[lightarrow]

there is an EM field propagating towards the mirror and the field has excitations called photons, then it interacts with the mirror, a new field is generated as consequence, it results that this new field is propagating backwards, this field has excitations which are called photons.

OK, while this is a useful view for some purposes, you need to be careful with it.  Because you can do an experiment where you turn down the intensity of the incoming light to the point where one photon at a time is incident on the mirror.  If you measure where the reflected photons come off, you will see them, one photon at a time, at an angle of reflection equal to the angle of incidence.

In such a case you can't simultaneously measure both angles for a single photon.

[burning]

OK, while this is a useful view for some purposes, you need to be careful with it.  Because you can do an experiment where you turn down the intensity of the incoming light to the point where one photon at a time is incident on the mirror.  If you measure where the reflected photons come off, you will see them, one photon at a time, at an angle of reflection equal to the angle of incidence.

In such a case you can't simultaneously measure both angles for a single photon.

You know something?  You can't simultaneously measure both angles for a classical wave either.  Any part of the wave that you intercept to measure its direction doesn't make it to the mirror.  You are taking it on faith that the parts that you don't intercept are in fact behaving the same as the parts that you do, and that pulling your detector out of the way makes no difference.  I'm not criticizing this; it's a damn good assumption, but don't pretend it's not being made.

And anyway, what we really do when we perform this kind of experiment is that we position our source and aim it.  We base our angle of incidence upon measurements of the physical setup of the experiment, not on a direct measurement of which way the light is travelling before it reaches the mirror.

What you can do with photons, and what is a perfectly legitimate experimental set up, is that you can start with a collimated photon source.  You can measure the output profile of that source.  Then you can aim it at a mirror.  You will know the angle of incidence to within an experimental error based on your first measurement, which lets you make a prediction of the angle of reflection with an acceptable margin of error.  You can then

Has anyone done that experiment?  I'll confess that I don't know.  I do know that interference and diffraction experiments have been done with a photon-at-a-time source.  I know that classical optics essentially treats specular reflection as a special case of diffraction.  And I know that modern astronomers rather rely on their telescopes (which use mirrors) being able to make images of stars and deep-sky objects even when the light from those sources is coming in one photon at a time.  Do you have serious doubts that specular reflection works the same when you turn down the intensity of your source to the point that you get one photon at a time?

[lightarrow]

No. What I say is that the particle/photon paradigma doesn't explain anything here.

[Im intrigued]

Since the silver backing is responsible for the reflection what does the glass add to the mirror? I'm assuming that the glass clarifies and/or removes the the metallic quality from the reflection. If so how?   

[lightarrow]

Since the silver backing is responsible for the reflection what does the glass add to the mirror? I'm assuming that the glass clarifies and/or removes the the metallic quality from the reflection. If so how?   

The glass does several things:
1. It allows the deposition of a very thin film of metal, saving metal.
2. It provides a very smooth and plane reflecting surface.
3. It protect the metal from wear, scratches and chemical corrosion and provides a very rigid media for the reflecting surface.
4. It allows to use the metal surface and not its unperfectly transparent oxide layer (in the case of Aluminum for example).

[MikeS]

I think the best explanation of how a mirror works was made by Richard Feynman.  I believe the explanation is covered in his video lectures available here
http://vega.org.uk/video/subseries/8

[FredL]

Sorry for butting in but---I just want to know---why does a mirror reverse things left and right but not up and down and how does it know the difference?

[burning]

Sorry for butting in but---I just want to know---why does a mirror reverse things left and right but not up and down and how does it know the difference?

Keep in mind that "right" and "left" are concepts defined relative to an individual, while "up" and "down" are concepts defined relative to the surface of the Earth.  This is, I think, where most of the confusion comes from in this question.  You can just as easily ask "When I'm talking face-to-face with someone, why do we agree on which directions are up and down but disagree on which directions are left and right?"

To see what's really going on in a mirror, you need to think about directions that are on the same footing.  So for the sake of argument, let's suppose you have a mirror on the north wall of your house.  When you look at yourself in the mirror, your up and down are your image's up and down, your east and west (directions on the same relative footing as up and down) are your image's east and west, but your north is the mirror's south and vice versa.

[Geezer]

Fred,

The reason it works that way is because the mirror does not actually reverse anything. The image in a mirror is a true reflection of reality. Relative to you, up is up and right is right.

When you look at a photograph, the image in the photograph was taken from a completely different position in space, so what you see is relative to that position in space.

[Don_1]

The image in a mirror is a true reflection of reality.

WHAT??? No, no, no. This can't be true......