Picture a substance that can cool itself down just by sitting in the sun, without a fan or an electrical compressor. This isn't science fiction; it traces back to a 2014 paper in Nature, "Passive radiative cooling below ambient air temperature under direct sunlight", by a team of Stanford University researchers. The cooling technology that grew out of that research is now used in a California grocery store's rooftop system and in a separate field test on bus shelters in Arizona. With heat waves growing longer and more brutal every year, this quiet piece of engineering could be one of the more pragmatic tools we have.
A coating that bounces off the sun and beams heat into space
