"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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Photon mass and life time

In this article, the author tried to explain that, Einstein's theory may not valid because he says "photon can decay because it may have minute amount of mass". I'm totally in a conundrum state that ...
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Do cosmologically redshifted photons violate energy conservation? [duplicate]

I understand that, due to the Doppler effect, different frames of reference moving at different velocities relative to each other will measure different photon frequencies and hence energy. The ...
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Adiabatic quantum evolution of single photon or biphoton system

The prerequisite for adiabatic quantum evolution of single photon or biphoton system is as follows. We have to prepare a single photon or biphoton quantum system which has a ground and a higher level ...
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Electromagnetic Momentum

My book says : The fact that electromagnetic radiation of energy carried momentum was known from classical theory and from the experiments of Nichols and Hull in 1903. This relation is also consistent ...
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Why does static electricity not make a charged body reflective?

If mirrors work by deflecting photons by free electrons in surface layer of mirror, so it could be possible to take a glass pane and provide it with extra free electrons by giving it massive static ...
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Is there spatial data loss in light passing through transparent crystal?

There is perfect parallelepipedal bar made of transparent crystal with cubic lattice floating in vacuum. Faces of parallelepiped are parallel to lattice axis. There is image, forming checkerboard ...
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How would it be to live in a very small universe, let´s say 20x20 square meters?

Let´s consider a curved universe that is very small, say 20 square meters and not expanding. If you stood at the middle of this tiny universe and looked forward, you wouldn´t see any walls, since it ...
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Can visible light be emitted from a non-thermal source?

I was reading about thermal and non-thermal radiation and I was wondering if visible light can be emitted from a non-thermal source?
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Slowing down light in an opaque crystal for a whole minute

I just read about a team of physicists at the University of Darmstadt, Germany, that managed to completely slow down a beam of light that traveled through an opaque crystal (article here). How is it ...
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Calculating an energy of an electron with known De Broglie wavelength (why can't we calculate it similar than we do it for a photon)

Lets say we have an electron with known De Broglie wavelength $\lambda$. Can anyone justify or explain why we calculate its energy $E$ using 1st the De Broglie relation $\lambda = h/p$ to get momentum ...
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GHz rate single photon counting

The fluorescent lifetimes of molecules used in biological applications tend to be in the sub-ns to a few ns timescale (let's say 0.8-4). The most direct methods to measure lifetimes typically involve ...
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Silicon Laser and Laser mirrors

If I will place Silicon as the active medium to create a Silicon Laser. Why I cannot achieve Lasing ? secondly, why do we always consider Laser mirrors in an standing position along the optical axis ...
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Polarization in Lasers and Liquid Crystal Displays

When we talk about Polarization in Lasers we mean placement of the crystal at Brewster angle to block the s-polarization and only the p-polarization will survive. How do we compare the term ...
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How do you build a simple low cost single photon detector?

Rather than buying a 4K-10K single photon detector, I was wondering if there were simple ways to build a simple single photon detector, of decent quality...
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Laser Transverse/Longitudnal Modes

When we say Laser transverse modes. Is that mean what we will get at the output spot of laser beam ? secondly In practice , what TEM01 or TEMnm means ?
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Energy of an EM wave compared to energy of a photon

Several posts on this forum ask the question about the role of amplitude in calculating the energy of an Em wave. This struck me as odd since I learned that E=hv. There is no amplitude in the Planck ...
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how can u split the Photon? [closed]

If any equations are there ,for split the light particle, means that i have a 1m length of light just consider that in that who can i split the light particle into 1/2 m length Pls tell
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Can a force stop a Photon since Photons have momentum and What does momentum mean when talking about massless particles?

Momentum measures how hard it is to stop an object. While Photons are massless they still have relativistic mass and energy. My question is can something stop photons other than being absorbed by ...
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Atom emitts a photon - what is the frequency of the energy of the photon?

Lets say I have an atom of known mass who goes from excited state to the ground state whose energy is $14.4 keV$ lower. I know that the emitted energy $14.4keV$ got converted into an energy of a ...
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Is it possible for a photon to be at rest? [duplicate]

I know it doesn't really make sense if looking at the photon from the wave point of view, but is there any law of physics which prohibits a photon from stopping completely? Thanks.
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Why does lightning emit light?

What exactly is causing the electric discharge coming from the clouds to emit light while traveling through the air. I've read and thought about it a little but with my current knowledge I cant really ...
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Photon propagation direction prediction possible after interacting with neutral hydrogen?

My current line of research deals a lot with hydrogen's Lyman-alpha emission and subsequent interactions of the Lyman-alpha photons with the surrounding hydrogen gas. My question is whether ...
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How does sun light after it has passed window's pane still heat me up?

I believe it is so because most of photons' energy has successfully passed the glass. But is it so? And how can I roughly estimate part of light's energy which will pass obstacles like glass? And how ...
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Do photoelectrons move fast enough to use special relativity? (+ homework)

What are the speeds of the photoelectrons which are knocked out of the metal during photoeffect? Do i have to use special relativity? I am having trouble solving a homework using relativity. But if ...
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How do individual photons make up an EM wave?

I'm trying to understand the connection between the wave model and the particle model for light. It's understood that the energy of a photon is given by E=hf, but from my understanding of fourier ...
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Can we see light as it 'interferes' with itself and produces the characteristic double-slit pattern?

This TED talk suggests that we can now watch as a beam of light propagates through a bottle filled with water. My question is: can we use this new technology to perhaps 'see' the photon as it makes ...
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Difference between $K_{\alpha}$, $K_{\beta}$ and binding energies

I'm having a small question regarding $K_{\alpha}$ and $K_{\beta}$ emissions. If I'm not mistaken this happens when there is a transition from the L shell to the K shell (Depending on the orbital), ...
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Virtual photons, what makes them virtual?

The wikipedia page "Force Carrier" says: The electromagnetic force can be described by the exchange of virtual photons. The virtual photon thing baffles me a little. I get that virtual particles ...
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Photon detection time in NMR rotating frame

I think of an NMR experiment, but with a single spin half nucleus initially set to the excited state. When the nucleus finally returns to its ground state, it will emit a photon. An observer in the ...
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Frame of reference of the photon? [duplicate]

In the frame of photon does time stop in the meaning that past future and present all happen together? If we have something with multiple outcomes which is realized viewed from such frame? Are all ...
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Can the photoelectric effect be explained without photons?

Lamb 1969 states, A misconception which most physicists acquire in their formative years is that the photoelectric effect requires the quantization of the electromagnetic field for its ...
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Why does the Sun feel hotter through a window?

I have this big window in my room that the Sun shines through every morning. When I wake up I usually notice that the Sunlight coming through my window feels hot. Much hotter than it normally does ...
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Photons: Collection of Wave Packets that produce a plane wave

Is it possible mathematically for photons, which behave as individual Gaussian wave packets, to combine in such a way that the approximate result is a plane wave at one particular frequency (i.e., the ...
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Born rule for photons: it works, but it shouldn't?

We can observe double-slit diffraction with photons, with light of such low intensity that only one photon is ever in flight at one time. On a sensitive CCD, each photon is observed at exactly one ...
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Equation for null geodesic around schwarzschild metric?

I'm trying to find the path of a photon around the Schwarzschild black hole, given its initial conditions. After much tribulation, I've basically given up on solving the equations by myself. I just ...
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How can we observe lights properties if it travels at the speed of light, or can we? [duplicate]

Special relativity says that anything moving (almost) at the speed of light will look like its internal clock has (almost) stopped from the perspective of a stationary observer. How do we see light as ...
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Discovery of $E=hf$?

How was the equation $E=hf$ discovered? Was the proportional expression between energy and frequency of light $E\propto f$ discovered only by experiment? Or is there some logical(theoretical) senses ...
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Specific energy and specific angular momentum of photon

In this PDF [1], is made reference to specific energy and angular momentum of a particle. If the particle has no mass, like a photon, how should I define these terms in the equations further down for ...
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What happens when a photon hits a beamsplitter?

Yesterday I read that we can affect the path and the 'form' (particle or wave) of a photon after the fact (Wheeler's delayed choice experiment). Part of what is puzzling me is the beam-splitter. Are ...
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Do excited electrons drop back to same quantum state?

I'm trying to wrap my head around spectroscopy, therefore, I am looking for as complete an answer as possible here, hence why I have broken the question into a different points. Here is what I know ...
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Photon Escape Angle From Black Hole

Consider a photon source emitting photons near the surface of a Schwarzschild black hole. What angle, as a function of the source's radius from the event horizon, must the photons be emitted at such ...
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If time stops at the speed of light is a photon 'everywhere' at once? [duplicate]

I am not a physicist so excuse my question if it's paticularly stupid. As a particle gets closer to the speed of light time slows down as for that particle as compared to a reference from the ...
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Why is the photon emitted in the same direction as incoming radiation in Laser?

When an atom “lases” it always gives up its energy in the same direction and phase as the incoming light. Why does this happen? How can this be explained? How does the photon generated because of ...
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Magnitude of a photon?

I encountered the following sentence in my textbook, which I don't quite understand, and after an unfruitful google search, I still can't figure out what they mean by magnitude in this context: ...
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Collision between a photon and an electron

Looking through this AP Physics question, I was struck by how the 'collision' between a photon and electron looks so much like a macroscopic collision. Is this even physically possible? Look at the ...
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How does optical phase modulation produce photons with different frequencies?

The classical description of electro-optic modulators is an index of refraction that depends on the applied voltage. For example, for a sine modulation $\sin(\Omega t)$, a monochromatic laser of ...
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Why is the Heisenberg Uncertainty Principle not obvious give the conservation of mass- energy?

A photons energy is given by $E=h *f$ and momentum $p=E/c$ (spin?) but the photon has no (rest) mass! Therefore it is the ultimate probing tool for looking at any mass position and velocity because ...
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Can we build a synthetic event horizon?

If we imagine ourselves to be a civilization capable of manipulating very heavy masses in arbitrary spatial and momentum configurations (because we have access to large amounts of motive force, for ...
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How do particles become entangled?

A person asked me this and I'm just a lowly physical chemist. I used a classical analogy (how good or bad is this and how to fix?) Basically, light has a net angular momentum of zero, insofar as ...
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Mass gap for photons

I am puzzled by the answers to the question: What is a mass gap? There, Ron Maimon's answer gives a clear-cut definition, which I suppose applies to any quantum field theory with Hamiltonian $H$, ...