Xinhua News Agency, Chengdu, December 7 (Reporter Xing Tuo, Xue Chen) On December 7, 10 experimental project teams including Tsinghua University and Shanghai Jiao Tong University officially settled in Jinping Underground Laboratory, China, to carry out a series of scientific experiments such as dark matter detection. What is Dark Matter?Why did scientists choose to conduct their research in the deep ground?
Looking up at the vastness of the universe and looking down at the prosperity of categories", in the vast universe, as small as a speck of dust, as large as mountains, rivers, lakes and seas, the sun, moon and stars, are all visible substances. But is the world really only made up of visible and observed matter?
In the century, Swiss astronomer Fritz Zwicky first proposed the conjecture of dark matter based on the anomalies of the movement of some galaxies through a large number of astronomical observations and derivations. "Dark matter refers to matter that cannot be seen or touched by the human eye and cannot be captured by astronomical telescopes and electromagnetic means. Dark matter has both 'wall-piercing' and 'stealth'. Liu Jiang, a professor at Shanghai Jiao Tong University and a spokesman for the pandax experiment, said. Dark matter may sound unfamiliar to most people, but scientists speculate that visible matter only accounts for about 5% of the mass of the entire universe, and the remaining about 95% is dark matter and dark energy.
Popular science materials displayed in the Jinping Underground Laboratory in China. Photo by Xinhua News Agency reporter Xu Bingjie.
Dark matter and dark energy have been likened by scientists to "two dark clouds hanging over the sky of physics in the 21st century", and they are difficult to explain with existing theories. "We are still at a loss for 95% of the universe, and this curiosity drives us to understand the unknown and the world. Yue Qian, a professor at the Department of Engineering Physics of Tsinghua University and the head of the CDEX dark matter experiment, said that dark matter research is a new research that breaks through the current cognitive boundaries and opens up human horizons.
However, it is very difficult to detect dark matter directly. The probability of dark matter interacting with ordinary matter is extremely low, and a vivid example can illustrate this: through actual calculations, about 1 billion dark matter particles hit our body every second, but most of them "pass through", and the number of collisions between dark matter particles and atoms in our body is very rare, about once a year. In addition, the ubiquity of cosmic rays can greatly interfere with detection, making already difficult detection even more difficult.
A "pure" laboratory that blocks cosmic rays, the experimental environment, and the low radiation background of the equipment becomes necessary for the detection of dark matter.
The Jinping Underground Laboratory is located 2,400 meters underground in Jinping Mountain, Liangshan Yi Autonomous Prefecture, Sichuan Province, with a total volume of 330,000 cubic meters, and the cosmic ray flux of the laboratory is only 1/100 million of the surface.
In 2010, the first phase of Jinping Underground Laboratory was completed and put into operation, and the CDEX experimental group of Tsinghua University and the PANDAX experimental group of Shanghai Jiao Tong University were the first to settle in to carry out direct detection experiments of dark matter. Since the first phase was put into operation, Jinping Underground Laboratory has made a number of world-leading scientific research achievements in the fields of dark matter detection and nuclear astrophysics.
Researchers from Tsinghua University's CDEX Experimental Group conducted relevant experiments in the Jinping Underground Laboratory in China. Xinhua News Agency.
After more than 10 years of hard work, China's dark matter research has grown from scratch, from 'following' to 'running' and then to gradually 'leading', and has come to the forefront of the world. Next, together with foreign scientists, we will challenge the same scientific problem facing mankind - on the road to finding dark matter, to see who can find dark matter first. Yue Qian said.
What is the significance of dark matter research for human society?Will our lives change as a result?"More than 100 years ago, we had detected electromagnetic waves, but we never thought that they would be closely related to our lives, and now we all have a mobile phone, and we are completely inseparable from the specific application of radio. Yue Qian believes that dark matter is the same, first you have to find dark matter, then conduct in-depth research on it, and finally naturally think of how to use it for the benefit of society.