Discovering the mystery of Qin Shi Huang's mausoleum
According to a study funded by the Chinese government, cosmic rays can help archaeologists pinpoint the secret room that preserves the remains and treasures of Qin Shi Huang, the first emperor of China.
The mausoleum of Qin Shi Huang in Xi'an, Xi'an Province, was built by hundreds of thousands of workers over nearly 4 decades and was completed around 208 BC, according to the scholar of the Han Tu Dynasty, who lived right after that time.
The mausoleum is located under a 76-meter-high mattress in the shape of a pyramid. The layout is simulated according to the Qin capital, Han Duong, divided into inner-city and suburban areas. The perimeter of the inner city is 2.5 km and the suburbs is 6.3 km. The main tomb is located in the southwest of the inner city and faces east. The main mausoleum containing coffins and buried artifacts is the focal point of the mausoleum architectural complex.
With a total area of 70 times the Great wall, this is the largest mausoleum ever built for an individual in the world.
The surface of the tomb is no longer solid, but the structures underground are still almost intact. Some archaeologists believe that the central room where the coffin of Qin Shi Huang is located and most of the valuable treasures are still not disturbed.
The central government-funded study to assess the project's feasibility shows that at least two cosmic ray detectors are needed at different locations about 100 meters below the grave surface.
These devices, the size of a washing machine, can detect universally-origin subatomic particles across the Earth.
SCMP quoted Professor Liu Yuanyuan and her colleagues at Beijing National University of Education as saying that this data will allow scientists to identify invisible structures. The study was published in Acta Physica Sinica, the official journal of the Chinese Physical Society, on December 13.
In the 1970s, more than 8,000 Terracotta Army - the army that protected Qin Shi Huang in the other world - were found buried far from the center of the mausoleum.
After decades of surveying, archaeologists have confirmed the existence of an underground palace over 30m high. They also found traces of evidence to prove the accounts of the Qin Shi Huan, which are considered fairy tales, such as lakes and waterways filled with mercury to simulate China's major rivers and seas.
However, the detailed structure of the palace and the exact location of the Imperial room are still uncertain. Other accounts of Tu Ma Thien such as traps equipped with bows and baskets to shoot anyone at the mausoleum have not been verified.
Application of cosmic rays in archaeology
Using cosmic rays in archaeology is a concept that has been around since the 1960s. Astronomical physicists have discovered that cosmic rays can hit air molecules and create a type of particle called a "muon" (a basic substance similar to an electron) that can penetrate most anything.
Muon seeds are more likely to be absorbed when passing through denser materials. By comparing the number of muon seeds that aunar explorer receives from many different angles, archaeologists can discover hollow structures, such as compartments or hidden paths in a building.
But the main idea is still the theory because muon seeds are not easily detected. And for decades, scientists have had to rely on bulky, room-like devices, making field applications difficult.
In recent years, thanks to advances in particle physics, the size of the cosmic ray detector has significantly shrunk. In 2017, an archaeological team in Egypt discovered a 30-meter long room in a 4,500-year-old pyramid using a mobile device.
As an ancient civilization with a long history, China has a large number of cultural relics that need urgent research. Muon seed images can be an important addition to traditional geophysical methods, Liu and his colleagues said in the research paper.
Is the project feasible?
Yang dikun, assistant professor of geophysics at Phuong Nam University of Science and Technology in Shenzhen, who was not involved in the project but was familiar with the technology, said the project was very feasible.
The Muon scooter that we have built and used for field surveys today has become too small, it can be carried on the person, he said.
Yang said that archaeologists have tried to map the mausoleums using other methods. The accelerator can detect substances of different densities, but its range is limited to a small area and its accuracy can be easily affected by environmental disturbances. Meanwhile, the most sensitive electromagnetic signals to structures containing metal and transverse radar can only reach limited depth.
However, the approach to cosmic rays is not without challenges. According to Yang, the tracking devices must be placed at appropriate depths without affecting the structure or creations above.
And unlike other detection methods that can get results almost immediately, the muon trackers must be in position long enough to collect enough hatles for analysis.
The computer simulation conducted by Liu's team said it could take a year to collect enough data to create a clear image.
It is unclear whether - or when - the project will receive government approval to go ahead. Liu and her colleagues said that some technical details, such as the number and exact location of the trackers, need to be further evaluated and optimized.
China is behind in the field of cosmic ray research, but activities in this field have increased rapidly in recent years.
For example, Lius team is one of the research teams working in the Can Binh laboratory, the worlds deepest cosmic ray discovery facility at a depth of more than 6,000 meters underground to study dark matter.
In May, Chinese scientists discovered the strongest light ever recorded in the universe by the world's largest, the most sensitive cosmic ray detector on a 4,410-meter peak in Dao Thanh district, Sichuan province.
Preserving the mausoleum of the Chinese emperor
Qin Shi Huang (18.2.259 - 11.7.210 BC) was the 36th king of the Qin Dynasty and the first emperor to unify China after defeating six vassal states, ending the Warring States period in 221 BC.
He became Emperor at the age of 13 and became emperor at the age of 38. Instead of continuing to title himself kings like the kings of the Tang and Chu dynasties, to mark the milestone of unifying China and proving that the Qin Dynasty was even greater than previous dynasties, he created a new title as "Emperor" and called himself the Imperial Water.
After unifying China, he and his lieutenant general Li Si passed a series of major economic and political reforms, including establishing a system of local power-held ministries appointed by the royal court instead of dividing the province into provinces and cities as before, allowing farmers to own land, unify the measurement system, currency, travel, and at the same time build a strict legal system.
Qin Shi Huang has carried out many major projects, including the construction of a citadel in the north, laying the foundation for the Ly Truong Thanh Temple, Linh Cu Canal, A Phong Palace, and the mausoleum of Qin Shi Huang protected by the Terracotta Army, conquering the South to expand the territory.
These policies have laid the foundation for a long-term unity for the vast China after nearly 500 years of division and continuous war, but with the price to pay for many human lives and the tiring epidemic and the hatred of the people.
When the construction of the mausoleum was completed, all workers and craftsmen were trapped and killed to keep the secret inside, according to Sima.
Most of the royal mausoleums in China have been robbed or damaged, but a few are still intact, including the mausoleum of Vo Tac Thien, the second empress of the Liu Shishi Dynasty, who later became the Emperor of the Wu Zhu Dynasty, who ruled when ancient China civilization reached its peak.
Chinese archaeologists opened a royal tomb of the Ming Dynasty (1368-1644) in Beijing in the 1950s and saw precious materials such as silk and paper decomposed immediately after being exposed to outdoor light.
Since then, the Chinese government has taken a strict stance against accessing these sites.
