Through gravitational wave signals, astronomers have observed more than 20 collisions or coalescence events of dense celestial bodies such as black holes and neutron stars. However, a recent study found that collisions between black holes and wormholes can also generate rich gravitational waves. On August 27, according to foreign media reports, an international research team simulated and analyzed a black hole with a mass of five times the mass of the sun through a wormhole with a mass of 200 times the mass of the sun. The results show that black holes can pass through wormholes stably. During the process of black holes entering and leaving wormholes, special gravitational wave signals which have never been detected before will appear. < / P > < p > Why do black holes “fall” into wormholes? What kind of special gravitational wave is emitted? Can people search wormholes and travel in time and space? Wormholes and black holes are special space-time structures predicted by Einstein’s general relativity theory. Astronomers generally believe that black holes are the product of the collapse of stars. The existence of black holes has been confirmed by observations, and even the first black hole photo appears in 2019. However, wormholes are still theoretical hypotheses and have not been confirmed by astronomical observations. If we can prove the existence of wormholes, astronomical research will make a great breakthrough. < / P > < p > in this study, through numerical simulation, the researchers found that a special gravitational wave signal – “anti chirp sound” is generated when a black hole falls into a wormhole, which is different from the “chirp sound” gravitational wave signal produced by the collision of two black holes. The researchers speculate that in the future, people can search for wormholes in the universe based on this special gravitational wave signal. < / P > < p > “the gravitational wave characteristic of double black hole collision is” chirp sound. ” Cai Ronggen, academician of the Chinese Academy of Sciences and director of the Institute of theoretical physics of the Chinese Academy of Sciences, explained that as the two black holes get closer and closer, the amplitude and frequency of gravitational waves will become larger and higher, and the sound emitted is vividly called “chirp sound”. < / P > < p > in this study, researchers simulated a black hole with a mass of 5 times the sun’s mass to “fall” into a stable, non rotating, and traversable wormhole with a mass of 200 times. This process was described by Cai Ronggen as “like a ball falling into a water pipe”. He told Science and Technology Daily that there are three possible outcomes of a black hole falling into a wormhole: first, the black hole is very fast, and it passes through the wormhole in an instant to reach another universe; the second possibility is that after the black hole falls into the wormhole, it stays at the throat of the wormhole due to the insufficient kinetic energy of the initial velocity, just like water staying at the bottom of the water pipe; and the third possibility is that the black hole falls into the wormhole After the wormhole, due to the interaction of gravity, it is pulled back to the original universe. < / P > < p > “the” anti chirp “mentioned by the author belongs to the third case Cai Ronggen said that this is just like when water enters the water pipe, the frequency is higher and higher, and the gravitational wave is characterized by “chirp”; then, the water returns to its original place from the bottom of the water pipe, and at this time, the frequency of the gravitational wave it emits becomes smaller and smaller, which is called “anti chirp sound”. In recent years, the mystery of black hole has been gradually uncovered. But why are wormholes so hard to find, which is also the space-time structure predicted by Einstein’s general relativity? How can the results of this study help to search wormholes? Cai Ronggen told Science and Technology Daily that wormholes are pipes or shortcuts connecting two different universes (or two different regions in the same universe), and objects can travel through time and space through wormholes. Wormholes can be as small as quantum scale or as large as cosmic scale. “Theoretically, we can’t rule out the existence of wormholes, but we still need to pay attention to two points: first, humans have never observed wormholes; second, theoretically, wormholes are very unlikely to exist.” He said. In general relativity, the so-called wormhole configuration can exist. However, the construction of wormholes requires a very special material, that is, the so-called “negative energy”. In spite of the difficulties, scientists continue to explore wormholes. Since the gravitational wave signal generated by the collision of two black holes was confirmed by observation in 2015, the scientific exploration of wormholes has become increasingly hot. For wormhole exploration, scientists also choose to start with gravitational waves. < / P > < p > “if a black hole falls into a wormhole, it will produce gravitational waves.” Dr. Dai Dechang, a domestic wormhole researcher and School of physical science and technology of Yangzhou University, explains that gravitational waves are disturbances of spatial structures, black holes and wormholes are two special spatial structures, and gravitational waves are indispensable to the study of spatial structures. < / P > < p > after the discovery of gravitational waves generated by black hole merging in 2015, scientists proposed that the structure of neutron stars, black holes, white dwarfs and other compact objects could be studied by using gravitational waves. In 2016, some scholars proposed that the spatial structure of wormholes is different from other dense celestial bodies, which should form different gravitational wave signals. In 2017, it was found that there was an echo in the gravitational wave signal emitted by the merging of black holes, that is, “anti chirp”. < / P > < p > “this is the significance of this study. Because the echo indicates that the merging objects may also be wormholes rather than black holes. So it’s important to verify this finding. ” Dai Dechang further explained that studying the merging of black holes and wormholes is to find out how to distinguish whether an object is a black hole or a wormhole. Wormholes are similar to the tunnel structure of two black holes cut apart and pasted together. This means that half of the space-time structures of black holes and wormholes are the same, and it is difficult to distinguish them. According to Dai Dechang, the purpose of simulating the merging of wormholes and black holes is to establish their gravitational wave signal templates, which can be used to compare the gravitational wave signals observed by gravitational wave detectors. If the template matches the gravitational wave signal, it is the best proof of wormhole existence. < / P > < p > scientists have detected the first gravitational wave signal in human history from the black hole merging event. Since the gravitational wave signal is a “clue” to find wormholes, how do scientists detect these gravitational wave signals? According to CAI Ronggen, like this study, the gravitational wave signal of a black hole begins with the computer simulation of the collision of two black holes. The results show that the collision of two black holes will produce a kind of gravitational wave signal, and then look for such signal from a large number of observation data. If such signals are successfully found, the existence of black holes can be proved. This way of searching for celestial bodies is called “matched filtering method”. The “language” of gravitational waves is very rich. The collision of black holes, neutron stars, white dwarfs and other dense celestial bodies will produce different gravitational wave signals. At this time, “matched filtering method” is going to show its skill. Cai Ronggen used the distinction between hydrogen bomb and hydrogen bomb as an analogy. He said: “the explosion intensity of both hydrogen bomb and hydrogen bomb is very large, but the equivalent of the two is different. By measuring the equivalent, we can deduce whether it is a hydrogen bomb or not. In the same way, the types of compact objects can also be deduced from the characteristics of gravitational wave signals < / P > < p > “this experiment is meaningful for us to find wormholes.” Cai Ronggen said that although the study uses a very simple mathematical model to simulate the whole process of a black hole falling into a wormhole, which is still some distance from the real situation, it can grasp the main physical characteristics and provide a new and possible gravitational wave signal for the interaction between wormholes and black holes, which has implications for future wormhole search and related research. < / P > < p > “in fact, a black hole falling into a wormhole can also destroy the wormhole.” For example, if the wormhole is unstable, the fall of a black hole will cause the wormhole to suddenly fracture or be destroyed. If the mass of the wormhole and the black hole are very close, then the wormhole may run around the black hole, or vice versa. If the mass of the black hole is significantly larger than that of the wormhole, the black hole may devour the wormhole in one bite. However, it is still necessary to study the nature of wormholes and wormholes. Chinese version of K-car: reading a10e design drawing exposure