Boeing, the world’s largest aircraft manufacturer, has admitted it is working on experimental anti-gravity projects that could overturn a century of conventional aerospace propulsion technology if the science underpinning them can be engineered into hardware. As part of the effort, which is being run out of Boeing’s Phantom Works advanced research and development facility in Seattle, the company is trying to solicit the services of a Russian scientist who claims he has developed anti-gravity devices in Russia and Finland. The approach, however, has been thwarted by Russian officialdom. The Boeing drive to develop a collaborative relationship with the scientist in...