>light is a photon
Makes sense. When we look around us, photons are the light that allows us to see.
>light is a wave. no wait, its not a wave. actually the electric and magnetic fields are oscillating and that creates the ability for you to see
Doesnt make sense. What exactly is "light" according to wave theorists? They say light is not an actual wave but the result of EM waves. We dont actually see the EM waves, so what is it we're seeing? Are photons moving in a wave motion?
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Your brain grew up surrounded by macroscopic things obeying macroscopically emergent physical laws, and that's what its world-model is trained to work with - so what "makes sense" to you does not include the quantum scale.
To make sense of the wave-particle crap you need to understand the concept of a vector field first. The "wave" bit comes from the fact that a photon changes the vector value of the electric and the magnetic fields in a point as it passes. Aka if you're at a point in space, and a bunch of light is passing through, you would see the direction and magnitude of electromagnetic forces change in a wavelike pattern.
The particle bit comes from the fact that these wavelike changes happen in discrete, indivisible packets.
So the changes in EM fields as a photon travels through is what is described by wave?
Also, how do photons and EM fields interact if photons dont carry charge?
if light is a particle, then how it possible to simultaneously see the light source in all directions?
checkmate, brainlet.
>So the changes in EM fields as a photon travels through is what is described by wave?
Essentially, yeah. And since the value each point in space has both magnitude and DIRECTION, you can get all that mindfuckery with polarization and such.
>Also, how do photons and EM fields interact if photons dont carry charge?
Photons don't "interact" with the fields, photons ARE the change in the EM field values.
Let me clarify: a photon is the change in an electromagnetic field. It's like a wave. But it propogates in discrete packets. So it's like a particle. But it's not really either, not in a way that would make macroscopic sense, this is all what the math works out to.
>photon is this, but not this, because photon is that, but not that and this all what the math works out to
you got a better idea, einstein?
Holy shit some of the answers in this thread are fucking horrible.
The photon is the quanta of the photon field, which is a relativistic quantity. Electric and Magnetic fields are not relativistic quantities, since they are manifested by spatial or temporal variations in the photon field. Distances and periods of time are not relativistic quantities themselves, so neither are the EM fields.
THAT BEING SAID, the relativistic photon field has components that in some sense satisfy the wave equation. The electric and magnetic fields also satisfy the wave equation, in some cases.
The quanta, which we call the photon (as opposed to the photon field which the quanta emerges from) is not so simple as to describe in a Veeky Forums post, nor to draw in an image of a gif.
If you want to know more, I suggest picking up a book on the subject and reading.
1. Griffiths Electrodynamics
2. Jackson Electrodynamics
3. Peskin and Schroeder Introduction to Quantum Field Theory
In that order.
Now in English, doc. OP couldn't get his head around photons being wavelike, chill.
>photon field
Luminiferous aether
SO the real question here whose answer would clear up a lot of confusion is
>what is a wave?
A wave is something that satisfies the wave equation, and that's it.
[math]\left(\frac{\partial^2}{\partial t^2}-v^2\nabla^2\right)f(\vec{x},t)=0[/math]
If the function f(x,t) is something which corresponds to something physical, call that something a wave.
A perfect example is the plane wave:
[math]f(x,t) = \exp(ik\cdot x - i\omega t)[/math]
It is known that in a quantum mechanical system, free states which begin their life with some uncertainty in their momentum (say they were produced at some location in space, then their momentum might be distributed in a Gaussian fashion) will evolve so that the momentum becomes more precise, and the position becomes less precise. In time scales much larger than the scales associated with the production of these states, the momentum will become infinitely well defined and the position the opposite. These "asymptotic states" that exist far away from their location of origin, must naturally be expressed as plane waves then. The plane wave is what I just described.
Thus in (asymptotic) quantum field theory, we may be justified in quantizing the field by expanding local field operators using a basis with the functional form of a plane wave and the algebraic form of a quantum state - namely using the harmonic oscillator algebra, where states do not define energies, but number of quanta. This looks like
[math]\hat{\phi}(x,t) = \int \frac{d^4k}{(2\pi)^4}\frac{1}{\sqrt{2\omega_k}}\left(f_{k}(x,t)\hat{a}_k + f^*_{-k}(x,t)\hat{a}^\dagger_{-k}\right)[/math]
The quantity
[math]\hat{\phi}(x,t)|0>[/math]
physically refers to the creation of a particle at position x and time t. |0> is the physical vacuum.
This not the quantization of the photon field, but something similar. Particle and wave do not refer to the same thing, but merely reference descriptive properties of something more fundamental, the quantum field.
So the photon is not really a "wave" and not really a "particle", the math just works out that way is what you're saying? And hey, what is that value you're geting out of that function, could it possibly be the vector value of the field across points in space?
So that particular field is a scalar field, and the only fundamental field known to be expressed in that form is the Higgs field. Of course there are further difficulties because one needs to build a theory or interacting physics from these fundamentals and that is generally hard to do.
>So the photon is not really a "wave" and not really a "particle", the math just works out that way is what you're saying?
Well, "photon" literally refers to the quantum state described by such an operator acting on the vacuum. That's the mathematical formalism for it and you can't really be more specific than math. The "wave" part is just that the functional form of these fields satisfies the wave equation.
In the sense of measuring waves vs measuring photons, it depends on the energy and the type of experiment. If you set up a radio telescope and measure radio waves produced by some astronomical event, you're not seeing single radio photons coming into a detector. You're feeling the effect of a countless stream of photons passing through the telescope and the effect this has on the matter around it is to move electrons back and forth periodically. No physical process can really produce just one radio-energy photon at a time. That just doesn't happen.
On the contrary, many physical processes can produce a small, countable number of high energy photons. Often one or two at a time. This is kind of the reason why quantum mechanics was invented in the first place. We didn't know why we weren't seeing more UV light. Now, these single high energy photons like to scatter off single electrons, since their wavelength is about the size that electrons can be localized around atomic nuclei. For this reason, they are often detected by a localized 'dump' of energy into a detector, like a calorimeter.
cont...
>The photon is the quanta of the photon field
Good fucking god, quantifying something based on an arbitrary concept of itself. How can people believe this shit.
>light is a photon
>Makes sense. When we look around us, photons are the light that allows us to see.
Fucking rofl that makes absolutely no sense. There is absolutely no such thing as a "particle" of anything because they are compromised of fields.
>What exactly is "light" according to wave theorists? They say light is not an actual wave but the result of EM waves. We don't actually see the EM waves, so what is it we're seeing?
"wave-particle duality" is short for "we don't fucking know so we'll give it a duality. They like to use the term "wave" as a noun when defining light which is hilarious because a wave is what something does, not what something is. "waves of what" is what you can ask them and then they'll tangent off about "electromagnetic waves" or other descriptors that once again explain nothing. Light does not move, it is a perturbation of electric and magnetic waves that causes a pressure difference in a "medium". This "medium" is still up for debate, it used to be called "aether" but now they call it "Quantum glue" or whatever other term they've now conjured up.
There's an aether, but it isn't quantifiable. It cannot be measured which is why the Michelson Morley experiment did not disprove the aether, just the aether as a medium that has substance.
>A wave is something that satisfies the wave equation
>An object is something that satisfies the idea of that object
shut up, Plato
>Light does not move, it is a perturbation of electric and magnetic waves that causes a pressure difference in a "medium". This "medium" is still up for debate, it used to be called "aether" but now they call it "Quantum glue" or whatever other term they've now conjured up.
So the wave is a propagating change in the value of some variable?
...cont:
Whether trillions upon trillions of high energy photons can even produce electric and magnetic fields is kind of up for debate. Things which can produce these are quite rare in the cosmos, and if you wanted to do an experiment like that, you're probably orbiting a neutron star. The Schwinger limit (Schwinger contributed to the foundations of quantum field theory, QED in particular) is a natural limit in which the behavior of collections of high energy photons changes dramatically. In the perturbation theory picture of QED, it's when photons scatter off one another through exchange of virtual electrons, but it's often quoted as creating a non-linearity in the Maxwell equations.
I've never studied this particular aspect in detail, but I don't know if these non-linearities still can be explained by wave solutions.
>>The photon is the quanta of the photon field
>Good fucking god, quantifying something based on an arbitrary concept of itself. How can people believe this shit.
It's just abuse of language. People believe it because it fits the data. You're not going to learn what it means just by reading the words and looking things up in a dictionary.
> (You)
>>A wave is something that satisfies the wave equation
>>An object is something that satisfies the idea of that object
>shut up, Plato
In the sense of being non-physical (gauge symmetry prevents it from being a directly measurable quantity), the photon field is a true example of Plato's Forms, as it truly describes reality, at least up to 10 decimal places.
That guy has no idea what he's talking about.
no the "wave" isn't "propagating" anything. It's a posterior attribute, it has no properties. You can splash your hand around and make "waves" in water and you can make "waves" in oil, you can also make waves in Jello. All you're moving is the medium and the change is EXPRESSED in waves. Change the medium and the wave you make will change too. In the end the origin is (you) and the motions you make emanate and the magnitude of such will change based on what medium it goes through.
Oh you're right I'm sorry. Why don't you go ahead and show me the way. First, I would really like to know what a "field" is and why and how it has "quanta".
>no the "wave" isn't "propagating" anything. It's a posterior attribute, it has no properties. You can splash your hand around and make "waves" in water and you can make "waves" in oil, you can also make waves in Jello. All you're moving is the medium and the change is EXPRESSED in waves. Change the medium and the wave you make will change too. In the end the origin is (you) and the motions you make emanate and the magnitude of such will change based on what medium it goes through.
So what you're saying is that
>the wave IS A propagating CHANGE in the value of some variable
>a wave is
>a wave isn't
Semantics. If it solves the wave equation call it a wave. Typically, the wave is a value (which changes - but in a very specific way) of some other quantity. In the case of classical electromagnetism, it's a specific type of change in the Electric and magnetic fields, which do exist in static form.
The particular issue in all these threads I keep seeing on Veeky Forums is about a specific thing that sometimes have wave solutions, what I've been calling the "photon field."
I'd like to point out though that the components of the photon field only solve the wave equation in a particular gauge. For more, see my post
>
Gauge freedom makes "interpretation" of the photon field solutions ambiguous, and even harder to quantize.
The curvature of the photon field (local value of derivatives and whatnot) is what we physically measure, and we call that the electromagnetic field. There is far less ambiguity here.
And all of this changes if we were in a different number of dimensions, so I'd suggest the best route to understanding this is to learn the mathematics instead of posting about semantics on the internet.
No it is not a "change" it is the "expression of a change". "the wave is a propagating" implies that it is the something doing the propagating.
A wave is not a thing. There is water and then there is the air above the water, you could say that the air also has a "wave form". So which is waving? The air or the water? The answer is neither because the "waving" is induced by your hand, a pump or whatever. And your hand and the pump are controlled by the "waving" of other EM waves and so on and so on, it never ends.
It is nothing more than a posterior attribute of something that cannot be reified, which therefore does not make it anything other than a arbitrary measurement of change.
Like a previous post mentioned, light is both particle and wave and not neither.
>the best route to understanding this is to learn the mathematics instead of posting about semantics on the internet.
I guess you're right. Trying to reason about intuitive allegories is crapshoot.
The universe does not understand Dimensional analysis
>for some specific equations it is more satisfactory to model light as particles, and for other it is more convenient to model light as wave
fixed
>compares water waves to light waves
you exposed yourself, nerd. water waves are water particles acting in a wave shape. thats different than light waves which dont act in a wave shape
how do you know that?
>water waves are water particles acting in a wave shape. That's different than light waves which don't act in a wave shape.
How so? Both water and light are emanations of other modalities. It would be quite interesting to hear what you think light actually is.
Light is not a thing in and of itself and there's a couple of ways this is provable.
1. Its privation has no reification or basis in reality (shadow)
2. The components that make up light have no reification as they are not "things in and of themselves. It is purely force,motion,inertia and acceleration.
3. You cannot "stop" light and view "just light". It always keeps moving, there is no origin of said light. I can turn on a flashlight, set of an explosion or do a variety of things that sets up a perturbation of the medium. The only difference between them all is how coherent the perturbations are. The smaller and more coherent, then more powerful and the closer to a laser light gets.
Th
Water molecules move through a water medium to create wave motion. Photons do not have a medium to travel through to create wave motion. Instead, there exists EM radiation. There is no water analog of EM radiation. These are different scenarios.
The real question that needs to be answered is what is EM radiation and why is it described by a wave framework? The current theory is that EM radiation acts as a wave due to oscillations in EM field. However, modern physics has gone beyond that and claimed that EM radiation itself is a wave. I think this is where the confusion comes in and what OP isnt understanding.
Also light is a "thing" it is photons and radiation.
>Photons do not have a medium
>what is luminiferous aether
>"wave-particle duality" is short for "we don't fucking know so we'll give it a duality.
This principle is based on the tests they used to describe photons.
This is literally high school physics brainlet. For certain tests photons satisfy the particle model and for different tests they satisfy the wave model.
Yeah obviously it isn't ideal, but it satisfies current mathematical models which allow for various applications such as spectroscopy, circular dichroism spectroscopy, polarimetry, elipsometry etc...
tl:dr
this person is a brainlet and their opinion is useless
>Photons do not have a medium to travel through to create wave motion
So if it has no medium to pass through then why does it's speed change?
>The real question that needs to be answered is what is EM radiation and why is it described by a wave framework
Because there has to be a DIFFERENCE in order for there to be a wave in the first place. You cannot have "just light" there would be nothing inbetween, there would be no change. Lamour precession dictates how a wave expresses itself and precession is not a fucking wave
>Also light is a "thing" it is photons and radiation.
>"light is a thing. It is light"
Stop defining things as themselves alone. What is the explanation, what is the cause? "light just is",well why goddammit? Radiation of what, by what? This is why light is not a thing. It is a posterior attribute of something else that causes it. I used the water as an analogy because you can still say the same damn thing about water as you can about light. The waves in water are caused by something else, it's not "wave-water" it's fucking water.
A hose moves water from where it is to where it isn't. A flashlight, a laser, a sun other any other phenomena that causes "light" to happen does the same thing. It creates an area of perturbations more in one area as opposed to the other, it moves "light" from where it is to where it isn't.
What do you think happens in a flashlight? Do you think that batteries store "light" particles and then shoot them out of a copper wire and lense? Do you think that a electromagnetic coil and a crystal magically makes "particles" shoot in a straight line in the case of a laser? Nothing is being emitted, you're creating a perturbation of what is already there.
A moving magnet, hundreds of miles away is powering the lights in your home, to say that anything is being "emitted" from said lights is delusional. It's just motion...
Light itself resonates into and from a higher dimensional plane. Thus as a result it behaves as both particle and wave.
It's why with all the arguments, all the experimentations and observations modern people still can't come to a general consensus as to what exactly light is. We're so used to seeing the universe in four dimensions when in fact the universe itself is not even four dimension at all, were just simply designed to see space/time this way and the subject in trying to define light is a perfect example that if we wish to better understand the universe and all its' intricacies including something as simple as what light is then we need to start seeing, not only thinking but also seeing outside of the box.
However if you insist on a four dimensional answer to what light is then you have to accept two answers at the same time....particle/wave.
