Einstein's general theory of relativity predicts that the main properties of gravitational waves are: propagating at the speed of light in a vacuum; Carrying energy and information related to the wave source; It is a shear wave, and it is a plane wave at the far source; The lowest order is quadrupole radiation; The radiation intensity is extremely weak; The absorption efficiency of matter to gravitational waves is extremely low, and the gravitational wave penetration is extremely strong, and the earth is almost transparent to gravitational waves; Its polarization characteristics are two independent polarization states, etc. Gravitational wave is a gravitational field with waveform and finite speed propagation. Although Einstein predicted that there might be gravitational waves in the accelerated mass in 19 16, his gravitational waves were related to the selection of coordinates. In one reference frame, gravitational waves may have energy, but in another reference frame, they may not. Therefore, at the beginning of gravitational waves, most people, including Einstein himself, were skeptical about gravitational waves. 1956, Pirani put forward a definition of gravitational wave that has nothing to do with the choice of coordinate system. 1957, the band-aid further proves theoretically the existence of plane gravitational waves that have nothing to do with the selection of coordinate system. 1959, Band-Aid, Pirani and Robinson further proved that stationary objects will move under the action of gravitational wave pulses, and indirectly proved that gravitational waves can carry energy and can be detected. Because the gravitational radiation is extremely weak, it is impossible to emit detectable gravitational waves in the laboratory at present, but the violent motion of massive celestial bodies, such as the revolution of binary star system, the rotation of neutron star, supernova explosion, the formation, collision and capture of theoretically predicted substances, can radiate strong gravitational waves. For many years, scientists all over the world have been committed to detecting gravitational waves. Weber, a scientist at the University of Maryland in the United States, took the lead in using an aluminum rod as an antenna for detection, and claimed to have detected a signal that did not rule out gravitational waves. But other scientists did not get this result, and Weber's conclusion was not recognized. Now the research on gravitational waves is in the ascendant, and the research on anti-gravity or anti-gravity has been put on the agenda. The possible results of this research may fully realize the dream of human beings to realize interstellar navigation, and scientists deserve to devote their life-long energy and talent to this research. Scientists in China have conducted valuable experiments and research in this field. Since the British science fiction writer Wells described "anti-gravity" (which can shield the influence of gravity and make the spacecraft fly to the moon), anti-gravity has become a dream of human beings for more than a century. If anti-gravity does exist, it will change the whole world. Cars, trains, ships, all the transportation systems you can think of can be driven by the energy obtained by the gravitational field. This anti-gravity research, which will change the taboos of the world scientific community and aerospace industry, has once again attracted people's attention, because it is reported that Boeing, the world's largest aircraft manufacturer, is exploring some new concepts, which may completely change the propulsion technology in the next century. The anti-gravity research carried out by Boeing can be summarized as a project of the company called "Grasp (Advanced Space Propulsion Technology Gravity Research)". A related document obtained by Jane's Defense Weekly expounds the great significance of Boeing's belief in the success of this project. The document reads: "If anti-gravity does exist, it will definitely change the entire aerospace industry." This evaluation may not be enough. If anti-gravity does exist, it will change the whole world. Cars, trains, ships, all the transportation systems you can think of can be driven by "no propellant propulsion"-a mode of obtaining energy from gravity field. Although anti-gravity is a beautiful dream, traditional science has always believed that anti-gravity is impossible. 1In April, 992, Brian Young, the late British Professor university of salford and then head of the strategic project of British space defense system, gave a speech at the London Institution of Mechanical Engineers. In his speech, he explained why anti-gravity research is related to the aerospace industry and even the world. The "Grasp" briefing explains why Boeing must hire Russian material expert yevgeny Podkretnov. Podcletnov claims to have invented a device that can shield the influence of gravity. 1992, Podkretnov, who works at Tampere University of Technology in Finland, submitted a paper to a British physics magazine. He described how an object placed on a high-speed rotating superconductor (which loses its resistance at extremely low temperatures) lost nearly 2% of its weight. This paper was leaked to a newspaper. First, because of the taboo concept of "anti-gravity", and second, because it caused an uproar in mainstream physics, Poldek Letnov was expelled from school. But the Russian research caught the attention of NASA. She has contacted a researcher at the University of Alabama in Huntsville, who claimed that she could create a gravitational field and repel or attract objects by using high-speed rotating superconductors. In the mid-1990s, the Marshall Space Center of the National Aeronautics and Space Administration (NASA) in Alabama failed to repeat Bode Crete's experiment. However, the center admits that it doesn't know the unique method of Russian manufacturing superconducting disks, and it is largely blind research. A few years ago, NASA paid $600,000 to Columbus Superconducting Components Company in Ohio, made the device that Podkletov used, and hired Russians as consultants. Although the experiment was postponed, Ron Kozol, the director of the experiment, was confident that the experiment could be completed. Podklenov, who now works in Moscow Chemical Research Center, further developed his ideas. Together with Italian scientist Giovanni Danis, he published a paper detailing the research work of a "pulse gravity generator", which can repel all objects. The device uses strong discharge power "emitter" and superconducting "emitter" to generate "gravity pulse". Pod Crete Novo said: "The time is very short. It travels along the discharge line at a very fast speed (actually instantaneous) and passes through many different objects without any obvious energy loss." He said that the experimental result is that any object hit by a light beam has a thrust effect, and the size is directly proportional to the mass of the object. When adjusting a laser aiming device, Pod Crete Novo said that his experimental device has shown the ability to knock down objects 1 km away. He claims that this device can knock down objects 200 kilometers away with the same energy. It is Poldek Letnov's research work on "Pulse Gravity Generator" that has attracted the attention of Boeing Company. In the "Grasp" briefing, Boeing described how the light beam emitted by the equipment can penetrate any object without any electromagnetic shielding. References: