Can someone explain in scientific terms why things like words appear backwards in a mirror?

Answer 1

This is a great question, especially if you phrase it this way: why is it that when you look in a mirror, things appear to be flipped horizontally, but not vertically? The answer depends on what you're looking at.
(1) Writing: when writing looks backwards in a mirror, that's because it actually *is* backwards with respect to your orientation. In order to see the writing in the mirror, the writing has to be facing *away* from you. The phenomenon is exactly the same as if you were trying to read a transparency from the wrong side, and has nothing to do with the mirror.
(2) Your reflection: when you look at yourself in the mirror, you probably get the impression that your left and right hands are switched. This has to do with the fact that when you look at another person facing you, you determine their left and right hand by imagining yourself, rotated 180 degrees. However your reflection in the mirror is not what you would look like rotated 180 degrees, it is what you look like reflected; hence the confusion.

Answer 2

Write a word on a piece of thin paper with a felt marker so that the word is visible on both sides of the paper. Now hold the paper with the word you wrote in front of the mirror.

The word on the back of the paper is exactly what the mirror "sees" on the front of the paper.
In order to look at the word in the mirror, you reversed it when you flipped the paper - the mirror did nothing but reflect the image you are showing it.

Answer 3

The mirror image is a reflection, not a reversal, of the incoming image (light). As the image hits the mirror, so is it seen in its reflection. If we stand in front of the mirror and hold our hand and move it to our left, we see the image also moving left. The same applies to all other directions, including 'up' and 'down'.

Thus, the image in the mirror is a reverse image (backward - forward) of the object.

Answer 4

Are there scientific terms for common sense? What's really puzzling is why things don't appear upside-down (vertically reversed), as well as backwards (horizontally reversed).