What is the origin of quantization?

[Choi]

What is the origin of quantization?

For example, electron of hydrogen atom has quantized energy level. But free particle has continuous energy level.

Interaction with another particle or any potential acting on particle makes such quantization?

 

[ZapperZ]

What is the origin of quantization?

For example, electron of hydrogen atom has quantized energy level. But free particle has continuous energy level.

It's the boundary conditions.

Zz.

 

[A. Neumaier]

Almost universally, an energy spectrum is discrete if only bounded motion is possible continuous if only unbounded motion is possible, and mixed otherwise.