# Mirror and letters

1. Feb 18, 2013

### Numeriprimi

Hello.
I have got basic question for you. Can you explain it simply?

Why are the letters in a mirror overturned on left-right and not upside-down?

Thanks. And sorry for my bad English.

2. Feb 18, 2013

### Staff: Mentor

They are not turned left-right. The left-most letter is still on the left and the right-most letter is still on the right.

When a person turns to face you the left-most letter is on the right and the right-most letter is on the left.

Mirrors do not switch left-right nor do they switch up-down. When people face you they do switch left-right but not up-down. That is why mirrors seem strange left-right but not up-down. They are strange because they do not do a turn that we are used to seeing people do.

3. Feb 18, 2013

### jbriggs444

A mirror reverses front and back (*). This means that the three-dimensional symmetry of an image in the mirror has been reversed; a mirror image of a right hand looks like a left hand and vice versa.

A front-to-back reversal is identical to a left-to-right reversal coupled with a 180 degree rotation. Either interpretation is valid. As Dale points out, the interpretation that feels natural is a left-to-right reversal with a 180 degree rotation.

(*) Where "front" and "back" are referenced against the plane of the mirror.

4. Feb 18, 2013

### mickybob

From the man himself:

Last edited by a moderator: Sep 25, 2014
5. Feb 18, 2013