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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Is this true about low-light/one photon at-a-time double-slit interference?

I've consistently noticed in pictures of double-slit interference when very low-light or one photon at-a-time is used, that there's lots of "stray" photons detected in the areas of destructive ...
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20 views

Time Dilation for a photon [duplicate]

Does a photon experience any time. Since a photon is massless and hence travels at (c) then it should suffer infinite time dilation, and hence shouldn't experience no time?
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1answer
863 views

How can my window not scramble the image of my yard?

How can an image pass through a window if the atoms in the glass randomly emit photons in any direction? I've read that glass is transparent because the atoms don't readily adsorb visible light, so it ...
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1answer
139 views

How far does a photon move in the 4th dimension when it travels one light second? [closed]

In one second a photon moves 3x10^8 meters through the three spatial dimensions. Light's velocity is 3x10^8 m/s. If the photon moved at all in the fourth dimension, it's velocity would no longer be ...
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20 views

Mirror shake emulation for the light

Is there any way to simulate mirror shaking? Final goal is to make send light beam to the mirror and get reflected beam the same, as it happens if mirror is vibrating. Mechanical vibration is limited ...
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31 views

Relationship between oscillator strength and cross section

In the context of absorption of photons by atoms, I have come across two seemingly very related quantities, cross section and oscillator strength. In the book Physics of the Interstellar and ...
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3answers
84 views

Where does the energy of a photon trying to escape a black hole go?

I've heard "light cannot escape a black hole" explained several ways. One is that if a photon inside the event horizon tries to escape a black hole it loses energy to gravity. As it loses energy its ...
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1answer
26 views

How to get explicit value of Wigner angle for massless one-particle state transformation?

The one-particle massless state $|\mathbf p , \sigma\rangle$ is transformed under the Lorentz group $U(\Lambda) \equiv U(\Lambda , 0)$ as $$ U(\Lambda)|\mathbf p, \sigma \rangle = \sqrt{\frac{(\Lambda ...
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1answer
51 views

What is the QED model about half wave plate?

Surely classical electrodynamics (CED) has a good and well-known answer about the change of light polarization in a HWP (or Quarter wave plate). I tried to find how does this look like from point of ...
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0answers
45 views

Can 2 photons make up the same colour as another photon?

So, my question deals with the excited electron shown above. (1st diagram) This electron can return to its ground state by either of two ways. One of the ways involves the emission of 2 photons. (2nd ...
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0answers
29 views

breaking bonds with light

Light, for instance green light (532 nm = 2.33 eV) has an energy comparable to that of many chemical bonds (C-C bond dissociation energy is about 3.6-3.7 eV). So how is it that I'm not being burned ...
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79 views

What is a soft photon?

I accidentally came across the words "soft photon" today after reading a few blogs. There was some discussion of special situations involving gauge redundancies and a theorem by Weinberg. What is a ...
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4answers
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Why have our eyes not evolved to see “gluons”? [closed]

Bit of a random question...photons are the propagators for QED, and we rely on photons to see the world around us. The gluon is the propagator in QCD. Why have our eyes not evolved to see gluons (...
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31 views

Photoelectric effect vs. electronegativity?

What connection exists between the photoelectric effect and the electronegativity of a material struck by light? I'm summing up some stuff in physics, and I got the feeling that the amount of energy (...
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3answers
76 views

The principle behind Inertia and it's connection to Equilibrium

Inertia is the tendency of a force-free body to remain in that state or it is something that opposes any act of changing its equilibrium state. Mass is a measure of inertia. I have some questions ...
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0answers
45 views

How Does Silicon Surface Barrier (SSB) radiation detectors work?

I'm dealing whith some old detectors (about 1980) called Silicon Surface Barrier, searching online I've seen that they consist on metal-semiconductor(Si n-type) junction (schottky diode) and in one ...
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0answers
27 views

How can absorbtion of a photon in an atom take place? [duplicate]

I will come back to a question posed here and the comment given by John Rennie: If the photon energy doesn't match an allowed transition energy it won't be absorbed and won't excite any transition. ...
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1answer
29 views

The highest photon energy ever measured and transplanckian energies

What is the highest energy of we have measured of a photon by any physical experiment? Has a transplanckian energy photon been measured? Can we study them -if they exist- with special relativity?
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3answers
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Mass and frequency of photons [duplicate]

Light is affected by gravity which means light has got mass. Quantum theory tells us that light consists of discrete quanta of energy, which we call photons. These photons have a rest mass of zero (as ...
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1answer
24 views

Point source of monochromatic photons - self-contradictory in QM?

Suppose we have a point source of photons located somewhere in space. So when the photons are released their location is well known, $\Delta x \approx 0, \Delta y \approx 0, \Delta z \approx 0$ ...
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1answer
27 views

What determines photoelectric yield

Is there any difference between the photoelectric yield of different metals apart from the threshold wavelength? To be more clear: Will metals with the same work function emit the same amount of ...
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2answers
77 views

How do single photons travel from here to there

I know there have been similar questions but I'm still unclear what the overall consensus is. (1) I assumed and have read that photons travel in straight lines unless deflected by gravity but there ...
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0answers
30 views

Estimating “attributes” of a single photoelectric interaction

Disclaimer: I'm a mathematics grad student working on medical imaging. My knowledge of physics and physical intuition is, for the most part, quite poor. Question: I've been reading a lot about the ...
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1answer
101 views

Does this length refer to wavelength or length? [closed]

In this question: A He-Ne laser emits red light of the wave length $\lambda = 632.8\ \mathrm{nm}$ with a beam diameter of $2.0\ \mathrm{mm}$ and a power output of $1.0\ \mathrm{mW}$ [...] (d) How ...
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0answers
31 views

How can air pollution contribute towards light pollution?

I was just wondering if air pollutants such as soot, could reflect light into the night sky, and thus be a potential source of light pollution. If that's true, can you please suggest any other air ...
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2answers
176 views

The lightest photon ever detected

Wiki says that a photon of mass equivalent to $10^{-62}$ kg has been detected: 10×10−62 kg Mass equivalent of the energy of the lightest photon detected [citation needed] this equates to a ...
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2answers
43 views

Is the electromagnetic spectrum bounded somehow? [duplicate]

Is there a maximum frequency that an electromagnetic wave can support?
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2answers
69 views

Description of a photon and quanta

Could someone please help to clarify the difference between a photon and a quanta? Below is my current understanding - please correct me if I am wrong. A photon - is a 'wave particle' of 'light'. I ...
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56 views

Why call it a particle and not a wave pulse?

My physics textbook says that photoelectric emission provides conclusive evidence for the particle theory of light. Apparently, since photoelectric emission only works at certain frequencies, we can ...
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0answers
44 views

Equation for Electric and Magnetic field from the equation for a “massive photon”

I was reading the Quantum Field Theory book by Maggiore. There he says that in side a superconductor the photon satisfies the equation $$(\Box+m^2)A_\mu=0$$ Then he adds that the electric field and ...
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1answer
33 views

DNA breaks with particles or photons (Radiation therapy)

When protons (or other particles) or photons are used in radiation therapy to treat cancer patients, the main effect is for it to make DNA breaks that hopefully will make the cancer cell die ...
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1answer
54 views

Does slowing light violate relativity?

Last year Scottish scientists managed to slow down photons in vacuum by changing their shape. Does this violate the special theory of relativity?
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26 views

Which information is lost, if we model photons via the Klein-Gordon equation?

The Klein-Gordon equation describes relativistic spin-0 particles. Each component of the Dirac equation fulfils the K-G equation, c.f. here. If one decides (for whatever reasons) to model photons via ...
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1answer
66 views

How do photons interact with nucleons [closed]

Is question can be considered as an extension of the interaction between photon and atomic electron, where the energy level of atomic electron is elevated when absorbing photons and the process is ...
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1answer
68 views

Is it possible to strip the magnetic, or electric field from a photon?

A photon is made up of a magnetic part and an electric part, but we can see the existence of these fields without the other one so I would like to know if it is possible to somehow separate one field ...
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22 views

Why triplet-triplet annihilation requires less power than two-photon absorption?

Both two-photon absorption upconversion (TPA-UC) and triplet-triplet annihilation upconversion (TTA-UC) have quadratic dependence on incident light intensity (ref): TPA requires two simultaneous ...
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1answer
137 views

Continuous X-Ray spectrum

I'm reading Eisberg's Quantum Physics book and came across the following graph I know very little about the subject, but from that figure I understand that, depending on the energy of the incident ...
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16 views

Shouldn't HDM drain photons energy?

Hot dark matter (HDM) would be made from very light, fast moving particles. Such particles could not possibly be gravitationally bound to any structure, but rather would be dispersed all across the ...
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1answer
29 views

When thermal IR gets reflected from an object, does it change its wavelength (frequency)

I'm working with thermal infrared (IR) cameras to detect human thermal radiation. I notice I can easily distinguish non-human objects throughout the camera's field of view, though all are at same room ...
2
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1answer
41 views

Number of photons through glass [closed]

I am getting mixed information on the total photon count involved with light transmission through glass. I'm not looking for percentages and I don't have equipment to count photons. For simplicity ...
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0answers
48 views

Exchange of virtual photons [duplicate]

How does the exchange of virtual photons as per QED explain the electrostatic attraction of particles of opposite charge?
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1answer
33 views

What is the difference between upconversion and two-photon absorption?

I thought that two-photon absorption is the underlying mechanism of upconversion, but according to Wikipedia (1, 2), Upconversion should be distinguished from two-photon absorption [...] and ...
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1answer
46 views

Particle nature of light [closed]

How particle nature of light can be observed in material world? To common man light does not hit them or make them fall when light beam is projected on them.
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1answer
86 views

What is a linear polarized photon?

According to Dirac a 'linear' polarized photon is a superposition of left and right rotating photons. Here is a puzzling aspect of this superposition. There are dichroic materials which can absorb ...
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0answers
11 views

Is the Poynting vector non-zero when two magnets are placed on either side of a charged capacitor? [duplicate]

I charge up a parallel-plate capacitor, and put a bar magnet on either side, such that the magnetic field is perpendicular to the electric field. S = E x B Do photons start coming out of the ...
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1answer
73 views

What happens to spacetime in a universe with no clocks?

For example, in the far future when all matter has been absorbed into BHs which have evaporated leaving only photons.
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2answers
151 views

Photon absorption by atoms vs compton scattering

In compton scattering, a photon may deliver only some of its energy to an electron. But when dealing with photon electron interaction in an atom, it's all or nothing. Why the difference? Also, ...
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0answers
25 views

Refraction Explanation From Particle Perspective

I was wondering if there was an intuitive way of understanding refraction from a particle perspective. By this I mean, that before entering a lattice, a photon has some momementum, it then enters at ...
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0answers
59 views

Do photons traverse through the vacuum of outer space as a helix? [duplicate]

I’m trying to understand “Electromagnetic waves”. If electromagnetic waves traverse as a helix then do photons traverse as a helix?
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1answer
72 views

Does light with opposite spins cancel out the probability of an event?

I'm an A level student and as i was reading QED by Richard Feynman, I came across something really interesting, that light can be reflected from all parts of the mirror according to the quantum theory....