A ridiculously simple question: How does a mirror work ?

Originally posted by Segador
www.ehow.com...
science.howstuffworks.com...

If it helps at all.

From: How Does a Mirror Work ?

The reflected image is comprised of photons, which are particles of light. When these photons initially hit the mirror they cause electrons to vibrate within atoms, which in turn produces an identical light photon. When light strikes a plane mirror, the light is reflected back at an equal angle, yet reversed from right to left.

and from:
How Light Works

In other words, the materials contain many free electrons that can jump readily from one atom to another within the material. When the electrons in this type of material absorb energy from an incoming light wave, they do not pass that energy on to other atoms. The energized electrons merely vibrate and then send the energy back out of the object as a light wave with the same frequency as the incoming wave.

The 2 examples above that purport to "explain" how reflection works are typical of the answers that are supplied when the question is asked. Its as if these "generalized answers" are deemed entirely sufficient to answer the question of how reflection works ... and yet not one of them actually explains reflection by getting in deep and explaining the actual intricate mechanism at work between incoming photons and electrons in the reflecting material.

So as I've been stating, we "know" how to make mirrors (and have for 1000's of years) but apparently we DO NOT understand fully what's actually happening at the atomic / quantum level that makes reflection work.

Originally posted by Phage

Originally posted by tauristercus

Now, how does this single atom perform this marvelous feat of reversing the photons path by exactly 180 degrees ?

That particular emitted photon may or may not be returned at 180º (assuming that 90º angle of incidence). That's exactly what Feynman explains. It's a matter of probabilities, some are and some aren't but the majority are. The probability is that the majority of photons are emitted at an angle equal to the angle of incidence. That majority composes the wave that leaves at 180º

You're asking for a simple answer to why or how. In quantum mechanics there is no such thing. Just gotta deal with it unless you want to go through the years of schooling required to "understand" it. I didn't, I don't. Not in detail but in concept.

edit on 9/19/2010 by Phage because: (no reason given)

I think your talking about the Huygen's principle As it iteracts with the surface molecules it energizes each one that the front reaches and releases photons in a spherical wavelet. Problem is saying a photon hits the atom is only half the answer. The thing about photons is theres never just 1 but a stream of them .

Originally posted by Phage

Originally posted by tauristercus

Now, how does this single atom perform this marvelous feat of reversing the photons path by exactly 180 degrees ?

That particular emitted photon may or may not be returned at 180º (assuming that 90º angle of incidence). That's exactly what Feynman explains. It's a matter of probabilities, some are and some aren't but the majority are. The probability is that the majority of photons are emitted at an angle equal to the angle of incidence. That majority composes the wave that leaves at 180º

You're asking for a simple answer to why or how. In quantum mechanics there is no such thing. Just gotta deal with it unless you want to go through the years of schooling required to "understand" it. I didn't, I don't. Not in detail but in concept.

edit on 9/19/2010 by Phage because: (no reason given)

I understand what you're saying but again, what you've described above is a "generality" type of answer. What I'm asking is why, at our present level of scientific/technological "brilliance", we still apparently have no detailed explanation of HOW the mechanism that allows an electron to absorb an incoming photon ... or the mechanism that allows the electron to store the absorbed energy ... or the mechanism that causes a release of that stored energy ... or how that released energy is converted back into a photon ... or whether that photon is created instantaneously (zero elapsed time) or takes some finite time to be "created" ... or the mechanism that causes the electron to move from one energy level to another ... or the mechanism that creates and maintains those energy levels ... or whether an electron "jumps" in zero time or whether it takes a finite amount of time to traverse energy levels ... etc, etc, etc

Do you get where I'm going with this ?

All the above questions are directly associated with the mechanism of reflection ... and yet we have no detailed and satisfactory answers to any of them.

So yes, we have a "general" concept of how reflection works and even have "laws" describing what we "observe" happening during reflection ... but deep, deep down ... we know very little regarding the rock-bottom reason why reflection works.

The photons are released on the angle you see because the mirror was designed to be perfectly flat thus relating the image perfectly flat

Take a look at a trick mirror, or a metal that is less reflective. The angle is changed, your appearance is warped.

It is to say water must have the same reflective properties as it will also give your reflection.

You need to look more into light than into the properties that reflect it

reply to post by tauristercus

Yup. Science is not big on why. It's all about how. We know how gravity works, not so much why. Best leave why to metaphysics, they'll have most of the answers you're looking for and if they don't they'll just make one up.

Me, I don't really care why it works as long as it I have an idea how. But in the past few years my mirrors have been acting kind of funny. I wonder why.

Explanation: Hmmm? Good Question! S&F!

I sourced this from my personal copy of "Physics" 5th edition by Giancoli page 834...

When a photon passes through matter, it interacts with the atoms and electrons. There are four important types of interactions that a photon can undergo:

1. The photon can be scattered off an electron [or a nucleus] and in the process lose some energy; this is the Compton effect. But notice that the photon is not slowed down. It still travels with speed c, but its frequency will be lower.
   
2. The photoelectric effect: a photon may knock an electron out of an atom and in the process itself disappear.
   
3. The photon may knock an atomic electron into a higher energy state in the atom if its energy is not sufficient to knock the electron out altogether. In this process the electron also disappears, and all its en energy is given to the atom. Such an atom is then said to be in an excited state, and we shall discuss this more later.
   
4. Pair production: A photon can actually create matter, such as the production of an electron and a positron. [A positron has the same mass as an electron, but the opposite charge, + e ]
   

Compton scattering [wiki]

Photoelectric effect [wiki]

Excited state [wiki]

Pair production [wiki]

In the case of the mirror, we are looking explicitly at the Compton effect and its mechanics are well defined!

Personal Disclosure: You can't fool me... I'm already stupid! What with a lowly IQ of 125 and having failed Yr10 I'm surprised I can even remember to breath! :shk:

reply to post by SaturnFX


Hey! I like your idea. It kind of makes sense in a way. So as soon as we start measuring things "change". Does it all stay changed or will it shrink back to what it was once we stop looking and measuring?

Mirrors, how do they work? LMAO this reminds me of a Saturday Night Live parody....



I know it's off topic, but it's good for a laugh or two.

Now wait a minute here Op . Your saying main stream science doesnt just say that the photon is bounced back but a new photon is somehow created and sent back at the incoming angle? And they try and support this using the proprieties of atoms? Kinda makes me wonder if we even know what light is . cool thread ty I did not know this)

reply to post by davespanners


Because someone else did. We not only create our awareness, but others as well. Maybe?

Originally posted by OmegaLogos
Explanation: Hmmm?

Good Question! S&F!

I sourced this from my personal copy of "Physics" 5th edition by Giancoli page 834...

When a photon passes through matter, it interacts with the atoms and electrons. There are four important types of interactions that a photon can undergo:

1. The photon can be scattered off an electron [or a nucleus] and in the process lose some energy; this is the Compton effect. But notice that the photon is not slowed down. It still travels with speed c, but its frequency will be lower.
   
2. The photoelectric effect: a photon may knock an electron out of an atom and in the process itself disappear.
   
3. The photon may knock an atomic electron into a higher energy state in the atom if its energy is not sufficient to knock the electron out altogether. In this process the electron also disappears, and all its en energy is given to the atom. Such an atom is then said to be in an excited state, and we shall discuss this more later.
   
4. Pair production: A photon can actually create matter, such as the production of an electron and a positron. [A positron has the same mass as an electron, but the opposite charge, + e ]
   

Compton scattering [wiki]

Photoelectric effect [wiki]

Excited state [wiki]

Pair production [wiki]

In the case of the mirror, we are looking explicitly at the Compton effect and its mechanics are well defined!

The above is a very good example of what I've been saying ... namely, that whilst we have a very good understanding of what we can observe happening and what we can experimentally measure as happening, we have next to no clear explanation as to whats happening at the atomic level.

In the above, descriptions are given that "seem" to explain whats happening but in fact tell us nothing about the actual mechanics underlying those descriptions.

The photon can be scattered off an electron [or a nucleus]... Ok, so how does this scattering actually happen ? What happens to the photon as it approaches the electron ? How close do they have to be before they interact ? What happens at the exact moment of interaction ? How does the photons energy get transferred to the electron ? How does the electron store the gained energy ? How does the electron release the stored energy ? How does the stored energy get converted into a photon ? How is the direction of the created photon get determined ?

And similar arguments can be made regarding the other statements of
...and in the process lose some energy Whats the mechanism behind the energy loss ?
...a photon may knock an electron out of an atom Whats the mechanism knocking the electron out ?
... and in the process itself disappear How does the photon disappear ? All at once or gradually over time ?
The photon may knock an atomic electron into a higher energy state How exactly does this work ?

As you can see, all we seem to have is a vague idea of the overall actual process but almost no explanations for the deep down, underlying mechanics of whats happening between the photons and electrons that make reflection happen.

reply to post by tauristercus


You seem to want light to only act as a particle. It doesn't. We don't live in a 'clockwork universe':

Wave-Particle Duality

The interesting experiment is the double-slit experiment.

The brain is also a modem, you project your image into the mirror, your seeing what you believe others see you like. So yes its all magic.

Originally posted by Ian McLean
reply to post by tauristercus

 

You seem to want light to only act as a particle. It doesn't. We don't live in a 'clockwork universe':

Again, you're missing my point. Particle or wave ... makes no difference whatsoever.
Where's the explanation for the exact mechanism by which energy is transferred from the (particle or wave) photon to the electron ? How is this transfer process initiated ? whats happening during the transfer process ? How (and where) does the electron store the received energy ?

Lots of questions ... very few answers

Originally posted by Phage
reply to post by tauristercus

 

Me, I don't really care why it works as long as it I have an idea how. But in the past few years my mirrors have been acting kind of funny. I wonder why.

Interesting that you should say that. I myself find it more important to know why something works and then figure out the how. in fact if you know why something works the how usually follows.

reply to post by tauristercus

All of your "how" questions are questions about quantum mechanics. Without knowing the math behind it (that stuff that takes years to pull together), the best you're going to get is answers like those which you have given. Quantum mechanics doesn't translate to English (or any other spoken language). Why?

Because.
That's why.

The better question is "How does light interact with matter?"

Every bit of matter is a mirror because without the source of light, there is no visible matter.

All matter reflects the source - for without it nothing is visible.

A mirror just happens to be a, generally, larger and more smooth form of all matter and therefore the reflection offers us a more vain lifestyle.

I will be back to give a good explanation of how I believe light interacts with matter.

And to top it off with mythology here, some jewish folklore/tale:

Lilith en.wikipedia.org...

Shes uses mirrors to possess the person with demons.

In the movie Constantine, starring Keanu Reeves who in the first scene of the movie takes out the demon from this possessed person with a MIRROR.

Originally posted by Phage
reply to post by tauristercus

 

All of your "how" questions are questions about quantum mechanics. Without knowing the math behind it (that stuff that takes years to pull together), the best you're going to get is answers like those which you have given. Quantum mechanics doesn't translate to English (or any other spoken language). Why?

Because.
That's why.

So I take it from your answer, that if we fall back on mathematics as the descriptive language, that the mechanics and principles to answer the questions that I have posed are thoroughly established, understood exactly and no longer considered unknown ?
Therefore somewhere, someone has derived an exact mathematical description and understanding of the mechanics for example, of the sequence of events that transpire as a photon approaches an electron and begins to transfer its energy to that electron ? And somewhere, someone has an exact mathematical description and understanding of the mechanics for example, of exactly how the electron has stored the absorbed energy ? And somewhere, someone has an exact mathematical description and understanding of the mechanics for example, of the sequence of events that transpire when the electron re-emits that stored energy and explains how the photon is created ?

Any chance you'd have a link to such explanations, please ? I've searched but unfortunately must be asking the wrong questions as all I'm getting are generalites

This is how the explanation normally goes ... the photons energy is absorbed by the electron causing it to jump to a higher energy level. The electron remains at that higher energy level until it spontaneously re-emits that energy as a photon.
But how about an explanation as to all the intricate, individual processes that happen within that above general explanation. Does anyone REALLY have a clue ?

It's akin to saying that put petrol (gas) in a car engine and it causes the car to move. But within that simple explanation are 1000's of individual processes ... and it's THAT detail that I want someone to hold up their hand and say "Yes, we completely and thoroughly understand everything that happens when that car moves" ... or in my case, "Yes, we completely and thoroughly understand everything that happens when a photon and electron interact."

When you say the following:

Quantum mechanics doesn't translate to English (or any other spoken language). Why?

Because.
That's why.

... unfortunately that's a very unsatisfying answer.

Either we KNOW or we DO NOT KNOW.

reply to post by tauristercus


Well, maybe you should get into quantum mechanics and find out.
Kind of late in the game for me.