Ancient and Modern Shadows

Excerpted from
Shadows; Unlocking Their Secrets, from Plato to Our Time
By Roberto Casati

Shadow and light are linked in the history of technology. Electrification erased the vast shadowy zones that made cities unsafe. It is our inheritance from the nineteenth century, which saw a radical improvement in lighting. In the space of sixty years, from 1820 to 1880, numerous kinds of lamps were invented, all of them easily powered and relatively economical. Until the end of the previous century lights were fueled primarily with whale oil, olive oil, and wax. At the beginning of the 1800s, lamps using natural gas and coal gas became popular. Streets were lighted with gas lamps in the major European and American cities from the very beginning of the century. The digging of the first petroleum well in 1859 made another combustible source available. Paralleling these advances was the discovery that electricity could be a source of light. At first a bolt of lightning was the model, in lamps that had an electric are leaping across the gap between two carbon electrodes; this system was perfected by the Russian engineer Pavel Yablochkov around 1875. The next step was the filament bulb, an invention that was in the air generally but which is now linked to Thomas Edison (1847-1931). Edison tried a thousand times with filaments of different materials (sealed in a vacuum tube) that were made incandescent by the passage of an electric current. On October 21, 1878, he decided to try a filament of burning carbon, which gave a stable glow for a couple of days. It was the solution

he had been looking for. After several months of testing, in May 1880 he launched the era of electrical lighting, which would in just a few years replace gas lighting entirely.

Electricity is easily transported and its fire risk is low-this was a remarkable improvement over torches, candles, and the saucers full of combustibles that had been used in previous centuries. But the progress was not limited to these technical aspects only. The quality of the light was completely different. The same basic phenomenon, incandescence, is produced by both candle flame and lightbulb. The matter loses part of its energy when heated, releasing a flow of photons. At higher temperatures the balance of intensity of the light emitted tilts closer to blue, and light in the room looks less reddish; the weaker candle has a redder light. It should be said that the gas lamps used since 1820 already had an important technological improvement: the principal source of illumination was not the flame but a chip of fireproof material that was heated by the flame. Thus a static component gave off the light, as in a modern lightbulb, where the filament is heated by a current of electricity passing through it, a current that the filament resists. This allows for higher temperatures and a greater release of photons.

So the newer light sources were more luminous, and they also had another property: they were stable. They no longer depended on a flame exposed to air currents, and they didn't flicker. This has extraordinary consequences for our story. As if by magic, shadows too stopped flickering along the streets and within the houses.

The nineteenth century didn't just vanquish shadows; it created new ones. They were the frozen shadows produced by a fragment of material heated to incandescence. These were new shadows: static shadows had never existed in nature, nor were they ever before produced by man.

Until just a few generations ago, shadows were always moving. No shadow was ever really still. Candles and hearths project shaky, agitated shadows on the walls of a room. Outdoors, all you have to do is trace an outline and then come back to it a few minutes later to see the movement of apparently static shadows cast by bodies in sunlight. Sundials work because of the movement of shadows. Artists have always had great difficulty painting landscapes or buildings lit by the sun. After an hour passes, the distribution of shadows in the landscape has changed so much that the view is unrecognizable. Partly for this reason, painting classes study the theory of shadows, which frees objects from the constant mutation of natural chiaroscuro. The pioneers of photography faced a similar problem. The photographic technique invented by Joseph-Nicephore Niepce (1765-1833) uses a bituminous substance that becomes insoluble when exposed to light. Unfortunately, eight hours of exposure is required, and in that time shadows move quite far around the subjects. If you want to freeze a shadow, you can make do with shadowgraphs, as did William Henry Fox Talbot (1800-1877): you immerse paper in sea salt and then in a silver nitrate solution, you artistically lay leaves, cutouts, and lace directly onto the surface, and you allow the sun to darken the bare parts while leaving the covered parts white. But then the only objects that you can capture in the image are just as flat and devoid of nuance as the shadows that represent them.

Modern shadows-stuck to walls, jammed between houses-are like a new species that has populated the earth by colonizing the empire of the night. And yet, even though they have sneaked in everywhere, they haven't managed to unseat the living shadows that have accompanied our species for millennia. Nowadays we don't time an appointment for the hour when our shadows are twice as long as our bodies, but we still sense the ineluctable force of shadows lengthening and shrinking in the course of the day. As every second passes, countless objects-pine needles, rocks, insects, people-cast shadows. As every second passes, these shadows shift imperceptibly but inexorably.

The ancient shadow is always, slowly, moving.