Imagine that you have a big ball and a smaller ball inside of it. Now, imagine that you have lines drawn on the big ball and on the small ball. These lines are like roads that go around the balls.
A harmonic morphism is like a musical sound that travels along these roads. The sound starts at the smaller ball and goes along the lines to the bigger ball. But, just like music, the sound changes as it travels.
The sound gets quieter when it goes up a hill and louder when it goes down. Similarly, the same thing happens to the sound in the lines on the balls. The pitch of the sound also changes based on the shape of the lines.
A harmonic morphism is a way to describe how these changes happen. It's like a map that tells you how the sound changes as it travels.
This concept is important in mathematics and physics because it helps us understand how things change and move in different shapes and dimensions. It's like a puzzle piece that helps us put together a bigger picture of the world around us.