Mirror Reflection Question

me227 · 16 Sep 2006 at 18:52

Belly said:
Bang, Bang = Clap, Clap

Have you tried peeing against a mirror by chance? Now if you hold your member in your right hand and.....................

Yeah if I pee'd infront of a mirror it would start coming out of my face or something would it not, while looking like it was being held by my left hand.

*It doesn't actually hurt when I pee.

Chronos-X · 16 Sep 2006 at 18:54

Actually after re-reading it I guess what he's asking is why mirrors only work horizontally and not vertically - i.e., why isn't our image upside-down as well as left-to-right.

ElRazur · 16 Sep 2006 at 18:56

Chronos-X said:
Actually after re-reading it I guess what he's asking is why mirrors only work horizontally and not vertically - i.e., why isn't our image upside-down as well as left-to-right.

The image is not upside down because, our eyes work like a pin hole camera - the actual image that goes through the eye is inverted but the brain translate it as being upright. (did this in Nigeria ages ago so please pardon me if it sounds like bullcrap)

Belly · 16 Sep 2006 at 18:58

Chronos-X said:
Actually after re-reading it I guess what he's asking is why mirrors only work horizontally and not vertically - i.e., why isn't our image upside-down as well as left-to-right.

Yes I think your right Mirrors only work horizontally but it would appear that spoons reflect both horizontally and vertically. Goodness knows about reflectors in public urinals judging by other replies.

Kappa · 16 Sep 2006 at 19:03

Belly said:
Yes I think your right Mirrors only work horizontally but it would appear that spoons reflect both horizontally and vertically. Goodness knows about reflectors in public urinals judging by other replies.

If you think about it, its not that mirrors work horizontally. But just reflect what is in front of them...its that simple. Dont get confused saying 'my left arm' 'his right arm' if you move your left arm up, the reflection shows the arm on the left going up.

A5H · 16 Sep 2006 at 19:04

The serious answer is 'because light travels in straight lines'
Draw imaginary lines from points on your face and it makes sense.

Abraham · 16 Sep 2006 at 19:05

ElRazur said:
The image is not upside down because, our eyes work like a pin hole camera - the actual image that goes through the eye is inverted but the brain translate it as being upright. (did this in Nigeria ages ago so please pardon me if it sounds like bullcrap)

as already posted:
it's because you're eyes are on the sides of your face, not top and bottom

ElRazur · 16 Sep 2006 at 19:08

Abraham said:
as already posted:
it's because you're eyes are on the sides of your face, not top and bottom

That's wrong, im sticking by what i posted.

Gilly · 16 Sep 2006 at 19:09

ElRazur said:
That's wrong, im sticking by what i posted.

Thats fine, you're still wrong

lay-z-boy · 16 Sep 2006 at 19:21

Gilly said:
Thats fine, you're still wrong

Owned

loopstah · 16 Sep 2006 at 19:25

The mirror only reflects your actions, there isn't a mirror person hiding inside doing the opposite of what you do.

If you touch yourself on the chin the reflection will, if you touch yourself on the top of your head the reflection will.

ElRazur said:
That's wrong, im sticking by what i posted.

You're right about the image on the retina being inverted and the brain interpreting it the correct way up, but that has nothing to do with a mirror image not being upside down, so in that respect you're incorrect.

Belly · 16 Sep 2006 at 21:19

loopstah said:
The mirror only reflects your actions, there isn't a mirror person hiding inside doing the opposite of what you do.

You're right about the image on the retina being inverted and the brain interpreting it the correct way up, .

I'm NOT conviced about the retina bit, because your retina is in your eye and if you look in a mirror you cannot see your eyeballs move but you can see an eye close, so maybe there is someone hiding upside down in the mirror?

growse · 16 Sep 2006 at 21:30

It's because top and bottom (as labels for the ends of the Z axis in 3D space) are absolute. Left and Right are more relative as there's no specific direction which way 'left' points in without a subjective reference. A better term would be East and West, because in a mirror image, your 'eastern' arm is still on the eastern side of you. Bugger all to do with the fact your eyes are on the horizontal I'm afraid. Try shutting one eye and notice the fact that a person with one eye in the middle of their face sees the same.

*edit* found this on groups:

Some Guy said:
Let the mirror be at the end of a hallway leading north.

You face the mirror.

Your mirror image faces south. This makes sense, because the mirror
faces south, and so the direction _perpendicular_ to the mirror is
special.

Your right hand, which is on your east side, is also on the east side
of your mirror image...

just as your head, which is on top of you, is on the top of your
mirror image.

So, considering you and your mirror image in absolute coordinates,
neither up and down nor east and west are reversed: north and south
are reversed, which are special, because that axis is the one
perpendicular to the mirror, the other two being parallel to its
surface.

Normally, though, you don't talk about your "east" hand or your "west"
hand. Instead, you talk about your right hand and your left hand.
Right and left aren't absolute directions, the way up and down (or
east and west) are; instead, they are relative directions. They're
defined in terms of up and down and front and back (look at an object
from its front - hence, you are looking in its relative "back"
direction: right is 90 degrees counterclockwise from up, left is 90
degrees clockwise from up).

So, when you are facing the mirror, what happens makes sense: up and
down stay the same, but since north and south, corresponding to front
and back, are reversed in your image, the relative direction "right",
for your image, points to the image of your _left_ hand.

Suppose you weren't facing the mirror, but looking sideways. Then
right and left would be reversed in a "real" sense, but that wouldn't
make a difference: one still sees right and left as reversed, because
one maps oneself on to one's image by performing a rotation with a
constant vertical axis. Because that's a kind of motion people do in
real life more often than, say, backflips.

Abraham · 16 Sep 2006 at 21:33

it is correct that the image "projected" onto your retina is back to front and upside down, as you correctly said because of the pinhole affect of your pupil

however
as said, this has zip to do with the mirror thing, the reason is because of the layout of your eyes, for full affect, and the disbelievers, make a mask, of a face, but with holes for eyes at the top and bottom of the nose, now look through it, top and bottom with be reversed

growse · 16 Sep 2006 at 21:36

Abraham said:
it is correct that the image "projected" onto your retina is back to front and upside down, as you correctly said because of the pinhole affect of your pupil

however
as said, this has zip to do with the mirror thing, the reason is because of the layout of your eyes, for full affect, and the disbelievers, make a mask, of a face, but with holes for eyes at the top and bottom of the nose, now look through it, top and bottom with be reversed

you mean tilt your head? If so, it doesn't work. The ceiling still maps into the same place in the reflection as it does in reality. It's nothing to do with the eyes. Otherwise a camera would see different things in a mirror than you do, and it doesn't.

The *only* thing that gets inverted in a mirror image is the axis perpendicular to the mirror. Everything else stays right where it should. The hand on the "east" side of me stays on the "east" side in the reflection. 'Left' and 'Right' have no meaning here.

Abraham · 16 Sep 2006 at 21:36

growse said:
It's because top and bottom (as labels for the ends of the Z axis in 3D space) are absolute. Left and Right are more relative as there's no specific direction which way 'left' points in without a subjective reference. A better term would be East and West, because in a mirror image, your 'eastern' arm is still on the eastern side of you. Bugger all to do with the fact your eyes are on the horizontal I'm afraid. Try shutting one eye and notice the fact that a person with one eye in the middle of their face sees the same.

*edit* found this on groups:

what do you mean bugger all to do with it...?
it's exactly the same reason, if you make it so as your eyes are oriented on the vertical axis the effect is switched, however, seeing as we're made this way and not that it's a hard thing to demonstrate, the best method i can think of is what i suggested above

Abraham · 16 Sep 2006 at 21:38

growse said:
you mean tilt your head? If so, it doesn't work. The ceiling still maps into the same place in the reflection as it does in reality. It's nothing to do with the eyes. Otherwise a camera would see different things in a mirror than you do, and it doesn't.

the camera see's the light reflecting exactly as it does to your eyes, your eyes interpret what they see on the camera
you only interpret this horizontal plane because that's where your eyes are
i dont mean just tilt your head on the side, i mean put yourself in a situation (through a mask) where the eyes run the same way as the nose rather than perpendicular to

growse · 16 Sep 2006 at 21:39

Abraham said:
what do you mean bugger all to do with it...?
it's exactly the same reason, if you make it so as your eyes are oriented on the vertical axis the effect is switched, however, seeing as we're made this way and not that it's a hard thing to demonstrate, the best method i can think of is what i suggested above

Nothing is switched, except the perpendicular! When you say the vertical axis, do you mean relative to yourself, or the absolute? What exactly is switched? The only thing I can think of is now the reflection's own right ear is on the bottom of the mirror, whereas my right ear is on the top. But we've established that left and right are meaningless when you're looking at a reflection.

Abraham · 16 Sep 2006 at 21:41

i mean relative to the face
whatever way your eyes are is the way in which things appear to be "opposite" in a reflection

i've just realised that it only works with "left" and "right" because there is little difference between your left and right, so they can be interpreted as the same in the reflection

that's part of it anyway, it's properly making my head hurt now

growse · 16 Sep 2006 at 21:44

I don't get that at all. If I cut two holes in the vertical direction in a mask and look through it, I can't see anything because my eyes aren't in the right place.

I don't understand what "You only interpret the horizontal plane" means. If I shut one eye, I see exactly the same.

As I said before, there is only one axis that is inverted in a reflection, and that's the axis between you and the mirror. In other words, the distance from your nose to the reflected nose is different to the distance from the back of your head to the reflection's. That's the *only* inversion.

Explain to me what else is inverted without using the words "left" and "right".