Go Deep Underground

In 2100, humans generally live in underground cities, and the earth's surface is returned to nature. This is the result of the great victory of environmental protection concepts and the great development of underground engineering technology. At the same time, humans have developed microscopic treatment technology that has completely overcome the effects of infectious diseases and almost completely replaced invasive surgical procedures. This technology has overcome the medical problems in long-term spaceflight and extraterrestrial colonization, thus making the Mars colonization that humans have long envisioned become a reality. The above two technologies have completely changed the human social structure, and thus gave rise to a new discipline - the history of human social structure. However, at this time, humans have not yet found a way to travel beyond the speed of light, nor have they found other intelligent life in space. Human technology and human evolution have reached a bottleneck during this period.