What evidence is there that light is a particle and not purely a wave?

it proves that the photon bundle moves like a particle and not like a wave

>the fact that we can measure light one photon at a time

No, we can only measure one electron being released at a time.

how?
wtf?
why?
that's not a photon. i don't know if you're baiting or if you're being retarded on purpose

But it is moving like a wave. You can't see it here but Its diverging. That's what a wave does. Its impossible for light to travel without diverging.

A wave's energy is dependent on its intensity. The energy of the emitted electrons only depends on the frequency of the wave though.

It depends on both the frequency and the intensity. Lots of red light has more energy than a small amount of blue light.

Yes, but if the intensity played a role you could vary the energy of the electrons by varying the intensity of the field. This however does not happen. As long as you don't change the frequency, the energy of the electrons stays constant. This is consistent with the particle picture.

Because it has properties of both. This is a fundamental observation. Now stop shitposting.

Sorry I misread your reply.

If I have a plate sitting on my table, and I play a musical note at a single frequency and vary it, at a particular frequency the plate will resonate and start to vibrate. If I vibrate it at this frequency hard enough it will fall off the table. At this macroscopic level the sound can safely be treated as purely a wave.

I hope you can see the analogy.

Still doesn't work though. Resonance (i.e driven oscillation) still is dependent on the intensity of the input. Also the excitation time (the time required to get to a certain height or amplitude) is dependent on the intensity. These are both not observed in the photoelectric effect.

Idk do you consider wavelets photons

you can shoot photons 1 by 1 and they land at single positions.

en.wikipedia.org/wiki/Resonance
First line
"In physics, resonance is a phenomenon in which a vibrating system or external force drives another system to oscillate with greater amplitude at a specific preferential frequency."

>Also the excitation time (the time required to get to a certain height or amplitude) is dependent on the intensity
Yes, more light means more electrons are released in a shorter time frame.

I don't get what you are trying to say with the wiki quote.

>Yes, more light means more electrons are released in a shorter time frame.
The peculiar thing about the PE is that the intensity has nothing to do with energy of the electrons, nor the time between stimulation and emission. It only goes into the number of electrons that are emitted.

In the wave-resonance picture you would get
a) an energy of the electrons (oscillators) that is dependent on the intensity of the incoming wave
b) a stimulation time of the electrons that is dependent on the intensity of the wave, since a low-intensity wave would take longer to excite the system than a high intensity one.

Neither of these are observed.

You said that resonance is dependant on the intensity. Yes, but it only happens at a
For the wiki post:
>specific preferential frequency

The energy of all the released electrons is of course equal to the intensity of the incoming wave. After the electron has received enough energy to be reliased, it no longer receives energy. Instead, other electrons are released. All this shows it that electrons requrie a certain amount of energy to be released, and need to be 'resonated' at the correct frequency. All of which can be described with purely wave like behaviour.

For the stimulation time I still don't understand your point. A low intensity wave does take longer to excite a system, less electrons are released per second. We just measure the intensity of the light in terms of the number of electrons that are released per second.

>You said that resonance is dependant on the intensity. Yes, but it only happens at a
>For the wiki post:
>>specific preferential frequency
This is not correct. Resonance happens at every frequency, but it's the strongest at a certain eigenfrequency.

>The energy of all the released electrons is of course equal to the intensity of the incoming wave.
No, only the number of electrons is proportional to the intensity. The energy is only dependent on the frequency of the incoming light. In a wave-like description the energy imparted on an oscillator is dependent on the intensity of the incoming stimulation, i.e a high amplitude wave would give the electrons more energy than a low amplitude one. This wold mean we could control the energy of the emitted electrons with the intensity, which we can't.

>For the stimulation time I still don't understand your point. A low intensity wave does take longer to excite a system
Yes, but that is not observed. You get instantaneous emission regardless of your intensity, whereas in the wave picture you need time to excite the oscillating electrons. And if you actually do the calculation you need way more time than what is being observed.

>Resonance happens at every frequency,
This might have been an awkward phrasing. What I meant was that the amplification by resonance is distributed around an eigenfrequency peak as shown in the pic, i.e. not bound to a single specific frequency.

Its literally a dude moving a flashlight behind the bottle lmaoo

>This is not correct. Resonance happens at every frequency, but it's the strongest at a certain eigenfrequency.

Similarly, emission can take place at any frequency, theres just orders of magnitude greater chance that it will happen at a certain frequency. If you blast enough light of the wrong frequency, eventually emission will happen.

If the electrons only require a certain amount of energy to be released, and will cease to absorb energy after this happens, then all the resultant electrons will have the same energy (or close enough)

>You get instantaneous emission regardless of your intensity

Yes, theres a small chance of it. Which can be explained by assuming that the intensity of the wave is always going to be random and non uniform.

and simarly

>Similarly, emission can take place at any frequency, theres just orders of magnitude greater chance that it will happen at a certain frequency. If you blast enough light of the wrong frequency, eventually emission will happen.
No this is not correct. You most use light with energy E= h * frequency larger than the work function. You won't observe emission if you shine low-energy light at any frequency (not even at the suppsed eigenfrequency of electrons) at the material. This, again, is a point AGAINST the idea of light as a wave.

>Yes, theres a small chance of it. Which can be explained by assuming that the intensity of the wave is always going to be random and non uniform.
I don't know what you mean by that? Are you saying you DO observe delayed emission? Because that is not true.

I don't know what you mean by that.

>Once an electron has received enough energy from the wave it will be released.
Yeah that sounds reasonable but the thing is that it doesn't happen for light below a certain frequency. That's because for the low frequency light the photon's aren't energetic enough to excite the electrons.

>Photon's

Autocorrect

Do you mean before the photoelectric effect or some other reason than the photoelectric effect?

Two quick examples are radiometers and doing the double slit experiment with single photons.

Isn't double slit a demonstration of the wave property?

>that's not a photon. i don't know if you're baiting or if you're being retarded on purpose

Nah this is legit. Almost 5 years old. The only argument to be made is the difference between single photons and a bundle of photons. But, yes that is a single burst of light slowed down enough to where we can see it move..

>But it is moving like a wave.

Yeah hence the wave particle duality. If you are looking for evidence that light is and only acts like a wave then good luck, but this is definitely evidence of particle behavior. Otherwise it would have diverged significantly more, like a light bulb in a lamp shade.

You can't see light moving, the only way you ever detect a photon with your eyes or a camera is when it goes into the retina/CCD

Yes it is. There is no evidence of light being purely a wave or purely a particle. That is the struggle that is wave-particle duality. But the particles go in the double slit as single photons or bundles of photons and exit the same way. Yes there is an interference pattern, which mind boggling to say the least, but formed from huge amounts of individual photons, not all at once like is practiced in hs physics. Thus the photons act as both particles and waves.

>Yes it is. There is no evidence of light being purely a wave or purely a particle.
OP asked for experiments that confirm the particle aspect though. If you assume a wave, the double slit experiment isn't very surprising.

Nah senpai there are a fuck ton of ways to detect photons. Yes, that is the case for our naked eyes, but it isnt the only instrument/tool we use to measure light.

You are getting to the point though how it is odd that light diverges not from the source but rather from this packet moving through space, hence the general confusion related to wave particle duality.

The interference pattern happens even if it's only one photon at a time

>OP asked for experiments that confirm the particle aspect though

I know he did, but there is evidence of only both in tandem, not singularly one property or another. Any experiment that shows one or the other has been mathematically rigorously shown to have both properties. The best example of just particles would be radiometers. It is well accepted that it is both, not one or the other.

Right, that is my point. But sending a single photon through a double slit absolutely does not create an interference pattern. You need to send hundreds before it forms. If it were purely a wave then a single photon would instantly create the interference pattern, and it doesnt.

>Nah senpai there are a fuck ton of ways to detect photons.
Yeah but they're all just a measure of whether a photon has hit something. There's no way of "watching" the trajectory of a photon. To do that with anything you need to bounce light off it to see where it is but light doesn't interact with itself like that.

The image is an example of a typical absorption spectrum. There exist peaks where absorption is strongest, but there is still a range of frequencies over which absorption occurs. Even in terms of specifically the photoelectric effect, the frequency is not absolute.Even individual laser modes always have some amount of broadening.

At low intensities, there is a very small chance that we will see near spontaneous absorption because there is a very small change that the intensity will be concentrated enough to allow the electron to be released. At larger intensities, this is more likely to happen, and there is a higher chance that we will see near instantaneous absorption.

By that logic high frequency light should always excite electrons. That's not the case.

Photoelectric effect isn't very wavey at all

>There's no way of "watching"

It sounds like you are wed to the idea that the only evidence of something is what we can see with our naked eye. This is simply not true and incredibly limiting.

>That's not the case.
Pretty sure it is. If it wasn't the case that would be inconsistent even with your wave only model.

okay, and you have your evidence?

im lost as to what you're getting at..

I think you're misinterpreting what I'm saying. I'm saying you can't measure where a photon is without destroying it so it makes no sense to say you can measure its trajectory because that involves measuring its location multiple times.

>The image is an example of a typical absorption spectrum. There exist peaks where absorption is strongest, but there is still a range of frequencies over which absorption occurs. Even in terms of specifically the photoelectric effect, the frequency is not absolute.Even individual laser modes always have some amount of broadening.

You're conflating absorption with the PE. These things are not the same.

>At low intensities, there is a very small chance that we will see near spontaneous absorption because there is a very small change that the intensity will be concentrated enough to allow the electron to be released

First of, we're talking about emission, not absorption. Second, you will see emission at any non-vanishing intensity if the frequency is high enough (again, points to particle picture). You will NOT find emission if your frequency is too low, and the energy of the photons smaller than the work function. And if you don't believe me you can do the experiments yourself, it's not very expensive.

Actually it diverges about as much as you would expect using wave based propagation theory.

I don't think you understand the amount of 'photons' that bundle would contain. So many, that its path can be absolutely described by wave propagation. The video is no evidence of anything.

>i literally spent all summer modelling light propagation

I'm saying the main properties of the photoelectric effect (instantaneous excitation and no excitation below certain frequencies) cannot be explained at all with waves so you can't say that every experiment shows behaviour of both particles and waves.

> I'm saying you can't measure where a photon is without destroying it

And/or changing it, yeah i agree.

But statistically we can create distributions as to where it is most likely to be. Hence you dont see a single pixel moving through the coke bottle, but rather a diverging light, hence the uncertainty.

Are you uncomfortable with making specific definitions from inherently statistical systems?

>I don't think you understand the amount of 'photons' that bundle would contain.

No one does, dont get all condescending for no reason mate.

>So many, that its path can be absolutely described by wave propagation.

Fantastic, we are back where we started with wave-particle duality.

Does it make sense that light which is entirely a wave conventionally makes more sense to diverge from it's source rather than where it exists in space at a particular moment?

When we describe electrons as waves, yeah it definitely can be explained by waves.

>Once an electron has received enough energy from the wave it will be released.

Except that's exactly what ISN'T observed. You can shine red light at a wall all day long and get zero photovoltaic effect, then flash it with a blue light and get a spike of emission. You can't explain this behaviour if light is a wave, only if it is quantised ie a particle.

I'm saying that that video isn't a video of a photon or photons or a light wave moving because you can't film light moving. Idk what it is but it isn't that.

>you can't film light moving.

What is it a video of?

Last i checked it was taken by a fairly reputable university program. We've been able to send and capture single photons for like 2-3 years now.

No offense to you because you are certainly well spoken. But i am more inclined to believe peer-research than an idk from some rando on the internet.

NO IT CAN'T JESUS

Instantaneous excitation doesn't make sense with waves because waves need time to get all the energy required in to excite the electron.

No excitation below a certain frequency makes no sense with waves because for a continuous stream of energy from a wave, if you wait long enough you will eventually put enough energy in and see an excitation. Another thing is that even if you make the low frequency light really fuckin intense you still don't get any electrons.

Why are we arguing the photoelectric effect is a given for OPs questions.

But more importantly instantaneous emission is not technically instantaneous, but rather on negligible time scales.

As I said, even for the case of PE .The light has to be absorbed be the material, and there is always at least some broadening in the frequency. Look at any real detector. Its impossible to build a detector that only absorbed light at one frequency.

Absorption of the light, emission of the electron.

> You will NOT find emission if your frequency is too low
Yes you will. The harmonics have a chance of triggering the photoelectric effect, again with a slightly broadened spectrum.

>The light has to be absorbed be the material
PE is scattering of photons with electrons. Absorption would imply the electron is taken into a higher energy state.

>Yes you will.
At this point I'm not willing to discuss this any further. Look at the experimental date. Do the experiment yourself. You will not find emission at low frequencies. You can shake your head as much as you want, it does not happen.

Waves travel across space as well as particles. Look at the ocean. Are we going to start calling groups of waves 'waveons'? Using wave prorogation theory you can model that perfectly. You don't need the particle description at all to explain what is happening.

>Its impossible to build a detector that only absorbed light at one frequency.

You have it backwards. It is impossible to build a source of light which is purely monochromatic due mostly to doppler broadening. It isnt a problem with the detector, but instead the source.

>> You will NOT find emission if your frequency is too low
>Yes you will
You can pretend that every PE experiment ever is wrong or you can just admit you're wrong.
If you want to perform the experiment yourself and contradict all prior evidence, go ahead and claim your Nobel prize while you're at it.

>You don't need the particle description at all to explain what is happening.

The main problem with only using the wave description is causality.

Looked it up, it actually sort of is, to be fair, but just calling it slow motion footage of a light pulse doesn't quite convey what it is. It's actually really clever what they've done, they deflect the light with an electric field somehow (not sure how that works) so I guess some of it comes off the pulse as if the pulse itself is emitting light as it moves.

That's p sick

Sure but those negligible time scales are still way shorter than the time required for a continuous wave to excite them.

>Absorption would imply the electron is taken into a higher energy state.
But that's exactly what happens. At a high enough state, the electron is able to overcome its bond to the atom and break free.

You can concede if you want, but there's plenty of evidence of the photoelectric effect occurring at frequencies below which the one defined by the work function. Look at non-linear optics.

And that video proves nothing about causality either way

>but there's plenty of evidence of the photoelectric effect occurring at frequencies below which the one defined by the work function. Look at non-linear optics.
No there is not. In optics you deal with light interacting with matter due to the matter's polarization. This is entirely different to the PE. You don't cause emission of electrons in optics.

Right, i was speaking more broadly, not about that specific video.

Yeah, totally, that video says jack shit about causality.

>Using wave prorogation theory you can model that perfectly
How about in the slit experiment where when you measure which slit the photon goes through the interference pattern completely disappears? I can't see how you explain any of that with waves.

>You don't cause emission of electrons in optics.

Yes you do. Optics is the study of the the electromagnetic spectrum. Electromagnetic radiation is what causes emission.

> In optics you deal with light interacting with matter due to the matter's polarization
wut

>You don't cause emission of electrons in optics.
No offense, but i literally dont know what else you do in optics other than emission/absorption spectrums..

I don't understand your point. The two slit experiment is literally the proof that light is a wave.

>but there's plenty of evidence of the photoelectric effect occurring at frequencies below which the one defined by the work function
I would love to see said evidence.

>ITT
>OP asks everyone to give evidence that photons are particles
>OP asks everyone to ignore the strongest evidence that photons are particles

8/10 bait

Emission of _electrons_

Sure, HOWEVER, like I said, if you measure which slit the photon went through each time the interference pattern completely disappears and you're only left with two discrete piles of photodetections, that's about as far from wave-like behaviour as you get.

So just because you do research in nuclear physics the kinematic equations are useless?

Researchers dont live in that small of a bubble.

exactly, if light were purely a wave then single photons would produce the entire interference pattern, albeit dimmer, as opposed to striking in a single place.

I think I may be confusing you with someone else because I don't think we actually have a disagreement here.

I don't understand what you mean. In optics in general you don't deal with ionizing radiation (optical light is below the energies of the work functions of most materials).

But this is a giant digression. OP just keeps shaking their head without producing one piece of evidence for his argument. Especially for the delayed reaction at low frequencies, which imho is the most compelling argument for treating light as a particle in the PE.

>wut
Hey, you started throwing nonlinear optics around, you should know at least a tiny bit about it.

>In optics in general you don't deal with ionizing radiation
Optics is the study of all electromagnetic radiation.

>OP just keeps shaking their head without producing one piece of evidence for his argument.
I'm using the evidence that is already out there. I'm questioning what it tells us.

>Especially for the delayed reaction at low frequencies
I don't remember discussing this. What delayed reaction.

I know a lot about it. Enough to find that statement incredibly confusing.

>Optics is the study of all electromagnetic radiation.
Possible the wrongest statement of this whole thread.

>I'm using the evidence that is already out there. I'm questioning what it tells us.
Incidentally not bothering to post any of it here.

>I don't remember discussing this. What delayed reaction.
Probably because you haven't been reading my posts properly. If there were excitation at lower frequencies you could shine a low frequency light on matter and just wait until it drives the oscillating electrons into energies higher than the work function, then you'd detect emission. But you can do that all day and find no emission whatsoever.

>Incidentally not bothering to post any of it here.
What citations do you need?

>But you can do that all day and find no emission whatsoever. If the intensity is high enough you WILL find emission.

en.wikipedia.org/wiki/Four-wave_mixing

My reply wasn't supposed to be greentexted as well. I'm tired.

>What citations do you need?
Evidence for photoelectric emission at incident energies lower than the work function of the material. Evidence for delayed photoelectric effect.
>en.wikipedia.org/wiki/Four-wave_mixing
This has literally nothing to do with emission of electrons via the PE. It's an entirely optical process. I have difficulties to understand why someone who works at this level would have difficulties grasping the PE.

>Evidence for delayed photoelectric effect.
This is a straw man you seem to have created. I never said that.

>This has literally nothing to do with emission of electrons via the PE. It's an entirely optical process
It has everything to do with PE. How do we detect these optical anomalies? Using detectors, built on the principles of the PE. Everything we know about light come from observations made through the photoelectric effect.

>This is a straw man you seem to have created. I never said that.
This is implied when you treat light as a wave in the interaction.

>Using detectors, built on the principles of the PE
Yes, and those detectors use materials whose work functions lie below the energies of the optical spectrum.

Ok, I'll make it simple for you. Low frequency waves can combine to make high frequency waves. You can do things to increase the chance of this happening, but it always happens. Its dependant on intensity. So if you have a frequency below the work function but at a high intensity, you can still cause the emission of electrons through the photoelectric effect,

>Low frequency waves can combine to make high frequency waves.
I don't have the energy to check this now so I'd love a source, but I have never seen this (while keeping the periodicity of the wave of course, which is necessary for your argument of resonators). And even then, its seems like a highly specific setup that does not apply in general. And to keep up with your wave argument you'd still need to show delayed emission.

Also, you'd still have give evidence that this actually works.

The source is any book on non-linear optics.

I don't think the wave argument necessitates delayed emission, but I'm going to bed now. Maybe I'll come back and argue some more later. Interesting discussion.