The photon is the quantum of the electromagnetic four-potential, and therefore the massless bosonic particle associated with the electromagnetic force, commonly also called the "particle of light". Use this tag for questions about the quantum-mechanical understanding of light and/or electromagnetic ...

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Why doesn't light affect a compass?

In our daily life a lot of photons of visible light, infrared and radio etc move around us. We know that light is an electromagnetic radiation. So why doesn't that electromagnetic radiation affect a ...
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2answers
85 views

Does a photon travel in all directions?

For example i am standing and a beam of light is passing in front of me. I am able to see that beam of light so does it mean that photons are travelling in all directions other than the photons which ...
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4answers
127 views

In $1$-dimensional space, how would the gravity generated by an electron affect a photon moving away from the electron if the photon can’t slow down?

Suppose we had a universe obeying the same physical laws as our own. But it had only one spatial dimension (represented by the $x$ axis) and it was totally empty. There are just two point-like ...
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Optics - Photodiodes - minimum photon energy that a photodiode will be sensitive to [closed]

I'm foraying into the world of photodiodes, and I'm trying to calculate the minimum photon energy required for the photodiode to be sensitive to. Symbolic expressions desired. Minimum detectable ...
0
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1answer
35 views

How does the photon differentiate between events?

As far as I know for a photon that's moving at the speed of light (obviously) time comes to a halt and space contracts to a point, making all travels instant from its perspective. Now this is the part ...
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In an electron-positron annihilation, in what direction are the photons released?

I read that, in an electron-positron annihilation, at least 2 photons are produced, because of the law of conservation of momentum. my question is: in what direction are those photons released? and ...
4
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3answers
295 views

Do photons lose energy due to gravitational redshift? If so, where does the lost energy go? [duplicate]

In the gravitational redshift, the frequency of photons radiated from some source is reduced. As the energy of a photon is given by $\hbar\omega$, if the frequency is reduced where is the lost energy? ...
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1answer
39 views

Photon propagator inverse

If i have the operator $D^{\mu\nu}=\partial^{\mu}\partial^{\nu}+m\epsilon^{\mu\alpha\nu}\partial_{\alpha}$. What's your inverse $(D^{\mu\nu})^{-1}$?
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31 views

Photons under pressure

Does it make sense for photons to be put under pressure, if so how would this be measured? I'm wondering because I would like to plug in $E = h\nu$ into the formula for enthalpy.
3
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2answers
109 views

How to count the number of modes/polarizations of a Gaussian field theory?

A Gaussian (free) field theory is described by a quadratic action of the field, e.g. $S=\int\psi^\dagger K\psi$ (or $S=\frac{1}{2}\int\phi^\intercal K\phi$ for real fields). Usually one just need to ...
0
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0answers
24 views

Does a superconducting coil need a minimum amount of electric current to be a superconducting magnet?

I'm not about that for a tiny amount of Cooper electrons perhaps we can't measure the magnetic field. I suppose that it needs some influental electric current below which the coil isn't a superfluid ...
4
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2answers
64 views

photon wave function, double slit, single photon source

There's an old argument by Newton and Wigner, that the photon as a massless particle can't have a position operator and therefore no position space wave function. How does this tie in with the double ...
2
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3answers
77 views

How does an Inductor “store” energy?

It seems to me that an electromagnetic field is nothing more than a collection of photons, which as I've heard, extends through space infinitely. Why is it, then, that an inductor such as simple ...
0
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2answers
57 views

Models of light

As far as I'm aware, there are two different (and almost contradictory) models that describe the behavior of light: light as a wave (EM), and light as a particle (QM). From what I've heard, depending ...
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0answers
37 views

Does photon polarization take place without scattering processes?

Behind two perpendicular crossed polarisation filters (for visible light) the intensity of light will be zero. After installing a third filter between the two others non parallel to each of them some ...
0
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1answer
49 views

Quantum mechanics between proton & electron but not electron and positron

An electron approaching a proton gives off the hydrogen spectra. An electron approaching a positron does not give off the spectrum of hydrogen. Why? Both scenarios are -1 charge approach a +1 charge. ...
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1answer
78 views

Can I use the grand canonical ensemble for a photon gas?

I have been reading about photon gases at https://www2.chem.utah.edu/steele/doc/chem7040/chandlerch4.pdf. They do the analysis using a canonical ensemble. Since photon numbers are not conserved, I ...
3
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3answers
183 views

Why most of physics is somehow related to light? [closed]

It seems that for the past 200 years, every physicist is concerned about light. For example : Newton's particle model, Young experiment, Photo-Electrict effect and Einstein's formula, Special ...
9
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3answers
770 views

Is Maxwell's field the wave function of the photon?

In his ArXiv paper What is Quantum Field Theory, and What Did We Think It Is? Weinberg states on page 2: In fact, it was quite soon after the Born–Heisenberg–Jordan paper of 1926 that the idea ...
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1answer
175 views

Is Magnetic Field is made of Photon? Is there any frequency of Magnetic Field waves? [duplicate]

(Considering the What is a magnetic field question which is asked on just 8th march, by @DragonSlayer3 and my own question which is left with negative points and closed, Photon Energies in sunlight, ...
2
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2answers
67 views

Why photon propagator has metric tensor additionally?

Klein Gordon propagator is (Peskin p-30) $$ D_F(x-y)=\frac{i}{p^2-m^2} $$ which is actually Green function of KG field. But photon has $g_{\mu\nu}$ additionally in the numerator. I would expect its' ...
0
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2answers
19 views

X-ray radiation - What does h * fmax = e * U mean?

I'm trying to figure out this formula for X-ray radiation $$h \times f_{max} = e \times U$$ $h$ = Planck's constant $f_{max}$ = maximum frequency, in hertz (?), that the photons can have because ...
3
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2answers
67 views

Dose-depth curve of photons vs. protons

The dose-depth curve of protons and photons can be seen in the image below: Now, what I've heard is, that in some cases, proton therapy is advantageous compared to photons, and of course the other ...
2
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3answers
122 views

Is it possible to create a beam of light with frequency of 0?

Is it possible to create a beam of light with frequency of 0? So this would involve photon(s) that move forward without fluctuating with any frequency. If yes, how could this be done? Also, ...
0
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1answer
10 views

Saturation point of incident Light on an object

Since the color of objects depends on the parts of the visible spectrum reflected out and the remaining is absorbed; is there any maximum limit to which the absorption can take place? In other words, ...
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2answers
108 views

Does each photon have a unique wavelength?

Since the frequencies (or inversely, wavelengths) of photons are part of a continuous realm, doesn't this mean that no photon has exactly the same frequency? Two photons might have the same apparent ...
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0answers
20 views

Do photons exert gravity? [duplicate]

I read about GR today and came across the Bonnor beam. As I understand it, two parallel light beams (in a flat space) will in fact creep – slowly – towards each other. As Wikipedia puts it: On the ...
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1answer
40 views

Do photons have a spectrum like light when they are treated as waves?

If light can be treated as both a particle and a wave, are there things called infrared photons, or ultraviolet photons etc, as there are infrared waves, or ultraviolet waves? Or are photons just ...
33
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6answers
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Where do photons go when they are absorbed?

The answer I usually get (and I'm paraphrasing here) is that they disappear and are instead absorbed as heat energy. But I find it hard to believe that the photon simply "disappears." Common sense ...
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1answer
60 views

Spectral lines and QM

In the various presentations I've seen so far in atomic physics of series such as the Balmer series, the wavelength of each spectral line is definite - but in QM, free particles have no definite ...
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4answers
370 views

Can we change a photon's frequency in mid-air?

Can we have a light source emitting photons in the infrared range and after, lets say, 5 meters, these photons become a photon in the x-ray range? The only way I know we can change a photon's ...
3
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2answers
95 views

Do light particle/waves have a frequency? [duplicate]

I sought the answer to the question about amplitude of light waves first, but I was actually thinking about whether the wavelength is the only property of a single quanta of light. I suppose direction ...
1
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1answer
46 views

Can an electron which is a bound in an atom absorb more than one photon at the same time? [duplicate]

Can an electron which is a bound in an atom absorb more than one photon at the same time ? In specific during photo-electric emission can an electron take in more than one photon if one photon doesn't ...
4
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2answers
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What happens to photons that get trapped in a black holes event horizon?

So, I know that photons do not travel fast enough to escape a black hole once it passes the event horizon. Also, I know that the photons themselves aren't affected by the gravity, but rather their ...
4
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2answers
105 views

If photon-photon interactions are impossible, how are higher harmonics generated?

In nonlinear optics, it is a rather common process to use nonlinear materials to produce higher harmonics of an incident wave. About the mechanism of the generation of such higher harmonics, it is ...
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0answers
38 views

Entangled Photon (laser pointer)

From a laser pointer emission; is it creating entangled pairs of photon? is it possible to get more than "pair" entangled, like group of photons all entangled?
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33 views

Is this fine to think of light as the following? [closed]

Is light quantums (increments [photons]) of the electromagnetic waves which are synchronized by oscillations of electromagnetic fields
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1answer
457 views

Have they really photographed light behaving both as a particle and a wave?

I just came across this article where they are claiming that they have photographed light behaving both as a wave and a particle! The paper has been published in Nature Communications and I read the ...
2
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1answer
24 views

Can a fluorophore emit a higher energy photon than it absorbed

It is unclear for me what processes are exactly in place during the absorption-reemission process of a fluorescing photon. I am thinking about the case when the absorption and emission spectrum ...
0
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1answer
71 views

Is it possible to give photons an electric charge?

I know that photons have no electric charge and that they are stable, but is it possible to give them a positive or negative charge? If so how?
3
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1answer
109 views

How do photons carry information?

In cosmology it's frequently said that photons from the early universe carry information from that time. However, wouldn't they also carry data from later interactions? How do we differentiate ...
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1answer
22 views

How does the flow of photons (qty/s) vary across the spectrum? (In everyday life)

Humans see only a narrow band of light wavelengths. Many animals see much deeper into infrared. Maybe one clue to explain why we don't see IR naturally, has to do with the light intensity as a ...
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1answer
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Is my calcualtion from the mass of a photon right? [closed]

The Mass off a Photon The right format can be found here: Photon E = hv E = mc2 E = av (amplitude, frequency) m = hv/c2 Mass = movement of electromagnetic fields Planck’s constant = electromagnetic ...
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3answers
125 views

How are photons made?

I mean in manufacturing a bicycle we know how to "ensemble" a bicycle, what actions and "assembly of parts". So what steps are needed for make a photon? Also is there a limit on how many photons for ...
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0answers
46 views

How can spacetime affect massless entities? [duplicate]

Why is light affected and "bent" by spacetime if it has no mass or density?
0
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2answers
107 views

Why does light travel as waves? [duplicate]

Why does light travel as waves instead of say just a straight line? What are the forces that make a light photon travel in a wavelike pattern?
3
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0answers
109 views

Is this “classical model of the photon” real?

I do not know how to phrase the question better but this article claims to have a classical model of the photon. Has this (rather extraordinary) claim been verified? Here is an extract from the link ...
2
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2answers
157 views

Are electron fields and photon fields part of the same field in QED?

I know in classical field theory we have the electromagnetic field. And Maxwell's equations show how electromagnetic radiation can propagate through empty space. I also have been reading about QED ...
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1answer
52 views

Question about electron-hole pair generation in depletion layer for a p-n junction photodiode

At the heart of operation of p-n (or p-i-n) junction photodiodes is the absorption of photons leading to generation of electron-hole pairs. If the diode is, e.g., reverse biased, then the motion of ...
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1answer
29 views

Why would a photon striking an electron “make both recoil”? [duplicate]

Why would a photon striking an electron "make both recoil" as I read in an answer to another question. If the photon is massless, how can it make an electron change momentum?