Explain THIS one!

[Iamme]

This morning I had a small pane of glass laying on my table, over a paper with writing on it. I noticed that the writing appears raised higher than the paper, when looking straight down through the glass. I took out my pen light and shone the light at it from different angles. Same thing.

What could cause this? Note that the writing isn't magnified. It just 'raises' it higher than the paper. I shifted the glass a little to where the writing was half on the paper and half under the glass. The writing under the glass looks about 1/16 inch higher.

Why?

[BillHoyt]

Originally posted by Iamme
This morning I had a small pane of glass laying on my table, over a paper with writing on it. I noticed that the writing appears raised higher than the paper, when looking straight down through the glass. I took out my pen light and shone the light at it from different angles. Same thing.

What could cause this? Note that the writing isn't magnified. It just 'raises' it higher than the paper. I shifted the glass a little to where the writing was half on the paper and half under the glass. The writing under the glass looks about 1/16 inch higher.

Why?

Oh, like this?
http://plus.maths.org/issue15/news/refract/pencil.jpg

Answer: refractive index

Cheers,

[Iamme]

Bill---I looked straight down through the glass...not at an angle. Whether you look straight down, or from an angle, it still appears raised. Explain refraction in this case.

[Dragon]

Originally posted by Iamme
Bill---I looked straight down through the glass...not at an angle. Whether you look straight down, or from an angle, it still appears raised. Explain refraction in this case.

Either or both of your eyes will be looking at a slight angle to the perpendicular. The "apparent depth" caused by the refraction of light at the boundary between the glass and the air will be less than without the glass - as seen in Bill's picture. When you look at a particular letter or word with both eyes your brain does its thing with the two different images and it appears to be raised. Does the effect disappear if you look straight down with one eye only?

[Ziggurat]

Originally posted by Dragon

Does the effect disappear if you look straight down with one eye only?

Actually the effect won't disappear completely even with one eye, because parts of the letter will always be at an angle, and because your eye needs to focus on the apparent depth, not the actual depth. But it will certainly be more pronounced at a higher angle, and with both eyes.

[Upchurch]

Originally posted by Ziggurat


Actually the effect won't disappear completely even with one eye, because parts of the letter will always be at an angle, and because your eye needs to focus on the apparent depth, not the actual depth. Actually, with only one eye, there wouldn't be any depth perception, would there? I mean, you can get some depth perception with one eye due to context, but in this case, I think both eyes would be required to make the optical illusion of depth.

[Dr. Imago]

lamme,

Just a quick question. Don't have to answer if you don't want to.

But, how old are you?

Just curious. :)

-TT

[no one in particular]

Originally posted by Iamme
Bill---I looked straight down through the glass...not at an angle. Whether you look straight down, or from an angle, it still appears raised. Explain refraction in this case. Index of refraction is not dependent on incident angle, only wavelength, density and chemical make-up. The index of refraction of most float glass (at 510nm) is approximately 1.5, while the refractive index of atmosphere is very near 1. The difference between the two media through which you were viewing the paper is what caused the apparent raise in the writing.

[Philip]

Originally posted by Upchurch
Actually, with only one eye, there wouldn't be any depth perception, would there? I mean, you can get some depth perception with one eye due to context, but in this case, I think both eyes would be required to make the optical illusion of depth.

As Ziggurat indicated, you also have some depth perception based on the distance to which your eye has to focus.

The virtual image of the writing under the glass is located closer your eye than the actual paper surface.

"3-D" movies that use the stereoscopic effect can cause eye strain because, even though the convergence of your left and right eyes on the two stereoscopic images is constantly changing, the distance to which the lenses of each eye focus remains the distance to the movie screen.

[hal bidlack]

Originally posted by ThirdTwin
lamme,

Just a quick question. Don't have to answer if you don't want to.

But, how old are you?

Just curious. :)

-TT

This post was reported, though I do not understand why. I find that this post does not violate the rules of the forum.

hal

[jj]

Originally posted by hal bidlack


This post was reported, though I do not understand why. I find that this post does not violate the rules of the forum.

hal

Great GHU, doesn't Hal have enough to deal with?

[Iamme]

Third Twin---I am 13 and am in school and we are playing with pieces of glass. There... (wheeeee) just threw one across the room (tschhhhhhhhhh) Oops. Rats. I missed the teacher!:D

I'm 50.

I'm not married, so I don't have a life. I like experimenting with stuff. I write companies if I feel like I have a good idea. I was experimenting with 'filler' concoctions on a piece of glass, when I noticed this effect.

I'm curious why you ask. I presume the worst.

I've been around a little bit. Seen -54 on thermometer. Seen so much snow on the ground that road plows had to tier to prepare for the next snow. Operated a dry kiln (Guages/wet/dry heat) by myself. Smoked 3 packs of cigarettes a day. (Quit cold turkey). Got a one in State competition for baritone and trumpet.Worked in !07 degrees on World's largest nuclear power plant. Never have been to a war (good draft number.) Driven 1100 miles nonstop. Been on trains, jets and helicopter. Lived through world record rain fall. Lived through hurricane (Had to board up and flee). Got in national magazine. Got in national syndicated doctors health column in paper and have written in my thoughts on things to local editorial page. Write state commissioners, congressmen, etc. Been to a live tv show. I ran a water system (albeit small one). I've met all kinds of different people from different states. Shook hands with my governor. Talked to a famous racer. Collected found fossilized mastadon bones and fossilized shark teeth. Worked on hotrod type cars. Fixed most appliances (washers, dryers, water heaters, furnaces, etc.) Lived with thousands of cockroaches (and the games in destroying them). Witnessed two nude guys chasing themselves around the beach. Hitch-hiked/picked up hitch-hikers. Had Australian bicykling around the world stay over at my house. Ate rattlesnake/killed rattlesnakes. Built unusual house (2-story a-frame... I remodified blueprints to include dormer window/more space upstairs. Formed concrete. Framed buildings. Walked while beams to be poured up 6 stories. Stretched and seamed carpet (an endless list when it comes to remodeling , electrical, and plumbing.) I can't hardly sit still and enjoy learning new stuff. Does this help some?

[T'ai Chi]

Originally posted by Iamme
This morning I had a small pane of glass laying on my table, over a paper with writing on it. I noticed that the writing appears raised higher than the paper, when looking straight down through the glass. I took out my pen light and shone the light at it from different angles. Same thing.

What could cause this? Note that the writing isn't magnified. It just 'raises' it higher than the paper. I shifted the glass a little to where the writing was half on the paper and half under the glass. The writing under the glass looks about 1/16 inch higher.

Why?

Hey Iamme,

How thick (tall) was the glass, and what type of paper document and ink (color) was used under the glass? I'd like to see if I can experiment around and duplicate the conditions on my coffee table.

My impressions before experimenthing is that as far as I know, a truly flat plate of glass does not magnify. To magnify an image, the glass must have a curved shape. But, since the text is being raised, ie. coming closer to you, I'd say it is being magnified, only slightly. I'd said that the pane is not exactly flat, or that some of the components that make up the glass are curved very slightly.

I'd probably try putting a 1" by 1" square under the glass, and then measure it's apparent dimensions and see if there is any change.

[BillHoyt]

Originally posted by T'ai Chi
How thick (tall) was the glass, and what type of paper document and ink (color) was used under the glass? I'd like to see if I can experiment around and duplicate the conditions on my coffee table.

Someone buy this jerk an education. Woodini, we're talking about refraction, you nitwit troll.

[WildCat]

Refraction is what makes it so hard to shoot an arrow into a carp that is swimming underwater. Or a gar or dogfish (bowfin) for that matter. Or even to spear one. :wink:

[patnray]

T'ai Chi: Refraction can occur without magnification. With flat, parallel glass surfaces it just moves the apparent location of the image. Refraction is just a change in the direction of a light ray as it moves across the interface of materials with different refractive indicies (or, alternatively, in which the speed of light propagation is different).

[peptoabysmal]

Originally posted by WildCat
Refraction is what makes it so hard to shoot an arrow into a carp that is swimming underwater. Or a gar or dogfish (bowfin) for that matter. Or even to spear one. :wink:

That's why some natives keep the tip of the spear underwater.

[T'ai Chi]

Originally posted by BillHoyt

Someone buy this jerk an education. Woodini, we're talking about refraction, you nitwit troll.

You can't get under my skin Bill, ever. :)

If you disagree with what I say, just address that. There is no need to resort to insults etc.

And plus as an educator I'm more interested in encouraging experimentation, rather than giving one-liner answers.

[BillHoyt]

Originally posted by T'ai Chi


You can't get under my skin Bill, ever. :)

If you disagree with what I say, just address that. There is no need to resort to insults etc.

And plus as an educator I'm more interested in encouraging experimentation, rather than giving one-liner answers.


Right. "Encourage experimentation." Why? So you can pop out your nitwit line about needing to test each instance? Each color? Each paper type? Each ink type? Holy piece of poseur poop. Cut the pose, peon.

You are the same troll you have always been. This time around you wish to pose as an educated troll. Knock it off, whodini. Dry up. Go away.

Your other choice is to listen and learn. Especially before spouting nonsense. To honestly be helpful to someone, know your subject matter first. Quit pretending to know until called out.

This is refraction, numbnit. Snell's law, stew. Color? Pah! Paper? Pah! Ink? Pah! T'ai Chi? Dry up.

Jeers,

[Beausoleil]

Originally posted by Iamme
This morning I had a small pane of glass laying on my table, over a paper with writing on it. I noticed that the writing appears raised higher than the paper, when looking straight down through the glass. I took out my pen light and shone the light at it from different angles. Same thing.

What could cause this? Note that the writing isn't magnified. It just 'raises' it higher than the paper. I shifted the glass a little to where the writing was half on the paper and half under the glass. The writing under the glass looks about 1/16 inch higher.

Why?

In the first paragraph you seem to say that the writing seen through the glass looks raised over the paper seen through the glass - in which case the simple refractive index explanations given here don't work.

They work for the second paragraph, though, where 'seen through the glass' seems higher than 'seen not-through the glass'.

[T'ai Chi]

Originally posted by BillHoyt

Right. "Encourage experimentation." Why? So you can pop out your nitwit line about needing to test each instance?


No, not each instance and not each color each paper type and each ink, by testing every possible combination that wouldn't test anything at all I'd think. I simply proposed the simple test of measuring the dimensions of an object before and after. I agree, it does sound like refraction here, but I wanted to see if anything was being magnified.


Your other choice is to listen and learn.


I am listening, I am learning as proven by my discussions on the more recent threads. You are the only one protesting me on any thread it seems.

"Peon", "troll", "nitwit", "numbnit", etc., please just put me on ignore if you feel that way. Notice I do not call you any names.

Let's note that you clearly 'started it' on this thread. You can't and won't bait me into another round of silly arguments with you which will take the thread further away from glass, refraction, and investigating a neat effect.

Now, I take you back to the regularly scheduled thread. :)

Here are some interesting links Iamme:

http://mainland.cctt.org/physicslab/content/Phy1/labs/refraction/indexglass.asp
http://musr.physics.ubc.ca/~jess/lab/8/node15.html
http://nebula.physics.uakron.edu/~light/refraction/index_of_refraction/index_of_refraction.html
http://vanadium.rollins.edu/~griffin/phy121/exp6.pdf

[Iamme]

Greeting T'ai. I'm glad to see that you are curious enough to want to check it out for yourself.

It is NOT magnifyig the letters though, as stated by others. One would THINK that it is a property of refraction. But IS it? I will explain more in a minute, about this, in great detail, as I spent more time with this this morning. (You see, as I post this, I am on a friends computer 20 miles from home and from the glass. That's why I couldn't offer more yesterday. O.k., here we go. What I found is quite interesting.

You put a pane of double-strength 1/8 inch glass over writing...newsprint..whatever. When you look straight down at the letters, the letters appear raised-up higher than the paper by...oh...1/32 inch (I said 1/16 yesterday).

If you cover one eye, you lose binocular vision, and you no longer see the letters as raised.

Now, to see better what is going on, you cover only 1/2 the row of letters with the glass. You will observe there is no distortion or shift between the letters on the paper and what you percieve as raised -up (by 1/32 inch) loetters through the glass. This ALONE is fascinating to me. One would think you would see an enlargement and/or shift in the letters. There is none.

If you look through the glass at the letters that are not directly below you, but off to the side more, you still see the letters as being raised. I expected THIS!

But...if you once again, go ahead and cover up an eye, and look at the letters through the glass...remember earlier I said that when you look straight down, you no longer see theis 3-d effect? Well, if you look at the letters over to the side, with one eye...they are still raised-up looking.

Then, I decided to see what kind of refractive shift I would get by looking straight down at the letters and covering one eye, then the other. THIS is what is odd to me: Yes, the letters shift. I expected them to. But...they only shift just an eensy-teensy bit.

So, when I noticed THIS, I said to myself that I am just going to cut to the chase...so I doubled up the glass. (I would have done more, but all I have is two. Maybe I will get more.) NOW, I see the letters raised a good 1/16 inch (at least the illusion makes it out that way). So...I doubled the glass...I doubled the raised-up letter height.

But this is what's odd: When I went to cover one eye, and then the other...the shift in the letters was still about the same eensy teensy bit, as it was with ONE pane of glass. Yet, with TWO panes of glass...the illusionary height was double-looking to me.

And, this is what ELSE seems odd. O.K.,....if refraction is the cause, you would know that your left eye would refract it to the right, and your right eye would refract it to the left 9or...whatever. The opposite way) WHYYYYY...don't they just cancel each other out...in your brain?

In closing; I hope you are all reading this, because here is something similar which is quite strange to explain. I noticed several years ago that if I looked at a glossy enamel color ad on something, that if it had red print, or blue...or both?...I can't rememberr anymore...that the colored image or print would look raised off the paper, as if I was reading that colored label or picture in 3-d. I THINK I had to have my nearsighted glasses on for this to happen. If I took them off, the effect would vanish. There would BE no effect.

But, with the window glass experiment, for which I used one pane of glass (1/8 inch thick) and doubled this up to be 1/4 inch when I stacked 2 on top of each other...I had my glasses off. I can focus good without glasses at about 1 foot high.

[BillHoyt]

Originally posted by T'ai Chi
"Peon", "troll", "nitwit", "numbnit", etc., please just put me on ignore if you feel that way. Notice I do not call you any names.
Right. Whodini takes the moral high ground. Don't make me sick.

[T'ai Chi]

Originally posted by BillHoyt

Right. Whodini takes the moral high ground. Don't make me sick.

I have not been the one using insults. I think I've been pretty kind in fact.

But let's not clutter the thread with the Days of Our Lives. It is obviously off topic, no?

[69dodge]

Originally posted by Iamme
And, this is what ELSE seems odd. O.K.,....if refraction is the cause, you would know that your left eye would refract it to the right, and your right eye would refract it to the left (or...whatever. The opposite way) WHYYYYY...don't they just cancel each other out...in your brain?The reason the refraction causes the paper to appear raised is this: if there were no glass, but instead the paper actually were raised, you would see exactly the same thing. If you bring an object closer to you, the image of it that your left eye sees gets shifted right, and the image of it that your right eye sees gets shifted left.

[BillyJoe]

ARE YOU SAYING THAT THE LETTERS ARE RAISED BUT THE PAPER IS NOT?

[BillyJoe]

If so could this be an optical illusion?

In the bathroom at work as I stand to do my business, I often look at the pattern on the tiles on the wall. The pattern appears to be in 3D. I think it only works with the side light coming in from the window. The tiles are not completely flat and I have attributed the effect to the different reflection of light off different parts of the surface (if you see what I mean)

Do the letters indent the paper a little?
If so, maybe you are seing a similar optical illusion?

BillyJoe

[BillHoyt]

Originally posted by T'ai Chi


I have not been the one using insults. I think I've been pretty kind in fact.

But let's not clutter the thread with the Days of Our Lives. It is obviously off topic, no?

How about you stop cluttering the whole board with your pretense at knowledge. Your post here was complete pap. You tried to ensnare a young mind with a hokum "experiment". Do you get off on this? Clean up your sticky keyboard and quit interfering with JREF's work, dolt. Go get counseling.

[Beausoleil]

Originally posted by BillyJoe
ARE YOU SAYING THAT THE LETTERS ARE RAISED BUT THE PAPER IS NOT?


That's the question I was asking. I'm not sure I gathered the answer from lamme's follow up post.

Maybe we could persuade BillHoyt and T'ai Chi to handbag one another somewhere else? I'm still mildly curious about the answer.

[BillHoyt]

Originally posted by Beausoleil


That's the question I was asking. I'm not sure I gathered the answer from lamme's follow up post.

Maybe we could persuade BillHoyt and T'ai Chi to handbag one another somewhere else? I'm still mildly curious about the answer.
Beau,

If the glass is over the paper's edge, it will appear shifted, just as the lettering does. Perhaps you could persuade me there is any merit to Troll Chi's questions. If so, which ones and why? How does color come into it? Ink?

The answer is: nothing. Troll Chi is here to troll. In his new incarnation, he is trying to appear reasonable and scientific. He even claims degrees in mathematics and statistics. I laced into the nitwit here because these questions are preposterous, and demonstrate the kid hasn't even mastered high school physics.

Refraction has nothing to do with the ink. Nothing to do with color. Nothing to do with the paper. It is a function of the interfaces between the paper and glass (on one side) and the glass and the air (on the other). The angles of refraction have to do with the refractive index of the glass.

Cheers,

[BillyJoe]

Yes, sorry Beausoleil, I was thinking the same as you after reading Iamme's first post, so when I read your post later on I decided to just repeat your question with emphasis hoping to get a clarification this time.

[hal bidlack]

this thread has been reported. The reportee complained that the thread had devolved into little more than two folks taking swings at each other. While that may or may not be true, it is not a violation of the rules. I do urge folks to stay on topic, but should they stray, it's not a violation.

hal

[Beausoleil]

Originally posted by BillHoyt

Beau,

If the glass is over the paper's edge, it will appear shifted, just as the lettering does. Perhaps you could persuade me there is any merit to Troll Chi's questions. If so, which ones and why? How does color come into it? Ink?



If the paper and ink are both viewed through the glass, refraction (at the level it's been explained so far) can't make one appear shifted relative to the other. A coin on the bottom of a swimming pool doesn't appear to be floating in mid-water. That's why I asked my question. The problem as outlined isn't clear to me, and your weighing in strikes me as premature.

Actually refraction does depend on colour, as perhaps you know, since refractive index is wavelength dependent. I'm not suggesting that's a solution, or even that a solution is necessary, since the problem didn't seem clear to me. Just wanted an answer to the question I asked the thread starter.

Billy - I wasn't complaining, just trying to highlight the question against the background noise of swinging handbags.

[T'ai Chi]

Originally posted by BillHoyt

How about you stop cluttering the whole board with your pretense at knowledge. Your post here was complete pap. You tried to ensnare a young mind with a hokum "experiment". Do you get off on this? Clean up your sticky keyboard and quit interfering with JREF's work, dolt. Go get counseling.

Wow.. ..

[BillHoyt]

Originally posted by Beausoleil
If the paper and ink are both viewed through the glass, refraction (at the level it's been explained so far) can't make one appear shifted relative to the other. A coin on the bottom of a swimming pool doesn't appear to be floating in mid-water. That's why I asked my question. The problem as outlined isn't clear to me, and your weighing in strikes me as premature.

Actually refraction does depend on colour, as perhaps you know, since refractive index is wavelength dependent. I'm not suggesting that's a solution, or even that a solution is necessary, since the problem didn't seem clear to me. Just wanted an answer to the question I asked the thread starter.
The RI for crystal glass, as an example, decreases from 1.57 @ 40 angstroms to 1.54 @ 80 angstroms. The naked eye isn't going to see much difference between red and blue ink with a simple pane of glass.

Slide a pane of glass over some large print and you will see the effect. No ink color dependency. No paper dependency. If you look at it from different angles you will see what is going on. The photons are refracted. Your brain traces back the photons caught by your eye as if they came at you in a straight line. So the shift, to you, is interpreted as an elevation. (A similar effect is used by programmers to make your windows buttons appear to be three dimensional. In that case, shading miscues you to believe you are looking at a 3-D object.)

Cheers,

[Iamme]

BillyJoe and Beausoleil---Yes, the letters 'appear' to be raised up off the paper, within the glass itself.

I am leaning more now towards believing that it is behaving similar to a hologram caused when a focal point becomes in a different location from the object itself. (Ever see one of those simple hologram makers where you have an open round pot with an object in the bottom of it, and the image of the object appears to be above the pot?)

I don't think it is 'angular' refraction. If there is any refracting, per se, I would say it's some phenomenon caused by the speed of light slowing down within the glass and when you are simultaneously focusing on the part of the letter outside of the glass, and the part of the letter under the glass....the image from the exposed letter gets to your eye faster than the image of the letter passing through the glass.

I have also considered the possibility of a tension, similar to water tension. This might cause some of the image to be 'reflected' back down toward the paper, lengthening the travel distance the light takes, to finally make it toward your eye.

As I said in an earlier post. I am going to get even MORE glass and keep stacking them. I think this will tell more what is going on. This will get rid of some of the subtleties.

[Iamme]

Remember in an earlier post I had also mentioned that I have witnessed this same effect with two different colors on a food label or that enameled magazine paper? It's coming to me more now. The effect occurs when either a red print is over a blue backround, or vice-versa. The one color will appear raised off the page, as if in 3-d!

I'd imagine that this too is caused by some speed of light differential between the blue light and the red light.

[T'ai Chi]

Originally posted by Beausoleil

Maybe we could persuade BillHoyt and T'ai Chi to handbag one another somewhere else? I'm still mildly curious about the answer.

Ouch. Point well taken Beau!

[BillyJoe]

Originally posted by Iamme
....when either a red print is over a blue backround, or vice-versa.....one color will appear raised off the page... I'd imagine that this too is caused by some speed of light differential between the blue light and the red light.Blue and red light travel at the same speed. It's their wavelength that is different.
I would lean more towards an optical illusion to explain this one.

BillyJoe

[wayrad]

lamme,

I am able to see the effect you mention using several microscope slides stacked together, but only using fairly smooth paper and at a foot or so distance. If I use paper with an obvious texture, like a paper towel, or if I get extremely close to it so that I can see surface detail, the paper as well as the writing looks raised. Do you notice this also? My guess is that it's hard to see the apparent change in distance (edited to add: this change being produced by refraction and binocular vision) where visual cues are lacking. However, I don't have much depth perception, so my experience may be atypical.

[Bluegill]

Originally posted by Iamme
Remember in an earlier post I had also mentioned that I have witnessed this same effect with two different colors on a food label or that enameled magazine paper? It's coming to me more now. The effect occurs when either a red print is over a blue backround, or vice-versa. The one color will appear raised off the page, as if in 3-d!

I'd imagine that this too is caused by some speed of light differential between the blue light and the red light.

I've noticed this effect, too. I mostly notice it on my computer screen and on bright red neon signs. The red part seems to "float" above the surrounding colors or shapes. It's very striking, but it goes away when I take off my glasses. I'm nearsighted, btw.

edited for spelling. One little allergy pill and my typing goes right over the edge.

[BillyJoe]

Originally posted by wayrad
lamme,

I am able to see the effect you mention using several microscope slides stacked together, but only using fairly smooth paper and at a foot or so distance. If I use paper with an obvious texture, like a paper towel, or if I get extremely close to it so that I can see surface detail, the paper as well as the writing looks raised. Hmmm....I think this is evidence to support my hypothesis that the effect is an optical illusion.

BillyJoe

[wayrad]

Originally posted by BillyJoe
Hmmm....I think this is evidence to support my hypothesis that the effect is an optical illusion.

BillyJoe I tend to agree. As long as I'm looking as close to straight down as possible, and there's nothing about the paper itself that I can really focus on to see the illusion, I think I just take my cue about its distance from the surrounding paper (outside the glass). The writing, on the other hand, would present a distinct image to each eye, so the brain tries to match the images up.

[Iamme]

wayrad and BillyJoe---But precisely what IS an optical 'illusion'. It is that your eyes are being fooled. But, they are being fooled in some scientificly explained way. I gave a reason as to why I thought this illusion could occur. What I'm NOT sure about however, is what speed of light reflecting off an object in your eye, causes your eye to perceive the image as being closer to your eye. And why this only occurs when you are nearsighted with your glasses on.There has got to be a l;egitimate explanation for this.

[wayrad]

Originally posted by Iamme
wayrad and BillyJoe---But precisely what IS an optical 'illusion'. It is that your eyes are being fooled. But, they are being fooled in some scientificly explained way. I gave a reason as to why I thought this illusion could occur. What I'm NOT sure about however, is what speed of light reflecting off an object in your eye, causes your eye to perceive the image as being closer to your eye. And why this only occurs when you are nearsighted with your glasses on.There has got to be a l;egitimate explanation for this.

There are several aspects to this. The first is refraction, the bending of light when it passes from one transparent medium to another. There's a nice treatment of this at
http://www.physicsclassroom.com/Class/refrn/refrntoc.html
Seems to involve the fact that different media slow down the light to a different extent (actually, this "slowing down" bit is kind of misleading, since what I've read leads me to think that the light energy is being absorbed and reemitted by atoms in the medium, but travels at its usual rate through the interatomic voids. Somebody correct me if I'm wrong.). Anyway, one way to look at it is that when a light wave hits the boundary between two media at an angle, the part that hits first speeds up or slows down the soonest, causing the light ray to bend. So the light rays that enter your eye after being reflected off an object under glass are actually bent at the point where they leave the glass and emerge into the air.

You are equipped to determine what vector light is entering your eyes on (it has to go through the pupil and hit some place on the retina, so from that you decide what direction it comes from). Quite reasonably, your brain "sees" the image along that vector. It has no way of directly sensing any bends the light took before it reached your eye! That is why an object seen at an angle through glass seems to be moved to one side.

OK, why does the object seem closer when you look at it head-on through glass? Well, you are not looking at it straight, but at two different angles, one for each eye. Under normal circumstances, an imaginary line drawn through the reflected light ray entering your left eye and one drawn through the ray entering your right eye would intersect at the place where the object is. But if your left eye sees an image that is shifted rightwards, and your right eye thinks it's shifted leftwards, those imaginary lines intersect at a point much closer to you than would otherwise be the case. Hence the illusion.

I suspect there may be a lot of interpersonal differences in how easily people see this and under what circumstances, depending on things like nearsightedness, farsightedness, whether one eye is better than the other, glasses prescriptions, degree of depth perception, etc.

I think that the reason that smooth paper doesn't show the effect well has to do with the fact that it's rather featureless - it looks pretty much the same whether your eyes are focused or not, so it's hard to get an idea of its distance, except by reference to external objects.

(edited for clarity)

[Iamme]

wayrad---...and other posters. There seems to be enough interest here by some of you that I propose that YOU guys go out and get some window glass. Get someone to cut you up a bunch of small pieces, and start stacking them, and make observations yourself. maybe by actually seeing it, moving your head, closing each eye...all that stuff...something will come to mind. I was going to get more glass today from my glass man, and I forgot.

[wayrad]

Originally posted by Iamme
wayrad---...and other posters. There seems to be enough interest here by some of you that I propose that YOU guys go out and get some window glass. Get someone to cut you up a bunch of small pieces, and start stacking them, and make observations yourself. maybe by actually seeing it, moving your head, closing each eye...all that stuff...something will come to mind. I was going to get more glass today from my glass man, and I forgot.

Already tried it, see my post before last. Can certainly attempt to replicate whatever observation you find to be unexplained, if you describe it, but it would not be time-effective to try to guess what that observation is.

[BillyJoe]

wayrad,

Originally posted by wayrad
I tend to agree [about it being an optical illusion]. As long as I'm looking as close to straight down as possible, and there's nothing about the paper itself that I can really focus on to see the illusion, I think I just take my cue about its distance from the surrounding paper (outside the glass). The writing, on the other hand, would present a distinct image to each eye, so the brain tries to match the images up. Sounds like a very reasonable explanation for the presumed optical illusion.

BillyJoe.

[Dr. Imago]

Originally posted by Iamme
I'm 50.

Thanks. As I stated, just curious. I enjoy your posts, but they can be a bit "naively provocative" at times so I was trying to correlate age/posting style, especially since you're a relatively new poster. I was WAY off, apparently. So much for "studies of one". ;)

Originally posted by Iamme
I'm not married, so I don't have a life. I like experimenting with stuff. I write companies if I feel like I have a good idea. I was experimenting with 'filler' concoctions on a piece of glass, when I noticed this effect.

I'm curious why you ask. I presume the worst.

I've been around a little bit. Seen -54 on thermometer. Seen so much snow on the ground that road plows had to tier to prepare for the next snow. Operated a dry kiln (Guages/wet/dry heat) by myself. Smoked 3 packs of cigarettes a day. (Quit cold turkey). Got a one in State competition for baritone and trumpet.Worked in !07 degrees on World's largest nuclear power plant. Never have been to a war (good draft number.) Driven 1100 miles nonstop. Been on trains, jets and helicopter. Lived through world record rain fall. Lived through hurricane (Had to board up and flee). Got in national magazine. Got in national syndicated doctors health column in paper and have written in my thoughts on things to local editorial page. Write state commissioners, congressmen, etc. Been to a live tv show. I ran a water system (albeit small one). I've met all kinds of different people from different states. Shook hands with my governor. Talked to a famous racer. Collected found fossilized mastadon bones and fossilized shark teeth. Worked on hotrod type cars. Fixed most appliances (washers, dryers, water heaters, furnaces, etc.) Lived with thousands of cockroaches (and the games in destroying them). Witnessed two nude guys chasing themselves around the beach. Hitch-hiked/picked up hitch-hikers. Had Australian bicykling around the world stay over at my house. Ate rattlesnake/killed rattlesnakes. Built unusual house (2-story a-frame... I remodified blueprints to include dormer window/more space upstairs. Formed concrete. Framed buildings. Walked while beams to be poured up 6 stories. Stretched and seamed carpet (an endless list when it comes to remodeling , electrical, and plumbing.) I can't hardly sit still and enjoy learning new stuff. Does this help some?

Umm... okay. I guess I got the "bonus plan".

:D

-TT

(P.S. Whomever reported me... well... :rolleyes: )

[BTox]

Originally posted by ThirdTwin


Thanks. As I stated, just curious. I enjoy your posts, but they can be a bit "naively provocative" at times so I was trying to correlate age/posting style, especially since you're a relatively new poster. I was WAY off, apparently. So much for "studies of one". ;)


And how old are you??


I want to get "reported", too! ;)

[Iamme]

ThirdTwin---I forgot. iIve been shot at also!:eek: I was caught in the crossfire, while I lived in Sarasota, Florida in the 70's, when the police ran down a bank robber and they had a 'shootout' with tons of cops and this dude. I was on a construction site and bullets were hitting the building and even made a car tire go flat. A cop later came over, after the riddled the robber to death and had to account for where all the bullets went. I was out front, landscaping and was 'in the line of fire. Another time when I lived in Texas about 6 years later, I thought I was being shot at and I ended up running and clotheslining myself at full speed. Got up and continued running through rattlesnake infested grass.

[Beausoleil]

Thanks for the explanation of refraction, BillHoyt, though it was unnecessary - I have a PhD in laser spectroscopy and still do related research. ;)

I was interested because the whole discussion vaguely rang a bell. A little looking around yielded this on chromostereopsis...

http://www.discover.com/neuroquest/chromo1.html

(it was a bit of a slow load this morning but worth the wait, I think.)

The illusion is neat, but I'm not so sure about the explanation. As I remember, the idea is that the eye tends to focus green best, and the lens has to be flexed in different directions to bring blue and red into focus. This need for flexing is the same as that required to focus at different distances, creating the illusion of depth.

[wayrad]

Originally posted by Beausoleil
The illusion is neat, but I'm not so sure about the explanation. As I remember, the idea is that the eye tends to focus green best, and the lens has to be flexed in different directions to bring blue and red into focus. This need for flexing is the same as that required to focus at different distances, creating the illusion of depth. Cool! This is a good example of the red-on-blue effect that was mentioned earlier. You're right, their explanatory diagram seems to make no sense. Are they saying binocular vision is needed for this particular illusion? It doesn't seem to be.

Looks like they "cheated" a bit in their placement of the red rectangle on order to enhance the illusion, but the effect is so obvious that it hardly seems necessary.

[Dr. Imago]

Originally posted by BTox


And how old are you??

Soon to be 35 (holy crap!), definitely WAY too old to be a medical student, and completely resistant to acting my age (at least outside of the hospital). ;)


Originally posted by BTox
I want to get "reported", too! ;)

Just use a few bad words. Sheriff Bidlack will come-a-knockin' in no time flat!

:D

-TT

[Iamme]

I went and got more glass today from the glass cutter. It is even THICKER glass. I now have 6 pieces probably thicker than an inch. I had the glass cutter take a look at print through the stacked glass. Then I made stairs out of them, over the print and for each step up of glass, so goes the print. He said, "Huh!". I just chuckled because he probably thinks I'm nuts.:D

As far as I can tell, even with well over an inch of glass, there is no refractive (sidewards)shift in the letters. They just look like they are 'inside' the glass. It looks like the letters are halfway into the glass thickness, and there is no magnification of letters or side-shift. I'll fiddle around with these tomorrow, some.

[BillHoyt]

Originally posted by Iamme
I went and got more glass today from the glass cutter. It is even THICKER glass. I now have 6 pieces probably thicker than an inch. I had the glass cutter take a look at print through the stacked glass. Then I made stairs out of them, over the print and for each step up of glass, so goes the print. He said, "Huh!". I just chuckled because he probably thinks I'm nuts.:D

As far as I can tell, even with well over an inch of glass, there is no refractive (sidewards)shift in the letters. They just look like they are 'inside' the glass. It looks like the letters are halfway into the glass thickness, and there is no magnification of letters or side-shift. I'll fiddle around with these tomorrow, some.
The shift is what causes the text to appear to be raised. Look at a line of text from an angle, below the baseline of text. Be sure an edge of the glass is perpendicular to the baseline of the text letters. The letters you see through the glass are shifted away from you. Your eyes/brain interprets this to mean the letters are raised.

Cheers,

[BTox]

Originally posted by ThirdTwin


Soon to be 35 (holy crap!), definitely WAY too old to be a medical student, and completely resistant to acting my age (at least outside of the hospital). ;)


-TT

Dang, I was off, too. I knew you were a 3rd year med student so just assumed you were ~ 25. oops!

PS I'm 45. think I could get through it??

[BillyJoe]

Originally posted by BTox
I knew you were a 3rd year med student so just assumed you were ~ 25. oops!The average third year medical student is 21 years of age

Originally posted by BTox
PS I'm 45. think I could get through it?? You will graduate at 51 and after the obligatory intern years you will be 53. Do you really want to?

[Dr. Imago]

Originally posted by BTox
PS I'm 45. think I could get through it??

Well, depends on how much you want to be in debt. You'll have to wait at least another year before you can start, assuming you've done all of the pre-med requirements (1 year of biology, 1 year of general chemistry, 1 year of organic chemistry, 1 year of physics [with all the labs for each], 1 year of college level calculus, and 1 year of college level english) and you have a good score on the MCAT. (Again, I'm assuming you're talking about going to a U.S. allopathic or osteopathic school. I'm not aware of the requirements for other countries.)

Originally posted by BillyJoe
The average third year medical student is 21 years of age

The average third-year medical student, at least in the U.S., is actually between 26-28.

Source: http://www.aamc.org/

Originally posted by BillyJoe
You will graduate at 51 and after the obligatory intern years you will be 53. Do you really want to?

Actually, the minimum length of a residency is three-years - even Family Practice - in order to be board-eligible in whatever field you intend to practice.

Many sub-specialty programs (e.g., Cardiology, Hematology/Oncology, Nephrology, Endocrinology, etc.) are an additional 2 1/2 - 3 years of "fellowship" training following an Internal Medicine (3 year) residency. So, if that's your calling, you're looking at an additional 5 1/2-6 years of training AFTER four years of medical school. I'll be 40 before I'm out on my own. You don't make squat during residency and fellowship... just enough to get by. And, you don't have a life either.

BTox, you're 45 now and, if you could start today, you'll be 52 before you're practicing on your own and making any money (which will be not that much depending on what field you go into). It's a tough profession - that I'm learning more and more everyday, and it gets harder as you get older. But, we have a few students in my program that are older than I. It's all up to you, if you want to make the life-changing (the only way to describe it) investment of time, money, blood, sweat, and tears. If you do, go full guns and jump in with both feet. That's the only way you can do it. But, it is a lifelong commitment to learning and putting others needs somewhat ahead of your own. It's a lifestyle, not an occupation. That's what many "youngsters" don't realize when they choose to pursue medicine as a career.

-TT

[Iamme]

ThirdTwin---My sister decided to go from retail, into nursing, and became an RN at 37.

O.K., I have more info on the glass. I stacked the 6 pieces of glass this morning = 1 1/8 inches. The illusion of raised appears to be 7/16 in heigth off the paper.

There is no distortion.

Refraction is only 1/16 inch (through all that thickness of glass!) out at the edges of the 4 inch square stack.

If you raise the stack straight off the table (let's say up one foot...close to your eye), the raised illusionary effect is still off the table by 7/16. It is not 'in' the glass. So, no matter if the glass is on the table, or raised off the table, the letters, writing, or whatever, appears higher than the paper by 7/16.

This holds true whether or not you have nearsighted glasses on.

If you have a straight line drawn on the paper and you stagger each piece of glass, over the line, like you are making stairs...the line 'curves' up in the air, off the paper. (neat visual)

If you take the whole pile of stacked glass and rock it from side to side (or front and back), then you definitely observe a lot of refraction.

But what's odd to me, is that when this tall stack of glass is laying flat on the print, the refraction of the letters is about only 1/16 inch when you look through the glass near the edges (which would be about 2 inches out from straight down.) But the illusionary image of letters is higher than this, at about 7/16 inch.

Near where I live is one of the world's tallest towers. It is 2000 feet tall. (the Sears tower is ONLY about 1450, to give you an idea). If you stand right under the tower, the tower looks like it might be only 100 feet tall. As you back away, the tower appears taller and taller and taller. Till you finally say, "No WAY would they get ME up there to change those light bulbs!!!":D There is some effect where distance becomes compressed when you are right at the base of a tower. I think the same effect is going on looking through the glass.

If instead of laying the glass on the table...suppose you held it up, with the paper ontop of the glass, and you looked at it from below, you would get the same affect of compression, as mentioned above.

Try THIS once: Take a piece of paper. Draw 2 heavy dots on it. Put one dot real near the edge of the paper, and another dot about 1 1/2 inches inward from it. Now hold it level with your eye. You can cock the paper so that the 2 dots appear to touch. Weird. Now listen to my way of saying this, to make it sound really weird.: If you have the paper on the table directly below your eyes. each dot is the same distance from your eye...and that is when you perceive the 1 1/2 inch distance. Yet...when you hold the paper level with your eye...when the farthest dot truly IS 1 1/2 inches farther from your eye than the leading edge dot...then you don't see them as 1 1/2 inches apart! Weird, eh? Try to explain this affect of why distance becomes bunched up.

[BillyJoe]

Originally posted by ThirdTwin
The average third-year medical student, at least in the U.S., is actually between 26-28.Hmmm.....In australia you go straight to Med School after year 12, that is to say at the age of 17 - 18. So the average third-year medical student would be 20 - 21.
What do they do over there for the five years after year 12?

Originally posted by ThirdTwin
Actually, the minimum length of a residency is three-years - even Family Practice - in order to be board-eligible in whatever field you intend to practice. I'm pretty sure in Australia it's two years.

Originally posted by ThirdTwin
AFTER four years of medical school.... Here its SIX years!!!!!!

Originally posted by ThirdTwin
You don't make squat during residency and fellowship... just enough to get by. And, you don't have a life either....it is an investment of time, money, blood, sweat, and tears.....it is a lifelong commitment to learning and putting others needs somewhat ahead of your own. It's a lifestyle, not an occupationSo....why....do....you....do....it???
Is there a pot of gold at the end of the rainbow at least?

BillyJoe.

[Aoidoi]

Originally posted by BillyJoe
Hmmm.....In australia you go straight to Med School after year 12, that is to say at the age of 17 - 18. So the average third-year medical student would be 20 - 21.
What do they do over there for the five years after year 12?In the US you go to med school after getting a Bachelor's degree with the prerequisite courses mentioned above (year of chem, etc). This usually takes 4 years. So most people start med school after getting a Bachelors at 22. A college roommate of mine spent a year working for a neurosurgeon after graduating then started an MD/PHD program which takes 6 years IIRC. So he won't even get out of school until he's almost 30.

Of course, it's also possible to get a bachelor's in less than 4 years... or in a lot longer than 4 years (if you can keep dealing with tuition that long :))

I think the general rule in the US is that you're legally required to be in school until you're 16, most people graduate High School at 18, 4 years of college to 22, then people do grad school or med school. I think a lot of people do grad school part time and have their company pay for it, I assume that's not an option for med school.

So....why....do....you....do....it???
Is there a pot of gold at the end of the rainbow at least?If I knew that, I wouldn't be an engineer. :D

It used to be that doctors made lots of money, were well respected, and were able to help people. From the complaints I've heard they're now stuck dealing with insurance more than patients, are in constant danger of lawsuits, and it seems like the quacks generally get better press than the real docs. But then, I'm a cynic and am probably cherry picking data. :)

[Dr. Imago]

Originally posted by BillyJoe
I'm pretty sure in Australia...

Duly noted. I'm not really all that sure about how the varied medical education systems work outside the U.S. and Canada. Each country is a little different. Sounds like Australia is based more on the English model.

Originally posted by BillyJoe
So....why....do....you....do....it???
Is there a pot of gold at the end of the rainbow at least?

Why do it? Because it's fascinating. Everyday I'm amazed at what I see and learn. When it becomes tedious to the point that I lose heart and become no longer a good caregiver, I'll go do something else. You can do a lot with an M.D. that doesn't involve direct patient care.

And, the pot of gold is still there, but it's gotten a lot smaller.

-TT

[BillyJoe]

Best of luck TT (and Aoidoi). Hope the satisfaction in the work is better than the money.

BillyJoe.

PS
Don't become a media Doc - they truely suck!