James' World 2

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Long ago, in lands that were always warm, people got ice from the heavens.

At sunset, they poured water into shallow earthen pits or ceramic trays insulated with reeds. All through the night, the water would radiate its heat into the chilly void of space. By morning, it turned to ice — even though the air temperature never dropped below freezing.

This wasn’t magic; it was science.

For centuries, desert dwellers in North Africa, India, and Iran tapped into the law of physics called radiative cooling. All objects — people, plants, buildings, planets — give off heat in waves of invisible light. On a clear, starry night, that radiation can rise through the atmosphere until it escapes Earth entirely. Coldness, which is really the absence of heat, is created through this invisible connection to the cosmos.

The world now cools off with the help of more than 3.5 billion refrigerators and air conditioners, a number that is quickly growing. But those appliances are also a major source of greenhouse gas emissions. In seeking relief from the heat, humans are making the globe even hotter, compounding the demand for cooling.

To break that cycle, University of California at Los Angeles materials scientist Aaswath Raman wants to turn ancient technology into a 21st-century tool.

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By Sarah Kaplan

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The Cold War had been concluded for less than a decade when NASA astronaut Bill Shepherd and two Russian cosmonauts, Sergei Krikalev and Yuri Gidzenko, crammed themselves into a Soyuz spacecraft and blasted into orbit on Halloween, 20 years ago.

Two days later their small spacecraft docked with the International Space Station, then a fraction of the size it is today. Their arrival would herald the beginning of what has since become 20 years of continuous habitation of the laboratory that NASA, leading an international partnership, would continue to build for another decade.

Born of a desire to smooth geopolitical tensions in the aftermath of the great conflict between the United States and the Soviet Union, the space station partnership has more or less succeeded—the station has remained inhabited despite the space shuttle Columbia disaster in 2003, and later, nearly a decade of no US space transportation. NASA, Roscosmos, and the European, Japanese, and Canadian partners have been able to rely on one another.

Not that it has been easy. Tensions have existed from those very first moments on the station. Shepherd, who would serve as the first ISS commander over his more experienced cosmonaut counterparts, wanted to nickname the station “Alpha.” He had support for this from Krikalev, but some Russian space officials believed their earlier Mir space station had earned that honor. The new station, they believed, ought to be named “Beta.” NASA, too, had not signed off on this designation.

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The essentially complete International Space Station in 2010, as seen by space shuttle Atlantis.

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On a mild autumn day in 2016, the Hungarian mathematician Gábor Domokos arrived on the geophysicist Douglas Jerolmack’s doorstep in Philadelphia. Domokos carried with him his suitcases, a bad cold, and a burning secret.

The two men walked across a gravel lot behind the house, where Jerolmack’s wife ran a taco cart. Their feet crunched over crushed limestone. Domokos pointed down.

“How many facets do each of these gravel pieces have?” he said. Then he grinned. “What if I told you that the number was always somewhere around six?” Then he asked a bigger question, one that he hoped would worm its way into his colleague’s brain. What if the world is made of cubes?

At first, Jerolmack objected. Houses can be built out of bricks, but Earth is made of rocks. Obviously, rocks vary. Mica flakes into sheets; crystals crack on sharply defined axes. But from mathematics alone, Domokos argued, any rocks that broke randomly would crack into shapes that have, on average, six faces and eight vertices. Considered together, they would all be shadowy approximations converging on a sort of ideal cube. Domokos had proved it mathematically, he said. Now he needed Jerolmack’s help to show that this is what nature does.

“It was geometry with an exact prediction that was borne out in the natural world, with essentially no physics involved,” said Jerolmack, a professor at the University of Pennsylvania. “How in the hell does nature let this happen?”

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Thomas Shahan for Quanta Magazine

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