People in ancient times in the evening, in the absence of light, one is often the beast attack at night, can't normal work and rest, then with the development of civilization, with the invention of the light bulb, human bid farewell to the darkness of the night, even at night is bright as day, especially after the emergence of LED lighting and neon, arguably, more bright at night than during the day. In recent years, the city has been regarded as fashionable in many places, not only a second-tier city but also a "world class lighting project", the construction of "the city of the night", and the third and fourth tier cities are also vying to follow suit. "Every time the sunset west, the Chinese lantern, the city night bright like the day, the neon light flashing" has been the most impressive development of Chinese cities. Big cities and small cities.

Is the city really brighter at night? And the more brilliant the night in a city, the more prosperous it is?

In fact, excessive pursuit of designs city-lighting, not only a large amount of energy, but also make light pollution, both violates the construction "the requirement of economical society", also violated the concept of scientific development.

Actually, let the city be dark, so what?

This article will take a look at how Los Angeles develops from pure pursuit of "brightness" to the pursuit of bright art and bright science, and really does it to make the city beautiful.

On a return flight to Los Angeles, EdEbrahimian, the Los Angeles streetlight director, likes to stare out of the window. The next time you fly over Los Angeles at night, you can look out the window and see what he's looking at. Five years ago, the city was enveloped in an orange glow and flushed the sky. Today, the city is lit by tens of thousands of silver dots. The road grid was clearer, and the night sky was dark.

"Now these lights look like candles, and they don't glare," Mr Abrahimin said enthusiastically. "the sky glow is the most amazing thing I've ever seen in my life."

Mr Abrahimin had good reason to be so excited. As a Los Angeles street lamp administration, who is overseeing the world's largest one of street lamp renovation project plan to transform the city's 215000 streetlights with $57 million, there are more than 400 styles these lamps. Today, five years after the program started, he has converted only 155,000 street lamps. The remaining 60,000 streetlights, including most of the decorative lights, will need $50 million.

In the rapid urbanization process, the world is facing an important but neglected struggle -- the light and the dark. In this struggle, Los Angeles is an important battleground. For business and security reasons, city managers and businesses want more light everywhere. In the past few decades, we have launched the "intensive bombing" light to dark, however, it also brings high electric bills, that affected the survival of wild animals, and even threats. For thousands of years the sky has been a source of inspiration for scientists, poets and explorers, but now the landscape has been lost in the light. Paul bogard, author of "TheEndofNight," said: "looking up at the stars was once the most common human experience, but now it is the rarest." The book strongly blames the unchecked light pollution.

The core technology of this shift is LED -- the light-emitting diode, a breakthrough in lighting history. Leds are solid-state semiconductors, so they are closer to the processors in smartphones than overhead lights. Los Angeles, New York, Chicago, Shanghai and Copenhagen and other dozens of cities around the world, in the deployment of LED street lamp, at least it can solve problems most of the traditional street light energy use efficiency is low.

LED street lamp upfront costs is a traditional high street lamp three to four times, but the service life of them is the latter three to four times, and the unit power lighting ability is also the the latter three times, each year can save 30% to 70% of the electricity. Because leds are digital chips, according to Moore's law, its costs will only get cheaper. And, as electronic components, they are more programmable, and more effectively connected to radio and sensor chip, thus to form a wireless network throughout the city, with monitoring to crime, power outages and water pipes burst problems and coordinate relief efforts.

There is a huge opportunity in this trend of LED street lighting. Of the 140 million lamps installed worldwide last year, only 19 million were LED street lamps, according to IHSTechnology, a consultancy. LED street lights are expected to account for 100 million of the 155 million street lamps by 2020. Annual sales of LED streetlights will also surge from $4.3 billion to $10.2 billion. Boston, Seattle and New York City are all on a massive upgrade. New York's $76 million project will be the largest in the United States: by the end of 2017, there will be 250, 000 street lamps. New York City officials expect to save $14 million a year in energy and maintenance costs.