Subject: Re: teaching physics
Similar is true for quantum effects at any scale we can see with our eyes

I don't disagree with anything in your post but wanted to point out a fun area where the human eye is able to see a quantum effect. If you wander into a Costco (or any other TV store) you might see an LCD Samsung TV that mentions QLED as a selling point. Turns out they are using quantum dots as phosphors.

As everyone knows, a combination of red, green and blue light can be used to make any other color (OK, black is a challenge for TVs but I won't tackle that here). Modern TVs start with blue light and then use phosphors to convert the blue light into red and green. The challenge is to have very pure reds (i.e. monochromatic) and very pure greens, so your orange doesn't look purplish.

Those of you who took a quantum mechanics class remember dealing with the "particle in a box" problem. If you constrain an electron into a small enough box it no longer has flexibility in its energy levels. The wave-nature of the electron senses the boundaries of the box and says, "I need to have nodes at both ends of the box, so I can have a 1/2 wavelength, or one, or two, or 10, but never 2.4 wavelengths inside this box". If the box is big enough the electron doesn't sense the walls and can take on all the the wavelengths required for an arbitrary energy level. By making nanoparticles with well-defined sizes you can force the electrons in the particle to absorb a blue photon and only emit red photons, or with another size particle only emit green photons. Thus the manufacturing challenge becomes a sizing problem rather than a materials problem.

So you are "seeing" the wave-nature of the electron in action when you see those vivid colors of the Samsung LCD display. Kinda cool!

Rgds,
HH/Sean