A ridiculously simple question: How does a mirror work ?

Originally posted by Phage
reply to post by tauristercus

 

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

That makes two of us ... oh, to be young again !

Anyway, one thing I've learned from this thread is that there appears to be no readily available source of information that essentially comes right out and states categorically, unambiguously and without a shadow of a doubt that we understand, at the very base level, something as essential as photon/electron interactions.
After all, isn't it somewhat of a concern that we've built up this huge edifice of a technological society based around what we "see" an electron and photon do but without an understanding of "how" they do it.

Let me quote a section of my avatar ....

"We've become a race of technologically advanced imbeciles living in a world we don't understand ..."

reply to post by tauristercus

Wait for it....

reply to post by tauristercus

Again, you don't get it. You keep describing electrons and photons like they're billiard-balls, with determinable locations and definite numbers that describe their properties at any point in time. They aren't like that. They only seem to act that way, sometimes. You keep asking for a 'sequence of events', but that's not how time works. It's simply wrong to assume that time continues in a determinable continuum between observed quantum events.

Did you read the double-slit experiment link I posted? Here's the interesting part:

When a great number of photons are sent through the apparatus one by one and recorded on photographic film, the same interference pattern emerges that had been seen before when many photons were being emitted at the same time.

That means that a single photon acts like the path it takes depends upon all the paths available to it. It's not like how billiard-balls act at all.

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.

That explanation is wrong. That's just an analogy given to people who insist that the universe must act the same at the atomic scale as it does at the macroscopic scale. It's not possible to account for actual experimental results within that conceptual model.

... oh, to be young again

Sometimes I feel like I wouldn't completely understand all this stuff if I had ten lifetimes to study it.

Originally posted by Ian McLean
reply to post by tauristercus

 

Again, you don't get it. You keep describing electrons and photons like they're billiard-balls, with determinable locations and definite numbers that describe their properties at any point in time. They aren't like that. They only seem to act that way, sometimes. You keep asking for a 'sequence of events', but that's not how time works. It's simply wrong to assume that time continues in a determinable continuum between observed quantum events.

Actually, yes I do get it and to repeat what I said earlier, it makes no difference to the topic of this thread whether we're talking particles or waves. I'm NOT concerned with that aspect ... though even at this level we're already getting bogged down ... is it a particle ? is it a wave ? is it just a probability smear ?

I'm more concerned with the actual physical interaction between the photon and electron and which no one seems able to answer definitively. Yes, I know it's the quantum realm where weird things happen but irrespective, nature has worked it out somehow that photons and electrons intimately interact on the lowest level possible.
Again, I don't care if it's a wave and wave interacting, or a particle and wave interacting, or even a particle and particle interacting ... I am looking for a detailed explanation as to what happens "behind the curtains" so to speak during the period that the photon and electron are busy interacting with each other. The trouble is I keep asking and searching, but nowhere does there seem to be an answer or an indication that anyone even knows.

What I'm looking for is a detailed and exhaustive explanation of how the energy contained in the photon is transferred from the photon to the electron.
Also ...
I want to know what mechanism "triggers" the start of this transfer.
I want to know how the energy is received and stored by the photon.
I want to know what mechanism triggers the electron into receiving the energy.
I want to know how the electron stores the energy and where.
I want to know what mechanism eventually triggers the electron into spontaneously re-emitting that stored energy.
I want to know how the stored energy is removed from the electron.
I want to know what mechanism uses that re-emitted energy and begins photon construction.
I want to know how the construction of the photon takes place.
I want to know if it takes time to build the photon or does it just "appear" fully created.
I want to know if the photon during the "creation phase" is at any point in time stationary or moving at a speed less than c, or is it immediately in motion at full c speed even as its being "created".
I want to know what mechanism determines the direction that the created photon will move off in.

And lots more questions all revolving around that "basic" photon/electron interaction.

Has current physics got the answers to the above questions ? Do we (physicists) clearly understand the mechanism that nature uses to do the above actions ?

Simple question ... is the answer YES or NO ??

reply to post by tauristercus


Heheheheh light! its a particle and a desert topping ummm... I mean a particle and a wave lol Ummm......... um , thats what they say about gravity. Im guessing `they` dont hava clue.

reply to post by tauristercus




As for what begins the transfer, obviously it would be difficult to find out what the very beginning catalyst in this universe was.

All things that have happened since the very first moment happen because of that first action. Therefore, all actions are always the effects of other actions since and all actions generate new effects.

IF you wanna get to what directly triggered the light from a flashlight bulb, that shouldn't be hard to determine.

As far as how matter interacts with light, this video has an answer.

reply to post by tauristercus


Your way over complicating things. The reason a mirror reflects light is it causes the electrons in the silver on the back of the glass to vibrate. Theres no storage of energy occurring at all. Its simple action and reaction. Did you wonder why mirrors use metal ? Metals work better as mirrors because they have many electrons shared by all the metal atoms, but the atoms in glass don’t share their electrons very well with their neighbors. That’s also why metals are used in wires to conduct electricity. The mirror is just like a wire it passes on the energy it receives.

Now we could get into an explanation of Fermi surface, Brillouin zones, lattice structure, and the electronic band structures But still comes down to the conduction of electrons just as if you ran electricity through a wire. Your making it more complicated because your not thinking of light as being energy which is all it is.

Originally posted by dragonridr
reply to post by tauristercus

 

Your making it more complicated because your not thinking of light as being energy which is all it is.

edit on 9/23/10 by dragonridr because: (no reason given)

Errrr ... actually if you read my posts, you'll find that all along I have been treating light (photons) as energy carriers.
Out of the many questions that I am asking, one of them is for someone to produce a complete explanation of HOW the energy contained in the photon is transferred to the electron.

So far, I've not seen a single post that confirms that we (physicists) really, really understand whats happening during reflection at the quantum level. We think we understand whats happening from an "overall point of view" ... but as for the underlying mechanics, we seem to be in the dark (pun intended).

I like your thinking tauristercus.

I don't want to disrupt your thread because I like where it is going.
Just a quick question for anyone who knows more than me about this ..

The only time I see a mirror produce an aberration is when I'm in an elevator with the typical LED display for the floor number.

When I see this in a reflection the straight lines on the 7 or the 1 appear to be at an angle. Probably about 20 degrees from straight. It's always puzzled me. Appears only to happen with LED displays reflected in a mirror.

I'd love an explanation.

Originally posted by ppk55

I don't want to disrupt your thread because I like where it is going.

Feel free to disrupt because from the responses I've been getting, this thread is actually going nowhere due to the fact that "reflection" appears to be such a fixed part of our daily experience that we take it essentially for granted ... a mirror reflects, and everyone accepts that it does and thats the end of that. We all "think" we know what reflection is all about until someone starts asking some very pointed questions about whats really happening down at the quantum level and then we start to see that we really have no idea whats actually happening "behind the scenes".
And this seems to be the case with the majority of our "scientific knowledge". We've learned essentially through trial and error how to manipulate light and electrons and as a result have created all the wonderful technology that we surround ourselves with. But when you start to really dig deeply in to the "why does it work", that we begin to see that we are essentially ignorant of how nature has created and operates the "machinery" that makes the quantum world tick.

Just a quick question for anyone who knows more than me about this ..

The only time I see a mirror produce an aberration is when I'm in an elevator with the typical LED display for the floor number.

When I see this in a reflection the straight lines on the 7 or the 1 appear to be at an angle. Probably about 20 degrees from straight. It's always puzzled me. Appears only to happen with LED displays reflected in a mirror.

I'd love an explanation.

Hmmm ... can't say that I've ever noticed that effect myself but does seem to be an interesting one. Unfortunately I have no idea what may be the cause but the next time I'm in an elevator similar to the one you described, I'll be sure to check out if that "effect" happens to me, too.

Originally posted by dragonridr
reply to post by tauristercus

 

Your making it more complicated because your not thinking of light as being energy which is all it is.

LIGHT IS 3-D.

You can STOP IT WITH YOUR HAND.

It is NOT just energy.

You cannot stop potential energy with your hand. Some forms of kinetic energy you cannot stop with your hand.

So how could the hand stop pure energy?

Originally posted by tauristercus

Originally posted by ppk55

I don't want to disrupt your thread because I like where it is going.

Feel free to disrupt because from the responses I've been getting, this thread is actually going nowhere due to the fact that "reflection" appears to be such a fixed part of our daily experience that we take it essentially for granted

Respond to my post before you get all depressed.

Pay attention to some logic before you quit, eh?

Hi tauristercus

Unfortunately the simple questions are often the hardest to answer. The answers can also be very dependent on the application area(what answer is good enough to the questioner).

As to your more explicit questions posted above. Here is the classical view(model):

I want to know what mechanism "triggers" the start of this transfer
I want to know how the energy is received and stored by the photon.
I want to know what mechanism triggers the electron into receiving the energy.

See a photon as a electromagnetic disturbance(wave packet). It will accelerate the electron(charge). Due to acceleration the electron will absorb the photon by linear superposition(emmit an "anti" photon).

I want to know how the electron stores the energy and where.

Potential energy (distance) between atom core and electron and kinetic energy (speed) of the electron.

I want to know what mechanism eventually triggers the electron into spontaneously re-emitting that stored energy.

No classic answer. See quantum physics.

I want to know how the stored energy is removed from the electron.

Deceleration of the electron reducing its kinetic/potential energy.

I want to know what mechanism uses that re-emitted energy and begins photon construction.
I want to know how the construction of the photon takes place

Any electric charge which accelerates produces electromagnetic radiation due to finite propagation speed of the electromagnetic field.
Problem: Why aren't atoms collapsing emmitting all their energy? No classic answer. See quantum physics.

I want to know if it takes time to build the photon or does it just "appear" fully created.

No idea. Not sure if I understand the question.

I want to know if the photon during the "creation phase" is at any point in time stationary or moving at a speed less than c, or is it immediately in motion at full c speed even as its being "created".

A photon as a electomagnetic wave(packet) has a speed of c in vacuum.

I want to know what mechanism determines the direction that the created photon will move off in.

There is no preferred direction.

reply to post by tauristercus


I have the same question lingering on from high school, just repeated the official stories in answer papers for getting scores.

Also agree that Feynmann did not touch upon how reflection takes place but about how light reaches a particular point after reflection happened (Oh God, but how did that happen ???) . definitely not the explanation we are looking for.
Have lot of similar queries along these lines myself too.

The photon is absorbed by an atom(charge em-field interaction). The atom is in an excited state. This state has a certain probability. There is also a half-life. This means after a certain time period a photon will be reemitted returning the atom in its stable state. It is actually analogous to radioactive decay.

Now we have absorption and emission. But what about the reflection angle?
A light ray has a width. Given an angle relative to the reflecting surface the photons won't reach the surface at the same time. This means there will also be a time difference in the emission creating a reflected ray by superposition. It is analogous to a reflection of a water wave.

How Fundamental Do You Want to Get?

Dear OP, I actually agree with your broader premise, which is that science may reach the limits of explanation at some point. In fact, I will go farther than you do, and say this is, in fact, inevitable.

However, this failure is not one of science, as you say; indeed, it is not a failing at all. It is simply a manifestation of our own physical nature, of the kind of organisms we are. Organic senses and brains have evolved over some few hundred million years to interact with the physical environment in certain very limited and specific ways. These ways differ from organism to organism (a bacterium lives in a universe in which distances are defined by gradients of chemical concentration, a bat lives in a world where sound is vision) but in each case they are inherent to the organism. They are 'reality' to the organism, but every different species experiences a different reality. And all these specific realities are only organic metaphors for absolute physical reality, which is not directly apprehensible or comprehensible to any organism. I am no mystic, but the Veil of Maya does, I believe, exist. It is what makes us perceive a table as a table, rather than a more-or-less strictly choreographed dance of energies in a vacuum.

These limits of sense and knowledge are inherent and ultimately inescapable. We can extend our senses using various artificial instruments to amplify and transduce the energies impingent upon them, but our understanding of what we perceive through our instruments is necessarily analogical or metaphorical; transduction is, after all, the physical equivalent of analogy! The limits of knowledge are similarly rigid; we can only know in terms of what we are evolved to know, meaning that we can only explain what we discover by analogy with what we already do understand. If we keep on mercilessly analyzing and dissecting, we eventually reach a point where analogy itself becomes useless; we end up piling metaphor on metaphor like crazy alchemists, explaining nothing. We will have reached the limits of the possible, as far as human knowledge is concerned.

Science is based on the assumption that the universe is ultimately explicable, that all questions have answers we can understand. There are no empirical grounds for this assumption whatsoever; it is only induction from the past successes of human inquiry that supports it, just as it is only induction from previous experience that tells us the Sun will rise tomorrow. But induction is not always right; one fine tomorrow, sooner or later, the Sun will not rise. And one fine tomorrow, we will discover that not all questions have answers we can understand.

Some may think we have reached that place already. I do not. We have much to learn, and a long way to go, before we reach the limits of scientific inquiry. I remain, despite what I have written above, a dedicated scientific materialist who will have no truck with magic or mumbo-jumbo in any form whatsoever.

One last thing: we must not forget that escape from this prison is possible. We need only cease to be human.

reply to post by tauristercus


Dude, I thought about this phenomenon again.How light is reflected and how actually we perceive it. It just doesn't make any sense. I think this is one of those " Newton's apples " which if pursued might have us rewrite modern science as we know it. Good luck pondering over it.