Mirrors - Lateral Inversion

[Fyncu Myncu]

Why do mirrios only invert reflections laterally (right to left) and not verically (top to bottom)?

[TheHitMaker]

It doesn't! Stand in front of a mirror and point to the left and the reflection points in the same direction. Point down and the reflection points in the same direction. Point towards the mirror and the direction of the point reverses. This happens whichever way the mirror is situated - stand on a mirror and point down and the direction the reflection points in is up. The problem is caused by the mirror reflecting in a vertical plane, not rotating the image - so your left hand is still on your left.

[Gef]

Sorry TheHitMaker but your answer is not correct, or at least not clear. If you look at yourself in a mirror and point to the left with your left hand then your reflection does point to the left but with its right hand. To understand lateral inversion just imagine that you are standing face to face with someone. Up and down are still the same but left and right (from each point of view) is reversed. Hope this helps.

[WaldoMcFroog]

No, the HitMaker is right! The mirror doesn't 'do' anything. It doesn't 'invert' anything - that is to imply a mechanism which simply doesn't exist! It simply reflects a beam of light - a beam of light travels from the origin to the mirror and is reflected. The 'lateral inversion' you see is purely perceptive. There is no figure 'in' the mirror - it doesn't have it's own left and right - they are mapped from the beams of light travelling from an object to the mirror and then to the observer.

[wildwood]

If you place a mirror at about 45 degrees against the wall on the floor, and fastened another mirror at 45 degrees against the ceiling and wall above it, you may be able to see a reflection of your reflection in the top mirror which is upside down but not 'laterally inverted'. (I think). This is doing my head in, I'm going to bed.

[Fyncu Myncu]

I understand WaldoMcFroog's distinction - i.e. that lateral inversion is a function of my perception. But my question now is "Why do I perceive a lateral inversion, but not a vertical inversion?"

[xyzzyplugh]

Agree with Hitmaker. See; http://www.guardian.co.uk/notesandqueries/query/0,
5753,-19877,00.html [Clip;] Mirrors don't reverse left to right, they reverse front to back. Consider this, when you look at yourself in a mirror, it appears to you that your reflection is another person who looks just like you standing behind a piece of glass, at the same distance from the glass as yourself and facing you. To get there, you reason, that person walked behind the glass and - here's the important bit - turned 180 degrees about the vertical axis to face you. Now his/her left hand should be opposite your right hand, and vice versa. In fact this assumption is wrong. Your reflection didn't do a 180 degree turn. It was reversed front to back with no rotation at all. Your brain mentally subtracts the 180 degree turn that you assume must have happened from the observed front to back reversal and what do you get? An apparent left to right reversal!

[Gef]

What a load of rubbish!!

[ralph1953]

The mirror shows what appears to be a lateral inversion and not a vertical one because your eyes are arranged laterally and not vertically

[Gef]

What you see in a mirror IS a laterally inverted image. It is not how you appear in a photograph or how other people see you.

[xyzzyplugh]

It is not and never has been a laterally inverted image. It is a reflection - The mirror doesn't have strange symmetry powers, it's just a shiny surface. However, if you do want odd reflections, look into a spoon. There you will indeed find top to bottom inversion but still, no left to right tosh. The left-right problems you're having is merely chirality Q.V. ok.

[Gef]

I can't understand why xyzzyplugh is continuing with this nonsense. I have just looked at the Guardian site quoted in an earlier answer and it is full of the same rubbish. I will state once again that the reflection seen in a mirror is laterally inverted. Hold your hands out in front of you with both palms down (or up). One hand is the mirror image of the other. One hand has a thumb on the left, the other has the thumb on the right - one is a lateral inversion of the other. By the way, I am not having chirality problems - I am an organic chemist and I know what the word means :-)