I Laser and hair - scattering or destructive interference?

[Spathi]

TL;DR

However it is still unclear for me: is this a real destructive interference which illustrates the wave properties of photons, or simply a scattering (if the hair reflects the light at an angle)?

There is a video, where the author shows the interference of laser beam on a strand of human’s hair:



I bought a laser pointer and reproduced this experiment. Indeed, when a single hair is placed on the way of the laser beam, I see the “scattering” picture (a series of points with intervals of approximately 1 mm). However it is still unclear for me: is this a real destructive interference which illustrates the wave properties of photons, or simply a scattering (if the hair reflects the light at an angle)?
Later on the authors tries to explain that this experiment illustrates something “magical” with the light, but I didn’t yet understand her idea.

 

[Drakkith]

However it is still unclear for me: is this a real destructive interference which illustrates the wave properties of photons, or simply a scattering (if the hair reflects the light at an angle)?

It's interference. Scattering from a near-homogenous object (like a hair) doesn't produce spaced patterns of light and dark spots.

Later on the authors tries to explain that this experiment illustrates something “magical” with the light, but I didn’t yet understand her idea.

I didn't spend 15 minutes going through the whole video so I can't answer this. If you have a timestamp I'll be happy to watch it.

 

[Nugatory]

However it is still unclear for me: is this a real destructive interference which illustrates the wave properties of photons, or simply a scattering (if the hair reflects the light at an angle)?

Neither, although it is destructive and constructive interference of light waves. It shows that light is a wave, a piece of classical physics observed early in the 19th century that has nothing to do with photons and quantum mechanics. To demonstrate any quantum behavior of light we need an experiment that builds up the interference pattern over time out of single-photon detections.

 

[jtbell]

You can think of diffraction around a narrow linear obstacle as sort of complementary to single-slit diffraction.

A related phenomenon is diffraction around a small 2-dimensional object such as a disk. This has a historically important example in Arago's spot, a.k.a. (ironically) Poisson's spot.

 

[Claude Bile]

Both. What you are seeing is interference between the (planar) incident and (cylindrical) scattered wave.