Whenever a new tower starts muscling its way toward the sky, it drains a bit more light from the streets and parks below, so walking along a sidewalk can sometimes feel like pacing the bottom of a deep well. But what if, even in the densest thickets of Manhattan, skyscrapers could be designed to shrink, or even bleach out, the shadows they cast? Imagine a structure that bends like a rubbery dancer to dodge as many rays as possible and let them fall on a park instead. That’s what Jeanne Gang’s Solar Carve tower will do for the High Line. Or think of a high-rise fitted out with angled mirrors that make its shadow glow. Jean Nouvel’s One Central Park in Sydney, Australia, does that. New Yorkers who fear that a 1,500-foot-high wall of deluxe condos will one day cast Sheep Meadow in permanent shadow could start demanding designs that cast soft, glare-free pools of light instead.

Software and high-tech glass offer precise ways of managing shadows, but the idea of maximizing solar access has a long pedigree. In the 1970s, the Los Angeles–based architect Ralph Knowles observed that the Acoma people of New Mexico had always oriented their terraced pueblos to the south, ensuring that every house would get maximum exposure to the low winter sun. Knowles proposed enshrining a right to sunshine in a legal concept he called the “solar envelope.” In New York, resistance to darkened streets is already baked into law. We’re approaching the centennial of the 1916 zoning code, which obliges buildings to retreat as they rise, opening up cones of sunshine that touch the ground. The pursuit of light created the classic New York skyscraper.

....