Diffraction is an evidence that light is wave

[brainyman89]

Introduction: diffraction is an evidence that light is wave. Photo electric effect shows that light is particle.

Question: What about reflection and refraction? Are they evidences of the wave nature of light or of the corpuscular theory?

 

[ProTerran]

Reflection and refraction are the phenomenas that are described generally in terms of wave optics (some specific examples may be described in terms of geometrical optics), but I guess that it is also possible to describe it in terms of quantum optics (treating light as a photons).

Best regards.

 

[ZapperZ]

Introduction: diffraction is an evidence that light is wave. Photo electric effect shows that light is particle.

Question: What about reflection and refraction? Are they evidences of the wave nature of light or of the corpuscular theory?

Please note that this is the "standard" intro presentation that one would get in one is either just learning about these things, or when one is being presented with the pedestrian story. The claim itself isn't that valid when one looks at the physics in great detail.

As starters, you should read the FAQ thread in the General Physics forum, especially on this so-called "wave particle duality". Note that in QM, there is no such duality. We can describe ALL of light's behavior (particle-like and wave-like) using ONE consistent formulation. We don't have to switch gears from wave to particle and back to wave. The diffraction pattern can be directly described using such formulation (search for the Marcella paper that I've mentioned several times on here where he derived, purely using quantum formulation, all the diffraction and interference effects that one would associate with wave-like behavior).

Secondly, the photoelectric effect, while it is a very STRONG evidence for particle-like behavior, cannot rule out wave mechanics if we invoke some stochastic mechanism. Other stronger evidence would come from which-way experiments, and photon antibunching experiments, both of which have no explanation using wave mechanics.

Rather than worry about "wave" or "particle", it is a lot more rewarding if we just focus on what QM (or QED) can describe (which seems to cover everything about light). Once you realize that there is just one consistent description of ALL of these phenomena, then this issue of wave-particle behavior or duality is really not that significant.

Zz.