The reflection — not the 
mirror — needs adjusting

There’s something wrong with our mirrors. I thought I understood a little bit about optics because of my years of experience working with microscopes. But our mirrors just aren’t working right, and I can’t figure it out. 

You’d think fixing a mirror would be pretty straightforward. I mean, you merely look into them. Light goes in, comes back out causing a reflection, and you’d think that would be it. But nothing is really that simple anymore.

Reflection is caused by a change in the direction of a wave. In the case of a mirror, a light wave enters a sheet of glass that has a metal backing, and it enters at an angle called the “angle of incidence.” The metal backing is important because metal is opaque and because metals tend to have smooth surfaces. A smooth surface causes the reflection to come back at the same angle as the angle of incidence, except in the opposite direction. 

When you are standing directly in front of a mirror, the angle of incidence in very small, and it appears to be directly in front of you.

However, since the light from your left is entering at a slight angle, it exits at the same angle only directed to your right. So what you see in the mirror is flipped, right to left. The light then returns to the media from which it originated, and hence, the “eye of the beholder.” 

They say that beauty is in the eye of the beholder, and this raises an interesting question. When we look in a mirror, do we see things as they really are? Or do we see things as WE really are?

Personally, I prefer to fix the mirror rather than myself, so I have been doing some research on mirror malfunctions.

Imagine my surprise when I discovered that there are two kinds of light reflection. Normal mirror reflection, described above, is called “specular reflection.”

This is what mirrors appear to have been doing for many generations. Well, actually, I can only speak for my generation. 

When I first learned that there was another kind of reflection called “diffuse reflection,” I thought perhaps some malevolent force had changed our mirrors to this alternate type.

Maybe diffuse reflection is part of a secret government project run by the NSA to distort how we view the world!

Diffuse reflection is the reflection of light from a surface such that a light ray is reflected at many angles instead of just one.

If the backing behind the glass has a rough surface like paper or plaster, the light waves are reflected in many directions as they bounce off many different angles of that rough surface. 

The total amount of light reflected stays the same for both kinds of reflection.

But with diffuse reflection, the image is greatly reduced in intensity.

Another way of saying this is that the energy remains the same, but the image is lost.

Therefore, I have concluded that my mirrors have not been malevolently changed on me. My image is as sharp as ever, but my energy has definitely been depleted.

Could this be an entirely new phenomenon in optical physics? 

I use diffuse reflection when I tie my tie using the back window of the car for a mirror. Does anyone else have trouble tying a tie unless he’s looking into a piece of glass? It doesn’t matter if you can see anything, you just have to pretend you’re looking in a mirror.

I was eventually forced to consult my old parasitology professor who taught me what I know about microscopy. He doesn’t live here, so we had to consult by email.

He asked me to send him a regular selfie and another taken in the bathroom mirror.

After careful analysis, he told me that he didn’t think my mirrors needed adjustment. The problem seems to be my face. 

Gary McCallister, .(JavaScript must be enabled to view this email address), is a professor emeritus of biological sciences at Colorado Mesa University.


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