Eye glasses and mirrors

uzless
Posers and Puzzles 19 Feb '09 04:32
1. uzless
The So Fist
19 Feb '09 04:32
If a person needs to wear glasses to see things far away but does not need glasses to see things that are close, can they do the following...?

To see an object far away without their glasses, why can't they just hold a mirror up close to their face with the object's image in the mirror?

The image in the mirror would only be a few centimeters from their eyes so would they be able to see the image clearly without their glasses or would it still be blurry??
2. 19 Feb '09 07:31
The image would still be blurry.
Consider this: if you held a piece of normal glass in front of your eyes, it would still be blurry, so why should a mirror be any different?
3. 19 Feb '09 15:24
"Science fail."

Why not put a mirror in a scanner and use the resulting image as a windows background! A mirror for a background! Cool!

(I'm being nasty... sorry)
4. uzless
The So Fist
19 Feb '09 18:461 edit
Originally posted by Dejection
The image would still be blurry.
Consider this: if you held a piece of normal glass in front of your eyes, it would still be blurry, so why should a mirror be any different?

Consider this. hold a book in one hand and a mirror in the other, each about a foot from your face. The person without the glasses can see the book no problem. But the images in the mirror (which are also only one foot away) are blurry. Or are they clear?

Both objects are only one foot away from their face.
5. uzless
The So Fist
19 Feb '09 18:48
Originally posted by Wumpus
"Science fail."

Why not put a mirror in a scanner and use the resulting image as a windows background! A mirror for a background! Cool!

(I'm being nasty... sorry)
I think you didn't understand the question. I'm talking about whether the image would appear blurry or clear to a person that needs glasses to see things far away.
6. 19 Feb '09 20:41
I perfectly understand the question.

The fact is that there is "no object inside the mirror", but merely a reflection. This reflection emanates from an object some distance away and the light particles have still traveled the same distance (they have only been reflected by the mirror).

The book on the other hand is physically only a foot away and the light that allows us to see it have only traveled 1 foot.

The argument that the image is only 1 foot away because there is an image "in" the mirror is flawed on the same grounds than that of scanning a mirror in the hope that you'll end with mirror.jpg
7. uzless
The So Fist
19 Feb '09 21:36
Originally posted by Wumpus
I perfectly understand the question.

The fact is that there is "no object inside the mirror", but merely a reflection. This reflection emanates from an object some distance away and the light particles have still traveled the same distance (they have only been reflected by the mirror).

The book on the other hand is physically only a foot away and the l ...[text shortened]... the same grounds than that of scanning a mirror in the hope that you'll end with mirror.jpg
what does the distance travelled by the light from the object have anything to do with it?

The problem for the person that needs glasses is that their eyes cannot focus on things far away properly. It has nothing to do with light particles.
8. richjohnson
TANSTAAFL
19 Feb '09 22:31
Originally posted by uzless
what does the distance travelled by the light from the object have anything to do with it?
Everything.
9. 20 Feb '09 05:29
Originally posted by uzless
what does the distance travelled by the light from the object have anything to do with it?

The problem for the person that needs glasses is that their eyes cannot focus on things far away properly. It has nothing to do with light particles.
this makes me think that you don't understand how vision actually works... which is i think what wumpus was trying to get at through his analogy with the scanner. it is similar to the analogy that was brought up about "looking through a pane of glass"

essentially the reason the object is blurry from far away is because the lens on your eye cannot properly receive and interpret the ambient light that is reflected off the object. placing a mirror in the middle of the light's path does not change the total distance it travels, and thus the perceived "distance" at which your brain attempts to construct the image. thus it appears blurry in the mirror, just as it would appear blurry if you stood at a distance of [distance from mirror to face] + [distance from mirror to object] and looked directly at the object.

as wumpus accurately assessed, the fallacy in your logic is an assumption that the reflection in the mirror is some actual physical object on the surface of the glass, whereas in truth, it is more like a "bumper" (like in a game of billiards) where the light that your eyes will use to see the object bounces off is taken in by your eye.

if you do not think vision has anything to do with the movement of light particles, consider these questions: can you see an object when there is no light? why can't you "see" an object if there is no direct (or reflected) pathway between your eyes and the object? why does a pencil "look" bent if you put it at an angle in a glass of water?
10. 20 Feb '09 05:37
Originally posted by richjohnson
Everything.
Indeed everything! Thank you! However, this is not the point being argued.

I was thinking yesterday of a better way to explain the concept of the image "in" the mirror. Imagine holding a mirror so that you can see your friend next to you in its reflection, but not yourself (i.e. roughly 45 degrees). Your friend on the other hand can see you, but not himself. Each of you can see the other person, but not yourselves. What image is "in" the mirror? This again stresses the point that there is no image inside the mirror. It is merely reflecting light well.
11. 20 Feb '09 05:39
Aetherael: A very well thought-through explanation. I could not have done it better.
12. 20 Feb '09 05:52
Originally posted by Wumpus
Aetherael: A very well thought-through explanation. I could not have done it better.
thanks! ðŸ™‚
13. uzless
The So Fist
20 Feb '09 15:15
Originally posted by richjohnson
Everything.
Um, this is posers and puzzles.

"Everything" as an answer would get you 0 out of 10 if you put that down as your answer.

I have yet to see someone provide an explanation as to why this won't work!
14. uzless
The So Fist
20 Feb '09 15:22
Originally posted by Aetherael
this makes me think that you don't understand how vision actually works... which is i think what wumpus was trying to get at through his analogy with the scanner. it is similar to the analogy that was brought up about "looking through a pane of glass"

essentially the reason the object is blurry from far away is because the lens on your eye cannot prope ...[text shortened]... ject? why does a pencil "look" bent if you put it at an angle in a glass of water?