does domeone know the principle that does invert images left/right when light reflects on a mirror, and why does not happen with up/down?

Mirrors don't invert things, they just reflect back exactly what you show them. Think about it.

mmmhhh... i do not understand... see the image generated in a mirror of writed text, its "fliped horizontally"... the question: why not vertically?

Images are not flipped horizontally in the mirror. Imagine you are holding a word on paper in font of the mirror, and imagine you can move the mirror image toward you so that the mirror image is right were the paper is. You are basically looking at the exact same thing from the other side. The image/word does not change at all.

hehe, i know, i just talking about the image generated, not the object itself

Okay, draw a word on a sheet of paper and hold it in both hands in front of the mirror. For example the word "Mirror". The "M" should be closest to your right hand. Also in the reflection, the "M" will be closest to your right hand.

lemme draw it...

Ok, a better example. Draw this:

1______________________2









3_______________________4

on your paper. Hold it by the top corners in front of you, toward the mirror. The 1 should be at your right hand, the 2 at your left hand. 1 and 2 up the top, 3 and 4 at the bottom. In the mirror's image, 1 will still be at the right, 2 will still be at the left, 1 and 2 will still be at the top, and 3 and 4 will still be at the bottom. Nothing changes.

hehe... i understand you are trying to say that nothing changes, because the point of comparison is not the same... my doubt is in optics, no in relativity, spacetime or something more :m: hehe...

It looks inverted to you because you invert the paper when you turn it around to face the mirror. Since you usually flip it around horizontally, it looks horizontally inverted. You could also flip it over vertically, in which case right and left would look the same but top and bottom would be reversed.

thats ok, i found this http://www.physicsclassroom.com/Class/refln/u13l2b.html

it explain how images are formed, tnx

http://math.ucr.edu/home/baez/physics/General/mirrors.html

Mirrors don't flip left and right; they flip front and back.

Hold your right hand up in front of a mirror. The front of your hand is closer to the front side of the mirror than the back side of your hand. What about the image hand? Your hand's image <b>also</b> has its front closer to the plane of the mirror than its back. What the mirror has done is to take everything an equal distance in front of the mirror and put it the same distance behind the mirror (in the image).

This is quite a weird transformation, and your brain has trouble coping with it. To interpret the image, your brain imagines how your body could have got from its present location in front of the mirror to the position it appears in the image. If the mirror was a sheet of glass with space behind, the logical thing to get you to the position of your image would be to walk around the glass sheet and then turn around to face the sheet again. That is what your brain assumes has happened. The only problem is that this assumption appears to reverse left and right. When you hold up your right hand, the image person holds up its apparent left hand (think of which hand would be right and left if you were standing where your image seems to be).

To summarise: a mirror seems to reverse left and right because your brain has trouble coping with a front-back transformation, and instead seeks to interpret the transformation as something more familiar.

If you have trouble coping with what you see and want to see the
REAL YOU, take two mirrors and place them together at right angles.

Look in the center: this is YOU. ;)

It is not only that mirrors "reverse" our picture.
Mirrors also reflect back our past. You cannot ever see yourself in the mirror as you look right now/at that moment. We are used to see the world only in some distance from real "now", but when we see ourselves in "past" it feels strange...

Originally posted by ProCop
It is not only that mirrors "reverse" our picture.
Mirrors also reflect back our past. You cannot ever see yourself in the mirror as you look right now/at that moment. We are used to see the world only in some distance from real "now", but when we see ourselves in "past" it feels strange...

Try to talk while listening to yourself with some delay (as sometimes happens on mobile phones): Listening to yourself in the past is REALLY strange.

He's correct, though. What you view in a mirror is the past.

Originally posted by Adam
He's correct, though. What you view in a mirror is the past.

yes, but not only in the mirror, all you see is the past.

Yep. Freaky... :eek:

If the mirror is concave...it will reflect an image flipped horizontally. Try looking into the front of a spoon...the image is inverted...I'm not sure with the optic principles though.

it can helps: concave mirrors (http://www.physicsclassroom.com/Class/refln/U13L3e.html)

yes, but not only in the mirror, all you see is the past.

The distance of seeing yourself in the mirror is twice as long as seeing the "world" around (normally the light goes to a wall then to your eyes - in the mirror situation it goes to you than to the mirror and back to you. And that's unusual (I think)

You're assuming no magnification occured. Its possible for an image to appear closer than the mirror its on if its magnified.