What ancient technologies can't be copied at present?

? We China people are talented people in every dynasty. Although it is a high-tech era, the ancients really couldn't do it because of machinery and equipment, electricity, energy and many other things, but in the field of scientific and technological inventions, I think it is no worse than it is now. In the history of thousands of years, the ancients created many treasures that shocked China and foreign countries with their wisdom and experience. Today, many ancient technologies have been lost, and those exquisite cultural relics have become unique. Even with today's technology, there is nothing we can do.

? First, Qin bronze sword. 1spring of 974, located at the east of Qin Shihuang Mausoleum 1.5km in Lintong County, Xi, Shaanxi Province. The bronze sword unearthed in pit 2 is 86 cm long and has eight sides, which is extremely symmetrical and balanced. They were excavated from the ground in 2000, but they are as clean as new, without corrosion and rust. Through modern scientific methods, the surface of these bronze swords is covered with an oxide film with a thickness of about 10 micron, which contains 2% chromium. This discovery immediately shocked the world, because this kind of salt oxidation treatment is an advanced technology that was mastered only in modern times. It is said that Germany invented and applied for a patent in 1937, and the United States invented it in 1950, and it was realized under a set of complicated equipment and technological processes.

? More importantly, the toughness of these bronze swords is amazing. A sword was bent by a clay figurine weighing 150kg, and the bending degree was more than 45 degrees. But when the clay figurine was removed, a miracle happened, and the bronze sword bounced straight, which naturally restored this superb industrial level, even with the current technology.

? Second, plain yarn clothes. Plain gauze clothing is a cultural relic excavated by China archaeologists in Mawangdui Han Tomb in Changsha in 1972. It is the peak of textile technology in the Western Han Dynasty and a national first-class cultural relic. The weight of such a big dress is only 49G, less than one or two. It is not an exaggeration to describe it as "as thin as cicada wings" and "as light as smoke". It is the lightest plain yarn garment in the world and the earliest printed fabric. Some people in modern times used the top technology of 13 years, and finally made it 0.5g heavier than in ancient times, so these things may not be worse than us in ancient times.