Popular Science

Editor-in-Chief Corinne Iozzio Design Director Russ Smith Executive Editor Rachel Feltman Managing Editor, PopSci+ Jean McKenna Deputy Editor Purbita Saha Managing Editor, PopSci.com Marina Galperina DIY Editor John Kennedy Technology Editor Rob Verger Features Editor Susan Murcko Social Media Editor Chelsey Coombs Engagement Editor Ryan Perry Digital Edition Editor Ben Guarino Associate Editors Jessica Boddy, Sandra Gutierrez G., Lauren J. Young Staff Writer Philip Kiefer Assistant Editors Charlotte Hu, Sara Kiley Watson Copy Editor S.B. Kleinman Researchers Stephanie Abramson, Cadence Bambenek, Jake Bittle, Diane Kelly, Alex Schwartz, Carolyn Shea Interns Maggie Galloway, Shi En Kim Executive Editor, Gear & Reviews Stan Horaczek Reviews Editor Mike Epstein Associate Managing Editor Tony Ware ART AND PRODUCTION Photography Director John Toolan Production Manager Glenn Orzepowski CONTRIBUTING EDITORS Brooke Borel, Kat Eschner, Tom Foster, William Gurstelle, Gregory Mone, Sarah Scoles, P.W. Singer, Nick Stockton, James Vlahos OPERATIONS General Manager Adam Morath Chief Executive Officer Lance Johnson Chief Operating Officer Alex Vargas Chief Revenue Officer…

I’VE BEEN somewhat dreading picking a theme for this issue, the 150th-anniversary edition of PopSci, almost since the day I took the chair as editor-in-chief a little more than two years ago. How could one hope to encapsulate a history so deep and broad as to be punctuated by the earliest telephones, the development of the polio vaccine, and the rollout of WiFi? Sure, all these things—and the literal thousands of other inventions that have appeared in our pages—have common threads in research and innovation, but words like that are the low-hanging fruit. They’re our DNA, as opposed to a discrete thought. What could possibly bring all this to a head in a tangible way? The answer, oddly enough, was a theme the editors have batted around for years: metal. Eras of…

WHEN ILLUMINATED by magenta and blue grow lights, Harpreet Sareen’s mini greenhouse looks like almost any other indoor gardening setup in New York City. But when the interaction designer switches the bulbs off to pitch the lab into darkness, a soft red glow persists. Nanosensors flow through the veins of a peace lily, allowing its broad leaf to fluoresce. The beacon fades over the course of a couple of hours, but this is by design: The dying light signals that its host is taking in toxic lead. The glowing lily is one of Sareen’s botanical “cyborgs”—vegetation he biohacks to serve as environmental watchdogs. Plants, he explains, are natural sentinels. When they absorb nutrients through their roots, they also sop up low concentrations of pollutants. “They are automatic absorbers or scrubbers of…

WHEN METALS first entered West Asian and Eastern Mediterranean kitchens in the form of bronze knives and copper cauldrons, only the wealthy could afford these tools. Today, such cookware and cutlery are staples—but with widespread use come common misconceptions. Microwaving metal is dangerous: FALSE (in some cases) If you’re wondering why you hear a loud zap when electromagnetic radiation hits a stainless-steel fork, know that it’s the shape, not the material, that’s the problem. Microwaves heat up food by vibrating water molecules, but if you raise the temperature on a knife or fork, the loose electrons on the metal will get stirred up, accumulating on sharp edges and potentially producing sparks. Set a spoon on the turntable instead, and the energy will disperse, resulting in nothing but a scalding utensil. Soap ruins cast-iron…

WE’VE BEEN using metal to fine-tune our smiles since ancient times. In Egypt, archaeologists have found evidence of gold wires attached to teeth dating from as early as 2500 BCE. But it wasn’t until the 19th and early 20th centuries that orthodontic innovation picked up speed. In 1928, the American dentist Edward Angle published a series of articles describing what came to be known as the “edgewise appliance.” It had the same fundamentals as the braces used today but was much clunkier, with wide metal bands wrapped around each tooth. Despite newer, gentler options, like plastic aligners, many orthodontists still choose versions of this tough hardware to capitalize on metal’s chomper-pulling power. Modern braces consist of three main parts: brackets, archwires, and ligatures. Orthodontists glue the rectangular brackets, usually metal, to each…

ON ANY GIVEN WEEKDAY, the United States Mint can churn out almost 126.4 million pennies, nickels, dimes, quarters, 50-cent pieces, and gold dollars from its presses in Denver and Philadelphia. Giant “cookie cutters” punch blanks out of 1,500-foot-long sheets of copper, nickel, and other metals. The discs are then heated, washed with citric acid and anti-tarnishing agents, and struck with presidential silhouettes. Despite seismic shifts in the very nature of money, the 230-year-old operation will keep on pumping fresh coins into circulation this way. Digital currency is more popular than ever, and countries around the world have unveiled bold plans for centralized electronic banks. But the alternatives won’t make physical cash go extinct, at least in the US. The total volume of hard currency in national circulation, including pennies and nickels…