[Science and Technology Frontier] It was learned from the National Astronomical Observatory of the Chinese Academy of Sciences that recently, an international team led by researcher Xu Cong of the National Astronomical Observatory of the Chinese Academy of Sciences discovered the largest atomic gas system that has been detected in the universe so far by using the "China Tianyan" FAST - during the imaging observation of the famous compact galaxy group "Stephen Quintuple Galaxy" and the hydrogen atomic gas in the surrounding sky, A huge atomic gas system with a scale of about 2 million light years was found, 20 times larger than our Milky Way Galaxy. This achievement was published in the international academic journal Nature on October 19, Beijing time. The origin of all celestial bodies in the universe can not be separated from atomic gas. For example, the main evolution process of galaxies is the process of absorbing atomic gas from space and then transforming it into stars. Therefore, observing the gas in the universe is a very important research topic in astrophysics. The radio astronomy band can directly observe the atomic gas in the universe, while the "China Tianyan" FAST is a single aperture radio telescope with the largest aperture and the highest sensitivity in the world today. Its ultra-high sensitivity enables mankind to have unprecedented extremely weak celestial body detection power, and can detect the faint radiation from the extremely thin diffuse atomic gas far away from the center of the galaxy, It opens a new window for studying the origin of celestial bodies in the universe. Xu Cong introduced that the latest discovery of "China Tianyan" FAST revealed the existence of large-scale low-density atomic gas structure in the outer space far from the center of the galaxy cluster. "We speculate that the formation of these gas structures may be related to the history of intergalactic interactions during the early formation of the 'Stephen Quintuple Galaxy', which has existed for about 1 billion years." This discovery challenges the study of the evolution of galaxies and their gases in the universe - it is difficult for existing theories to explain why these thin atomic gases have not been ionized by the ultraviolet background radiation in cosmic space for such a long time. This also indicates that there may be more such large-scale low-density atomic gas structures in the universe. Xu Cong said, "I believe FAST will bring us more discoveries." (Outlook New Times)