The End of Night: Searching for Natural Darkness in an Age of Artificial Light. Paul Bogard

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СКАЧАТЬ finding an example of something so commonplace we don’t even see it anymore. What better example than the brilliant starry night over a nineteenth-century Concord lit by oil lamps?

      I didn’t have to visit Concord to know that its sky holds many fewer of Emerson’s “envoys of beauty.” But I wanted to talk with Lewis, to learn more about how too much light could actually act in a negative way. A longtime optometrist and former president of the Illuminating Engineering Society of North America (IESNA), the lighting professionals who have much to say about how we light our world, Alan Lewis has spent the last forty years helping to “educate lighting people about how the visual system operates.”

      For example, Lewis says, most streetlights are actually designed in a way that often causes more problems than they solve.

      “Badly designed street lighting, which is probably eighty percent of street lighting, are glare sources,” he explains. “That is, they actually reduce the contrast of things you’re trying to see rather than increase it, because of this disability glare problem that occurs due to scatter in the eye.”

      Disability glare from poorly designed streetlights—picture the traditional cobrahead drop-lens fixtures used on most American streets—is the main reason drivers, especially older drivers, have a tough time at night. As we age, proteins in the lens of our eye begin to accumulate, and we lose the transparency we had when we were younger. In the same way that a brand-new windshield is crystal clear but ages over time with accumulated minuscule chips and dings, these proteins reduce the eye’s transparency as they scatter the light coming into the eye. The effect is that instead of going to the retina and focusing, the light is distributed across the retina, casting what Lewis calls “a veiling luminance” that significantly reduces contrast.

      To optimize vision, Lewis says, the key is to maximize the contrast—the brightness difference between what you’re trying to see and the background—while minimizing the amount of light going directly from the light source into the eye, because when light goes directly into the eye the greater portion of it is scattered. “You don’t want bright lights coming in from anywhere but the target you’re trying to see,” he says. “I mean any additional source of light out there, like a streetlight shining in your eye or a headlight coming at you or glare sources on a building just makes things harder to see.”

      The second major factor in our seeing well at night (or not) is adaptation, the way our eyes adapt as we move from brighter areas to darker areas. Because of the way our streetlights are usually placed, our eyes constantly have to go back and forth. “If you’re in a place that’s relatively uniformly illuminated by streetlights, then your adaptation remains fairly constant and that’s okay,” Lewis explains. “But what happens is streetlights tend to get dispersed somewhat willy-nilly and so you leave this bright spot and drive into this dark spot but you’re not adapted, and so visibility is actually worse than if you hadn’t had the streetlight there to begin with.” Lewis compares this situation to walking into a movie theater: the way it takes a few moments for your eyes to adapt. “So, as you move from lighted areas to nonlighted areas visibility can actually get worse. In many cases, an equal level of darkness is better than a sporadic light-dark, light-dark area.”

      It isn’t only streetlights that cause this problem. The worst offenders, he says, are intensely lit places like gas stations and parking lots. About twenty years ago in America, gas stations began to increase the level of lighting, not for any real safety concerns but for marketing purposes. (“People like light, they’re attracted to it. There’s no question about it,” he says.) “You go in and you fill up under a canopy that was highly lit from a marketing standpoint to attract you, rather than a need for vision,” explains Lewis. “And then you drive out into a dark road and it may be a minute or two before you can readapt to the darkness, which can be very dangerous.”

      “Because you might get hit?”

      “Generally you’re okay,” he laughs, “you’re in the car. It’s the other folks who have to worry.”

      In other words, it’s for marketing purposes (to get you to stop and buy stuff) that gas stations, shopping malls, and car dealerships are lit so brightly—not, as we might think, primarily for safety. If safety were the primary goal for these establishments, Lewis and others told me, they would be lit much more dimly so that the adaptation and glare problems would be reduced. The problem is that if one business raises its lighting level, the others will feel compelled to as well because by contrast, their establishment will seem dim and therefore less attractive—even closed.

      The same scenario holds true for our society in general. As our surroundings grow brighter, we grow used to that level of brightness, and so anything dimmer seems extraordinarily dim, even dark. This is exactly what happened as artificial lighting developed through the ages. The once glorious oil lamps became dim and disgusting with the advent of wonderful gas lighting, which then became smelly and awful and unbearably dim the moment we saw electric light. In other words, once our eyes get used to seeing brighter lights, we must have brighter lights.

      Roger Narboni, a lighting designer in Paris, explained this concept to me by telling of how he’d been hired to renew the lighting in a very large, very old fish market near Paris, where the business took place between 1:00 and 3:00 a.m.

      “The plan was 400 lux on the fish. But when the people selling the fish saw it, they said, This is dull, we can’t see the fish. They were used to having big halogen lamps—which were hot lamps that were terrible for the fish, but they were used to them. With the new lights the atmosphere was totally different, and for them it was no good. So they said, Can you raise the level a little? And we said, Sure. And they said, Can we have double? And we said, Wow, double, okay.” He laughed. So, Narboni said, they raised the level of lighting to 800 lux, but when the fishmongers came to work they asked if the lights had even been changed. “I took out my light meter and showed them: 800 lux. And they said, Are you sure it’s working? Can we go higher? So we went to 1,200, then 1,600, 1,800, and they were never pleased. They kept saying, It’s dull, we want more. And finally I said, Okay, forget it, because we’re not going to go to 3,000 lux or 5,000 lux or to daytime. This is insane; I don’t want to do that. So I quit. And I told them, Your eyes are not able to understand what’s going on. And even if we put more, you cannot compare it, and you will ask for more and more and more, and it’s like addicts. And they never understood that.”

      But a fish market in the middle of the night is one thing, I said. What about in the city itself?

      “It’s the same for the urban city. If you put more lights for safety, very often and very quickly people will say, Oh, we don’t see enough, it’s not working, people are still being attacked, and we have problems and so we should put more light. And we’re going to go up and up and up. There is no limit, because the vision gets accustomed to that and we need more.”

      The fascinating thing, though, Narboni said, is that this works the other way, too.

      “If you go to darkness, the eye opens a lot, you get more focus, and even in a very dark environment you see very well.”

      It’s a fact most of us don’t know: The human eye has an amazing ability to adapt to different lighting levels, including levels we normally think of as quite dim. While the human eye will never match those of truly nocturnal or crepuscular (active at dawn and dusk) animals, in dimly lit situations our pupil expands, our iris relaxes, and thirty times more light can enter our eye. Faced with bright lights, the pupil contracts and the iris closes down for protection. But given time to adapt to low light levels—levels that would allow the stars back into our skies and make our streets safer by eliminating glare—we actually see fairly well.

      “And I try to tell the politicians, ‘Try it and you’ll see,’” Narboni explained. “In Berlin it’s like СКАЧАТЬ