“Virtually nothing has gotten better and cheaper faster over the past 30 years than LEDs. From 2010 to 2019 alone, LEDs went from accounting for 1 percent of the global lighting market to nearly 50 percent, while their cost has declined ‘exponentially,’ as much as 44 percent a year, one government report found. And as LEDs have improved, so, too, have any number of technologies reliant on or related to them: tablets, at-home-hair-removal devices, televisions, smartphones, light-up toys, cameras. LEDs have also transformed cultural events involving creative lighting. They’re why stadium shows and EDM festivals look so freaking awesome, to fangirl for a minute, and why even many just-getting-started...