President Joe Biden has caused confusion after predicting some commercial airplanes could fly at speeds of up to 21,000 miles per hour in the next 10 years, faster than the hypersonic weapons under development by the military. “We’re going to talk about commercial aircraft flying at subsonic speeds, supersonic speeds, be able to figuratively, if you may, if we decide to do it, be able to traverse the world in an hour, travel at 21,000 miles an hour," Biden said. The White House has yet to clarify Biden's comments, made during a Wednesday address aimed at promoting his $2.25 trillion...