When I call Blake Scholl from New York, he says it’s a shame we couldn’t have met at his office in Colorado. If only there were a supersonic jet that could cruise at 1.7 times the speed of sound, and get me there two hours quicker than the typical JFK-to-Denver route. There soon might be. Scholl is the CEO of Boom Supersonic, a company betting that ordinary civilians want to shoot across the sky at 1,100 miles (1,700 kilometres) per hour. After the pandemic brought a slump to the skies, air travel has returned to its former levels, and in-person...