LEDs’ potential to save our night skies

LED 拯救夜空的潜力

In the chill of a London spring night, under overcast skies, iconic Trafalgar Square opens around me. Admiral Nelson rises on his pedestal, the National Gallery rests behind, the church of St Martin-in-the-Fields sits nearby. From the 13th century, the site served as the Royal Mews for hawks and then horses. By 1844, it was a public space at the heart of one of the biggest cities in the world.

在伦敦一个寒冷的春夜，天空阴云密布，标志性的特拉法加广场在我眼前展开。纳尔逊海军上将的雕像矗立在基座上，国家美术馆坐落在后方，圣马丁教堂就在附近。自 13 世纪以来，这里曾是饲养猎鹰和马匹的皇家马厩。到了 1844 年，它已成为这座世界大都市中心的一处公共空间。

Despite the square’s presence through that grand sweep of history, it’s not why I’m here. My interest is far more specific: I want to find out what happens to spaces like this when artificial light, specifically from light-emitting diodes (LEDs), intrudes. My companion tonight is Simon Thorp, a local lighting designer, who crouches in the shadows near Nelson’s spire, light meter in hand. “Two lux,” he reports, “and it’s very comfortable here.” Two lux is 10 to 20 times the illuminance of a full moon. We can see each other clearly, and a nearby sign assures us that closed-circuit television (CCTV) is in operation for safety’s sake.

尽管这座广场见证了宏大的历史变迁，但这并非我此行的目的。我的兴趣点更为具体：我想探究当人造光——特别是发光二极管（LED）——侵入这样的空间时会发生什么。今晚陪伴我的是当地照明设计师西蒙·索普（Simon Thorp），他手持照度计，蹲在纳尔逊纪念柱附近的阴影中。“两勒克斯（lux），”他报告说，“这里感觉非常舒适。”两勒克斯的亮度是满月照度的 10 到 20 倍。我们可以清晰地看到彼此，附近的一块标志牌也向我们保证，为了安全起见，这里有闭路电视（CCTV）监控。

Trafalgar Square captures the relationship between lighting and darkness that exists in almost every city, suburb, small town, and village around the world. The lighting here is a mishmash of old technologies and new, of shadow and glare, the ornamental gas lamps fronting the National Gallery all but washed out by the LEDs inside modern versions of traditional “brass and glass” fixtures a few meters away—21st-century technology housed in 19th-century designs.

特拉法加广场折射出世界各地城市、郊区、小镇和乡村中普遍存在的光与暗的关系。这里的照明是新旧技术的混杂，交织着阴影与眩光。国家美术馆前装饰性的煤气灯几乎被几米外现代版“黄铜与玻璃”灯具中的 LED 灯光所淹没——那是装在 19 世纪设计外壳里的 21 世纪技术。

The ugly truth of artificial lighting today is that in parts of London, as in many cities around the world, lighting levels are excessive, with unshielded illumination blasting in all directions. And the irony is that too much light invites danger: It creates shadows, impedes our vision, and gives the illusion, without the reality, of safety. Thorp notes that modern CCTV cameras are “pretty great” even at low-light levels, while harsh light makes it hard for both human eyes and digital sensors to see.

当今人造照明的一个残酷事实是，在伦敦的部分地区，正如世界上的许多城市一样，照明水平过高，未加遮蔽的光线向四面八方肆意投射。讽刺的是，过度的光线反而带来了危险：它制造了阴影，阻碍了我们的视线，并营造出一种虚假的安全感。索普指出，现代闭路电视摄像头即使在低光照水平下表现也“相当出色”，而刺眼的光线反而让人的眼睛和数字传感器都难以看清事物。

“The more bad light we add, the more bad light we think we need,” says Thorp. “We can’t see because of the light we’ve added. And it makes areas that were perfectly okay seem darker.”

“我们添加的劣质光线越多，就越觉得需要更多的劣质光线，”索普说，“我们因为添加了这些光线反而看不清了。这让原本完全没问题的区域看起来反而更暗了。”

Among the costs of this excess, the most alarming may be its toll on human health (and that of other animals) by disrupting circadian rhythms, impeding the production of melatonin, and contributing to sleep disorders that are tied to every major modern disease. New research shows that increased exposure to blue light from LEDs is having “substantial biological impacts” such as suppression of the sleep hormone melatonin and an increased risk for obesity, certain cancers, and type 2 diabetes.

在这些过度照明带来的代价中，最令人担忧的或许是它对人类（以及其他动物）健康的损害。它扰乱了昼夜节律，阻碍了褪黑素的分泌，并导致了与现代所有重大疾病相关的睡眠障碍。最新研究表明，更多地暴露在 LED 发出的蓝光下会产生“重大的生物学影响”，例如抑制睡眠激素褪黑素，并增加肥胖、某些癌症和 2 型糖尿病的风险。

I have come to London and Paris—which led the way in the expansion of public street lighting in the 19th century—because they embody both the current enormity of the problem as well as a future certain to be lit by trillions of chips: controllable, tunable, and energy-efficient LEDs.

我来到伦敦和巴黎——这两座城市在 19 世纪引领了公共街道照明的扩张——是因为它们既体现了当前问题的严重性，也预示了一个必然由数万亿芯片点亮的未来：即可控、可调且节能的 LED。

The first visible red light-emitting diode was invented by Nick Holonyak in 1962, but LED lighting technology took several decades to develop, before exploding in recent years. Just a decade ago, LED streetlamps were rare. By 2019, more than half of U.S. streetlights were LEDs, and that number is predicted to top 90 percent by 2030. Similar uptake has occurred around the world, even in developing countries, where inexpensive Chinese-made LED fixtures are increasingly common.

第一颗可见红光发光二极管由尼克·何伦亚克（Nick Holonyak）于 1962 年发明，但 LED 照明技术经历了数十年的发展，才在近年来迎来爆发。仅仅十年前，LED 路灯还很罕见。到 2019 年，美国超过一半的路灯已换成 LED，预计到 2030 年这一比例将超过 90%。世界各地也出现了类似的普及趋势，即使在发展中国家，廉价的中国产 LED 灯具也越来越普遍。

This rapid global migration to LEDs represents a shift in the fundamental physics of how we illuminate our world. From oil lamps and candles to gas lamps, early examples of artificial light at night relied on a burning wick, an incredibly inefficient way to create light. An incandescent bulb is effectively a heater that happens to produce light as a by-product, so it squanders nearly all of its energy as heat. By contrast, LEDs use semiconductors to convert electricity into light. Through this process of electroluminescence, LEDs use up to 90 percent less energy than…

这种全球范围内向 LED 的快速转型，代表了我们照亮世界方式在基础物理层面的转变。从油灯、蜡烛到煤气灯，早期的人造夜间照明都依赖燃烧的灯芯，这是一种效率极低的照明方式。白炽灯实际上是一个加热器，光只是其副产品，因此它将几乎所有的能量都浪费在了发热上。相比之下，LED 利用半导体将电能转化为光。通过这种电致发光过程，LED 比（传统灯具）节省了高达 90% 的能源……