Feels like a deep metaphor for something
In: Physics
If you look at dust on the mirror, the mirror is not blurred. Your reflection is. That because you’re focusing at the distance where the mirror is, but the image is behind the mirror. If you’re 4 feet from the mirror, the image is 8 feet in front of you.
The tough part to understand is that the image you see in the mirror is a virtual image.
Even harder to understand is that there’s a toy which produces a 3D holographic image, which is a real image:
[https://www.amazon.com/Illusion-Creator-Hologram-Parabolic-Reflector/dp/B001TFV4BE](https://www.amazon.com/Illusion-Creator-Hologram-Parabolic-Reflector/dp/B001TFV4BE)
I’m trying to think of a way to describe real vs virtual images to a 5 year old, but it’s not happening. I guess the easiest way is to ask why does a room covered in mirrors look bigger than it really is?
A reflection preserves the relative direction and angle of the light. This means that the focus distance is preserved for objects you see reflected. Imagine you’re 1m from a mirror and there’s an object behind you, 3m from the mirror. To focus on the object you need to focus as if for 4m. To focus on the mirror you need to focus 1m away. So you won’t be able to focus on both the mirror and the object at the same time, especially in dim conditions when focussing needs to be more precise.
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