Those lost technologies

The world has never had so much advanced technology, but that doesn't mean we haven't lost something along the way. Many ancient technologies, inventions and manufacturing processes have been lost over time; and some technologies are still not fully understood by modern scientists. Some technologies have been rediscovered by us, but many of the more mysterious lost technologies have become legends.

　　Antikythera device

　　One of the most mysterious archeological artifacts, the Antikythera device is a bronze device discovered by divers more than 100 years ago in the wreck of an ancient ship on the Greek island of Antikythera. The device consists of a series of controllable copper gears (more than 30), cranks and dials used to calculate the positions of the sun, moon and other planets. Scientists calculate that the device was made in the 1st to 2nd centuries BC. Scientists still do not fully understand its true purpose, and the mysterious structure and use behind it have puzzled researchers for many years.

　　The consensus now seems to be that the Antikythera device was a primitive clock that could calculate the phases of the moon and the year of the sun, leading some to call it the earliest "analog computer."

　　Many scientists speculate that its use may have been widespread at the time. However, in the historical record, devices similar to the Antikythera device did not appear until the 14th century.

　　Roman cement

　　The development of modern concrete began in 1700. Today, cement is the most widely used building material in the world, but the formula developed in the 18th century was not the first invention of concrete. In fact, in ancient times, concrete was widely used by the Persians, Egyptians, Assyrians and Romans. Among them, the Romans were the first to mix fenugreek stones with crushed rock and water to perfect the formula. Their mastery of the craft led them to build pantheons, arenas, ditches and Roman baths.

　　How did it get lost? The most popular view is that its recipe was a trade secret of the masons, and that the cement and concrete-making methods disappeared with the death of those masons. What's more interesting is that buildings built with Roman cement still stand after thousands of years, while Portland cement, the most commonly used today, wears out much faster. One theory is that the Romans added different chemicals to it, including milk and even blood. These things are said to create air bubbles inside the cement, help the cement expand, and resist severe cold and heat without harming itself.

　　Arabian Irrigation System

　　In the Arab Empire more than 1,000 years ago, due to the heat of the desert, the cultivation of food became a big problem. For this reason, Arab scientists devoted themselves to the study of water conservancy and irrigation systems. They spent a hundred years building countless oases in the Arabian deserts, all thanks to great water conservancy irrigation technology, pumping water from many rivers with wooden pumping facilities into the ditches all over the desert. Inside, the water flows along the ditches to all parts of the empire, eventually forming oases! Even today's technology is quite difficult to form oases in deserts, and soil and water conservation is a big problem. Later, with the decline of the Arab Empire, this irrigation technology was also lost! An oasis is transformed into a desert.

　　The strongest forging technology in the age of cold weapons - Damascus steel

　　Damascus steel is an exceptionally strong metal that was widely used between 1100 and 1700 AD. Damascus steel is famous for its swords. The blade strength and cutting force forged from Damascus steel are amazing, and it is said to be able to divide rocks and other metals in two. It is said that Damascus steel is forged from Indian "Uzi steel ingots", which form a special pattern on the surface when cast into swords. The patterns on Damascus steel knives are basically two materials with different properties. The bright places are pure snow charcoal iron, which is stronger than glass; the dark places belong to Vostian iron and wave iron, which are very tough. Soft and hard iron combine to make the sword both tough and sharp.

　　How did it get lost? The forging process of Damascus steel appears to have disappeared around 1750 AD, and the exact reason for the loss of the technology is unclear, but there are several theories. Most predominantly, supplies of the special ore needed for Damascus steel began to run short, and swordsmiths were forced to develop other techniques. Another claim is that the entire recipe for Damascus steel, especially carbon nanotubes, could only be discovered by accident, and that the swordsmiths didn't actually know the full technique. Instead, they just cast swords in bulk and tested them to determine which ones met Damascus steel's standards.

　　Greek fire

　　Perhaps, the most famous of all the lost technologies is Greek fire. It was an arson weapon used by the armies of the Byzantine Empire and was the original form of napalm. Greek fire is a "sticky fire" that continues to burn even in water. Greek fire can be used effectively in a number of different ways. The earliest form was to pour it into a jar and throw it at the enemy like a grenade or incendiary bomb. Later, giant bronze pipes were installed on warships, and people used siphons to spray incendiary agents onto enemy ships.

　　How did it get lost? The technology behind Greek fire is certainly not entirely new, after all, modern armies have been using similar weapons for years. However, the napalm that came closest to Greek fire was not perfected until the early 1940s, meaning that the technology was lost for hundreds of years. With the fall of the Byzantine Empire, the weapon appears to have disappeared as well, but the reason is unknown. An early theory suggested that the incendiary mixture included large amounts of saltpeter, which made it chemically similar to gunpowder. This theory has been dismissed because saltpeter cannot burn in water. Instead, modern theory suggests it's more likely a mixture of petroleum and other chemicals, which could include quicklime, saltpeter or sulfur.