Modern materials such as carbon fiber are lighter and stronger than aluminum, and modern engines are much more efficient than the Concorde’s. A modern jet could reach the same speed as the Concorde for one-fourth of the price, about equivalent to today’s business class air fare.
Getting speeds significantly above Mach 2 is harder. At these speeds, the main issue is drag. Air resistance is so intense that aircraft traveling at Mach 3 will have to tolerate temperatures hundreds of degrees higher than those at Mach 2. Alternatively, they could fly much higher in the atmosphere, where drag is less of an issue. Ultimately, if we want speeds to increase beyond Mach 3, we’ll need to get to the point where we are shooting people out of the atmosphere, briefly into space, and then bringing them down for a landing at their destination. Using this technique, we could get to Mach 5 or more. But it all starts with getting Mach 2 aircraft back in the air again.
But even allowing a commercial Mach 2 aircraft will change how we think about travel. Imagine being able to go on a cross-country flight, attend a business meeting, and return home in time for dinner with your family . Or imagine flying to Asia in 6 hours instead of 14 hours. Faster travel brings the world together. With supersonic flight, we’ll initially see business travel that is a lot more tolerable, but, as prices come down, there will be a lot more exploration of the planet.
A sonic boom standard, that is 100 times quieter than the Concorde’s boom, would be no louder than a lawnmower or a motorcycle, and unlike these other sources of nuisance noise, they would be over in half a second.