Mirror Reflection Question

[Abraham]

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.

i know it's an interpreted inversion, i realise that my mask idea cant work because of the symmettry of the face issue
it isnt possible to detatch yourself from the concepts of left right up and down, because you'll always attribute these to your reflection the same way as to yourself

and yes i realised i stopped making sense a long time ago

 

[growse]

i know it's an interpreted inversion, i realise that my mask idea cant work because of the symmettry of the face issue
it isnt possible to detatch yourself from the concepts of left right up and down, because you'll always attribute these to your reflection the same way as to yourself

and yes i realised i stopped making sense a long time ago

Well, you can detach and abstract yourself away by using different terms. If the three axes are x,y and z, then the mirror can be in the xz plane, and the y axis is normal to it. Now the terms like Positive x, Negative y etc are good as absolute direction terms. In the mirror case, postive & negative x & z both map onto the same as each other, and y is inverted North/South/East/West/Top/Bottom are also good terms, as long as you remember that Top/Bottom are relative the the Earth's surface.

 

[Daniel]

Put another mirror behind you and then look in the mirror in front of you and you will be the right way around. look to the side a bit and you will see lots of you as a reflection of your reflection....Count how many of you, you see and get back to us...lol

*Edit*...The first bit isnt right...You will see the back of your head


Dan

 

[Belly]

Put another mirror behind you and then look in the mirror in front of you and you will be the right way around. look to the side a bit and you will see lots of you as a reflection of your reflection....Count how many of you, you see and get back to us...lol

*Edit*...The first bit isnt right...You will see the back of your head


Dan

Hey I tried that but when I scratched my chin with my left hand, it didn't show me scratching the top of my head with my right.

 

[delta555]

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

Light does not actually travel is a straight line, it can go wherever it pleases

But the phases of the further lines start to cancel each other out, and there are lots more going pretty much in a straight line, so their phases build on each other to leave an average that is pretty much a straight line. This is why light bends when it travels from one density to another. Which is why things look closer underwater, and why prisms work.

 

[Robosapien]

Light does not actually travel is a straight line, it can go wherever it pleases

But the phases of the further lines start to cancel each other out, and there are lots more going pretty much in a straight line, so their phases build on each other to leave an average that is pretty much a straight line.

So light travels in a straight line then?

 

[Robosapien]

Yeah, the problem is deffo the terms left and right because they are always gonna be relative to yourself.

E.g. If you place two objects A above B and look at a reflection A is always going to be above B.
If you place A on the left of B, turn around and look in a mirror behind you and B will be on the left.
However if you place the objects between you and the mirror then object A is always on the left in reality and in reflection.

Furthermore when you look at another person their left is gonna be your right and vice/versa. It is slightly silly to think this when looking at yourself in a mirror though, as if you were looking at another person. Are you on any medication?

 

[delta555]

So light travels in a straight line then?

Well, the average is pretty much a straight line, but it is never really going to be dead on. Will depend upon room conditions, but because the air currents are moving there are denser and slightly less dense areas due to wind and heat, so that will help to make the average meander.

But when people talk about light, it is the average that is usually considered. Not many travel along the average, most take a slight curve to the desired end point.

 

[AmaTeX]

Could all the people who did not know how a mirror works go stand in front of a moving bus please. That is medical advice btw

*Save the human race, kill an idiot.

 

[Meridian]

Well, the average is pretty much a straight line, but it is never really going to be dead on. Will depend upon room conditions, but because the air currents are moving there are denser and slightly less dense areas due to wind and heat, so that will help to make the average meander.

But when people talk about light, it is the average that is usually considered. Not many travel along the average, most take a slight curve to the desired end point.

It will also curve VERY slightly due to the mavity of the earth.


M

 

[dirtydog]

Everyone knows that when you look in the mirror and close your left eye your reflection shows you that your right eye is closed but when you scratch your chin with your left hand the reflection does not show you scratching the top of your head with your right hand? Why is that?

 

[Meridian]

Answer to the original question: all mirrors invert at right-angles to their face. What is actually happening is a piece of human psychology. It happens because when people look in a mirror, they perceive the object they see as if it was a real person, and therefore appears to be "reversed". Stand facing a full-length mirror, and hold your left arm out sideways. Draw a mental line between the tip of that arm and the surface of the miror, such that it hits the mirror at a right-angle. Entend the line onwards into the reflection - it hits the tip of what you are thinking of as the "right" arm of the image. But it's not - it's the left arm, as defined by spacial co-ordinates. The image of yourself is reversed front-to back, not left-to-right. Turn sideways - now it's obvious that the mirro inverts at right-angles to the face. Stand on or under a mirro, and again it is obvious what is happening.

You are being fooled by your brain. Now you might also understand why some pets have odd reactions to reflections! And try to track down a copy of Martin Gardner's "Ambidextrous Universe".


M

 

[Belly]

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:

Quote:
Originally Posted by Some Guy
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.

Thanx Growse, yes this is so simple I wonder why I didn't think of it myself
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