One of the many arguments for high-wattage storefronts, streets and parking lots is that bright lights deter crime. Since neighborhood thugs lurk in the shadows, the reasoning goes, it's best to make sure there are no shadows at all. This commonsense conclusion has been called into doubt by findings that show no correlation between crime levels and lighting.
So why is this finding great news? It gives us all an excuse to turn off the lights. Artificial lighting at night wreaks havoc on our circadian rhythms, leaving us at risk for obesity, depression, even cancer. It's also bad for wildlife, from birds to turtles and flying insects. Light pollution is even unhealthy for our sense of awe: Eight in ten kids born in the United States today will never see the Milky Way outside of a planetarium.
The end of bright, pushy electric lights might also make way for more humane nighttime lighting. Imagine navigating canals by bioluminescent bacteria, or walking down side streets illuminated with gentle bacterial glow. Or, just plant the whole city with rows of bioluminescent trees.