During the Spring and Autumn Period and the Warring States Period, the most intense period of conquest in Chinese history before Christ, there was a man who suddenly appeared and shouted, "Oppose war!"

This is Mozi, the representative of Mohism, who emphasized universal love, which is to love all people. In an era of wars of aggression dominated by the logic of the law of the jungle, the small cry of this philosopher armed with the spirit of humanity could not change the trend of the times, but his spirit was enough to leave a clear mark on later generations.

Could that be the reason? The reason China chose 'Mozi' as the name of the quantum communication satellite it launched last year seems to contain the meaning of opposition to war and peace. The Mozi, which took over 8 years to prepare, is the world's first independently developed quantum satellite by China and flew into space aboard a rocket called 'Long March 2-D'.

So why did China invest so much time and money? The quantum satellite was launched for the purpose of commercializing quantum communications. Quantum communications are made to utilize quantum mechanics, which has uncertainty, for communications. The biggest advantage of quantum communications is that they are impossible to hack, let alone eavesdrop on. According to quantum mechanics, which has the principle of uncertainty I mentioned earlier, the moment eavesdropping is attempted, the encryption key itself is damaged, making the content of the communication unknowable. In particular, in the era of the Internet of Things (IoT) where information connectivity is a hot topic, the ability to prevent security breaches at the source is the greatest advantage of quantum communication.

This bold challenge from China seems to have borne its first fruit(?) in June. The Chinese Academy of Sciences announced that it had succeeded in an experiment to teleport quantum information 1,200 km away using a quantum communications satellite. The research team generated 6 million pairs of photons per second from the Mozi satellite in an orbit 500 km above the ground and transmitted one of them to the base. This means that the quantum sent from the satellite was teleported to a 1m-sized ground device target. The 'quantum teleportation' used in this experiment is a technology that uses the quantum entanglement state of photons to make quantum information disappear from one place and appear in another place at the same time. (That's why there are talks that human teleportation is possible.)

Countries around the world, recognizing the importance of quantum technology, have been working on developing quantum information and communication technology for over 10 years. Since it is a field that requires astronomical costs from the beginning, development is still being carried out mainly in technologically advanced countries such as the US, Japan, and Europe, but research and development is being expanded to include China, which launched a quantum satellite, and Korea, an IT powerhouse.

The United States has established a national quantum information science vision and announced that it will invest 1 trillion won annually. Europe has been continuously investing in a project called 'Quantum Europe', and Japan built a quantum cryptography test network in Tokyo in 2010. Korea, which established a mid- to long-term quantum information communication strategy in 2014, built the first domestic quantum cryptography communication test network last year and opened a quantum cryptography communication test bed to enable testing and verification. Last June, SK Telecom announced that it had developed the first quantum cryptography communication relay device in Korea and successfully transmitted quantum cryptography keys over a 112 km round trip experimental network from Bundang to Yongin and Suwon.

Quantum technology development and Mozi's secret

However, everything has a bright side and a dark side. Although quantum communication is said to be a technology that is completely unhackable, there are also claims that it is still just a theory. There is no perfect spear or shield. Also, although it is a technology that is absolutely necessary for secure communication, it also carries the risk that it can be diverted for military purposes. A clear example is that North Korea’s quantum cryptography technology has recently been revealed to be at a considerable level. Unlike advanced countries that have stepped forward to use it in the information and communication field, North Korea’s use is very likely to be military.

Let's go back to the story of Mozi. In the classic [Mozi], there is a section called "Non-aggression" that says that one should not attack others and wage war. In the great state of Chu, the famous engineer Gong Su-ban developed a new siege weapon called the "cloud ladder" and was planning to attack the weak state of Song. When Mozi heard the news, he rushed to Chu and requested that they stop the attack, but the king of Chu did not give up his will to invade. In front of the king of Chu, Mozi fought a mock war with Gong Su-ban and blocked all of the mock cloud ladder attacks, so the king gave up his plan to attack Song.

This anecdote tells us that Mozi was a practical philosopher who stood up to invaders with his bare body for the peace of all mankind, leaving aside the peace of an individual. This is why history calls the era of Mozi the era of human discovery and human awakening. Now that the quantum communication satellite Mozi, named after the ancient pacifist, is floating in space, we are once again reminded of the relationship between cutting-edge technology and peace.