Why is it that when I’m looking at a mirror with my glasses off, everything is blurry, even though the mirror is really close to me?
In: Physics
Mirrors from a physics perspectives don’t work like an object on the wall in front of you. In light-terms, the light is coming off that object 6 feet behind you, bouncing off the mirror, and then back into your eye.
Effectively, the mirror is a “copy” of the light behind it, and works as if the things 6 feet behind you are “6 feet behind” the mirror itself. Thus the maximum focus length you can get without your glasses is the same (actually probably less) looking in a mirror as looking behind yourself.
If you were 100 miles away from the mirror and turned on a torch / held up a sign, would you expect someone standing by the mirror to be able to see it/read something? No. Same thing.
The mirror is just duplicating what you’d see if you turned round.
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