A study on Hong Dae-yong’s scientific thought through 『Uisan Questions and Answers』

In the 8th century, Joseon did not easily bring about social change due to the long-rooted Neo-Confucian order following the Two Wars. Hong Dae-yong, a Silhak scholar of the late Joseon Dynasty, felt skeptical of Neo-Confucianism after being dispatched to the Qing Dynasty on an envoy to Yan, and came into contact with Western scientific civilization and books related to Western learning at Heumcheongam, which led to his modern scientific ideology. Hong Dae-yong's thoughts through 『Uisan Mundap』 judged that the Christian worldview of geocentrism was wrong, and supported the modified geocentrism of Danish astronomer Tycho Brahe, asserting that the sun, moon, and fixed stars revolve around the Earth, and the rest of the planets revolve around the Sun. In fact, although some scientists before Hong Dae-yong had argued for the geocentric theory, they lacked a modern-oriented character due to their scientific interpretation using traditional mathematical approaches. Hong Dae-yong develops the theory of the four elements, the theory of the earth, and the theory of the infinity of the universe based on the concept of Gi (氣) of Neo-Confucianism through a scientific approach that is quite logical and objective. We can see that there are many similarities between the scientific views of ancient scientists such as Aristotle and Empedocles and the scientific thoughts of modern scientists. In addition, since the Earth is not the center of the universe and China is not the center of the world, it was believed that it was necessary to abandon the idea of Sinocentrism and independently achieve a wealthy and strong country.