Seeker's Questions: Mirror and the Virtual Image

[Qfwfq]

Turtle, even with one eye, you can appreciate 3D by parallax when you move in front of what you see. When you move sideways, the alignment between nearer and further objects changes. This can't occur with a painting, even if it has the perfect perspective of the Rennaissance masters!

 

Here is a mirror poser that I never heard an "authoritative" answer to; why is your mirror image reversed left to right but not top to bottom?

Great question! :rolleyes:

 

I once spent a highly amusing evening with my old university chronies, walking around the steets of Padova, trying to get the solution through their heads. It took a lot of doing before they began to see the light, passers by must have thought we were escaped looneys, and yet it is really simple.

 

In the fewest words: if you turn to look back at what is reflected in the mirror, you turn your head around in a horizontal plane. You don't bend your head back down your back! That's the way you compare the object with the image, so that's how you interpret the parity switch.

 

Objectively, the inversion is neither left to right nor up to down, it is front to back if you are looking toward the mirror.

[Turtle]

Great question! :hihi:

In the fewest words: if you turn to look back at what is reflected in the mirror, you turn your head around in a horizontal plane. You don't bend your head back down your back! That's the way you compare the object with the image, so that's how you interpret the parity switch.

 

Objectively, the inversion is neither left to right nor up to down, it is front to back if you are looking toward the mirror.

 

___This sounds similar to what I thought up for a solution. I decided it is because our eyes are on a horizontal plane & if our eyes were in a vertical plane the image WOULD appear reversed top for bottom. Is this saying the same thing Q? :rolleyes:

[Qfwfq]

Perhaps T but I'm not sure exactly what you mean about the eyes being in the horizontal plane. It's more to do with our habits than with our eyes but, instead of nitpicking, I'll suggest the following considerations:

 

Place yourself between the mirror and the object, but not quite in line, and face the object. Turn your head over backwards until it's upside down and compare; you will see the image of the object upside down but not exchanged left to right. We're not in the habit of doing this, our habits are more two dimensional and in the horizontal plane.

 

As an object, consider a transparent plaque with an inscription. Instead of standing in between, stand behind the plaque and compare the writing on it and in the reflection. They will read equally, although the image is seen from the other side, as could be evidenced by making the inscription layered with a different colour for instance on each side.

[Turtle]

Perhaps T but I'm not sure exactly what you mean about the eyes being in the horizontal plane. It's more to do with our habits than with our eyes but, instead of nitpicking, I'll suggest the following considerations:

 

___What I meant is that if our eyes were one above the other on the front of our heads instead of next to each other side-to-side on the front of our head?

___I had to try your experiment in my minds eye, as my back is too buckled to bend over like that. :D I see the point you make however. :)

[Qfwfq]

Obviously, it was a Gedankenexperiment! :)

 

Might be a good classroom demo too.

[Turtle]

Obviously, it was a Gedankenexperiment! :D

 

Might be a good classroom demo too.

I do not know that reference? :) :D

Confusedly yours once again,

One-eyed Turtle :D :D :D

[Qfwfq]

Sorry, it was referred to:

I had to try your experiment in my minds eye

It certainly isn't necessary to turn somersaults, if one has enough imagination! The outcome of the "experiments" is obvious enough. :)

[Turtle]

Sorry, it was referred to:

It certainly isn't necessary to turn somersaults, if one has enough imagination! The outcome of the "experiments" is obvious enough. :D

 

___Ahhh. So why Gedanken? I know danke, thank, but nicht gedanken; bitte? Ich weis nicht. If auch (aus?) mein kopf standen; schnell bitte! :D No really. :)

[Turtle]

____While you chuckle over that, I seriously wonder what effect on us, i.e. how different would life look, if we humans had 2 eyes but they took the arrangement of one over another rather than side-by-side? :) Mirrors or otherwise. Would we perhaps have a different standard of beauty? Not just how we look of course, but how we see affect say our standard for a beautiful tree or building? :D

[Qfwfq]

I know danke, thank, but nicht gedanken; bitte?

Gedanken ist 'thought', hatte du nicht an es gedacht?

 

Another Gedankenexperiment is: chop your head off your neck and re-attach it turned on its side, sort out all the trivial anatomical-physiological details and see how the world looks with your head turned that way! :D

 

You might want to also give each eye a quarter turn in its socket and sort out the visual circuits of the brain to match up the two images in the new manner, but I doubt the difference being so essential. :)

[Turtle]

___Rats! Lost another post. :) Must remember to copy the text before I hit Submit! :D :D

___Anyway, it does seem to me exactly as you suggest a brain wiring problem. If we have to rotate the eyes a quarter turn & rewire to get our usual view, then we have some difference. Gedanken indeed. Oh yeah, before I forget, Gedanken schon for replying. :doh:

___