Does the universe have a center?

That time, that place

A late Joseon scholar. In 1765 he traveled to Beijing with an embassy, met Western missionaries there, and saw their astronomical instruments firsthand. On returning he built a private observatory at home and made an armillary sphere.

Why this question

His Uisan mundap is written as a dialogue between a Confucian scholar who has done nothing but read for thirty years and a figure living in the mountains.

The mountain figure unsettles, one by one, what the scholar took for granted — and the argument that goes furthest concerns the heavens.

What was found

The Earth is round and turns once a day on itself. The universe has no edge, the stars are beyond counting, and each of them may hold another world.

If so, the universe has no center.

Here Hong takes one further step. On a round Earth, wherever you stand is the middle. So the idea that China is the center of the world and Korea its periphery does not hold either. Each place is central where it stands.

An argument about astronomy had become a critique of a worldview.