NASA's experimental jet, referred to as the "son of Concorde", has reportedly broken the sound barrier without producing a sonic boom. The jet, also known as the X-59, has achieved a major milestone, although it is unclear if this was during its maiden flight or a test. The successful test paves the way for potential supersonic travel, but details of the achievement, such as the exact speed reached, vary across reports, with one outlet citing a speed of 713mph.