The word "explains" is ambiguous. Compare: Jack's girlfriend explains why the sky is blue. Rayleigh scattering explains why the sky is blue. "Rayleigh scatte

The word "explains" is ambiguous. Compare: Jack's girlfriend explains why the sky is blue. Rayleigh scattering explains why the sky is blue. "Rayleigh scattering explains the blueness of the sky", Jack's girlfriend explains.