Why Does the Earth Rotate?

After physics class in high school, I asked my teacher,

“Why does the Earth rotate?”

My teacher said,

“Newton didn’t know either, so he simply said God gave the Earth a kick, and that’s why it spins.”

But the problem is, it is not just the Earth that rotates—many celestial bodies spin as well.

Back then, I was reading a popular science book on quantum mechanics.

I searched online, and the answer that came up was:

Rotation is a natural property of celestial bodies.

That answer was obviously unsatisfying.

In college, I read Einstein’s General Relativity, which broadened my horizons tremendously.

Gravitation arises from the curvature of spacetime.

Einstein’s field equations make it especially clear:

Spacetime tells matter how to move; matter tells spacetime how to curve.

This question occupied my thoughts for at least fifteen years.

Then one spring day, as I wandered in a riverside park,

with white clouds drifting across a bright blue sky,

an idea suddenly struck my mind—as if floating down from the heavens.

Rotation is caused by the distortion of space.

If the curvature of spacetime produces gravity and drives orbital motion,

then the very distortion of spacetime must be what gives rise to rotation.