# Elastic scattering violates energy conservation?

In our introductory solid state lectures, the professor described von Laue's$$^1$$ diffraction conditions making the assumption of elastic scattering, which states that the incoming and the scattered radiation have the same wavelength. We also assumed scattering by each lattice point in all directions.

Now, don't these statements lead to violation of energy conservation, in the photon picture? (The corresponding wave picture makes sense though.) Because there was just one incoming photon while there were scattered photons in all the directions of the same wavelength. How to resolve this?

Or is that that I'm getting the photon picture of the elastic collision completely wrong? Maybe the correct photon picture is that a single lattice point scatters the incoming photon in a single but random direction. Please help!

$$^1$$Should it be von Laue or Von Laue?

• Typically we don't capitalize the "von" or "van" -- see, e.g. Rembrandt. However, if a person was specifically named Van Whatever, that's different. The 'van' prefix is a now-obsolete way of indicating a person's geographic (or other affiliation) origin. – Carl Witthoft Aug 31 '20 at 12:00
• @CarlWitthoft Thanks for noticing! And answering :) – Atom Aug 31 '20 at 12:23