"Photon" is the name given to particles of light in the quantum mechanical understanding. In interaction where the classical and quantum mechanical understandings of light agree they are fully equivalent to electromagnetic waves.

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Coupling of matter field with gauge boson and Goldstone boson:

What's the fundamental difference between the way a gauge boson gets coupled to a matter field, preferably a Fermionic field and the way a Goldstone boson gets coupled to the matter field ? In ...
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How non-invasive blood glucose concentration measurement work? [migrated]

Diabetes patients need to conduct the “fingerstick” a few times a day. One of the mechanisms of "fingerstick" is to take small amount of blood sample and put it onto a test strip. The enzyme on the ...
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In QED, why is the $e^- + e^+\leftrightarrow\gamma$ process forbidden on-shell?

QED has a vertex that couples a single photon to two fermions. This vertex describes the annihilation of an electron-positron pair into a photon. Why is this process forbidden for all three particles ...
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The needs of photonic senseor for biomedical applications

I am doing a literature review on the topic mentioned in the title. When I write the review, I found myself a contradiction. Just want to listen to opinions from others :P Nowadays, the development ...
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37 views

Why does gravity enact force? [on hold]

Gravity would cause two objects in a vacuum to move toward each other. I understand that gravity is a force that exists as a product of energy's original conversion into mass and the continuing change ...
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Convergence of light by light scattering amplitude

Perhaps I'm too exhausted to see the answer of why the photon-photon scattering should contain no divergences. In Peskin and Schroeder page 320 we find that because of the Ward identity the ...
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how refraction takes place at atomic level? [duplicate]

when light beam is incidented at some angle on the surface of a medium some part of the light is reflected and some refracted. I want to know about refraction. As the photons interact with the atom ...
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29 views

Scintillator Length Calculations

This is sorta homeworkish, yet it still relates to my understanding of the physics behind it as well. Does anyone know how you determine t_98 (aka the length to contain 98% of the energy) for a ...
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How much energy does a photon need to form a black hole?

I was wondering if it is possible for a single photon to form a black hole if it has a small enough wavelength.If so, what would this wavelength be? I came across this question because I am reading ...
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Flip of polarisation of light

Consider an optical experiment with photons or light pulses. Is there an optical element that acts in the polarisation degree of freedom like the unitary $$ U = \frac 1 {\sqrt 2} \begin{pmatrix} 1 ...
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Mirror that flips polarisation?

Is it possible to build a mirror which not just reflects a photon but also flips its polarisation from horizontal tho vertical (or vice versa)? The reason why I ask is the following: If I put an ...
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What is DX technology and what are the effects on digital cameras?

I am photographing in a high power voltage field in Industry producing aluminium, called DX technology. How do I know if my digital camera will not be affected? At 350kA current my film cameras were ...
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Is there a connection between gluons and photons?

I was wondering if there is any sort of connection between a gluon and a photon since they are both considered massless.
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Photons, electomagnetism

I read that photons are carriers of the electromagnetic force (one of the four fundamental forces). So, I would like to know what a photon has to do with, for example, working of a motor or ...
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Does light lose energy in transit?

Consider a photon is an energetic particle and therefore has a gravitational field. When a photon passes a molecule or particle of dust in space it will pull the dust towards it and deform the dust. ...
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Is there a difference between the speed of light and that of a photon?

As in the title I am curious whether there is a difference between the speed of photon and the speed of light, and if there is what is the cause of such a difference?
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312 views

Do photons have relativistic mass?

I am conducting research on photons and was wondering if they have relativistic mass. I already know that they they have zero rest mass. Any answers are welcome!
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Can time pass for a photon if it's moving in a medium? [duplicate]

If time does not pass for a photon traveling at the speed of light, which can only occur when traveling in a vacuum, what happens when it is slowed down by traveling through non vacuum space like ...
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If a photon goes up, does it come down?

If light can be bent by gravity, does a mass as dense as a star pull any fraction of photons back towards itself?
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EM Fields Transmitted from an antenna and photons [duplicate]

What is the relationship between The EM waves (light) and photons in some context i studied light as photons and others as EM fields but how they are related....another questions : what's the name of ...
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What happens when Antimatter interacts with a photon?

So... I was just pondering the energy and particles in the universe. It makes sense that matter is attracted to it's self by a gravitational force - it clumps and forms some kind of gravity ...
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What prevents photons from getting mass from higher order Feynman diagrams

The Higgs boson and gluons have no electric charge and photons couple to charge, so there is no tree level interaction between them and photons. But what prevents higher order diagrams from ...
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A quantum mechanical description of a polarizing filter

When a single photon with polarization $\mathbf{a}$ arrives at a linear polarizing filter in the direction $\mathbf{p}$, the photon has a probability of $(\mathbf{a}\cdot\mathbf{p})^2$ to pass through ...
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How does the human eye knows how far the object from which the photon was reflected?

A photon is emitted from a source and reflected off an object (or objects) until it hits the human eye. The color of the object we see depends on the photon wavelength. If photon travels with constant ...
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Will an un-scattered photon go to the edge of the universe? [duplicate]

Will an unhindered (un-scattered) photon go to the edge of the universe?
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A few questions about photons

I have a few questions about photons. I know the emitting and absorbing of photons is related to quantum leaps. Does a quantum leap cause emitting/absorbing, or is it the other way around? Do ...
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How do we know that there is more than one photon in the universe?

Excuse this possibly dumb question and correct me - i am not a physicist, but i wondered: A photon is massless and travels with lightspeed, which means for the photon itself, that time stands still ...
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Do Photons Accelerate Upon Creation? [duplicate]

Of course the speed of light is constant relative to everything. Its frequency can change, but its speed is constant. Photons may be absorbed by atoms or release by atoms as energy, but as soon as it ...
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How can a photon exist on its own without a mass? [duplicate]

For example, thermal energy exists and has no mass, but is carried by particles which have mass. A photon is described as a particle - how can a photon exist on its own, travel in space and even push ...
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What happens to photons after they hit objects?

If I am not wrong when light hits for example white wall most of the photons are absorbed and transformed into heat and few of the photons at certain wavelength are reflected from the object. So white ...
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Is the emission spectrum of a muonic atom different?

From my quick investigation, the spectrum is based on the Rydberg formula, and with a small change, would lead to $$ {1 \over \lambda_\mu} = {m_\mu \over m_e} \left( R \left( {1\over n_1^2} - ...
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Spontaneous parametric down conversion and relative time of emission of two entangled photons

A pump beam excites a non-linear crystal which produces two entangled photons with perpendicular polarization, namely in the state $|HV>+|VH>$. Are there examples where one of the photons was ...
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What will happen if two photons collide perpendicularly? [closed]

Suppose there is an object placed at (-1,0) on x-axis. A light ray coming from it is observed by an observer somewhere on positive x-axis. In addition, a second object is placed somewhere on y-axis. ...
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What are the factors affecting transparency and color of a substance [duplicate]

What is the reason behind visual properties like color and transparency of different substances? I have always heard that the structure of the substance is responsible for these properties. I always ...
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Simple Mach-Zehnder Interferometer with Polarizing Beam Splitters

I am wondering which state leaves the simple interferometer below. The beam splitters are polarizing beam splitters (PBS) which transmit vertical polarization and reflect horizontal polarization. Say ...
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Energy loss in the photoelectric effect

If a photon hits an electron with an energy that is less than the energy required to change the energy level of an electron, what happens to the energy of the photon (is it not absorbed and just pass ...
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How do photons “decide”?

I was reading that when horizontally polarized light hits a vertical Polaroid all the light is blocked out. But when the Polaroid is off the vertical, some but not all photons "decide" to jump into ...
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Can light produce weak gravitational waves?

I have read online that light can produce a weak gravitational field (for example antiparallel beams should, in principle, attract weakly). This made me wonder if light can produce minute ...
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Does a normal torch emit entangled photons?

I was reading a sciencenews.org post about three photons being entangled. My question here is, why is the chance of producing an entangled pair once in a billion times? Isn't every particle produced ...
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Invisible stars due to finite photons [duplicate]

When we study black body radiation, we often make calculations assuming a continuum of radiation with some amount of flux. In reality, there is a very very large number of photons being emit per unit ...
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Is there a relationship between the energy of a photon and the energy of an electromagnetic wave?

If the energy of a photon $E_{p}=hv$ And the energy of an electromagnetic wave is $E_{w}\propto \hat{\mathbf B}^2$ What is the relationship between $E_{w}$ and $E_{p}$?
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Only transverse photons are gauge-invariant (Peskin page 298)

Seven lines down from the top of page 298 of P & S, it says "Single particle states containing one electron, one positron, or one transversely polarized photon are gauge-invariant, while states ...
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How did photons and electrons arise out of the quark-gluon plasma?

I am just beginning to learn about the ideas of the early universe, so this is probably a beginner question. I understand that protons and neutrons (which are baryons, which are hadrons) are made out ...
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Electric charge of light? [duplicate]

Light (or any radiation as a matter of fact) is an electromagnetic wave so why doesn't it have a electric charge associated with it? As far as I know only static or flowing electric chargers can ...
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DO the condensed photon particles-waves-longitudinal-waves exist? [closed]

This is kind of hard to explain, because weird as it sounds, i have experienced a phenomenon that i would like to see if it exists and if i can explain it mathematically. The longitudinal waves of ...
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Is the photon first a wave, then a particle? [duplicate]

When the 'photon' is emitted, it would reason that the result of the energy fluctuation that creates 'it' rather is created as an energy wave, which when measured by us or a surface, it 'becomes' as a ...
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Internal energy and photon absorption

I just wish to confirm whether my understanding is correct. I know that photon absorption/emission brings about quantised changes in electron energy levels. Photons (infrared) also interact with ...
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Polarizing Beam Splitter Interferometer

In "Dance of the Photons" by Anton Zeilinger (pgs. 82-84), Zeilinger has a polarising beam splitter interferometer as such- ...
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Can a $\gamma$-ray photon give some of his energy to an atom and accelerate it?

I know gamma-ray photon can only give its momentum energy to the electrons of an atom. My question is: Can a photon give some of its momentum to the atom (including its nucleus) to give it heat or ...
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How do you isolate a single photon?

How do scientists/researchers isolate a single photon (for single photon sources)? How do they know they have isolated it? Is it really totally "isolated"? What is the photon isolated in? Sorry if ...