven, NY, and a shot taken by the Hubble Space Telescope of the gaseous pillars in the Eagle Nebula. The latter is a striking composition that could well pass for a modernist painting and certainly evokes strong emotions on the part of the observer.
Light and the Big Crunch
In his final chapter, "Universal Light," Perkowitz discusses the possibility of the reverse of the Big Bang--the Big Crunch that would represent the end of the cosmos as we know it. As with the Big Bang, light would signal the process of universal contraction, claims Perkowitz. Of course, such a scenario "lies unimaginably far in the future," Perkowit¥says. For now "We live still in a world flooded with photons and waves, with light and color, with an ethereal energy we do not fully understand, that defines what we are and what we know--an empire of light that holds sway in space, time, and meaning." Perkowitz`s book reminds us of the central role light plays in the life of the universe. I, for one, am grateful to him for reminding me not to take light and vision for granted.