Thread: Is Light Really Made of Photons?

Everyone seems to take for granted these days the scientific certitude of the fact that light is actually made of photons but consider the following: Visible light forms only a comparatively small fragment of the entire electromagnetic spectrum. On the same spectrum are ultraviolet light, X-rays, gamma rays, infrared, microwaves and radio waves. Both gamma rays and radio waves, for example, are therefore made of exactly the same stuff as visible light is.

But are radio waves really comprised of photons as well?

Some radio waves have wavelengths measured in kilometres. If the wavelengths are measurably this long then how extensive are these ‘photons’ the radio waves are made from? Are they also kilometres in length?

Also when you turn your radio on first thing in the morning you may be interested to know that the aerial attached to the radio is actually a ‘photon capturing device’, photons which are in turn carrying the signal transmitted from the local radio station.

And how do these photons induce a current in the length of a conducting aerial which is amplified and sent to the speaker to produce the sound you can then hear? The length of the aerial usually has to bear some relation to the wavelength being captured, typically it has to be one quarter of a wavelength in length. And then there has to be an oscillating charge along the length of the aerial so as to induce an alternating current within it. But if radio waves are made of photons then how do the photons produce this effect within the radio aerial unless of course they are very large spatially?

I think you’ll agree the whole thing is nonsense.

Radio waves cannot possibly be made of photons at all. Radio waves are created by a rapidly oscillating charge within a conductor, the frequency of this oscillation being identical to the frequency of the radio waves produced, and a rapidly oscillating charge within a conductor does not emit photons.

But if radio waves are not made of photons then neither is visible light either.

I, for one, believe that light is made of waves and that photons do not exist. Your not alone.

Originally Posted by galexander

Everyone seems to take for granted these days the scientific certitude of the fact that light is actually made of photons but consider the following: Visible light forms only a comparatively small fragment of the entire electromagnetic spectrum. On the same spectrum are ultraviolet light, X-rays, gamma rays, infrared, microwaves and radio waves. Both gamma rays and radio waves, for example, are therefore made of exactly the same stuff as visible light is.

But are radio waves really comprised of photons as well?

Some radio waves have wavelengths measured in kilometres. If the wavelengths are measurably this long then how extensive are these ‘photons’ the radio waves are made from? Are they also kilometres in length?

Also when you turn your radio on first thing in the morning you may be interested to know that the aerial attached to the radio is actually a ‘photon capturing device’, photons which are in turn carrying the signal transmitted from the local radio station.

And how do these photons induce a current in the length of a conducting aerial which is amplified and sent to the speaker to produce the sound you can then hear? The length of the aerial usually has to bear some relation to the wavelength being captured, typically it has to be one quarter of a wavelength in length. And then there has to be an oscillating charge along the length of the aerial so as to induce an alternating current within it. But if radio waves are made of photons then how do the photons produce this effect within the radio aerial unless of course they are very large spatially?

I think you’ll agree the whole thing is nonsense.

Radio waves cannot possibly be made of photons at all. Radio waves are created by a rapidly oscillating charge within a conductor, the frequency of this oscillation being identical to the frequency of the radio waves produced, and a rapidly oscillating charge within a conductor does not emit photons.

But if radio waves are not made of photons then neither is visible light either.

All electromagnetic radiation is photons. The only difference is the energy per photon.
What we call an electromagnetic wave is a very large number of photons.

The general theory is quantum electrodynamics. See the sticky thread in this forum for a link to lectures by Richard Feynman on the subject. It is hardly nonsense. Rather it is ine of the most successful physical theories ever.

Waneman28 can and should be ignored.

I would like to give a humorous reply which is also a question:

There is a joke which runs thus:

How many Surrealists does it take to change a light bulb?
Answer: Fish.

There must be an equivalent joke for Quantum Physicists:

How many Quantum Physicists does it take to change a light bulb?
Answer: As it is uncertain where the light bulb is at any given point in time there is only a probability that several Quantum Physicists could achieve the task successfully. But then again the light bulb could be a wave!

Sorry, that was the best I could do but I am open to suggestions as to an alternative punchline.

Originally Posted by galexander

Everyone seems to take for granted these days the scientific certitude of the fact that light is actually made of photons but consider the following: Visible light forms only a comparatively small fragment of the entire electromagnetic spectrum. On the same spectrum are ultraviolet light, X-rays, gamma rays, infrared, microwaves and radio waves. Both gamma rays and radio waves, for example, are therefore made of exactly the same stuff as visible light is.

But are radio waves really comprised of photons as well?

Some radio waves have wavelengths measured in kilometres. If the wavelengths are measurably this long then how extensive are these ‘photons’ the radio waves are made from? Are they also kilometres in length?

Also when you turn your radio on first thing in the morning you may be interested to know that the aerial attached to the radio is actually a ‘photon capturing device’, photons which are in turn carrying the signal transmitted from the local radio station.

And how do these photons induce a current in the length of a conducting aerial which is amplified and sent to the speaker to produce the sound you can then hear? The length of the aerial usually has to bear some relation to the wavelength being captured, typically it has to be one quarter of a wavelength in length. And then there has to be an oscillating charge along the length of the aerial so as to induce an alternating current within it. But if radio waves are made of photons then how do the photons produce this effect within the radio aerial unless of course they are very large spatially?

I think you’ll agree the whole thing is nonsense.

Radio waves cannot possibly be made of photons at all. Radio waves are created by a rapidly oscillating charge within a conductor, the frequency of this oscillation being identical to the frequency of the radio waves produced, and a rapidly oscillating charge within a conductor does not emit photons.

But if radio waves are not made of photons then neither is visible light either.

I think you are right to want specific answers to these questions. Searching the forum it appears that people only have dogmatic one-liners to offer when the answer is obscure. Anyone who has been in a school knows the drill: waves have a dual nature, but to me that is the same as saying: "we have no real understanding as to what waves are, but by analysing them as though they were particles and waves, we are able to make predictions". It seems to me a very indirect understanding of nature, but perhaps the theory is explained adequately somewhere else (?)

.o:0|O|0:o.

Originally Posted by .o:0|O|0:o.

Originally Posted by galexander

Everyone seems to take for granted these days the scientific certitude of the fact that light is actually made of photons but consider the following: Visible light forms only a comparatively small fragment of the entire electromagnetic spectrum. On the same spectrum are ultraviolet light, X-rays, gamma rays, infrared, microwaves and radio waves. Both gamma rays and radio waves, for example, are therefore made of exactly the same stuff as visible light is.

But are radio waves really comprised of photons as well?

Some radio waves have wavelengths measured in kilometres. If the wavelengths are measurably this long then how extensive are these ‘photons’ the radio waves are made from? Are they also kilometres in length?

Also when you turn your radio on first thing in the morning you may be interested to know that the aerial attached to the radio is actually a ‘photon capturing device’, photons which are in turn carrying the signal transmitted from the local radio station.

And how do these photons induce a current in the length of a conducting aerial which is amplified and sent to the speaker to produce the sound you can then hear? The length of the aerial usually has to bear some relation to the wavelength being captured, typically it has to be one quarter of a wavelength in length. And then there has to be an oscillating charge along the length of the aerial so as to induce an alternating current within it. But if radio waves are made of photons then how do the photons produce this effect within the radio aerial unless of course they are very large spatially?

I think you’ll agree the whole thing is nonsense.

Radio waves cannot possibly be made of photons at all. Radio waves are created by a rapidly oscillating charge within a conductor, the frequency of this oscillation being identical to the frequency of the radio waves produced, and a rapidly oscillating charge within a conductor does not emit photons.

But if radio waves are not made of photons then neither is visible light either.

I think you are right to want specific answers to these questions. Searching the forum it appears that people only have dogmatic one-liners to offer when the answer is obscure. Anyone who has been in a school knows the drill: waves have a dual nature, but to me that is the same as saying: "we have no real understanding as to what waves are, but by analysing them as though they were particles and waves, we are able to make predictions". It seems to me a very indirect understanding of nature, but perhaps the theory is explained adequately somewhere else (?)

.o:0|O|0.

What is nonsense is everything in your post. Radio waves are most certainly photons, and your inability to understand the theory hardly changes that fact. Go view the videos on quantum electrodynamics. Or read a book.

Originally Posted by DrRocket

Originally Posted by .o:0|O|0:o.

Originally Posted by galexander

Everyone seems to take for granted these days the scientific certitude of the fact that light is actually made of photons but consider the following: Visible light forms only a comparatively small fragment of the entire electromagnetic spectrum. On the same spectrum are ultraviolet light, X-rays, gamma rays, infrared, microwaves and radio waves. Both gamma rays and radio waves, for example, are therefore made of exactly the same stuff as visible light is.

But are radio waves really comprised of photons as well?

Some radio waves have wavelengths measured in kilometres. If the wavelengths are measurably this long then how extensive are these ‘photons’ the radio waves are made from? Are they also kilometres in length?

Also when you turn your radio on first thing in the morning you may be interested to know that the aerial attached to the radio is actually a ‘photon capturing device’, photons which are in turn carrying the signal transmitted from the local radio station.

And how do these photons induce a current in the length of a conducting aerial which is amplified and sent to the speaker to produce the sound you can then hear? The length of the aerial usually has to bear some relation to the wavelength being captured, typically it has to be one quarter of a wavelength in length. And then there has to be an oscillating charge along the length of the aerial so as to induce an alternating current within it. But if radio waves are made of photons then how do the photons produce this effect within the radio aerial unless of course they are very large spatially?

I think you’ll agree the whole thing is nonsense.

Radio waves cannot possibly be made of photons at all. Radio waves are created by a rapidly oscillating charge within a conductor, the frequency of this oscillation being identical to the frequency of the radio waves produced, and a rapidly oscillating charge within a conductor does not emit photons.

But if radio waves are not made of photons then neither is visible light either.

I think you are right to want specific answers to these questions. Searching the forum it appears that people only have dogmatic one-liners to offer when the answer is obscure. Anyone who has been in a school knows the drill: waves have a dual nature, but to me that is the same as saying: "we have no real understanding as to what waves are, but by analysing them as though they were particles and waves, we are able to make predictions". It seems to me a very indirect understanding of nature, but perhaps the theory is explained adequately somewhere else (?)

.o:0|O|0:o.

What is nonsense is everything in your post. Radio waves are most certainly photons, and your inability to understand the theory hardly changes that fact. Go view the videos on quantum electrodynamics. Or read a book.

Actually, I only quoted another post in order to say that he is right to ask questions when the answers are not clear. Specifically, where trying to understand radio reception in terms of photons.

Who said that waves don't have photons? Not me. I have already pointed out the dual nature of waves in my very first posts, which you have read.

It seems you are unable to read a post without making "guesses" as to what the poster is thinking.

If unsure, ask for a clarification before jumping (like an ape...) to wild conclusions.

Go get some therapy!

.o:0|O|0:o.

Originally Posted by galexander

And how do these photons induce a current in the length of a conducting aerial which is amplified and sent to the speaker to produce the sound you can then hear?

Because light is electromagnetic in nature. Along the length of an electromagnetic wave, we essentially have oscillating changes in the magnetic and electric field strength, which in turn cause oscillations in the electrically charged electrons in the aerial.

These oscillations, if in the right plane (along the length of the wire) can be viewed as an alternating current, which can then be amplified.

Originally Posted by galexander

I think you’ll agree the whole thing is nonsense.

I think you'll agree that if basic physics looks like nonsense, then you haven't understood it properly.

Originally Posted by galexander

Radio waves cannot possibly be made of photons at all. Radio waves are created by a rapidly oscillating charge within a conductor, the frequency of this oscillation being identical to the frequency of the radio waves produced, and a rapidly oscillating charge within a conductor does not emit photons.

Photons are the "carrier-particles" of the electromagnetic force. The oscillation you are describing is electromagnetic in nature, therefore the waves produced must consist of photons.

Originally Posted by drowsy turtle

Originally Posted by galexander

And how do these photons induce a current in the length of a conducting aerial which is amplified and sent to the speaker to produce the sound you can then hear?

Because light is electromagnetic in nature. Along the length of an electromagnetic wave, we essentially have oscillating changes in the magnetic and electric field strength, which in turn cause oscillations in the electrically charged electrons in the aerial.

These oscillations, if in the right plane (along the length of the wire) can be viewed as an alternating current, which can then be amplified.

That doesn't explain anything at all really.

Originally Posted by galexander

I think you’ll agree the whole thing is nonsense.

It is.

Originally Posted by galexander

Radio waves cannot possibly be made of photons at all. Radio waves are created by a rapidly oscillating charge within a conductor, the frequency of this oscillation being identical to the frequency of the radio waves produced, and a rapidly oscillating charge within a conductor does not emit photons.

Photons are the "carrier-particles" of the electromagnetic force. The oscillation you are describing is electromagnetic in nature, therefore the waves produced must consist of photons.

Thats a terrible argument. Why must waves produced consist of photons? Why not be just waves?

Originally Posted by Waveman28

Thats a terrible argument. Why must waves produced consist of photons? Why not be just waves?

Go ask a Priest.

No scientist knows WHY electromagnetic waves are composed of photons. What science does tell us is that electromagnetic waves ARE composed of photons. The fact that you don't like it and refuse to accept it does not change a damn thing.

Thats a terrible argument. Why must waves produced consist of photons? Why not be just waves?

http://en.wikipedia.org/wiki/Planck_constant

http://en.wikipedia.org/wiki/Ultraviolet_catastrophe

http://en.wikipedia.org/wiki/Photoelectric_effect

Without the existence of photons, CCD cameras would not be able to function. The electric charge gathered inside the individual pixels is a direct measure of the number of photons absorbed.

Originally Posted by Dishmaster

Without the existence of photons, CCD cameras would not be able to function. The electric charge gathered inside the individual pixels is a direct measure of the number of photons absorbed.

Yep

And there are detectors that can detect a single photon.

Is it perhaps possible that Feynman, Schwinger and Tomagawa received the Nobel Prize for developing a theory that actually describes real physics ?

Originally Posted by Waveman28

Originally Posted by drowsy turtle

Originally Posted by galexander

And how do these photons induce a current in the length of a conducting aerial which is amplified and sent to the speaker to produce the sound you can then hear?

Because light is electromagnetic in nature. Along the length of an electromagnetic wave, we essentially have oscillating changes in the magnetic and electric field strength, which in turn cause oscillations in the electrically charged electrons in the aerial.

These oscillations, if in the right plane (along the length of the wire) can be viewed as an alternating current, which can then be amplified.

That doesn't explain anything at all really.

Really? I thought it explained how electromagnetic radiation induced an alternating current in a conductor. Hell, I even explained it in terms of waves, rather than particles: I'm surprised that you're upset by this.

Think of it this way: an antenna that is analyzing the radiation for the information contained therein is designed to single out a property. If you're looking to make a detector to detect the particle nature of light, you can do that. If you want to detect the wave nature of light, you can do that too. But saying that one detector detects one part and another detector detects another part isn't to say that it only has 1 nature, the one you're observing.

Think of it this way: Think of any of the members of the hit TV show called 'The View'. Not only are they ugly, they sound really stupid too. But if you only had audio, and you heard them talk about stupid crap, you wouldn't think to yourself "Wow, there is no way they are ugly", in the same way that your detector detecting the wave like motion would cause you to think "Wow, there's no way that they are particles". vice Versa for the video. Turns out they're BOTH ugly and stupid in the same way that light displays wave-like properties in one regard and particle-like properties in another.

Also, photons, if I remember correctly, are virtual particles (albeit with an infinite range due to masslessness) and so they have no size.

Adding to the above it would be interesting to comment on the “Wave/Particle Duality” theme that is central to modern Quantum Theory.

I therefore move from the photon to the electron.

It is claimed that electrons behave ‘like’ waves because they produce a diffraction pattern on passing through a diffraction grating. But so what? There could be a whole number of different explanations as to why this happens. It could be due to electronic interference and deflection for example.

Indeed De Broglie himself actually stated that the ‘wave’ of the electron was ‘fictitious’. And even quantum physicists today are of the opinion that the ‘wave’ of the electron is purely a probability distribution of the likelihood of finding an electron at a given point in space. So we even have quantum physicists themselves admitting that the electron isn’t really a ‘wave’ after all.

So what happened exactly to this Wave/Particle Duality?

Is it just a case of sensationalism from 'news people' and nothing else?

Originally Posted by galexander

It is claimed that electrons behave ‘like’ waves because they produce a diffraction pattern on passing through a diffraction grating. But so what? There could be a whole number of different explanations as to why this happens. It could be due to electronic interference and deflection for example.

How about fullerenes?

Originally Posted by galexander

Indeed De Broglie himself actually stated that the ‘wave’ of the electron was ‘fictitious’. And even quantum physicists today are of the opinion that the ‘wave’ of the electron is purely a probability distribution of the likelihood of finding an electron at a given point in space. So we even have quantum physicists themselves admitting that the electron isn’t really a ‘wave’ after all.

A single electron isn't a wave, no. A group of electrons can exhibit wave properties, though, in exactly the same way that a group of photons can while a single photon cannot.

Originally Posted by galexander

So what happened exactly to this Wave/Particle Duality?

In short, you misunderstood it.

Originally Posted by drowsy turtle

Originally Posted by galexander

It is claimed that electrons behave ‘like’ waves because they produce a diffraction pattern on passing through a diffraction grating. But so what? There could be a whole number of different explanations as to why this happens. It could be due to electronic interference and deflection for example.

How about fullerenes?

Originally Posted by galexander

Indeed De Broglie himself actually stated that the ‘wave’ of the electron was ‘fictitious’. And even quantum physicists today are of the opinion that the ‘wave’ of the electron is purely a probability distribution of the likelihood of finding an electron at a given point in space. So we even have quantum physicists themselves admitting that the electron isn’t really a ‘wave’ after all.

A single electron isn't a wave, no. A group of electrons can exhibit wave properties, though, in exactly the same way that a group of photons can while a single photon cannot.

Originally Posted by galexander

So what happened exactly to this Wave/Particle Duality?

In short, you misunderstood it.

So why is it that a single electron IS a particle but a group of electrons are waves.

Its like suggesting that a herd of cows is not made up of individual cows at all. The basic logic has to be flawed surely?

So why is it that a single electron IS a particle but a group of electrons are waves.

An(1) H^2O molecule and the ocean. That's the simple answer.
Now here's the complex one; http://en.wikipedia.org/wiki/Wave%E2...rticle_duality.

Originally Posted by galexander

Its like suggesting that a herd of cows is not made up of individual cows at all.

No it's not. It's like suggesting that a herd of cows do not exhibit the same behaviour as a single, lone cow. A single cow runs in one direction; a herd of cows stampedes in a uniform direction.

That is as close as I can get to wave-particle duality using the cow analogy...

Originally Posted by GiantEvil

So why is it that a single electron IS a particle but a group of electrons are waves.

An(1) H^2O molecule and the ocean. That's the simple answer.
Now here's the complex one; http://en.wikipedia.org/wiki/Wave%E2...rticle_duality.

Well GiantEvil and drowsy turtle, you both didn't make any sense at all.

A water molecule behaves like water and an ocean behaves like water since they are both liquid etc., etc. I think what GiantEvil was trying to say is that the "chemical model" of an H2O molecule when displayed on the shelf in a chemists laboratory looks very different from an ocean. But what has that got to do with it? Every molecule in an ocean looks exactly the same and behaves exactly the same.

You would never make a philosopher GiantEvil!

As for drowsy turtle's comments about a herd of cows stampeding in the same direction......................God know's!

Well GiantEvil and drowsy turtle, you both didn't make any sense at all.

We make perfect sense, your'e just dense like neutronium dude.
The metaphorical point is that a single water molecule like a single cow like a single electron exhibits singular behavior and a bunch of things exhibit group behavior. DUH.

You would never make a philosopher GiantEvil!

Considering;

There is no position so ridiculous that it hasn't been held by some philosopher. -Cicero-

I must say it is much more fortunate to be poor at philosophy as opposed to poor at third grade science.

We have two very successful models of the universe, QM and EM. Both models work a lot of the time, and also fail some of the time but in different ways, both are crucial to modern civilisation, but both are only models of the universe, they are not the universe itself. So sometimes one model works best, sometimes the other.

For example (a trivial one I know) take the case of a rocket heading for earth at half lightspeed.

In QM: The rocket emits red photons towards earth with a red photon's energy. It arrives at earth and it is now a blue photon, but with a red photon's energy, so it should not be able to trigger an atomic transition and be detected. But it can, so something is wrong with the QM model.

In EM: The rocket shines a beam of red light towards earth which travels as a wave, and when it gets to earth it is detected as a blue light. But the detector can detect the light only in quanta of fixed energy, so it does not behave like a wave any more. Something is wrong with the EM model.

It is easiest to assume that QM can handle the conversion from energy transitions to electromagnetic form while EM cannot. And that the transport of this energy form through space is best handled by EM rather than QM, even though there is a convenience in QM same-frame experiments that allows the transport to be dealt with as discrete photons.


However, in the case of radio waves there seems to be a giant leap of faith involved in transferring the concept of photons, where the energy is controlled by atomic and molecular energy-level transitions, to antenna, where the energy is controlled by Maxwell's Laws which are not quantised. I have not seen evidence of energy level transitions in a Maxwellian antenna. To be sure, you can use a Maxwellian radiator to generate microwaves and use a quantised molecular energy transition to detect them, but that proves nothing we do not already know.

Originally Posted by muppet

We have two very successful models of the universe, QM and EM. Both models work a lot of the time, and also fail some of the time but in different ways, .

wrong

QED is the best available theory and it contains classical EM theory as the appropriate limit. So what you call EM is just an approximation to the appropriate quantum field theory. There is no conflict between the two.

Classical EM theory is an excellent approximation under most circumstances, but ultimately it is subordinate to quantum electrodynamics. Period.

Originally Posted by GiantEvil

Well GiantEvil and drowsy turtle, you both didn't make any sense at all.

We make perfect sense, your'e just dense like neutronium dude.
The metaphorical point is that a single water molecule like a single cow like a single electron exhibits singular behavior and a bunch of things exhibit group behavior. DUH.

You would never make a philosopher GiantEvil!

Considering;

There is no position so ridiculous that it hasn't been held by some philosopher. -Cicero-

I must say it is much more fortunate to be poor at philosophy as opposed to poor at third grade science.

So what you are saying is that a single water molecule is a particle but a group of water molecules are a wave? And this explains the waves in the ocean?

And a herd of cows are a wave also. If you herd them through a narrow gate then in theory you should produce a diffraction pattern!

And I'm sure De Broglie would argue that, yes, indeed you would!

Two gates are needed for the diffraction pattern and a single cow still possesses a DeBrouglie wavelength.
http://en.wikipedia.org/wiki/DeBroglie_wavelength

Originally Posted by galexander

And a herd of cows are a wave also. If you herd them through a narrow gate then in theory you should produce a diffraction pattern!

Can you use your maths to calculate the wavelength of a running cow? Something like 10^(-35) metres, no?

How do you propose we herd cows through a gate of a similar size to observe the diffraction pattern? 8)

Originally Posted by drowsy turtle

How do you propose we herd cows through a gate of a similar size to observe the diffraction pattern? 8)

Ever been in a milking parlor ?

Bring rubber boots.

Originally Posted by GiantEvil

Two gates are needed for the diffraction pattern and a single cow still possesses a DeBrouglie wavelength.
http://en.wikipedia.org/wiki/DeBroglie_wavelength

Correction.

Two gates are needed for an interference pattern.

One gate, or even half a gate, is needed for a diffraction pattern.

Galaxander, your question regarding wave particle duality is best answered by interference as opposed to diffraction. Even when the double slit experiment is performed using single quanta(electron, photon, etc...) an interference pattern develops. http://en.wikipedia.org/wiki/Double-slit_experiment

The light is a short microscopic circuit of the Veegtrón.