4 ms·

My guess is that the paper scaters the light, so the image can bounce on the scanner's mirror, even with a small offset. The mirror, on other hand, reflects in

My guess is that the paper scaters the light, so the image can bounce on the scanner's mirror, even with a small offset. The mirror, on other hand, reflects in a coherent way, so the light doesn't hit the scanner's reflector.

ColinWright 8y ago
That is what's happening, yes. But that still doesn't explain the why. It would seem that people really don't understand the question I'm asking, and I'm at a loss to find another way of asking it that makes it clearer. Everyone is answering the how, no one is answering the why. Here's another way of asking the question: Based purely on what a photocopier does, and without knowing anything about how it works, can you deduce the result of photocopying a mirror?
- gus_massa 8y ago
  Let's imagine a photocopier that has a camera that looks at each "pixel" and then it prints the color of the "pixel" to a paper. In this case you can align the light source and the camera and put them perpendicular to the surface of the paper/mirror. So, the mirror will be white instead of black. It's a less efficient design than the standard photocopier model, so nobody uses it. Anyway, this is the main idea of the confocal microscopy. You want to illuminate a very small point with a lot of light, but keep the surrounding parts as dark as posible. You want to see that point. And it's very difficult to aim two optical systems to the same point, so you use the same lens for illumination and for detection. https://en.wikipedia.org/wiki/Confocal_microscopy https://en.wikipedia.org/wiki/Confocal_microscopy
  - ColinWright 8y ago
    Again, that's all true, and all interesting, but it's not answering the question. I'm starting to wonder if this is a difference/distinction that people don't see, and perhaps can't understand[0]. People don't seem to understand the question I'm asking, and I genuinely don't know how to ask it differently. Try to answer the question without referring to how the photocopier/scanner works, and only refer to what it does. If anyone can see the difference, I'd welcome suggestions as to how better to ask the question. [0] Experiments have been done with infants and adults, native French speaking and native English speaking[1]. There are vowel sounds which when played to the infants or the French-speaking adults cause different parts of the brain to light up, but when played to the English speaking adults cause the same place to respond. Not learning French seems to have resulted in the loss of ability to hear the difference between the sounds. Perhaps that ability can be trained and thus regained, but this is an example where not doing something (hearing and recognising the sounds) results in a physiological reason why an ability is lost. Perhaps this distinction between "how" and "why" is an analogous one. [1] For the infants this distinction is moot.
    - gus_massa 8y ago
      A mirror has no intrinsic color. The "color" of the mirror is whatever is reflected in it from the camera point of view. If you take a photo of a mirror in a room where there is a single puntual source of light and the walls are far away, and dark to avoid reflection, the mirror will appear black in the photo. If you take a photo of a mirror in a room where there is a very diffuse source of light (like the sky, or a professional diffuse illumination equipment) the mirror will appear white (or sky blue) in the photo. --- My wife make artistic paintings and sometimes she uses shiny mirror-like materials in parts of the frame. It's difficult to take good pictures of them, because you want to make these parts appear shiny, but not too shiny. Also, you don't want too much light reflection in the normal part of the frame. So you must carefully select the angle to take the photo and the position of the lights and how puntual/diffuse they are. (Photographs of a real mirror are also difficult, if you want it to appear like a mirror. There is some reflection of light in the borders, where the glass is cut. And that reflections make it appear as a mirror instead of a plain surface.)
- howard941 8y ago
  > Based purely on what a photocopier does, and without knowing anything about how it works, can you deduce the result of photocopying a mirror? Setting aside technology the only thing I'm left (no pun intended) with is the experience of a mirror's handedness swapping. It doesn't seem like the correct why (dark page) can be adduced from the fundamental of a light emitter/detector pair coupled with lateral motion across the thing being copied because the result would be undefined absent some averaging feature at the output, and that's not what happens with most photocopiers that generate a dark print, and those are all forbidden hows. Will you be posting additional hints here or at the OP? EDIT > Try to answer the question without referring to how the photocopier/scanner works, and only refer to what it does. The thing reproduces an image of the source, that is, the mirror. I'm not satisfied with that because it feels like it's begging the question or leads to a series of infinite reflections.
  - ColinWright 8y ago
    >> ... without knowing anything about how it works ... > Setting aside technology the only thing I'm left (no pun intended) with is the experience of a mirror's handedness swapping. You also know what a copier is supposed to accomplish, so you can consider the results of copying several different things. > Will you be posting additional hints here or at the OP? I will be posting a discussion of this on my blog - I'm unlikely to post additional hints here. >> Try to answer the question ... only refer to what it does. > The thing reproduces an image of the source ... Try thinking about different, related sources. Believe it or not, there is actually a connection here to some aspects of cryptography, although that's not necessarily helpful, and certainly isn't essential. (and thank you for engaging with the question)

ColinWright 8y ago

That is what's happening, yes. But that still doesn't explain the why. It would seem that people really don't understand the question I'm asking, and I'm at a loss to find another way of asking it that makes it clearer. Everyone is answering the how, no one is answering the why. Here's another way of asking the question: Based purely on what a photocopier does, and without knowing anything about how it works, can you deduce the result of photocopying a mirror?

gus_massa 8y ago
Let's imagine a photocopier that has a camera that looks at each "pixel" and then it prints the color of the "pixel" to a paper. In this case you can align the light source and the camera and put them perpendicular to the surface of the paper/mirror. So, the mirror will be white instead of black. It's a less efficient design than the standard photocopier model, so nobody uses it. Anyway, this is the main idea of the confocal microscopy. You want to illuminate a very small point with a lot of light, but keep the surrounding parts as dark as posible. You want to see that point. And it's very difficult to aim two optical systems to the same point, so you use the same lens for illumination and for detection. https://en.wikipedia.org/wiki/Confocal_microscopy https://en.wikipedia.org/wiki/Confocal_microscopy
- ColinWright 8y ago
  Again, that's all true, and all interesting, but it's not answering the question. I'm starting to wonder if this is a difference/distinction that people don't see, and perhaps can't understand[0]. People don't seem to understand the question I'm asking, and I genuinely don't know how to ask it differently. Try to answer the question without referring to how the photocopier/scanner works, and only refer to what it does. If anyone can see the difference, I'd welcome suggestions as to how better to ask the question. [0] Experiments have been done with infants and adults, native French speaking and native English speaking[1]. There are vowel sounds which when played to the infants or the French-speaking adults cause different parts of the brain to light up, but when played to the English speaking adults cause the same place to respond. Not learning French seems to have resulted in the loss of ability to hear the difference between the sounds. Perhaps that ability can be trained and thus regained, but this is an example where not doing something (hearing and recognising the sounds) results in a physiological reason why an ability is lost. Perhaps this distinction between "how" and "why" is an analogous one. [1] For the infants this distinction is moot.
  - gus_massa 8y ago
    A mirror has no intrinsic color. The "color" of the mirror is whatever is reflected in it from the camera point of view. If you take a photo of a mirror in a room where there is a single puntual source of light and the walls are far away, and dark to avoid reflection, the mirror will appear black in the photo. If you take a photo of a mirror in a room where there is a very diffuse source of light (like the sky, or a professional diffuse illumination equipment) the mirror will appear white (or sky blue) in the photo. --- My wife make artistic paintings and sometimes she uses shiny mirror-like materials in parts of the frame. It's difficult to take good pictures of them, because you want to make these parts appear shiny, but not too shiny. Also, you don't want too much light reflection in the normal part of the frame. So you must carefully select the angle to take the photo and the position of the lights and how puntual/diffuse they are. (Photographs of a real mirror are also difficult, if you want it to appear like a mirror. There is some reflection of light in the borders, where the glass is cut. And that reflections make it appear as a mirror instead of a plain surface.)
howard941 8y ago
> Based purely on what a photocopier does, and without knowing anything about how it works, can you deduce the result of photocopying a mirror? Setting aside technology the only thing I'm left (no pun intended) with is the experience of a mirror's handedness swapping. It doesn't seem like the correct why (dark page) can be adduced from the fundamental of a light emitter/detector pair coupled with lateral motion across the thing being copied because the result would be undefined absent some averaging feature at the output, and that's not what happens with most photocopiers that generate a dark print, and those are all forbidden hows. Will you be posting additional hints here or at the OP? EDIT > Try to answer the question without referring to how the photocopier/scanner works, and only refer to what it does. The thing reproduces an image of the source, that is, the mirror. I'm not satisfied with that because it feels like it's begging the question or leads to a series of infinite reflections.
- ColinWright 8y ago
  >> ... without knowing anything about how it works ... > Setting aside technology the only thing I'm left (no pun intended) with is the experience of a mirror's handedness swapping. You also know what a copier is supposed to accomplish, so you can consider the results of copying several different things. > Will you be posting additional hints here or at the OP? I will be posting a discussion of this on my blog - I'm unlikely to post additional hints here. >> Try to answer the question ... only refer to what it does. > The thing reproduces an image of the source ... Try thinking about different, related sources. Believe it or not, there is actually a connection here to some aspects of cryptography, although that's not necessarily helpful, and certainly isn't essential. (and thank you for engaging with the question)